Buzsáki
- Rhythms of the Brain |
|
|
Book |
Page |
|
Topic |
|
|
Buzsáki; Rhythms of the Brain |
3 |
|
Introduction |
|
|
Buzsáki; Rhythms of the Brain |
10 |
|
Self-organization is a fundamental brain operation. |
|
7 |
Buzsáki; Rhythms of the Brain |
11 |
|
Representation of external reality is a continual adjustment of the brain's self generated
patterns by outside
influences.
[recursion] [Bayesian
inference] [Llinás; brain operates as a reality emulator.] |
|
1 |
Buzsáki; Rhythms of the Brain |
11 |
|
Systems with features such as "self-organized" and "emergent" are often
called "complex." |
|
0 |
Buzsáki; Rhythms of the Brain |
11 |
|
The term "complex" does not simply mean complicated
but implies a nonlinear relationship between constituent components. As a result, very small perturbations can cause large effects or no effect at all. |
|
0 |
Buzsáki; Rhythms of the Brain |
13 |
|
Complex systems live by the rules of nonlinear
dynamics, better known is chaos theory. |
|
2 |
Buzsáki; Rhythms of the Brain |
13 |
|
Complexity
can be formally defined as nonlinearity, and from nonlinear equations,
unexpected solutions emerge. |
|
0 |
Buzsáki; Rhythms of the Brain |
13 |
|
Complex behavior of a dynamic system cannot easily
be predicted or deduced from behavior of individual lower-level entities. |
|
0 |
Buzsáki; Rhythms of the Brain |
13 |
|
Emergent order
and structure arise from the manifold interaction of numerous constituents. |
|
0 |
Buzsáki; Rhythms of the Brain |
13 |
|
Emergent self-organized dynamic, for example, a rhythm, imposes contextual constraints on its constituents, thereby restricting their degrees of freedom. |
|
0 |
Buzsáki; Rhythms of the Brain |
14 |
|
The evolution of complex systems is based upon cooperation and competition among its parts, and in the process certain
constituents gain dominance over the others. This dominance is called the "attractor" property in chaos theory. |
|
1 |
Buzsáki; Rhythms of the Brain |
14 |
|
Spontaneously organized brain
patterns |
|
0 |
Buzsáki; Rhythms of the Brain |
29 |
|
Structure defines function |
|
15 |
Buzsáki; Rhythms of the Brain |
30 |
|
Basic circuit -- hierarchy of multiple parallel loops. |
|
1 |
Buzsáki; Rhythms of the Brain |
30 |
|
A universal function of all
brains is to move the body. |
|
0 |
Buzsáki; Rhythms of the Brain |
30 |
|
Neuronal loops are the principal organization at nearly all levels, comprising a multilevel,
self-similar organization -- a fractal of loops. |
|
0 |
Buzsáki; Rhythms of the Brain |
31 |
|
Brain is
organized in a hierarchy of multiple parallel loops (diagram) |
|
1 |
Buzsáki; Rhythms of the Brain |
31 |
|
In addition to multiple parallel loops, links between lower and higher layers are
formed, generating a hierarchical form of organization among the parallel loops. |
|
0 |
Buzsáki; Rhythms of the Brain |
31 |
|
"New" brains are modified versions of older
ones, and the new
brain carries the major
features of all previous versions. |
|
0 |
Buzsáki; Rhythms of the Brain |
31 |
|
Oldest circuits of the brain are located at the bottom. Subsequently
developed levels rest in an intermediate position, while the most recently developed structures a situated on top. |
|
0 |
Buzsáki; Rhythms of the Brain |
32 |
|
In simple
brains there are few
neuronal steps between sensation and action. |
|
1 |
Buzsáki; Rhythms of the Brain |
32 |
|
An unexpected
loud noise produces a startle
reflex, which involves a sudden contraction of many of our muscles. |
|
0 |
Buzsáki; Rhythms of the Brain |
32 |
|
Sound waves in our ears may
trigger a neuronal representation of memorable musical performances. The neural
circuitry involved in this process is quite elaborate and not well understood. |
|
0 |
Buzsáki; Rhythms of the Brain |
32 |
|
The neuronal
loop connections between sensors and output are calibrated by experience so that
the actions directed by senses can be meaningful and effective. [Stereotyped motor
programs] [FAPs] |
|
0 |
Buzsáki; Rhythms of the Brain |
33 |
|
The result of a calibration-teaching process is
that from past experience the brain can calculate the
potential outcomes and convey this prediction to the effectors (e.g. skeletal muscles). [Stereotyped motor programs] [FAPs] |
|
1 |
Buzsáki; Rhythms of the Brain |
33 |
|
Human brain has about 100 billion (1011) neurons with an estimated 200 trillion (2 x 1014) contacts between them. |
|
0 |
Buzsáki; Rhythms of the Brain |
33 |
|
Although neurons are sparsely connected, they are within a few synaptic steps from all of the neurons. |
|
0 |
Buzsáki; Rhythms of the Brain |
34 |
|
Frequency bands of the various brain oscillators are relatively constant throughout mammalian evolution. |
|
1 |
Buzsáki; Rhythms of the Brain |
34 |
|
Scaling problems in brains of
various sizes. |
|
0 |
Buzsáki; Rhythms of the Brain |
35 |
|
Axons
occupy much more volume
in the brain than do the cell bodies, dendrites,
and spines combined. |
|
1 |
Buzsáki; Rhythms of the Brain |
36 |
|
Most connections among neurons are local in most brain structures. |
|
1 |
Buzsáki; Rhythms of the Brain |
37 |
|
Two organization principles -- (1) the degree of local clustering and (2) the
degree of separation between distant parts of the brain (call it synaptic
path length) -- compete
with each other. |
|
1 |
Buzsáki; Rhythms of the Brain |
37 |
|
The "optimal"
ratio of short and
long-range connections has yet to be discovered. |
|
0 |
Buzsáki; Rhythms of the Brain |
39 |
|
Connections
in scale-free networks
obey a statistical rule called the power law. |
|
2 |
Buzsáki; Rhythms of the Brain |
39 |
|
Scale-free systems are governed by Power Laws. |
|
0 |
Buzsáki; Rhythms of the Brain |
44 |
|
Cortical column diagram. |
|
5 |
Buzsáki; Rhythms of the Brain |
47 |
|
Rorschach inkblot test, developed by Hermann Rorschach. |
|
3 |
Buzsáki; Rhythms of the Brain |
53 |
|
Complexity of wiring in the
neocortex. |
|
6 |
Buzsáki;
Rhythms of the Brain |
55 |
|
Giulio Tononi, Olaf Sporns, and
Gerald Edelman from the Neurosciences Institute in La Jolla, California
searched for a structure-based metric that could objectively define "neuronal complexity,"
and capture the relationship between functional
segregation and global
integration of function in the brain. Using the concepts of statistical entropy and mutual information, they estimated
the relative statistical independence of model systems with various connectivity
structures. |
|
2 |
Buzsáki; Rhythms of the Brain |
55 |
|
Statistical independence is low
when the system constituents are either completely
independent (segregated) or completely dependent (integrated). |
|
0 |
Buzsáki; Rhythms of the Brain |
56 |
|
Complexity
reaches a maximum when
a large number of assemblies of varied sizes are combined. This
feature is a hallmark of scale-free systems, governed by a power laws. |
|
1 |
Buzsáki; Rhythms of the Brain |
61 |
|
Diversity of cortical functions is provided by inhibition. |
|
5 |
Buzsáki; Rhythms of the Brain |
62 |
|
Inhibitory networks generate nonlinear effects. |
|
1 |
Buzsáki; Rhythms of the Brain |
65 |
|
Interneurons
multiply the computational ability of principal cells. |
|
3 |
Buzsáki; Rhythms of the Brain |
65 |
|
Some interneurons do project as far as principal cells. |
|
0 |
Buzsáki; Rhythms of the Brain |
67 |
|
Interneuron
networks are the backbone of many brain oscillators. |
|
2 |
Buzsáki; Rhythms of the Brain |
67 |
|
Five main principle-cell types have distinct functional
properties. |
|
0 |
Buzsáki; Rhythms of the Brain |
67 |
|
Distinct functional properties of principle-cell types result from the unique combination of ion
channels in the membrane and from their morphological individuality. |
|
0 |
Buzsáki; Rhythms of the Brain |
68 |
|
Diversity
of cortical interneurons. |
|
1 |
Buzsáki; Rhythms of the Brain |
68 |
|
Thalamus, basal ganglia, and cerebellum have low variability in their neuron types. |
|
0 |
Buzsáki; Rhythms of the Brain |
68 |
|
Cortical structures have evolved not only five
principle-cell types but also numerous classes of GABAergic inhibitory interneurons. |
|
0 |
Buzsáki; Rhythms of the Brain |
68 |
|
Every surface
domain of cortical
principle cells is under the specific control of a unique interneuron class. |
|
0 |
Buzsáki; Rhythms of the Brain |
68 |
|
Using numerous
classes of GABAergic
inhibitory interneurons
enormously multiplies the functional repertoire of principle cells, using mostly local interneuron
wiring. |
|
0 |
Buzsáki; Rhythms of the Brain |
68 |
|
Adding novel
interneuron types, even in small numbers, offers
a nonlinear expansion of qualitatively different possibilities. |
|
0 |
Buzsáki; Rhythms of the Brain |
69 |
|
Scientific understanding of cortical interneurons has changed
dramatically in the decade spanning the year 2000. Interneurons are now understood to be a large
family of intrinsically
different cells with unexpectedly complex circuit wiring. |
|
1 |
Buzsáki; Rhythms of the Brain |
69 |
|
Different domains of principle cells have different functional dynamics. |
|
0 |
Buzsáki; Rhythms of the Brain |
70 |
|
Dendrite-targeting interneuron family displays the largest
variability. |
|
1 |
Buzsáki; Rhythms of the Brain |
70 |
|
Interneurons
also innervate each other by an elaborate scheme and affect each other's biophysical
properties. |
|
0 |
Buzsáki; Rhythms of the Brain |
70 |
|
Long-range interneurons -- axon trees span two or more anatomical
regions, some axon
collaterals cross the hemispheric
midline and/or innervate subcortical structures. |
|
0 |
Buzsáki; Rhythms of the Brain |
70 |
|
Long-range interneurons with distant clouds of terminal
boutons are separated by myelinated axon collaterals that
provide fast conduction speed for temporal synchrony of all terminals. |
|
0 |
Buzsáki; Rhythms of the Brain |
70 |
|
Widely-projecting, long-range interneurons are rare. |
|
0 |
Buzsáki; Rhythms of the Brain |
71 |
|
Long-range interneurons provide the necessary conduit for synchronizing distantly operating oscillators
and allow for coherent timing of large numbers of neurons that are not directly connected with each other. |
|
1 |
Buzsáki; Rhythms of the Brain |
71 |
|
The axons of some interneurons avoid principle cells and contract exclusively
other interneurons. |
|
0 |
Buzsáki; Rhythms of the Brain |
71 |
|
Existence of interneuron-specific
interneurons provides support for a unique organization of the inhibitory system. |
|
0 |
Buzsáki; Rhythms of the Brain |
71 |
|
Interneuron-specific family also
overlaps with the long-range interneuron subclass, emphasizing the importance
of interregional synchronization of inhibition, and consequent coherent
oscillatory entrainment of their target principle-cell populations. |
|
0 |
Buzsáki; Rhythms of the Brain |
75 |
|
Because interneurons connected by GABAA receptors are ubiquitous throughout the brain, gamma
frequency oscillation can arise in almost every structure. |
|
4 |
Buzsáki;
Rhythms of the Brain |
75 |
|
In "gamma
clocks," no single neuron is responsible for
initiating or maintaining the oscillation, yet all
of the neurons contribute to the rhythm whenever
they fire. The responsibilities are
distributed, and the result depends on cooperation. Once a collective
pattern arises, it constrains
the timing of the action potentials of the individual cells because of the collectively generated inhibition. |
|
0 |
Buzsáki; Rhythms of the Brain |
75 |
|
In gamma
clocks, firing and connectivity are essential,
but the exact wiring
is not critical as
long as enough convergence and divergence are present. |
|
0 |
Buzsáki; Rhythms of the Brain |
77 |
|
The least
numerous cells belong to the long-range interneuron family |
|
2 |
Buzsáki; Rhythms of the Brain |
78 |
|
Synaptic path length and, consequently, synaptic and
conduction delays become
excessively long for synchronization in larger networks. |
|
1 |
Buzsáki; Rhythms of the Brain |
78 |
|
Long-range interneurons connect local interneurons residing in different cortical
regions. |
|
0 |
Buzsáki; Rhythms of the Brain |
78 |
|
The same
physiological function in different-sized mammalian brains is
supported by circuits with different compositions of neuronal proportions and connectivity. |
|
0 |
Buzsáki; Rhythms of the Brain |
79 |
|
Balance
between excitation and
inhibition is often
accompanied by oscillations. |
|
1 |
Buzsáki; Rhythms of the Brain |
79 |
|
Connections
among interneurons,
including electrical gap
junctions, are especially suitable for
maintaining clocking actions. |
|
0 |
Buzsáki; Rhythms of the Brain |
79 |
|
Cerebral cortex is not only a complex system with complicated
interactions among
identical constituents but also has developed a diverse system of components. |
|
0 |
Buzsáki; Rhythms of the Brain |
80 |
|
Windows on the Brain |
|
1 |
Buzsáki; Rhythms of the Brain |
81 |
|
Recording EEG
traces from a few sites is sufficient to
determine whether the brain is alive or dead or whether it is the sleeping or
awake. |
|
1 |
Buzsáki; Rhythms of the Brain |
81 |
|
Scalp electrodes placed too close together will sense pretty much the same electrical fields. |
|
0 |
Buzsáki; Rhythms of the Brain |
81 |
|
In contrast to the excellent temporal resolution, scalp recording EEG methods have serious spatial resolution problems. |
|
0 |
Buzsáki; Rhythms of the Brain |
84 |
|
Magnetoencephalography |
|
3 |
Buzsáki; Rhythms of the Brain |
84 |
|
The magnetic
fields that emanate from the brain are only one 100
millionth to one billionth of the strength of the Earth's
magnetic field. |
|
0 |
Buzsáki; Rhythms of the Brain |
84 |
|
The sensor that can detect the weak magnetic
signals emanating from the brain is known as a SQUID (superconducting quantum
interference device), operating at a temperature of -270° C. |
|
0 |
Buzsáki; Rhythms of the Brain |
84 |
|
Liquid helium
in the SQUID cools the
coils to superconducting temperatures. |
|
0 |
Buzsáki; Rhythms of the Brain |
84 |
|
For magnetoencephalography, need many sensors around the head to increase spatial
resolution. |
|
0 |
Buzsáki; Rhythms of the Brain |
84 |
|
For magnetoencephalography, detector coils are placed as close to each other as
possible, forming a spherical honeycomb-like
pattern concentric with the head. |
|
0 |
Buzsáki; Rhythms of the Brain |
84 |
|
Magnetoencephalographic (MEG) signal reflects mostly intracellular currents. |
|
0 |
Buzsáki; Rhythms of the Brain |
84 |
|
Spatial resolution of MEG is better than EEG mainly because the magnetic fields are not scattered and
distorted by inhomogeneities in the skull and scalp. |
|
0 |
Buzsáki; Rhythms of the Brain |
86 |
|
Neurons Communicate with Spikes |
|
2 |
Buzsáki; Rhythms of the Brain |
88 |
|
Synaptic Potentials |
|
2 |
Buzsáki; Rhythms of the Brain |
89 |
|
Extracellular Currents |
|
1 |
Buzsáki; Rhythms of the Brain |
92 |
|
Functional Magnetic Resonance
Imaging (fMRI) |
|
3 |
Buzsáki; Rhythms of the Brain |
94 |
|
Positron Emission Tomography
(PET) |
|
2 |
Buzsáki; Rhythms of the Brain |
99 |
|
Triangulation of Neurons by
Tetrodes |
|
5 |
Buzsáki; Rhythms of the Brain |
107 |
|
Forms of Oscillatory Synchrony |
|
8 |
Buzsáki; Rhythms of the Brain |
111 |
|
A System of Rhythms -- From
Simple to Complex Dynamics |
|
4 |
Buzsáki; Rhythms of the Brain |
111 |
|
Not all neurons and connections are used all the time. The dynamically changing functional or effective connectivity gives rise to short lived
oscillations that are perpetually
created and destroyed by the brain's internal dynamics. |
|
0 |
Buzsáki; Rhythms of the Brain |
111 |
|
Brain dynamics constantly shift from the complex to the predictable. Neuronal ensemble activity shuttle back and
forth between the interference-prone complexity and robust predictable oscillatory
synchrony. |
|
0 |
Buzsáki; Rhythms of the Brain |
111 |
|
Systems of Rhythms – from simple to complex dynamics |
|
0 |
Buzsáki; Rhythms of the Brain |
112 |
|
Oscillations
have been documented in the brains of numerous mammalian
species, ranging from very slow oscillations with
periods of minutes to
very fast oscillations with frequencies reaching 600
Hz. |
|
1 |
Buzsáki; Rhythms of the Brain |
112 |
|
Frequency coverage of the traditional bands was confined by
the EEG recording technology. |
|
0 |
Buzsáki; Rhythms of the Brain |
112 |
|
Hippocampal theta oscillation was discovered in the anesthetized rabbit. |
|
0 |
Buzsáki; Rhythms of the Brain |
112 |
|
The exact
mechanisms of most brain
oscillations are not
known. |
|
0 |
Buzsáki;
Rhythms of the Brain |
113 |
|
Relationship among three hippocampal rhythms observed in the rat -- theta
(4 -- 10 Hz) and gamma (30 -- 80 Hz) rhythms and fast oscillation (140 -- 200 Hz). These rhythms are
independently generated, because the gamma
oscillations persist without theta oscillations and compete with the fast
oscillation. |
|
1 |
Buzsáki; Rhythms of the Brain |
113 |
|
The theta,
gamma, and fast
oscillation relate to each other on a natural logarithmic scale. |
|
0 |
Buzsáki; Rhythms of the Brain |
113 |
|
Discrete oscillation bands form
a geometric progression on a linear frequency scale and a linear progression on a natural logarithmic scale. |
|
0 |
Buzsáki; Rhythms of the Brain |
113 |
|
All frequencies from 0.02 Hz to 600 Hz are continuously present, covering more than four orders of
magnitude of temporal scale. |
|
0 |
Buzsáki; Rhythms of the Brain |
113 |
|
At least 10
postulated distinct mechanisms are required to cover the large frequency range. |
|
0 |
Buzsáki; Rhythms of the Brain |
113 |
|
Because a single structure does
not normally generate all oscillatory classes, structures
must cooperate to
cover all frequencies. |
|
0 |
Buzsáki; Rhythms of the Brain |
113 |
|
Different mechanisms in
different brain structures can give rise to the same oscillatory band, but
there should be at least one distinct mechanism for each oscillation class. |
|
0 |
Buzsáki; Rhythms of the Brain |
113 |
|
There is a definable
relationship among all the brain oscillators -- a geometrical progression of mean frequencies from band to band with a roughly constant
ratio of e = 2.17 -- the base for the natural
logarithm. |
|
0 |
Buzsáki; Rhythms of the Brain |
113 |
|
Sinse e is an irrational number, the phase of coupled oscillators of the various bands will vary on
each cycle forever, resulting in a nonrepeating, quasi-periodic weakly chaotic pattern -- this is the main characteristic
of the EEG. |
|
0 |
Buzsáki; Rhythms of the Brain |
115 |
|
A number of psychological
phenomena argue in favor of the idea that cognitive events require hierarchical processing. Separate processing requires the engagement
of neuronal networks
and multiple spatial scales. |
|
2 |
Buzsáki; Rhythms of the Brain |
115 |
|
Each oscillatory cycle is a temporal processing window. |
|
0 |
Buzsáki; Rhythms of the Brain |
115 |
|
The brain
does not operate continuously but discontiguously, using temporal packages or quanta. |
|
0 |
Buzsáki; Rhythms of the Brain |
115 |
|
Networks with cycles have orders of magnitude larger
capabilities than networks without cycles (e.g. a
feedforward net) |
|
0 |
Buzsáki; Rhythms of the Brain |
115 |
|
The wavelength of the oscillatory category determines the temporal windows of
processing, and, indirectly, the size of the neuronal pool
involved. |
|
0 |
Buzsáki; Rhythms of the Brain |
115 |
|
In general,
slow oscillators can
involve many neurons in large
brain areas, whereas the short time windows of fast oscillators facilitate local integration, largely because of the limitations of the axon conduction delays. |
|
0 |
Buzsáki; Rhythms of the Brain |
119 |
|
Brain oscillators should be considered as a system of oscillators with an intricate relationship between the various rhythmic components. |
|
4 |
Buzsáki; Rhythms of the Brain |
119 |
|
Synaptic activity in the brain can lead to a complex
system organized at
multiple timescales. |
|
0 |
Buzsáki; Rhythms of the Brain |
119 |
|
Slow rhythms
involve very large numbers of cells and can be "heard" over
a long distance, whereas localized fast oscillations
involving only a small fraction of neurons may be conveyed only to a few partners. |
|
0 |
Buzsáki; Rhythms of the Brain |
119 |
|
Power spectrum of the EEG is a straight line on a log-log
plot, the hallmark of scale-free
systems (i.e. systems that obey power laws) |
|
0 |
Buzsáki; Rhythms of the Brain |
119 |
|
The amplitude of the EEG power spectrum increases as
the frequency decreases. This inverse
relationship is expressed as the "one over f" power
spectrum (also called "pink"
noise). |
|
0 |
Buzsáki; Rhythms of the Brain |
120 |
|
A critical aspect of brain oscillators is that the mean frequencies of the neighboring oscillatory families
are not integers of each other. Adjacent bands
cannot simply lockstep because the prerequisite
for stable temporal locking is phase synchronization. |
|
1 |
Buzsáki;
Rhythms of the Brain |
120 |
|
The 2.17
ratio between adjacent
oscillators can give rise only to transient or metastable dynamics, a
state of perpetual fluctuation between unstable and transient phase synchrony, as long as the individual
oscillators can maintain
their independence and do not succumb to the duty cycle influence of a strong oscillator. |
|
0 |
Buzsáki; Rhythms of the Brain |
120 |
|
Multiple oscillators that perpetually engage and disengage each other. |
|
0 |
Buzsáki; Rhythms of the Brain |
120 |
|
Locally emerging stable
oscillators in the cerebral cortex are constantly being pushed and pulled by the global dynamics. |
|
0 |
Buzsáki; Rhythms of the Brain |
120 |
|
Despite the chaotic
dynamics of the transient
coupling of the oscillators at multiple spatial scales, a unified system with multiple time scales emerges. |
|
0 |
Buzsáki; Rhythms of the Brain |
121 |
|
The inverse
relationship between
frequency and its power is an indication that
there is a temporal relationship between
frequencies -- perturbations
of slow frequencies cause a cascade of energy dissipation at all frequency scales. |
|
1 |
Buzsáki; Rhythms of the Brain |
121 |
|
Long-term scalp recordings confirm power-law scaling behavior for all frequencies tested and expand
the temporal scale of the 1/f line beyond a
minute. |
|
0 |
Buzsáki; Rhythms of the Brain |
121 |
|
An alpha
wave at this instant in your occipital cortex can
influence the amplitude
of another alpha wave
a thousand cycles later
and all waves in between. |
|
0 |
Buzsáki; Rhythms of the Brain |
121 |
|
The scale-invariant
feature of the EEG is the mathematical telltale sign of self-organization. |
|
0 |
Buzsáki; Rhythms of the Brain |
121 |
|
The speed at which the power decreases from low to high frequencies measures the length of the
correlations or, using another phrase, the "temporal memory effects"
of the signal. |
|
0 |
Buzsáki; Rhythms of the Brain |
121 |
|
If there were
no relationship among
the frequency bands, the power density would be
constant over a finite frequency range, and the spectrum would be flat -- 1/f0. Physicists call this pattern "white noise." |
|
0 |
Buzsáki; Rhythms of the Brain |
121 |
|
Brownian motion -- "brown noise," the power density decreases much
faster with frequency (1/f2) than is the case for pink
noise. Brown
noise is random at
longer intervals but is easily
predictable and strongly
correlated at short
intervals. |
|
0 |
Buzsáki; Rhythms of the Brain |
122 |
|
The cerebral
cortex with its most
complex architecture generates the most complex noise known to
physics. |
|
1 |
Buzsáki; Rhythms of the Brain |
122 |
|
Brain oscillators are not independent. The same elements, neurons, and neuronal pools are responsible for all rhythms. |
|
0 |
Buzsáki; Rhythms of the Brain |
122 |
|
When brain
rhythm is fast, only small groups can follow the beat perfectly, because of the
limitations of axon conductance and synaptic delays. |
|
0 |
Buzsáki; Rhythms of the Brain |
122 |
|
Slow oscillations, spanning numerous axon conduction
delay periods, allow the recruitment of very large numbers of neurons. |
|
0 |
Buzsáki; Rhythms of the Brain |
122 |
|
The slower
the oscillation, the more
neurons can participate. |
|
0 |
Buzsáki; Rhythms of the Brain |
122 |
|
With local
connections only, an emerging
rhythm at one place would aggressively invade neighboring territories, resulting in traveling waves. |
|
0 |
Buzsáki; Rhythms of the Brain |
122 |
|
When rhythms
emerge simultaneously in several locations, they might be synchronized by the intermediate and long-range connections. |
|
0 |
Buzsáki; Rhythms of the Brain |
122 |
|
The inevitable delays and the time-limited recruitment of neuronal pools can account for a
good part of the 1/f functionality. |
|
0 |
Buzsáki; Rhythms of the Brain |
123 |
|
The firing
patterns of single cells depend not only on on
their instantaneous external inputs but also on the history of their
firing patterns and the state of the network in which they
are embedded. |
|
1 |
Buzsáki; Rhythms of the Brain |
123 |
|
The power
(loudness) fluctuations of brain generated and perceived sounds, like music and speech, and numerous other time related
behaviors, exhibit 1/f
power spectra. |
|
0 |
Buzsáki; Rhythms of the Brain |
123 |
|
Perhaps what makes music fundamentally different from (white) noise for the listener is that music has temporal
patterns that are tuned to the brain's ability to detect them,
because it is another brain (the composer) that generates
these patterns. |
|
0 |
Buzsáki; Rhythms of the Brain |
123 |
|
The long-time and large-scale note structure of Bach's First Brandenburg
Concerto is quite
similar to the latest
hit played by rock station or to Scott Joplin's Piano Rags. |
|
0 |
Buzsáki; Rhythms of the Brain |
123 |
|
High temporal predictability, such as the sound of dripping
water, and the total lack of predictability, such as John Cage's stochastic music
(essentially white noise)
are quite annoying to
most people. |
|
0 |
Buzsáki; Rhythms of the Brain |
123 |
|
If self-generated brain dynamics have
a link to the spectral composition of speech and music, one might expect that the same
dynamics would influence a plethora of other behaviors. |
|
0 |
Buzsáki; Rhythms of the Brain |
123 |
|
Dynamics of cortical patterns in all mammals exhibit 1/f spectra. |
|
0 |
Buzsáki; Rhythms of the Brain |
126 |
|
Fractal Nature
of EEG |
|
3 |
Buzsáki; Rhythms of the Brain |
126 |
|
The spectral
content and frequency
bands of the human EEG and electrocardiogram are remarkably similar to those of mice, rats, guinea pigs, rabbits, cats, dolls,
and monkeys. |
|
0 |
Buzsáki; Rhythms of the Brain |
126 |
|
The long-term
temporal structure of the macroscopic neuronal signal,
reflecting the collective behavior of neurons that give rise to it, is macroscopically
similar in virtually
all cortical structures and in brains of various mammalian species. |
|
0 |
Buzsáki; Rhythms of the Brain |
126 |
|
A collective pattern
recorded from a small portion of the cortex looks like the pattern recorded from the whole. This "scale
invariance" or "self-similarity" is a decisive characteristic of fractals. |
|
0 |
Buzsáki; Rhythms of the Brain |
126 |
|
Fractal dynamic processes -- such as pink noise -- are self-similar in that any
piece of the fractal design contains a miniature of the entire design. |
|
0 |
Buzsáki; Rhythms of the Brain |
127 |
|
Macroscopic EEG and EEG patterns describe the large-scale functions of neuronal
networks as a unified whole,.
independent of the details of the dynamic
processes governing the subunits that make up the whole. |
|
1 |
Buzsáki; Rhythms of the Brain |
127 |
|
The concept that physical
systems, made up of a large
number of interacting subunits, obey universal laws that are independent of the microscopic details is a relatively
recent breakthrough in statistical physics. |
|
0 |
Buzsáki; Rhythms of the Brain |
127 |
|
The scale
freedom of spatial and temporal dynamics in the cortex has emerged as a useful direction of research. |
|
0 |
Buzsáki; Rhythms of the Brain |
127 |
|
The seductively simple 1/fα function is, in fact, very
complex. Every
new computation takes into consideration the entire past history of the system.
[Recursion] [Bayesian inference] |
|
0 |
Buzsáki; Rhythms of the Brain |
127 |
|
The response of a neuron depends on
the immediate discharge
history of the neuron and the long-term history of the connectivity of the network in
which it is embedded. |
|
0 |
Buzsáki; Rhythms of the Brain |
127 |
|
Even a weak
transient local perturbation can invade large parts of the network
and have a long-lasting effect, whereas myriads of other inputs remain ignored. |
|
0 |
Buzsáki; Rhythms of the Brain |
127 |
|
Although neuronal
networks of the brain are in perpetual flux, due to their
time-dependent state changes, the firing patterns
of neurons are constrained by the past history of the network. Complex networks have memory. |
|
0 |
Buzsáki; Rhythms of the Brain |
134 |
|
Most oscillations are transient but last long enough to provide stability for holding
and comparing information at linear time scales. |
|
7 |
Buzsáki; Rhythms of the Brain |
135 |
|
Scale-free dynamics generate complexity, whereas oscillations allow for temporal predictions. |
|
1 |
Buzsáki; Rhythms of the Brain |
135 |
|
Order in the brain does not
emerge from disorder. Instead, transient order emerges from halfway between order and disorder,
from the territory of complexity. |
|
0 |
Buzsáki; Rhythms of the Brain |
135 |
|
The dynamics in the cerebral cortex constantly alternate between the most complex metastable state and the highly predictable oscillatory state. |
|
0 |
Buzsáki; Rhythms of the Brain |
135 |
|
Neural networks can shift quickly from a highly
complex state to act as predictive coherent units due to the deterministic nature of the oscillatory order. |
|
0 |
Buzsáki; Rhythms of the Brain |
136 |
|
Synchronization by Oscillation |
|
1 |
Buzsáki; Rhythms of the Brain |
159 |
|
Hebb's cell assembly is a transient coalition of
neurons, much like the dynamic
interactions among jazz
musicians. |
|
23 |
Buzsáki; Rhythms of the Brain |
159 |
|
Information reverberates within the assembly, and the direction
of flow is determined by the synaptic strengths. |
|
0 |
Buzsáki; Rhythms of the Brain |
159 |
|
Hebb
believed that activity reverberates in loops of synaptically connected
chains of neurons. |
|
0 |
Buzsáki; Rhythms of the Brain |
159 |
|
The reverberation explains why activity can outlast the physical presence of an input
signal. |
|
0 |
Buzsáki; Rhythms of the Brain |
160 |
|
In the cell recordings of behaving rats, the receptive fields of hippocampal neurons are
characterized by the animal's position in the
environment. |
|
1 |
Buzsáki; Rhythms of the Brain |
163 |
|
For a hippocampal
population of neurons, the optimal window for cell assembly was found to be between 10 and 30 ms. This time scale may
be of particular functional significance because many physiological
variables share this time window. |
|
3 |
Buzsáki; Rhythms of the Brain |
163 |
|
The time
constant of pyramidal
cells is perhaps most important, because this is
the window that determines a cell's integration
ability. |
|
0 |
Buzsáki; Rhythms of the Brain |
163 |
|
The cell
assembly time-window also matches the time period of gamma frequency oscillations. |
|
0 |
Buzsáki; Rhythms of the Brain |
163 |
|
We can conclude that cell assemblies are synchronized within the time window of gamma oscillation, because this allows an assembly to exert the largest possible
impact on their downstream
targets. |
|
0 |
Buzsáki; Rhythms of the Brain |
163 |
|
Duration of excitatory
postsynaptic potentials in pyramidal cells in vivo is also in the 10 -- 30 ms range. |
|
0 |
Buzsáki; Rhythms of the Brain |
163 |
|
The 10 -- 30
ms range temporal
window is most critical for spike-timing dependent plasticity
of synapses. |
|
0 |
Buzsáki; Rhythms of the Brain |
175 |
|
Rest and sleep are the best examples of self-organized operations within neuronal
circuits and systems. |
|
12 |
Buzsáki; Rhythms of the Brain |
175 |
|
Default State – Self Organized
Oscillation |
|
0 |
Buzsáki; Rhythms of the Brain |
176 |
|
Sleep is an
excellent model of evolving brains states because it occurs without outside influence -- evolves from within. |
|
1 |
Buzsáki; Rhythms of the Brain |
176 |
|
Virtually every psychiatric ailment is associated with some kind of alteration of sleep duration and pattern. |
|
0 |
Buzsáki; Rhythms of the Brain |
176 |
|
Thalamus -- A Partner for
Neocortex |
|
0 |
Buzsáki; Rhythms of the Brain |
176 |
|
In large systems with complex connectivity, it is often difficult to draw boundaries. This is the case with in neocortical mantle, with its myriads of cortical modules and high density local
connectivity, supplied by neurons whose biophysical features do not vary greatly across the cortex. |
|
0 |
Buzsáki; Rhythms of the Brain |
177 |
|
A very large part of the thalamocortical circuits do not
have much to do with the primary sensory
information. |
|
1 |
Buzsáki; Rhythms of the Brain |
177 |
|
There are important inputs to the thalamocortical
circuits from the cerebellum and the basal ganglia, but the bulk of the afferents are supplied by the neocortex. |
|
0 |
Buzsáki; Rhythms of the Brain |
177 |
|
Clustering
of long-range connections provide some anatomical clues for subdivisions of the neo-cortex
and justifies designations of cortical systems as
visual, auditory, somatosensory, motor, language-related, spatial, or other. |
|
0 |
Buzsáki; Rhythms of the Brain |
177 |
|
Further segregation of neocortical functions as well is integration of information across the distant regions derives from the main afferent
and efferent expansion -- the thalamus. |
|
0 |
Buzsáki; Rhythms of the Brain |
177 |
|
The thalamus is a football-shaped structure located in the origin of the two neocortical hemispheres, like the central atom of the large molecule. |
|
0 |
Buzsáki; Rhythms of the Brain |
177 |
|
The function of the thalamus
geometrical arrangement could be that being equidistant from all cortical areas demands the least length of reciprocal wiring and provides the fastest axonal communication. |
|
0 |
Buzsáki; Rhythms of the Brain |
177 |
|
A very large part of the thalamocortical circuits do not have much to do with primary
sensory information. There are important inputs from the cerebellum and the basal ganglia, but the bulk of the afferents are supplied
by the neocortex. |
|
0 |
Buzsáki; Rhythms of the Brain |
178 |
|
The importance of the cortical feedback to the thalamus is best illustrated by
the fact that the thalamus is the only corticofugal target of the layer 6 pyramidal cell
population, and these neurons innervate
virtually all thalamic nuclei. |
|
1 |
Buzsáki; Rhythms of the Brain |
178 |
|
Collaterals of layer 5 pyramidal cells, whose fast-conducting main axons are
destined for the brainstem, target those thalamic nuclei that did
not receive primary sensory or motor information. |
|
0 |
Buzsáki; Rhythms of the Brain |
178 |
|
Thalamocortical circuits are associated with thalamic divisions "higher order" nuclei, as
opposed to the "first-order" nuclei with specific sensory motor
information. |
|
0 |
Buzsáki; Rhythms of the Brain |
178 |
|
Afferents
from higher-order cortical nuclei send widespread projections to cortical areas, disseminating their
thalamocortical information via extensive axon harbors and larger cortical coverage. |
|
0 |
Buzsáki; Rhythms of the Brain |
179 |
|
The pattern of thalamic connectivity coevolved with the neocortex. |
|
1 |
Buzsáki; Rhythms of the Brain |
179 |
|
The number of
thalamocortical neurons
in the mouse is only 1/10 the number of target neurons in the cortex, where is in the human brain to ratio is less than 1/1000. |
|
0 |
Buzsáki; Rhythms of the Brain |
179 |
|
In partnership with the cortex, the reciprocal excitatory connections of the thalamus are prone to oscillation, and such a mechanism
is perfectly poised to mix thalamocortical information. |
|
0 |
Buzsáki; Rhythms of the Brain |
179 |
|
Cytoarchitectural organization of the thalamus is unique. Most GABAergic interneurons in the thalamus reside in the thin shell
surrounding the thalamic chamber, call the reticular
nucleus, and some other
subcortical nuclei. |
|
0 |
Buzsáki; Rhythms of the Brain |
180 |
|
Rudolfo Llinás and colleagues (1984) discovered that some neuron types, such
as thalamocortical cells,
can be discharged not
only by excitation but
also by releasing the neuron from inhibition, releasing a "burst" of spikes at
intervals of 3 -- 5 ms. |
|
1 |
Buzsáki;
Rhythms of the Brain |
181 |
|
Thalamocortical cells can fire in two qualitatively
different ways. -- (1) Depolarization can induce rhythmic single spikes, similar to
those observed in neocortical pyramidal cells. (2) When released from hyperpolarization, the slow calcium spike is depolarizing and lasts for tens of milliseconds, typically with a series of fast
spikes riding on it. |
|
1 |
Buzsáki; Rhythms of the Brain |
181 |
|
Every thalamocortical
neuron can be converted into a delta frequency clock when properly hyperpolarized. |
|
0 |
Buzsáki; Rhythms of the Brain |
182 |
|
Single-cell Oscillation in a
Thalamocortical Neuron (diagram) |
|
1 |
Buzsáki; Rhythms of the Brain |
183 |
|
Brain evolution adopted a channel from the heart just to sustain oscillations during
sleep. |
|
1 |
Buzsáki; Rhythms of the Brain |
183 |
|
When coordinated across multiple thalamocortical
neurons, the single-cell
properties can provide a delta-frequency pacing of their cortical targets. |
|
0 |
Buzsáki; Rhythms of the Brain |
183 |
|
Inhibition-induced rebound
spikes are not elicited by
any specific sensory input. Because they are
triggered by inhibition, they are prime examples
of self-generated
spike patterns that communicate to downstream neurons
primarily determined by the state of the thalamic
network. |
|
0 |
Buzsáki; Rhythms of the Brain |
183 |
|
Reticular neurons are similar to thalamocortical
cells; however, reticular
neurons are not
critical players in delta oscillations. |
|
0 |
Buzsáki; Rhythms of the Brain |
184 |
|
Numerous rhythms have been described in a resting sleeping thalamocortical system,
including alpha waves (8 -- 12 Hz), mu rhythm (8
-- 12 Hz), sleep spindles (10 -- 20 Hz) and
associated ultrahigh frequency oscillations (300
-- 600 Hz), delta waves (1 -- 4 Hz), and slow 1 to 4 slow rhythms (0.05 -- 1 Hz). |
|
1 |
Buzsáki;
Rhythms of the Brain |
184 |
|
A common feature of all
self-governed thalamocortical
oscillations is that
they bring about constraints regarding whether and when information about the outside world, detected
by the peripheral senses,
can pass through the thalamus and be distributed for further processing
in cortical networks or is ignored outright. |
|
0 |
Buzsáki; Rhythms of the Brain |
185 |
|
At sleep
onset, subcortical neurons, releasing acetylcholine, serotonin, norepinephrine, and histamine, decrease their firing rates. So do specific
thalamic afferents and primary
sensory cortical neurons. |
|
1 |
Buzsáki; Rhythms of the Brain |
185 |
|
Generally, slower
frequencies involve more
extensive synchronous
activation of the neuronal
pool. |
|
0 |
Buzsáki; Rhythms of the Brain |
185 |
|
In contrast to the rigid
interarea corticocortical connections, with progressively increasing axon conduction delays, the transthalamic "shortcuts" are nearly
equidistant from all
neocortical areas. |
|
0 |
Buzsáki; Rhythms of the Brain |
185 |
|
With the thalamus as a matchmaker, the effective connectivity between local neocortical populations can
be changed according
to current computational needs. |
|
0 |
Buzsáki; Rhythms of the Brain |
185 |
|
The key ingredient in the cortical globalization process is the ability of the oscillatory
mechanisms to recruit anatomically distant cortical
neurons into temporal
coalitions. |
|
0 |
Buzsáki; Rhythms of the Brain |
185 |
|
In addition to the long-range connections among the various cortical regions, the thalamus provides additional radial "shortcuts"
necessary for reducing
the synaptic path lengths between the various cortical
areas. |
|
0 |
Buzsáki; Rhythms of the Brain |
185 |
|
Weak connections can be amplified by phase modulation, due to the resonant properties of the thalamic and cortical
modules involved. |
|
0 |
Buzsáki; Rhythms of the Brain |
185 |
|
Modules with resonant
relations between
their frequencies can exchange
information more easily than modules with nonoscillating properties or dissimilar frequencies. |
|
0 |
Buzsáki; Rhythms of the Brain |
186 |
|
The thalamus is no longer viewed as a gigantic
array of independent relays, but as a large communication hub that
assists in linking large cortical areas in a flexible manner. The principal
mechanism of the cortical-thalamic-cortical flow of activity is self-sustained
oscillations. |
|
1 |
Buzsáki; Rhythms of the Brain |
186 |
|
Oscillatory Patterns of Sleep |
|
0 |
Buzsáki; Rhythms of the Brain |
187 |
|
Unlike most body parts, the brain is busy at night. |
|
1 |
Buzsáki; Rhythms of the Brain |
187 |
|
In humans, at least five stages of sleep with progressively higher wakening
thresholds can be distinguished, with the deepest stage being a rapid eye movement (REM) phase. |
|
0 |
Buzsáki; Rhythms of the Brain |
187 |
|
Separation of the first four stages of sleep, known
collectively as non-REM sleep, is based mostly on the relative number of sleep spindles and delta waves. |
|
0 |
Buzsáki; Rhythms of the Brain |
187 |
|
Stage one is the phase transition between wake and
sleep. |
|
0 |
Buzsáki; Rhythms of the Brain |
187 |
|
Stage two is heralded by the
emergence of sleep spindles. |
|
0 |
Buzsáki; Rhythms of the Brain |
187 |
|
Stage three is a mixture of spindles and delta waves. |
|
0 |
Buzsáki; Rhythms of the Brain |
187 |
|
Stage four is characterized by
the dominance of delta activity with only
traces of spindles. |
|
0 |
Buzsáki; Rhythms of the Brain |
187 |
|
Approximately half
of sleep consists of stages
2 and 3, stage 4 composes only 5 --15 percent of
total sleep time and may be completely missing after 40 years of age. |
|
0 |
Buzsáki; Rhythms of the Brain |
187 |
|
Stages 3 and 4 are often referred to as slow
wave or delta sleep. |
|
0 |
Buzsáki; Rhythms of the Brain |
187 |
|
Stage 5, REM
sleep, is characterized by a waking-type EEG, rapid eye movements, loss of muscle tone, and dreaming. |
|
0 |
Buzsáki; Rhythms of the Brain |
187 |
|
REM sleep
composes usually 20 -- 25% of total sleep time in humans adults, and is an indication of the end of a non-REM/REM sleep cycle. |
|
0 |
Buzsáki; Rhythms of the Brain |
187 |
|
Typically, four or five non-REM/REM cycles with a period of 70 -- 90 minutes each,
occur within a night. |
|
0 |
Buzsáki; Rhythms of the Brain |
188 |
|
Sleep spindles are the hallmark of natural non-REM
sleep. |
|
1 |
Buzsáki; Rhythms of the Brain |
189 |
|
All that is needed for the emergence of oscillation is a seed of enough synchrony so that some reticular neurons discharge,
preferably a synchronous burst of spikes. |
|
1 |
Buzsáki; Rhythms of the Brain |
189 |
|
Discharging reticular
cells hyperpolarize the same and more thalamocortical neurons because
their axon collaterals diverge onto many thalamocortical neurons. |
|
0 |
Buzsáki; Rhythms of the Brain |
194 |
|
Recurrent and lateral excitation is the main mechanism through which excitation
can spread.
This process takes time, given the low velocity of axon conductance. |
|
5 |
Buzsáki; Rhythms of the Brain |
195 |
|
Origin of Delta Waves |
|
1 |
Buzsáki; Rhythms of the Brain |
200 |
|
Origin of Alpha
Rhythms |
|
5 |
Buzsáki; Rhythms of the Brain |
201 |
|
Occipital alpha rhythm is prominent in animals with saccadic
eye movements, large visual cortex, and binocular frontal vision, but is
virtually absent in the rat and other nocturnal species. |
|
1 |
Buzsáki; Rhythms of the Brain |
202 |
|
In contrast to vision, rodents have an elaborate somatosensory representation. The face whisker system has an orderly and large representation in
both the thalamus and
the sensory cortex. |
|
1 |
Buzsáki; Rhythms of the Brain |
203 |
|
Occipital alpha and auditory cortical tau
oscillations may arise as a result of complex interaction between the GABAergic thalamic neurons and thalamocortical neurons combined
with neocortical amplification of the thalamic signals. |
|
1 |
Buzsáki; Rhythms of the Brain |
203 |
|
The extent
of alpha oscillations
is an indication of the cortical disengagement from inputs of the body and the environment. |
|
0 |
Buzsáki; Rhythms of the Brain |
203 |
|
The alpha
peak in the human scalp EEG power spectrum is prominent under virtually all waking conditions, not only
when eyes are closed
and muscles are relaxed,
although these conditions robustly increase the power in alpha band. |
|
0 |
Buzsáki; Rhythms of the Brain |
204 |
|
Sleep and rest-associated oscillations are
the best examples of self-organized operations in the brain. |
|
1 |
Buzsáki; Rhythms of the Brain |
205 |
|
The thalamus is a hub
for the neocortex that provides functional shortcuts between the
vast areas of the cerebral hemispheres and reduces
the synaptic pathways between various cortical areas. |
|
1 |
Buzsáki; Rhythms of the Brain |
205 |
|
Both the excitatory thalamocortical and the inhibitory neurons of the reticular nucleus are endowed with various intrinsic conductances, which
promote oscillations
at various temporal
and spatial scales. |
|
0 |
Buzsáki; Rhythms of the Brain |
205 |
|
First-order and higher order
nuclei of the thalamus have reciprocal relationships with sensory and
associational cortices, respectively. |
|
0 |
Buzsáki; Rhythms of the Brain |
205 |
|
In the absence of environmental
inputs, the brain gives rise
to self-organized
activity that follows a complex trajectory in time
and neuronal space
during sleep. |
|
0 |
Buzsáki; Rhythms of the Brain |
205 |
|
The isolated neocortex or small pieces of the neocortex alone
can sustained self-organized patterns. |
|
0 |
Buzsáki; Rhythms of the Brain |
205 |
|
The most prominent oscillation of the waking brain is the family of alpha rhythms that occur
selectively in every sensory and motor thalamocortical system in the
absence of sensory inputs. |
|
0 |
Buzsáki; Rhythms of the Brain |
206 |
|
Perturbation of the Default
Patterns by Experience |
|
1 |
Buzsáki; Rhythms of the Brain |
228 |
|
Ambiguous figures such as the Necker cube -- a critical element in perception is the object's continual
surveillance by eye
movements.
Seeing (i.e. perception) is an active exploration of the
environment. |
|
22 |
Buzsáki; Rhythms of the Brain |
229 |
|
Metastability
of ambiguous figures
such as the Necker cube
involve perceptual shifts initiated by eye movements. |
|
1 |
Buzsáki; Rhythms of the Brain |
229 |
|
Sleep is
the default state of the brain -- it develops as a self-organized or spontaneous state without an external input. |
|
0 |
Buzsáki; Rhythms of the Brain |
231 |
|
Invention of functional
imaging of the intact
human brain in the early
1990s. |
|
2 |
Buzsáki; Rhythms of the Brain |
231 |
|
Society for Neuroscience meeting
in Washington, DC, fall of 1993, Wolf Singer, Max Planck Institute,
Frankfurt-am-Main, Germany. |
|
0 |
Buzsáki; Rhythms of the Brain |
231 |
|
Gamma Buzz – Gluing by
Oscillations in the Waking Brain |
|
0 |
Buzsáki; Rhythms of the Brain |
232 |
|
Representation of the various attributes of the visual world by distributed neuronal assemblies
can be bound together
harmoniously in the time
domain through oscillatory
synchrony. |
|
1 |
Buzsáki; Rhythms of the Brain |
232 |
|
Features
processed in separate parts of the cortex by different
sets of neurons are bound into a complex representation in a matter of 200 ms or so. |
|
0 |
Buzsáki; Rhythms of the Brain |
237 |
|
The existence of rhythms in the visual system, such as the
prominent alpha waves,
is a physiological telltale sign of excitatory
feedback loops in
action. |
|
5 |
Buzsáki; Rhythms of the Brain |
238 |
|
Binding by Temporal Coherence. |
|
1 |
Buzsáki; Rhythms of the Brain |
238 |
|
Peter Millner and Christoph von
der Malsburg -- spatially distributed cell groups should synchronize their responses when activated by a single object. |
|
0 |
Buzsáki; Rhythms of the Brain |
238 |
|
Systems with emergent
features require feedback. |
|
0 |
Buzsáki; Rhythms of the Brain |
238 |
|
Feedback loops are likely to be very important in processing
sensory information or combine
the sensory inputs with past
experience. |
|
0 |
Buzsáki; Rhythms of the Brain |
239 |
|
Oscillation
as a linking mechanism
-- synchronization by oscillation is effective even through a few and weak links. |
|
1 |
Buzsáki; Rhythms of the Brain |
240 |
|
Gamma bursts,
lasting from tens to thousands of milliseconds, are rarely observed spontaneously, but are reliably induced by visual stimuli. |
|
1 |
Buzsáki; Rhythms of the Brain |
240 |
|
Research results show that oscillatory dynamics in the brain is not
directly related to the stimulus, but are added on by the brain. Gamma oscillation in the activated neural cortex has a
function. |
|
0 |
Buzsáki; Rhythms of the Brain |
240 |
|
Neurons
with overlapping receptive fields and similar response properties, synchronize robustly with zero time lag, whereas neurons that do not share the same receptive fields do not synchronize. |
|
0 |
Buzsáki; Rhythms of the Brain |
240 |
|
It is the response features of the neurons, rather than their spatial separation, that determined the vigor of synchrony. |
|
0 |
Buzsáki; Rhythms of the Brain |
240 |
|
Neurons
several millimeters apart in the same or different stages of the visual system, and even across the two cerebral hemispheres, have been shown to come together in time transiently by gamma
frequency synchronization. |
|
0 |
Buzsáki; Rhythms of the Brain |
243 |
|
Attributes
of an object
are not in the object; they're generated by the observer's brain. |
|
3 |
Buzsáki;
Rhythms of the Brain |
243 |
|
Gestalt psychologists have long known that the whole is often faster recognized than its parts,
indicating that object recognition is not simply
representation of elementary
features,
but the result of bottom-up and
top-down interactions, in harmony with the architectural organization of the cerebral cortex. |
|
0 |
Buzsáki; Rhythms of the Brain |
243 |
|
Binding by gamma oscillation hypothesis. |
|
0 |
Buzsáki; Rhythms of the Brain |
243 |
|
Although the
binding problem was
originally formulated in terms of visual object
recognition,
the idea of various attributes making up a
whole is quite
general and should apply to all modalities. |
|
0 |
Buzsáki; Rhythms of the Brain |
243 |
|
Every part
of the cortex should
be able to support gamma
oscillations under the right conditions. |
|
0 |
Buzsáki; Rhythms of the Brain |
243 |
|
Consciousness
is a state that requires linking global features of the brain-body-environment interface. |
|
0 |
Buzsáki; Rhythms of the Brain |
243 |
|
Coherence
measurements of MEG
signals over the whole
extent of the cerebral
hemispheres indicates that significant coupling in the gamma frequency band is present in the waking brain as well is during REM sleep. |
|
0 |
Buzsáki; Rhythms of the Brain |
243 |
|
Sensory
perturbation can easily reset gamma rhythm in the waking state, whereas the same
stimulus is largely ineffective during REM sleep. |
|
0 |
Buzsáki; Rhythms of the Brain |
244 |
|
Gamma oscillation is not ubiquitous but localized temporarily to areas engaged in a particular operation. |
|
1 |
Buzsáki; Rhythms of the Brain |
244 |
|
Gamma frequency power has been observed in motor areas during, but more typically prior to, voluntary
movement in sensory-motor
tasks. |
|
0 |
Buzsáki; Rhythms of the Brain |
244 |
|
Significant
difference in gamma
power
was reported between patterns induced by words versus pseudowords in both visual and auditory tasks. |
|
0 |
Buzsáki; Rhythms of the Brain |
244 |
|
Induced gamma
activity emerges at a
variable latency
between 150 and 300 ms
after stimulus onset, approximately at the time when stimuli acquire meaning. |
|
0 |
Buzsáki; Rhythms of the Brain |
245 |
|
Research observations indicate
that a coherent perception
of an object involves synchronization of large cortical areas. |
|
1 |
Buzsáki; Rhythms of the Brain |
245 |
|
Low spatial resolution of scalp recordings. |
|
0 |
Buzsáki; Rhythms of the Brain |
245 |
|
Gamma oscillations should be confined to discrete
active locations rather than being diffusely present over a wide
cortical region. |
|
0 |
Buzsáki; Rhythms of the Brain |
245 |
|
Recording sites as close as 3--4 mm from each other in the visual
cortex yielded quite
different amplitudes of gamma oscillations. |
|
0 |
Buzsáki; Rhythms of the Brain |
245 |
|
Short bouts of oscillations detected by scalp electrodes correspond to localized events that are integrated over time and
space. |
|
0 |
Buzsáki; Rhythms of the Brain |
245 |
|
Gamma oscillations are used in the brain for temporally
segmenting representations of different items. |
|
0 |
Buzsáki; Rhythms of the Brain |
246 |
|
Neuronal assemblies in the waking brain self-organize themselves into temporal packages of 15 -- 30 ms. |
|
1 |
Buzsáki; Rhythms of the Brain |
246 |
|
Temporal integration abilities of individual pyramidal
cells. |
|
0 |
Buzsáki; Rhythms of the Brain |
246 |
|
Neuronal connections are subject to use-dependent
modification. |
|
0 |
Buzsáki; Rhythms of the Brain |
246 |
|
Two fundamental ways in which neuronal coalitions can be altered -- (1) forming physical
connections between neurons or eliminating them, (2) changing the synaptic strengths of existing connections. |
|
0 |
Buzsáki; Rhythms of the Brain |
247 |
|
Two fundamental requirements for affecting synaptic strength -- (1) sufficiently
strong depolarization
of the postsynaptic neuron, (2) appropriate timing between presynaptic activity and the discharge of the
postsynaptic neuron. |
|
1 |
Buzsáki; Rhythms of the Brain |
247 |
|
Because mechanisms for affecting
synaptic strength of neuronal coalitions are affected by
the gamma-oscillation-mediated synchronization, adjustment of synaptic strength is a perpetual process in the cortex. |
|
0 |
Buzsáki; Rhythms of the Brain |
247 |
|
Every time a postsynaptic
neuron fires in a manner that the discharge leads
to an increase of free Ca2+ in the dendrites, the previously or subsequently active presynaptic connections are modified. |
|
0 |
Buzsáki; Rhythms of the Brain |
247 |
|
The critical temporal window of plasticity for pre-synaptic connection modification
corresponds to the length of the gamma cycle. |
|
0 |
Buzsáki; Rhythms of the Brain |
247 |
|
Spike-timing-dependent
plasticity highlights the
essential role of spite timing in modifying network connectivity, a fundamental brain mechanism. |
|
0 |
Buzsáki; Rhythms of the Brain |
247 |
|
Gamma oscillation remains a central timing mechanism essential for synaptic plasticity. |
|
0 |
Buzsáki; Rhythms of the Brain |
247 |
|
Synchronization by gamma oscillations results in not only perceptual
binding but, inevitably, modification of connections among
the neurons involved. |
|
0 |
Buzsáki; Rhythms of the Brain |
247 |
|
The assembly
bound together by gamma-oscillation-induced
synchrony can reconstruct
patterns on the basis of partial cues because of the temporally fortified connections
among neuron assembly members. |
|
0 |
Buzsáki; Rhythms of the Brain |
262 |
|
Perceptions and actions are
brain state dependent |
|
15 |
Buzsáki; Rhythms of the Brain |
277 |
|
Perceptions of natural scenes,
speech, music, and body image as well as our occasional illusions can be
attributed largely to the unique organization of the iso-cortex. |
|
15 |
Buzsáki; Rhythms of the Brain |
277 |
|
Navigation in Real and Memory
Space |
|
0 |
Buzsáki; Rhythms of the Brain |
278 |
|
The implicit
experience of learning how to walk comfortably in high heeled
shoes or ignoring the annoying
sound of the air-conditioner in your office does not require that we be aware of the
process. |
|
1 |
Buzsáki; Rhythms of the Brain |
280 |
|
The best way to start
speculating about the functions of brain structure is to inspect the anatomical
organization carefully. The dictum "structure
defines function" never fails. |
|
2 |
Buzsáki; Rhythms of the Brain |
281 |
|
The "limbic"
system derives from the ringlike arrangement of allocortical structures, including
the amygdala, hippocampus, entorhinal cortex, and hypothalamus, that provide
a relative distinct border separating the brain
stem from the new
cortex. |
|
1 |
Buzsáki; Rhythms of the Brain |
284 |
|
The entire hippocampus can be conceived as a single giant
cortical column.
(diagram) |
|
3 |
Buzsáki; Rhythms of the Brain |
284 |
|
One important entry
point to the hippocampus is the granule cells of the dentate gyrus. |
|
0 |
Buzsáki; Rhythms of the Brain |
284 |
|
The axon
terminals of granule
cells excite about half
of the hippocampal pyramidal cells; these reside
in the CA3 region. |
|
0 |
Buzsáki; Rhythms of the Brain |
284 |
|
The CA3
region is actually two
layers with a continuous
transition.
Pyramidal cells
in the portal area engulfed by the granule cells send their main collaterals to the CA1 pyramidal cells. The remaining CA3 and Ca2 neurons compose a
strongly recursive network. |
|
0 |
Buzsáki; Rhythms of the Brain |
284 |
|
The major
difference between neocortical and hippocampal organizations lies mainly in the
manner in which the two systems grew during the course of the mammalian
evolution. |
|
0 |
Buzsáki; Rhythms of the Brain |
285 |
|
The hippocampus grows as a single large multilayer space. The evolutionary
advantage of such an architectural solution is
the creation of a giant random connections space, a requisite for combining arbitrary information. |
|
1 |
Buzsáki; Rhythms of the Brain |
285 |
|
The hippocampus is the neocortex's librarian. |
|
0 |
Buzsáki; Rhythms of the Brain |
289 |
|
The computational
properties of recursive organization, such as the extensive
CA3 recurrent system, meet the requirements of an "autoassociator." |
|
4 |
Buzsáki; Rhythms of the Brain |
289 |
|
An autoassociator is a self-correcting network that can recreate a previously stored pattern that most closely
resembles the current
input pattern,
even if it is only a fragment of the stored version. |
|
0 |
Buzsáki; Rhythms of the Brain |
289 |
|
Give the autoassociative network part of the content, and it returns the whole. |
|
0 |
Buzsáki; Rhythms of the Brain |
289 |
|
The performance of an associative network is
characterized by the memory capacity and content addressability. |
|
0 |
Buzsáki; Rhythms of the Brain |
289 |
|
Content addressability refers to an ability to recall a
whole episode from a retrieval
cue, consisting of only
a small part of the original information. |
|
0 |
Buzsáki; Rhythms of the Brain |
289 |
|
The extensive
axon arbors of the CA3 pyramidal cells indicate that
the probability of connecting to nearby or distant CA3 neurons is approximately the same. |
|
0 |
Buzsáki; Rhythms of the Brain |
290 |
|
Anatomical
data and computational
modeling have provided guidelines for the assessment of storage capacity and content addressability of networks. |
|
1 |
Buzsáki; Rhythms of the Brain |
290 |
|
The coding of a memory trace needs a sparse and distributed memory. |
|
0 |
Buzsáki; Rhythms of the Brain |
290 |
|
Sparse representation means that only a fraction of the trace is represented at one
physical storage location. |
|
0 |
Buzsáki; Rhythms of the Brain |
290 |
|
The anatomy of the hippocampus meets the requirements
a sparse representation. Unlike the primary
sensory cortices, cell
assemblies in the hippocampus, representing the same information, consists of neurons that are distributed virtually
randomly over the entire CA3 -- CA1 regions. |
|
0 |
Buzsáki; Rhythms of the Brain |
290 |
|
Spreading memory traces in a large coding space reduces overlaps among the stored
patterns. |
|
0 |
Buzsáki; Rhythms of the Brain |
292 |
|
Episodic memory is claimed to be uniquely
human, a
mental travel back in time that endows the
individual with the capacity to reference personal experiences in the context of both time and space. |
|
2 |
Buzsáki; Rhythms of the Brain |
292 |
|
It is these lifelong
experiences,
representing unique events through space-time, that give rise to
the feeling of the self and are the
sources of individuality. |
|
0 |
Buzsáki; Rhythms of the Brain |
292 |
|
Semantic knowledge is largely a context-free form of
information. It is the "meaning" of things. |
|
0 |
Buzsáki; Rhythms of the Brain |
292 |
|
Forward associations are stronger than backward associations. |
|
0 |
Buzsáki; Rhythms of the Brain |
293 |
|
Recall of a
fragment of the episode recreates the temporal context of the episode, and the temporal context facilitates sequential free recall. |
|
1 |
Buzsáki; Rhythms of the Brain |
308 |
|
Theta rhythm,
the major temporal organizer of the hippocampal -- entorhinal cortex. |
|
15 |
Buzsáki; Rhythms of the Brain |
308 |
|
It is the theta
oscillation through which one can understand the relationship between one-dimensional and two-dimensional navigation and
between episodic and semantic memory. |
|
0 |
Buzsáki; Rhythms of the Brain |
308 |
|
Hippocampal theta oscillations (6 -- 10 Hz in the rat and somewhat slower in higher species) is a sustained rhythm in the sense that
as long as the animal is engaged in the same
behavior, theta waves occur continuously. |
|
0 |
Buzsáki; Rhythms of the Brain |
308 |
|
Neurons in many structures can fire phase-locked to hippocampal theta oscillations,
although the extent of the phase entrainment depends on the structure, cell type, and task. |
|
0 |
Buzsáki; Rhythms of the Brain |
309 |
|
In the strongly
interconnected system of the brain with multiple loops, identifying the key ingredient responsible for the emergence of theta
rhythm is not trivial. |
|
1 |
Buzsáki; Rhythms of the Brain |
310 |
|
Although hippocampal
pyramidal cells do not typically oscillate in isolation, they have resonant properties at theta frequency, due mainly to the
time constants of currents flowing through ion channels. |
|
1 |
Buzsáki; Rhythms of the Brain |
310 |
|
Layer 2 entorhinal cortical
neurons (the grid cells), are endowed with subthreshold
oscillations at theta
frequency. |
|
0 |
Buzsáki; Rhythms of the Brain |
310 |
|
Evolution
has dedicated a consortium of mechanisms to secure a precise timing mechanism at the theta time period. |
|
0 |
Buzsáki; Rhythms of the Brain |
311 |
|
Timing of principle cell action potentials is secured by a coordinated action of interneuron classes. (diagram) |
|
1 |
Buzsáki; Rhythms of the Brain |
312 |
|
Single-cell properties perfectly match circuit features in both principle cells and interneurons. |
|
1 |
Buzsáki; Rhythms of the Brain |
312 |
|
Multiple
theta oscillations mechanisms can contribute to the computational properties of hippocampal -- entorhinal neurons
in complex ways. |
|
0 |
Buzsáki; Rhythms of the Brain |
312 |
|
Generation of theta oscillation
currents. |
|
0 |
Buzsáki; Rhythms of the Brain |
312 |
|
Theta currents arise primarily from the laminarly-arranged
pyramidal cells and granules
cells. |
|
0 |
Buzsáki; Rhythms of the Brain |
312 |
|
Theta currents have been most extensively studied in the CA1 region. |
|
0 |
Buzsáki; Rhythms of the Brain |
312 |
|
The largest
amplitude theta is observed at the distal apical dendrites of the CA1 pyramidal cells, the layer
where the afferents
from layer 3 entorhinal cortial cells and the thalamic reunions nucleus terminate. |
|
0 |
Buzsáki; Rhythms of the Brain |
313 |
|
The basket family of interneurons also appears critical
because they fire rhythmic bursts of spikes at theta frequency, thereby inducing inhibitory
currents in the perisomatic region |
|
1 |
Buzsáki; Rhythms of the Brain |
313 |
|
Although nearly all interneuron types are entrained to the theta rhythm,
their maximum activity
referenced to the phase of the theta cycle
differs systematically. |
|
0 |
Buzsáki; Rhythms of the Brain |
314 |
|
The interference of two oscillators
beating at slightly different frequencies and acting on the same neurons can systematically affect spike
timing. |
|
1 |
Buzsáki; Rhythms of the Brain |
314 |
|
Spikes of a
place cell shifts systematically relative to the phase of the
ongoing theta oscillation. This phenomenon is
called "phase precession." |
|
0 |
Buzsáki; Rhythms of the Brain |
314 |
|
There is a unique
and systematic relationship between spikes and theta phase. |
|
0 |
Buzsáki; Rhythms of the Brain |
314 |
|
The phase of
spikes and animal's
position on the track are correlated. |
|
0 |
Buzsáki; Rhythms of the Brain |
315 |
|
The phase precession demonstration was the first convincing example of a long
suspected temporal "code," and it has remained the most
compelling evidence in support of the critical role of oscillations in brain function. |
|
1 |
Buzsáki; Rhythms of the Brain |
315 |
|
With the discovery of phase precession, timing directly
entered the field of place-cell research, offering the opportunity to combine space and time in the service of episodic memory. |
|
0 |
Buzsáki; Rhythms of the Brain |
315 |
|
Navigation in rats and episodic
memory in humans. |
|
0 |
Buzsáki; Rhythms of the Brain |
318 |
|
The discovery of temporal coordination of neuronal spikes by theta oscillations offered new insights into the assembly
functions of hippocampal
neurons. |
|
3 |
Buzsáki; Rhythms of the Brain |
318 |
|
Transient phase coupling of two or more oscillators with different frequencies is an effective method for producing a continuously moving phase vector. |
|
0 |
Buzsáki; Rhythms of the Brain |
318 |
|
The discovery of phase precession in hippocampal place cells arose from
the idea of two
interfering oscillators, tentatively identified
with the entorhinal input (noncholinergic) and the intrahippocampal
CA3 (cholinergic)
theta oscillators. |
|
0 |
Buzsáki; Rhythms of the Brain |
320 |
|
Hippocampal neurons, like members of an orchestra, are embedded in an interactive synaptic environment, and the timing of the action potentials is biased not only
by theta oscillation pacing but also by their synaptically
connected spiking peers. |
|
2 |
Buzsáki; Rhythms of the Brain |
320 |
|
The key idea is that sequentially activated cell
assemblies in the hippocampus are connected by synaptic links, and the strengths of these links are reflected by the temporal
relations between them. |
|
0 |
Buzsáki; Rhythms of the Brain |
321 |
|
Compression of items into theta cycles is reminiscent of the mnemonic
technique called "chucking." |
|
1 |
Buzsáki; Rhythms of the Brain |
324 |
|
Functional connections within the feedforward CA3 -- CA1 system and
the CA3 excitatory recurrent system is able to maintain self-organized activity, with the emergence of theta like oscillation. |
|
3 |
Buzsáki; Rhythms of the Brain |
324 |
|
Excitation and inhibition build
up and die in a relatively parallel matter during the theta
cycle in CA3 region. |
|
0 |
Buzsáki; Rhythms of the Brain |
324 |
|
The buildup of excitation and inhibition in the CA3 region also gives rise to a transient gamma oscillation, associated with the increased gamma-cycle-locked
oscillation of basket and chandelier cells. |
|
0 |
Buzsáki; Rhythms of the Brain |
326 |
|
Distance information between positions on a linear track is stored by synaptic weights among neurons in
the CA3 -- CA1 collateral system. |
|
2 |
Buzsáki; Rhythms of the Brain |
326 |
|
During each theta
cycle, the large
synaptic space of the CA3 -- CA1 collateral system
is searched, recalling
several temporally linked cell assemblies. |
|
0 |
Buzsáki; Rhythms of the Brain |
327 |
|
Research work in humans suggests that the hippocampal -- entorhinal system
is involved in both episodic and semantic memories. |
|
1 |
Buzsáki; Rhythms of the Brain |
328 |
|
Understand how a useful neuronal mechanisms that evolved in a small-brain animal (e.g.
navigation in physical space) can be exploited for another purpose (e.g. memory
storage and retrieval) at later stages of the brain
evolution. |
|
1 |
Buzsáki; Rhythms of the Brain |
329 |
|
Free recall
is essentially a pattern-completion problem. |
|
1 |
Buzsáki; Rhythms of the Brain |
329 |
|
The asymmetric nature of the
recursive CA3 -- CA3 and CA3 -- CA1 connections, combined with temporal
ordering of cell assemblies and spike timing dependent plasticity, favor
temporally forward associations. |
|
0 |
Buzsáki; Rhythms of the Brain |
329 |
|
Similar to the physical distances on a linear track, positional distances
among items of an episodic
list can be coded by
the synaptic strengths between cell assemblies, which represent the items. |
|
0 |
Buzsáki; Rhythms of the Brain |
329 |
|
Because distance
representations are brought
together into the cycle
time of theta, not only temporally adjacent but
also noncontiguous items can be linked together by synaptic plasticity. |
|
0 |
Buzsáki; Rhythms of the Brain |
329 |
|
The higher
order links of noncontiguous
items can be established because the probability of anatomical connections among any cell pairs is similar
in the hippocampus. |
|
0 |
Buzsáki; Rhythms of the Brain |
329 |
|
It is the timing
rule of synaptic
plasticity that functionally
connects assembly A more
strongly to assembly B than to assembly C in a sequence. |
|
0 |
Buzsáki; Rhythms of the Brain |
330 |
|
Multiple overlapping
observations with common
junctions are the source of semantic knowledge. |
|
1 |
Buzsáki; Rhythms of the Brain |
330 |
|
Seeing a dog for
the first time in life is an episode. After seeing many
different dogs and pictures of dogs, the
universal features assume a semantic meaning -- a common name. |
|
0 |
Buzsáki; Rhythms of the Brain |
330 |
|
Although episodic
memories are the prerequisite
of semantic information, storage of consolidated semantic knowledge may
no longer required the
large combinatorial associational network provided by the hippocampus. |
|
0 |
Buzsáki; Rhythms of the Brain |
330 |
|
Once semantic
information is
solidified, it can be transferred in neocortical destinations. |
|
0 |
Buzsáki; Rhythms of the Brain |
331 |
|
The hippocampus is the ultimate search engine for the retrieval of archived information. |
|
1 |
Buzsáki; Rhythms of the Brain |
331 |
|
Hippocampal theta oscillations are related to episodic and semantic memory. |
|
0 |
Buzsáki; Rhythms of the Brain |
331 |
|
Episodic memory and semantic memory consolidation have been associated with the hippocampal
-- entorhinal system, primarily on the basis of
lesion cases in humans
and research studies in smaller animals. |
|
0 |
Buzsáki; Rhythms of the Brain |
331 |
|
The hippocampus and associated structures are organized in multiple loops in a part of the allocortex, with reciprocal connections to the neocortex. |
|
0 |
Buzsáki; Rhythms of the Brain |
331 |
|
The most prominent collected
pattern of hippocampal
neurons is theta
oscillation, a sustained
rhythm associated with it would explorative navigation. |
|
0 |
Buzsáki; Rhythms of the Brain |
331 |
|
A consortium of circuit and single-cell properties supports theta oscillations, which provides
timing for individual hippocampal pyramidal and granule cells and the principal cells of the limbic system. |
|
0 |
Buzsáki; Rhythms of the Brain |
331 |
|
The major theta current generator in the hippocampus is the entorhinal input to the distal apical dendrites of CA1 pyramidal cells. |
|
0 |
Buzsáki; Rhythms of the Brain |
331 |
|
The medial
septum is a key rhythm
generator of theta
cycles, but the
recurrent CA3 system can also generate theta oscillations. |
|
0 |
Buzsáki; Rhythms of the Brain |
331 |
|
Interactions
between CA3 pyramidal cells and basket interneurons also give rise to gamma frequency oscillations, phase-locked to the slower theta rhythm. |
|
0 |
Buzsáki; Rhythms of the Brain |
331 |
|
Inhibition
and gamma power are built up simultaneously in the CA3 and CA1 regions, the
consequence of which is that pyramidal cells in these sectors, on average, discharge on the opposite phases of the theta cycle. |
|
0 |
Buzsáki; Rhythms of the Brain |
331 |
|
The various theta
oscillation mechanisms
are responsible for the temporal organization of pyramidal
neurons. |
|
0 |
Buzsáki; Rhythms of the Brain |
332 |
|
Similar to the theta cycle representation of
physical distances in one-dimensional tasks, positional
"distances" among items of an episodic list can be coded by the synaptic strengths between cell assemblies, representing the items of the
episode. |
|
1 |
Buzsáki; Rhythms of the Brain |
332 |
|
Higher order links can be established because the probability
of anatomical connections among cell pairs is similar in the hippocampus. |
|
0 |
Buzsáki; Rhythms of the Brain |
332 |
|
An ideal
structure for episode
coding and recall is an autoassociator with a large random synaptic space, since free recall is essentially a pattern
completion problem. |
|
0 |
Buzsáki; Rhythms of the Brain |
332 |
|
The extensive
axon arbors of CA3
pyramidal cells and their recursive CA3 -- CA3 and CA3 -- CA1 connections are ideal for storing large numbers of episodic
memories and for retrieving
them efficiently. |
|
0 |
Buzsáki; Rhythms of the Brain |
333 |
|
Episodic
and semantic memory
representations may have evolved from mechanisms serving dead-reckoning and map-based navigation, respectively. |
|
1 |
Buzsáki; Rhythms of the Brain |
334 |
|
Coupling of Systems by
Oscillations |
|
1 |
Buzsáki; Rhythms of the Brain |
334 |
|
A purely
feedforward scheme is an exception in cortical systems; the typical connectivity is reciprocal and recurrent innervation. |
|
0 |
Buzsáki; Rhythms of the Brain |
334 |
|
There is no real structural top in neuronal hierarchy. |
|
0 |
Buzsáki; Rhythms of the Brain |
334 |
|
The top end
of computation in neural networks is generally heralded by time, marked by inhibition of activity, rather than
by some defined anatomical boundary. |
|
0 |
Buzsáki; Rhythms of the Brain |
334 |
|
Neuronal information is propelled in parallel in multiple juxtaposed and superimposed loops, making the distinction between top and bottom
processing very difficult. |
|
0 |
Buzsáki; Rhythms of the Brain |
334 |
|
A candidate physiological
mechanism of attention is gain control, which is a quantitative rather than a qualitative change, reflecting an enhanced sensitivity of the processing circuits to inputs. |
|
0 |
Buzsáki; Rhythms of the Brain |
334 |
|
Enhanced
gain in neuronal
networks can be achieved mainly by subcortical neurotransmitters,
such as acetylcholine
and norepinephrine,
which enhance cortical gamma oscillations. |
|
0 |
Buzsáki; Rhythms of the Brain |
335 |
|
Cortical activity is in perpetual
motion, and every
motor and cognitive act is a synthesis of self-generated, circuit maintained activity and environmental perturbation. |
|
1 |
Buzsáki; Rhythms of the Brain |
335 |
|
Invariant
responses of the
brain, irrespective of its state is true only for elementary
reflexes involving short
loops. |
|
0 |
Buzsáki; Rhythms of the Brain |
335 |
|
In most situations, the brain's reaction to environmental changes is not invariant but depends on the outcome of previous reactions in similar
situations and on the brain's current state, determined by the multiple interactions among various oscillators. |
|
0 |
Buzsáki; Rhythms of the Brain |
335 |
|
If different
brain areas and systems constantly generate their autonomous self-organized patterns, the fundamental basis of communication
and exchange of information between them is oscillatory phase locking. |
|
0 |
Buzsáki; Rhythms of the Brain |
335 |
|
In reciprocally
interconnected systems, temporal
ordering of neuronal
activity by way of phase
locking can direct the
flow of excitation. |
|
0 |
Buzsáki; Rhythms of the Brain |
335 |
|
Neurons that discharge earlier
can drive the neurons of the trailing oscillator. |
|
0 |
Buzsáki; Rhythms of the Brain |
335 |
|
By simply reversing
the phase of offset, the direction of drive can be reversed. |
|
0 |
Buzsáki; Rhythms of the Brain |
335 |
|
Because it is largely past experience that determines the brain's response to environmental inputs, it is
expected that the dialogue between the hippocampus and the relevant parts of the neocortex is virtually continuous. |
|
0 |
Buzsáki; Rhythms of the Brain |
335 |
|
Hippocampal theta oscillations are among the rare sustained
rhythms in the brain. |
|
0 |
Buzsáki; Rhythms of the Brain |
336 |
|
Various neocortical
regions are capable of generating
their own local theta oscillations under the
right conditions, such that hippocampal and neocortical theta oscillators entrain each
other. |
|
1 |
Buzsáki; Rhythms of the Brain |
336 |
|
Stochastic resonant properties of neocortical local circuits can extract the data-coding message. |
|
0 |
Buzsáki; Rhythms of the Brain |
337 |
|
The advantages of hippocampal theta engagement of neocortical circuits are that coupling can be established by very weak links, and many cortical assemblies can be entrained with short time lags
after just one cycle
such that their joint outputs would be synchronized with minimal delays. |
|
1 |
Buzsáki; Rhythms of the Brain |
337 |
|
Distant cortical networks with nonexistent or weak
anatomical connections can orchestrate their activity in such
a way that their temporally locked outputs can select common downstream
assemblies. |
|
0 |
Buzsáki; Rhythms of the Brain |
337 |
|
Overall, the temporally-locked
neural mechanisms, in isolation or combination,
would allow top-down hippocampal neural cortical
communication at a pace determined by the hippocampal
theta oscillations. |
|
0 |
Buzsáki; Rhythms of the Brain |
337 |
|
Entorhinal cortex, the main hub between the hippocampal system and neocortex. |
|
0 |
Buzsáki; Rhythms of the Brain |
337 |
|
The relative
phase-delayed activity of neurons in the hippocampus or entorhinal cortex
determine the direction of neuronal communication between the two structures, and the direction
of impulse flow changes as a result of experience. |
|
0 |
Buzsáki; Rhythms of the Brain |
338 |
|
Training-reversed direction of
information. Time
courses of perceptual
and memory retrieval
signals. |
|
1 |
Buzsáki; Rhythms of the Brain |
338 |
|
Perceptual
signal reached the temporal cortex before the perirhinal cortex, confirming its forward
propagation. |
|
0 |
Buzsáki; Rhythms of the Brain |
338 |
|
Memory retrieval signals appeared earlier in the perirhinal
cortex, and neurons in the temporal cortex where gradually recruited to represent
the sought target. |
|
0 |
Buzsáki; Rhythms of the Brain |
338 |
|
Coupling by
theta oscillations has
also been reported in the amygdalalohippocampal
circuit. |
|
0 |
Buzsáki; Rhythms of the Brain |
338 |
|
As a result of fear conditioning, theta oscillations emerge in the amygdala of mice, with waves in synchrony with hippocampal theta oscillations. |
|
0 |
Buzsáki; Rhythms of the Brain |
338 |
|
Temporal coordination may allow fear signals conveyed by the amygdala to to be associated with the environmental
context provided by spatial inputs to the hippocampus. |
|
0 |
Buzsáki; Rhythms of the Brain |
338 |
|
Scalp recordings of EEG
in humans has provided
indirect support for the role of theta
oscillations in memory
functions. |
|
0 |
Buzsáki; Rhythms of the Brain |
338 |
|
Sensory stimuli and semantic memory performance are best correlated with a decrease of the high alpha power ("desynchronization"),
whereas increased theta power above the occipital region is associated with encoding of new
information. |
|
0 |
Buzsáki; Rhythms of the Brain |
339 |
|
In working
memory studies, using either verbal or visiospatial
stimuli, an increase in theta
coherence was observed between the prefrontal cortex and posterior association areas. |
|
1 |
Buzsáki; Rhythms of the Brain |
339 |
|
In a working
memory task, both encoding and retrieval items reset the MEG theta signal, the dipole source was attributed to be the anterior
hippocampus. |
|
0 |
Buzsáki; Rhythms of the Brain |
340 |
|
Although task
related modulation of power occurred
simultaneously in hippocampal and neocortical sites, the induced oscillations were rarely phase coherent. |
|
1 |
Buzsáki; Rhythms of the Brain |
340 |
|
Coherence
was also rare among cortical sites, and it decreased and the power law function of distance. |
|
0 |
Buzsáki; Rhythms of the Brain |
340 |
|
The simultaneous appearance of oscillations in the theta frequency without phase coherence
across structures poses challenging questions
regarding the functional role and origin. |
|
0 |
Buzsáki; Rhythms of the Brain |
340 |
|
Alpha oscillations do not necessarily reflect idling of cortical
networks but rather indicate an active disengagement from environmental inputs with an
emphasis on an internal mental operations. |
|
0 |
Buzsáki; Rhythms of the Brain |
341 |
|
Simultaneous recordings of hippocampal and neocortical cell assemblies in rats lend support to the idea that
at least some forms of the dialogue between hippocampus and neocortex occur in the packages of theta
oscillatory waves. |
|
1 |
Buzsáki; Rhythms of the Brain |
341 |
|
Phase-locked
action potentials of the medial prefrontal neurons are delayed by approximately 50 ms, indicating the hippocampoprefrontal
directionality. |
|
0 |
Buzsáki; Rhythms of the Brain |
341 |
|
Theta phase-locked discharge of neurons in anatomically direct targets of the hippocampal system is perhaps not
so surprising. But can neurons in other areas of the neocortex,
several synapses away from the hippocampus, display theta
phase-locking, if even transiently? |
|
0 |
Buzsáki; Rhythms of the Brain |
341 |
|
The majority of the phase-locked somatosensory neurons
transiently coherent with theta oscillations were inhibitory
neurons, some of which fire
rhythmic bursts at theta
frequency. |
|
0 |
Buzsáki; Rhythms of the Brain |
341 |
|
Induced fields at various cortical sites in episodic memory tasks are not necessarily coherent with hippocampal theta
oscillations. |
|
0 |
Buzsáki; Rhythms of the Brain |
342 |
|
If the hippocampal
output manages to temporally
bias the firing
patterns of distant
cortical sites by polysynaptically
entraining some of their interneurons, well timed messages
from those saying cortical areas will be treated preferentially over others
in the hippocampus. |
|
1 |
Buzsáki; Rhythms of the Brain |
342 |
|
A temporally
specified "call-up" mechanism can be an
effective solution for top-down selection of bottom-up inputs. |
|
0 |
Buzsáki; Rhythms of the Brain |
343 |
|
Gamma oscillations tie together the hippocampal CA3
and CA1 regions. The CA3
autoassociator generates an intrinsic theta rhythm. Both theta and gamma oscillations are
affected by the oscillatory pattern of the dentate gyrus. |
|
1 |
Buzsáki; Rhythms of the Brain |
343 |
|
The activity
of the neocortex under various anesthetics alternates between neuronal silence with nearly all neocortical principle cells sitting
at a hyperpolarized level (down state) and the up state, with many neurons spiking. |
|
0 |
Buzsáki; Rhythms of the Brain |
344 |
|
In the dentate region, gamma activity is the most conspicuous pattern. |
|
1 |
Buzsáki; Rhythms of the Brain |
345 |
|
Self-organized hippocampal
activity can invade large
cortical areas.
(diagram) |
|
1 |
Buzsáki; Rhythms of the Brain |
345 |
|
In the approximately 100 ms time window of a hippocampal sharp wave, 50,000 --
100,000 neurons discharge together in the CA3 --
CA1 -- subicular complex -- entorhinal axis of
the rat, qualifying it as the most synchronous
network pattern in the brain. |
|
0 |
Buzsáki; Rhythms of the Brain |
363 |
|
Circuit Plan of the Cerebellum |
|
18 |
Buzsáki; Rhythms of the Brain |
363 |
|
All vertebrate
animals have a cerebellum with highly preserved phylogenetic
homology, and it continues to serve identical functions. |
|
0 |
Buzsáki; Rhythms of the Brain |
363 |
|
Computation in the cerebellar cortex is carried out cooperatively by four
types of GABAergic inhibitory cells -- the Purkinje cells, basket cells,
stellate cells, and Golgi cells -- and excitatory
granule cells. |
|
0 |
Buzsáki; Rhythms of the Brain |
363 |
|
Purkinje cells are the principal computational
neurons of the cerebellum and exhibit many differences from the pyramidal cells of the cerebrum. |
|
0 |
Buzsáki; Rhythms of the Brain |
364 |
|
Cerebellum
is organized as multiple parallel loops without interloop communication. (diagram) |
|
1 |
Buzsáki; Rhythms of the Brain |
364 |
|
The extensive dendrite arborization of the Purkinje cells is the most
elaborate in the brain. |
|
0 |
Buzsáki; Rhythms of the Brain |
364 |
|
In contrast to the cortical pyramidal cells that have cylindrical dendrite arbors and extensive mutual overlap with thousands of other nearby pyramidal
cells, Purkinje
cells are flat, and their dendrites
hardly touch each other. |
|
0 |
Buzsáki; Rhythms of the Brain |
364 |
|
The cerebellar organization
provides maximum autonomy for
each Purkinje cell. |
|
0 |
Buzsáki; Rhythms of the Brain |
365 |
|
Circuit Plan of the Basal
Ganglia |
|
1 |
Buzsáki; Rhythms of the Brain |
366 |
|
Inhibitory loops of the basal ganglia (diagram) |
|
1 |
Buzsáki; Rhythms of the Brain |
366 |
|
The collective term "basal ganglia" refers
to the serially connected striatum, globus pallidus external segment, globus
pallidus internal
segment,
substantia nigra. |
|
0 |
Buzsáki; Rhythms of the Brain |
366 |
|
What makes the basal ganglia so special is that nearly all of their neurons use GABA as neurotransmitter. |
|
0 |
Buzsáki; Rhythms of the Brain |
366 |
|
The ventral
thalamic nuclei provide the cerebellum a link to the basal ganglia. |
|
0 |
Buzsáki; Rhythms of the Brain |
367 |
|
The striatum receives its major excitatory inputs from the neocortex and allocortex. |
|
1 |
Buzsáki; Rhythms of the Brain |
367 |
|
The similarity between cerebellar and basal ganglia architectural
organizations is striking. Very large numbers of parallel
inhibitory loops are funneled
back into a relatively small,
excitatory hub with widespread
projections. |
|
0 |
Buzsáki; Rhythms of the Brain |
368 |
|
A fundamental difference between
the in inhibition dominated cerebellum and basal ganglia circuits and the cortical networks is the inability of the cerebellum and basal ganglia circuits to support large-scale,
self-organized spontaneous patterns. |
|
1 |
Buzsáki; Rhythms of the Brain |
368 |
|
Supersynchronous, epileptic discharges never arise from the GABAergic-neurotransmission-dominated cerebellar and basal ganglia networks. |
|
0 |
Buzsáki; Rhythms of the Brain |
368 |
|
The computation
and locally organized networks of the cerebellum and basal ganglia represent an antithesis of cortical performance, which is
characterized by perpetual spontaneous activity and temporally coordinated
patterns over wide
spatial domains. |
|
0 |
Buzsáki; Rhythms of the Brain |
368 |
|
The inferior olive provides a rhythmic input in the range of 5 -- 13 Hz to the Purkinje cells of the cerebellum by way of the climbing fibers. |
|
0 |
Buzsáki; Rhythms of the Brain |
369 |
|
Individual neurons in the cerebellar nuclei fire
remarkably rhythmically
between 20 and 150 Hz during both waking and sleep states, but they seldom show population
synchrony. |
|
1 |
Buzsáki; Rhythms of the Brain |
369 |
|
Coordinated
network activity in the basal ganglia neurons is provided by the cortical
inputs, but oscillatory
patterns remain highly
localized. |
|
0 |
Buzsáki; Rhythms of the Brain |
369 |
|
Only structures that display persistent neuronal activity and
involve large neuron pools support consciousness. |
|
0 |
Buzsáki; Rhythms of the Brain |
369 |
|
Although oscillations can arise
from many types of networks, only special architectures, such is the cerebral cortex, can support spatially widespread oscillations
at multiple temporal scales and with the consequent 1/f-type, self-organized criticality
features. |
|
0 |
Buzsáki; Rhythms of the Brain |
370 |
|
Regenerative activity requires positive, excitatory
feedback, a critical ingredient conspicuously
absent in cerebellar
and basal ganglia circuits. |
|
1 |
Buzsáki; Rhythms of the Brain |
370 |
|
Regenerative feedback can incorporate the past into the system's present state, and it threads the
system through both time and space, thereby allowing input-induced perturbations
to
be compared with the effects of previous similar encounters. |
|
0 |
Buzsáki; Rhythms of the Brain |
370 |
|
It is the reconstructive
feedback and a sustained
neuronal activity it supports that can place the inputs into context. |
|
0 |
Buzsáki; Rhythms of the Brain |
370 |
|
The most striking, yet perhaps
the least appreciated, behavior of cortical networks is their regenerative,
spontaneous activity. Every spike, sensory evoked or spontaneous, in cortical principles cells can reach distant neurons. |
|
0 |
Buzsáki; Rhythms of the Brain |
370 |
|
The spontaneous,
self-organizing ability of cortical networks is what gives
rise to originality
and freedom in the brain. |
|
0 |
|
|
|
|
|
|