Ramachandran;
Phantoms in the Brain |
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Book |
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Topic |
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Ramachandran;
Phantoms in the Brain |
1 |
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The Phantom Within |
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Ramachandran;
Phantoms in the Brain |
19 |
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The annular
gyrus is somehow necessary for numerical computational tasks but is not needed for other abilities such as short-term memory, language or humor. |
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18 |
Ramachandran;
Phantoms in the Brain |
19 |
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The annular gyrus region is involved in adding, subtracting, multiplying and dividing. |
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0 |
Ramachandran;
Phantoms in the Brain |
19 |
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The annular
gyrus is
not needed for understanding the numerical concepts underlying computations. |
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0 |
Ramachandran;
Phantoms in the Brain |
19 |
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Scientists do
not know how the arithmetic
circuit in the annular gyrus works, but at least they know where to look. |
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0 |
Ramachandran;
Phantoms in the Brain |
19 |
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Specialized circuits or modules do it exist in the brain. |
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0 |
Ramachandran;
Phantoms in the Brain |
20 |
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To what extent is the intricate circuitry in the brain innately specified by your genes or acquired gradually via your early experiences, as an infant
interacting with the world? |
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1 |
Ramachandran;
Phantoms in the Brain |
21 |
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"Knowing Where to
Scratch" |
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1 |
Ramachandran;
Phantoms in the Brain |
25 |
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During the 1940s
and 1950s,
Wilder Penfield
in Montreal performed extensive brain surgeries on patients for temporal lobe epilepsy. |
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4 |
Ramachandran;
Phantoms in the Brain |
25 |
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Penfield stimulated specific brain regions with an electrode and asked the
patient what they felt. All kinds of sensations,
images, and even memories were elicited by the electrode, and the areas
of the brain that
were associated could be mapped. |
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0 |
Ramachandran;
Phantoms in the Brain |
26 |
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Penfield
generated a sensory homunculus, a greatly
distorted
representation
of the body on the surface of the
brain, with the parts that are particularly important taking a disproportionately
large areas. |
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1 |
Ramachandran;
Phantoms in the Brain |
26 |
|
Lips and fingers, which are highly
sensitive to touch and are capable of very fine discrimination, and take up much
space on the sensory
homunculus. |
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0 |
Ramachandran;
Phantoms in the Brain |
26 |
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For the most part, the homunculus map is orderly though upside down: the foot is represented at the top and the outstretched
arms are at the bottom. |
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0 |
Ramachandran;
Phantoms in the Brain |
27 |
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The homunculus map is not entirely continuous. The face is not
near the neck, but is below
the hand.
The genitals,
instead of being between the thighs, are located below
the foot. |
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1 |
Ramachandran;
Phantoms in the Brain |
27 |
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A map of the entire body surface exists in the brain, with each half of the body mapped onto the opposite side of the brain. |
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0 |
Ramachandran;
Phantoms in the Brain |
28 |
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The results of surgical research on monkeys shows that you can change the map; you can alter the brain circuitry of an adult animal, and connections can be modified over distances spanning a centimeter or more. |
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1 |
Ramachandran;
Phantoms in the Brain |
28 |
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It takes
years to train a
monkey to carry out even very simple
tasks. |
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0 |
Ramachandran;
Phantoms in the Brain |
29 |
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Patients who have recently
amputated arms can have a phantom arm transform the homunculus map resulting
in a peculiar mapping of body parts in the brain, with a face lying right
beside the hand. |
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1 |
Ramachandran;
Phantoms in the Brain |
31 |
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Using MEG, it is relatively easy
and just a two hour session to map out the entire body surface on the brain
surface of any person willing to sit under the magnet. |
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2 |
Ramachandran;
Phantoms in the Brain |
31 |
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The map generated by NEG is
quite similar to the original Pintail homunculus map, and there is very
little variation from person to person and the gross layout of the map. |
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0 |
Ramachandran;
Phantoms in the Brain |
31 |
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Research results suggest that
brain maps can change, sometimes with astonishing rapidity. |
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0 |
Ramachandran;
Phantoms in the Brain |
31 |
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The research findings of
modifying the sensory home all colors flatly contradicts one of the most
widely accepted dogmas in neurology -- the fixed nature of connections in the
adult human brain. |
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0 |
Ramachandran;
Phantoms in the Brain |
31 |
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Highly precise and functionally
effective pathways can emerge in the adult brain as early as four weeks after
injury. |
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0 |
Ramachandran;
Phantoms in the Brain |
33 |
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Distinct neural pathways that
mediate sensation of warmth, cold and pain also originate on the skin
surface. |
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2 |
Ramachandran;
Phantoms in the Brain |
33 |
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The distinct neural sensory
pathways have their own target areas are maps in the brain, but the paths
used by them may be interlaced with each other in complicated ways. |
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0 |
Ramachandran;
Phantoms in the Brain |
34 |
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The question of how millions of
neural connections in the brain are hooked up so precisely during development
-- and the extent to which this precision is preserved when they are
recognized after injury -- is of great interest to scientists who are trying
to understand the development of pathways in the brain. |
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1 |
Ramachandran;
Phantoms in the Brain |
34 |
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Highly precise and organize new
connections can be formed into you adult brain and a few days. |
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0 |
Ramachandran;
Phantoms in the Brain |
34 |
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Research experiments don't tell
us how the new pathways actually emerge, what the underlying mechanisms are
at the cellular cellular level. |
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0 |
Ramachandran;
Phantoms in the Brain |
34 |
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There may be a tremendous
redundancy of connections in the normal adult brain, but most of them are
nonfunctional or have no obvious function. |
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0 |
Ramachandran;
Phantoms in the Brain |
35 |
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Far from signaling a specific
location on the skin, each neuron in the map may be in a state of dynamic
equilibrium with other adjacent neurons; its significance depends strongly on
what other neurons in the vicinity are doing (or not doing). |
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1 |
Ramachandran;
Phantoms in the Brain |
35 |
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In the Penfield homunculus map the foot is beside the genitals. |
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0 |
Ramachandran;
Phantoms in the Brain |
36 |
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If a person loses a leg and is
then stimulated in the genitals, she will experience sensations in the
phantom leg. This is what you'd expect if input from the genital area were to
invade the territory vacated by the foot. |
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1 |
Ramachandran;
Phantoms in the Brain |
37 |
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Women with
a radical mastectomy
reported tingling,
erotic sensations in
their phantom nipples when
the earlobes were stimulated. |
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1 |
Ramachandran;
Phantoms in the Brain |
37 |
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In the Penfield
homunculus map,
the nipple and
ear are next to
each other. |
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0 |
Ramachandran;
Phantoms in the Brain |
37 |
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Many women
report feeling erotic sensations when the ears are nibbled during sexual foreplay. |
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0 |
Ramachandran;
Phantoms in the Brain |
37 |
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In the original Penfield homunculus map the genital
area of women is mapped right
next to the nipples. |
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0 |
Ramachandran;
Phantoms in the Brain |
37 |
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People with gaze
tinnitus hear a ringing
sound when they look
left or right. |
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0 |
Ramachandran;
Phantoms in the Brain |
37 |
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Patients with gaze tinnitus had suffered damage to the auditory nerve. Once in the brainstem, the auditory nerve hooks up with the auditory nucleus, which is right
next to the oculomotor nerve nucleus, which sends commands to the eyes, instructing them to move. |
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0 |
Ramachandran;
Phantoms in the Brain |
38 |
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The study of phantom limbs offers fascinating glimpses of
the architecture of the brain and its astonishing capacity for growth and renewal. |
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1 |
Ramachandran;
Phantoms in the Brain |
39 |
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Chasing the Phantom |
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1 |
Ramachandran;
Phantoms in the Brain |
39 |
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Biologist J.B.S.
Haldane -- more species of beetles than
any other group of
living creatures. |
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0 |
Ramachandran;
Phantoms in the Brain |
39 |
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Brain maps
abound. |
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0 |
Ramachandran;
Phantoms in the Brain |
39 |
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30 different maps concerned with vision. |
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0 |
Ramachandran;
Phantoms in the Brain |
39 |
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For tactile or somatic
sensations -- touch, joint and muscle sense -- there are several maps. |
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0 |
Ramachandran;
Phantoms in the Brain |
39 |
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Penfield homunculus map |
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0 |
Ramachandran;
Phantoms in the Brain |
39 |
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Tactile or somatic sensation
maps are largely stable throughout life, thus helping ensure that perception
is usually accurate and reliable. |
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0 |
Ramachandran;
Phantoms in the Brain |
39 |
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Tactile or somatic sensation
maps are being constantly updated and refined in response to vagaries of
sensory input. |
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0 |
Ramachandran;
Phantoms in the Brain |
40 |
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Neurology is full of surprises. |
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1 |
Ramachandran;
Phantoms in the Brain |
41 |
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The brain region responsible for
smooth, coordinated swinging of the arms when we walk is quite different from
the one that controls gesturing. |
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1 |
Ramachandran;
Phantoms in the Brain |
42 |
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A person's body image is laid
down partly by genes and partly by later motor and tactile experience. |
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1 |
Ramachandran;
Phantoms in the Brain |
42 |
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Each of us has an entirely
hardwired image of the body and limbs at birth -- an image that can survive
indefinitely, even in the face of contradictory information from the senses. |
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0 |
Ramachandran;
Phantoms in the Brain |
52 |
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Pain is one
of the most poorly understood of all sensory experiences. |
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10 |
Ramachandran;
Phantoms in the Brain |
53 |
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Consider what happens in your
brain when motor commands
are sent from the pre-motor and motor cortex to make it this. What your hand is clenched, feedback signals
from your muscles and joints are sent back through the spinal cord to your
brain. This proprioceptive feedback applies brakes, automatically, with
astonishing speed and precision. |
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1 |
Ramachandran;
Phantoms in the Brain |
61 |
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Galvanic skin response (GSR) |
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8 |
Ramachandran;
Phantoms in the Brain |
62 |
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Your body image, despite all its
appearance of durability, is an entirely transitory internal construct that
can be profoundly modified as a result of tactile and somatosensory inputs. |
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1 |
Ramachandran;
Phantoms in the Brain |
63 |
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The Zombie in the Brain |
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1 |
Ramachandran;
Phantoms in the Brain |
66 |
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The human brain contains
multiple areas for processing images, each of which is composed of an
intricate network of neurons that is specialized for extracting certain types
of information from the image. |
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3 |
Ramachandran;
Phantoms in the Brain |
66 |
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Any object invokes a pattern of
neural activity -- unique to each object -- among a subset of these the
multiple image processing areas. |
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0 |
Ramachandran;
Phantoms in the Brain |
66 |
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When you look at a pencil, a
book, or a face, a different pattern of nerve activity is elicited for each
case, "informing" higher brain centers about what you are looking
at. |
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0 |
Ramachandran;
Phantoms in the Brain |
66 |
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The patterns of neural activity
symbolize the representational objects in much the same way that the
squiggles of ink on paper symbolize or represent objects in the world. |
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0 |
Ramachandran;
Phantoms in the Brain |
66 |
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As scientists trying to
understand visual processes, our goal is to decipher the code used by the
brain to create symbolic descriptions. |
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0 |
Ramachandran;
Phantoms in the Brain |
67 |
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A perception involves much more
than replicating an image in your brain. Perceptions can change radically
even when the image on your retina stays the same. Example is a Necker cube. |
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1 |
Ramachandran;
Phantoms in the Brain |
67 |
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Necker cube |
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0 |
Ramachandran;
Phantoms in the Brain |
67 |
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Every act of
perception involves
an act of judgment by the
brain. |
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0 |
Ramachandran;
Phantoms in the Brain |
68 |
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In making judgments for perception, the brain takes advantage of the
fact that the world
we live in
is not chaotic and amorphous; it has stable physical properties. |
|
1 |
Ramachandran;
Phantoms in the Brain |
68 |
|
During evolution -- and partly
during childhood as a result of learning -- the stable properties of the
world become incorporated into the visual areas of the brain, and certain
"assumptions" or hidden knowledge about the world that can be used
to eliminate ambiguity and perception. |
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0 |
Ramachandran;
Phantoms in the Brain |
68 |
|
As an example of worldly
knowledge, when a set of dots moved in unison -- like the spots on her
leopard -- they usually belong to a single object. |
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0 |
Ramachandran;
Phantoms in the Brain |
68 |
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Helmholtz
called perception an "unconscious inference." |
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0 |
Ramachandran;
Phantoms in the Brain |
71 |
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Visual cortex (diagram) Bottom of the human brain viewed from
below, showing the arrangements of fibers going from the retina to the visual
cortex. |
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3 |
Ramachandran;
Phantoms in the Brain |
72 |
|
One of the most famous examples
in neurology is a case of a Swiss woman who suffered from "motion
blindness" resulting from bilateral damage to an area of the brain
called the middle temporal (MT) area. |
|
1 |
Ramachandran;
Phantoms in the Brain |
72 |
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When patients suffer bilateral damage to an area V4, they become completely for color-blind. |
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0 |
Ramachandran;
Phantoms in the Brain |
73 |
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Excluding areas
MT and V4, the remaining
30 visual areas are undoubtedly doing something important, but
scientists still have don't
have clear ideas about
what their functions might be. |
|
1 |
Ramachandran;
Phantoms in the Brain |
73 |
|
Despite the
bewildering complexity of the areas, the visual system appears to have a relatively simple overall organization. |
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0 |
Ramachandran;
Phantoms in the Brain |
73 |
|
Messages from the eyeballs go through the optic nerve and immediately bifurcate along two pathways -- one phylogenetically old and the second, newer pathway that is most highly developed in primates, including humans. |
|
0 |
Ramachandran;
Phantoms in the Brain |
73 |
|
The older
pathway goes from the eyes straight down to the superior colliculus in the brainstem, and from there
eventually gets to the higher cortical areas especially in the parietal lobes. |
|
0 |
Ramachandran;
Phantoms in the Brain |
73 |
|
The newer pathway travels from the eyes to the lateral geniculate nucleus, which
is a relay station en
route to the primary visual cortex. From there, visual information is transmitted
to the 30 or so visual areas for
further processing. |
|
0 |
Ramachandran;
Phantoms in the Brain |
73 |
|
Why do we have an old
pathway and a new
pathway? |
|
0 |
Ramachandran;
Phantoms in the Brain |
73 |
|
One possibility is that the older pathway has been preserved as a sort of early warning system and is
concerned with what is sometimes called "orienting
behavior." |
|
0 |
Ramachandran;
Phantoms in the Brain |
73 |
|
The older
pathway tells where
the object is, enabling
a person to swivel
eyeballs and turn head and body to look at it. This primitive reflex brings potentially important events into
the fovea, the high-acuity central region of the eyes. |
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0 |
Ramachandran;
Phantoms in the Brain |
73 |
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The
phylogenetically newer system determines what the object is. |
|
0 |
Ramachandran;
Phantoms in the Brain |
74 |
|
The "new" visual
pathway goes to the visual cortex then diverges into two pathways -- a
"how" pathway in the parietal lobes that is concerned with
grasping, navigating and other spatial functions, and the second,
"what" pathway in the temporal lobes concerned with the recognizing
objects. (diagram) |
|
1 |
Ramachandran;
Phantoms in the Brain |
75 |
|
Larry Weiskrantz, a scientist
working at Oxford University, discovered and named the "blindsight"
phenomenon. |
|
1 |
Ramachandran;
Phantoms in the Brain |
76 |
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Blindsight phenomenon -- when
the primary visual cortex is destroyed and nonfunctional, the
phylogenetically primitive orienting pathway is still intact and is presumed
to mediate blindsight. |
|
1 |
Ramachandran;
Phantoms in the Brain |
76 |
|
Even though visual input fails
to activate the newer visual pathway, which is damaged, the light gets
transmitted through the superior colliculus to higher brain centers such as
the parietal lobes. The old visual pathway can use input for all kinds of behavior,
even though the person is completely unaware of what is going on. |
|
0 |
Ramachandran;
Phantoms in the Brain |
77 |
|
The ability to identify an
object is contained in the "what" pathway. The fact that the
majority of the ~30 visual areas are located in this system gives some idea
of its importance. |
|
1 |
Ramachandran;
Phantoms in the Brain |
77 |
|
Researchers including Edmund
Rolls, have found that if you put an electrode into a monkey's brain to
monitor the activity of cells in the "what" system, there is a
particular region where you will find so-called "face cells" --
each neuron fires only in response to the photograph of the particular face. |
|
0 |
Ramachandran;
Phantoms in the Brain |
77 |
|
The existence of a cells does
not mean that a single cell is somehow associated with the recognition of the
particular face; the recognition probably relies on a network involving many
thousands of synapses. |
|
0 |
Ramachandran;
Phantoms in the Brain |
78 |
|
Face cells exist as a critical
part of the network of cells involved in the recognition of faces and other
objects. |
|
1 |
Ramachandran;
Phantoms in the Brain |
78 |
|
Once face cells are activated,
their message is relayed to higher areas in the temporal lobes concerned with
semantics -- all your memories and knowledge of that person. |
|
0 |
Ramachandran;
Phantoms in the Brain |
80 |
|
The discovery of multiple visual
areas and the division of labor between the two pathways is a landmark
achievement in neuroscience, but it barely begins to scratch the surface of
the problem of understanding vision. |
|
2 |
Ramachandran;
Phantoms in the Brain |
81 |
|
The discovery of multiple
specialized areas and vision makes the problem of visions sizable, at least
in the foreseeable future. |
|
1 |
Ramachandran;
Phantoms in the Brain |
81 |
|
Answers to big questions such as
"What is this self?" |
|
0 |
Ramachandran;
Phantoms in the Brain |
82 |
|
Many illusions were used by
Gestalt psychologists to show that perception is always relative -- never
absolute -- always dependent on the surrounding context. |
|
1 |
Ramachandran;
Phantoms in the Brain |
85 |
|
The Secret Life of James Thurber |
|
3 |
Ramachandran;
Phantoms in the Brain |
88 |
|
What is visual
imagination? |
|
3 |
Ramachandran;
Phantoms in the Brain |
88 |
|
The human
visual system and an astonishing
ability to make educated
guesses based on the fragmentary and evanescent images dancing in the eyeballs. |
|
0 |
Ramachandran;
Phantoms in the Brain |
88 |
|
The brain has a remarkable capacity for dealing with inexplicable
gaps in the visual
image -- a process that is sometimes loosely
referred to as "filling-in." |
|
0 |
Ramachandran;
Phantoms in the Brain |
88 |
|
"Filling-in" occurs at several different
stages of the visual
process. |
|
0 |
Ramachandran;
Phantoms in the Brain |
89 |
|
Migraine sufferers are well aware of this
extraordinary phenomenon the brain has for filling-in. |
|
1 |
Ramachandran;
Phantoms in the Brain |
89 |
|
For migraine
sufferers, when a blood
vessel goes into a spasm, they temporarily lose a patch of visual cortex and this causes a corresponding blind region -- a scotoma -- visual field. |
|
0 |
Ramachandran;
Phantoms in the Brain |
89 |
|
Instead of seeing an enormous void, the region
corresponding to the missing object is simply covered with the same color of paint or wallpaper. |
|
0 |
Ramachandran;
Phantoms in the Brain |
109 |
|
In the not-too-distant past,
physiologist drew diagrams with the image is being processed at one level,
then said up to the next level, until the Gestalt eventually emerged. |
|
20 |
Ramachandran;
Phantoms in the Brain |
109 |
|
This was the bottom-up view of
vision, championed by artificial intelligence research is over the last three
decades. |
|
0 |
Ramachandran;
Phantoms in the Brain |
109 |
|
A newer view of perception --
championed by Gerald Edelman of Neurosciences Institute in La Jolla,
California -- suggests that the brain's information flow is continually
reflected back and forth, taking many different paths, sometimes emerging,
sometimes reinforcing, sometimes traveling in opposite directions. |
|
0 |
Ramachandran;
Phantoms in the Brain |
110 |
|
Consider what's going on in your
brain when you imagine a cat. |
|
1 |
Ramachandran;
Phantoms in the Brain |
110 |
|
Our memories of all cats and
this particular cat flow from top to bottom -- from higher regions to the
primary visual cortex, and the combined activities of all these areas lead to
the perception of an imaginary cat. |
|
0 |
Ramachandran;
Phantoms in the Brain |
110 |
|
There is a dynamic interplay
between the brain's early visual areas and the higher visual centers,
culminating in a virtual reality simulation of a cat. |
|
0 |
Ramachandran;
Phantoms in the Brain |
110 |
|
Certain brain injury patients
may be filling in missing information using high-level stored memories. |
|
0 |
Ramachandran;
Phantoms in the Brain |
110 |
|
In a particular syndrome, the
images are based on conceptual completion rather than perceptual completion;
the image's being filled-in or coming from memory (top down) -- not from the
outside (bottom-up). |
|
0 |
Ramachandran;
Phantoms in the Brain |
110 |
|
If early visual areas are
activated each time you imagine something, these early visual sensory
pathways produce a baseline signal, which vetoes the activity evoked by
top-down imagery. |
|
0 |
Ramachandran;
Phantoms in the Brain |
111 |
|
If early visual pathways are
damaged, the baseline signal is removed and you hallucinate. |
|
1 |
Ramachandran;
Phantoms in the Brain |
111 |
|
Interaction between top-down
imagery and bottom-up sensory signals in perception. |
|
0 |
Ramachandran;
Phantoms in the Brain |
111 |
|
It is suggested that all these
bizarre visual hallucinations are simply an exaggerated version of the
processes that occur normally in the brain every time we let our imagination
run free. |
|
0 |
Ramachandran;
Phantoms in the Brain |
111 |
|
Somewhere in the confused welter
of interconnecting forward andbackward pathways is the interface between
vision and imagination. |
|
0 |
Ramachandran;
Phantoms in the Brain |
112 |
|
Perception is really the end
result of a dynamic interplay between sensory signals and high-level stored
information about visual images from the past. |
|
1 |
Ramachandran;
Phantoms in the Brain |
112 |
|
Each time anyone of us
encounters an object, the visual system begins a constant questioning
process. Fragmentary evidence comes in and the higher visual centers project
partial "best fit" answers back to lower visual areas including the
primary visual cortex. |
|
0 |
Ramachandran;
Phantoms in the Brain |
112 |
|
The massive feedforward and
feedback projections conduct successive iterations that enable us to home in
on the closest approximation to the truth. |
|
0 |
Ramachandran;
Phantoms in the Brain |
112 |
|
To overstate the argument
deliberately, we are hallucinating all the time and what we call perception
is arrived at by simply determining which hallucination this conforms to the
current sensory input. |
|
0 |
Ramachandran;
Phantoms in the Brain |
113 |
|
Through the Looking Glass |
|
1 |
Ramachandran;
Phantoms in the Brain |
116 |
|
Attention requires a bit
dissipation of many far-flung regions of the brain. |
|
3 |
Ramachandran;
Phantoms in the Brain |
116 |
|
The visual, auditory and
somatosensory systems are involved in attention. |
|
0 |
Ramachandran;
Phantoms in the Brain |
116 |
|
The reticulata activating system
in the brain stem project to widely to vast regions of the brain and
activates the entire cerebral cortex, leading to arrive so and wakefulness or
when needed, a small portion of the cortex leading to selective attention. |
|
0 |
Ramachandran;
Phantoms in the Brain |
116 |
|
The limbic system is concerned
with emotional behavior and evaluation of the emotional significance and
potential value of events in the external world. |
|
0 |
Ramachandran;
Phantoms in the Brain |
116 |
|
The frontal lobes are concerned
with abstract processes like judgment, foresight and planning. |
|
0 |
Ramachandran;
Phantoms in the Brain |
116 |
|
All of these areas are
interconnected in a positive feedback loop -- a recursive, acolyte
reverberation -- it takes a stimulus from the outside world, extracts its
salient features and then bounces it from region to region, before eventually
figure out what it is and how to respond to it. |
|
0 |
Ramachandran;
Phantoms in the Brain |
116 |
|
Should I fight, flee, eat or
kiss? |
|
0 |
Ramachandran;
Phantoms in the Brain |
116 |
|
The simultaneous deployment of
all these mechanisms culminates in perception. |
|
0 |
Ramachandran;
Phantoms in the Brain |
117 |
|
Neglect occurs primarily after
injury to the right parietal lobe and not to the left. |
|
1 |
Ramachandran;
Phantoms in the Brain |
117 |
|
Given its role in holistic
aspects of vision, the right hemisphere has a broad searchlight of attention
that it encompasses both the entire last an entire right visual fields. |
|
0 |
Ramachandran;
Phantoms in the Brain |
117 |
|
The left hemisphere has a much
smaller searchlight, which is confined entirely to the right side of the
world (perhaps because it is so busy with other things, such as language). |
|
0 |
Ramachandran;
Phantoms in the Brain |
117 |
|
If the left hemisphere is
damaged, it loses its Searchlight, but the right can compensate because it
casts a Searchlight on the entire world. |
|
0 |
Ramachandran;
Phantoms in the Brain |
117 |
|
With the right hemisphere is
damaged, the global searchlight is gone but the left hemisphere cannot fully
compensate for the loss because it's searchlight is confined only to the
right side. |
|
0 |
Ramachandran;
Phantoms in the Brain |
117 |
|
The preceding several statements
explain why neglect is only seen in patients whose right hemisphere is
damaged. |
|
0 |
Ramachandran;
Phantoms in the Brain |
127 |
|
The Sound of One Hand Clapping |
|
10 |
Ramachandran;
Phantoms in the Brain |
131 |
|
Anosognosia is an extraordinary
syndrome about which almost nothing is known. |
|
4 |
Ramachandran;
Phantoms in the Brain |
132 |
|
Neurological theories of denial
argue that denial is a direct consequence of neglect, which occurs after
right hemisphere damage and leaves patients profoundly indifferent to
everything that goes on within the left side of the world, including the last
side of their own bodies. |
|
1 |
Ramachandran;
Phantoms in the Brain |
133 |
|
A century of clinical neurology
and a shown clearly that the two hemispheres are specialized for different
mental capacities and that the most striking asymmetry involves language. |
|
1 |
Ramachandran;
Phantoms in the Brain |
133 |
|
The left hemisphere is
specialized not only for the actual production of speech sounds but also for
the imposition of semantic structure own speech and for much of what we call
semantics -- comprehension of meaning. |
|
0 |
Ramachandran;
Phantoms in the Brain |
133 |
|
The right hemisphere seems to be
concerned with more subtle aspects of language such as nuances of metaphor,
allegory and ambiguity -- skills that are vital for the advance of
civilizations through poetry, myth and drama. |
|
0 |
Ramachandran;
Phantoms in the Brain |
133 |
|
Of the brain hemispheric
specialization's involved vision and emotion. |
|
0 |
Ramachandran;
Phantoms in the Brain |
133 |
|
The right hemisphere it can is
concerned with holistic aspects of vision such as seeing the overall picture,
reading facial expressions and responding with appropriate emotion to
evocative situations. |
|
0 |
Ramachandran;
Phantoms in the Brain |
134 |
|
After right hemisphere strokes,
patients tend to be blissfully unconcerned about their predicament, even
mildly euphoric, because without the emotional right hemisphere they simply
don't comprehend the magnitude of their loss. |
|
1 |
Ramachandran;
Phantoms in the Brain |
134 |
|
At any given moment in our
waking lives, our brains are flooded with a bewildering array of sensory
inputs, all of which must be incorporated into a coherent perspective that's
based on what stored memories already tell us is true about ourselves and the
world. |
|
0 |
Ramachandran;
Phantoms in the Brain |
134 |
|
In order to generate coherent
actions, the brain must have some way of sifting through the superabundance
of detail and ordering it into a stable and internally coherent belief system
-- a story that makes sense of the available evidence. |
|
0 |
Ramachandran;
Phantoms in the Brain |
136 |
|
The left hemisphere's job is to
create a belief system or model and a full new experiences into this belief
system. |
|
2 |
Ramachandran;
Phantoms in the Brain |
136 |
|
The right hemisphere's strategy
is to play "devil's advocate," to question the status quo and look
for global inconsistencies. |
|
0 |
Ramachandran;
Phantoms in the Brain |
136 |
|
If the right hemisphere is
damaged, the left hemisphere has free rein to pursue its denials,
confabulations and other strategies. In the absence of the counterbalance or
"reality check" provided by the right hemisphere, there is no limit
to how far a person will wander along the delusional path. |
|
0 |
Ramachandran;
Phantoms in the Brain |
137 |
|
Talking to denial patients bring
us face to face with some of the most fundamental questions one can ask as a
conscious human being -- what is the self? |
|
1 |
Ramachandran;
Phantoms in the Brain |
147 |
|
People spend a third of their
lives sleeping, and 25% of that time their eyes are moving as they experience
vivid, emotional dreams. |
|
10 |
Ramachandran;
Phantoms in the Brain |
148 |
|
Memory has been called the holy
grail of neuroscience. Although many a weighty tome has been written on the
topic, in truth we know very little about it. |
|
1 |
Ramachandran;
Phantoms in the Brain |
148 |
|
Much research work in recent
decades has been focused on the memory trace formed by physical changes
between synapses and the chemical cascades within their cells. |
|
0 |
Ramachandran;
Phantoms in the Brain |
148 |
|
Much research on memory emanated
from the study of patient HM, whose hippocampus was removed surgically for
epilepsy. |
|
0 |
Ramachandran;
Phantoms in the Brain |
149 |
|
For reasons not understood, most
patients tend to recover completely from the denial syndrome after two or
three weeks. |
|
1 |
Ramachandran;
Phantoms in the Brain |
152 |
|
Most neurologists are very
skeptical of the ideas of Sigmund Freud. The entire neuroscience community is
deeply suspicious of him because he touted elusive aspects of human nature
that ring true but that cannot be empirically tested. |
|
3 |
Ramachandran;
Phantoms in the Brain |
152 |
|
Even though Freud wrote a great
deal of nonsense, there is no denying that he was a genius, especially when
you consider the social and intellectual climate of Vienna at the turn of the
century. |
|
0 |
Ramachandran;
Phantoms in the Brain |
152 |
|
Freud's most valuable
contribution was his discovery that your conscious mind is simply a façade
and that you are completely unaware of 90% of what really goes on in your
brain. |
|
0 |
Ramachandran;
Phantoms in the Brain |
153 |
|
Psychological defenses and the central role they play in human
nature. |
|
1 |
Ramachandran;
Phantoms in the Brain |
153 |
|
Denial -- |
|
0 |
Ramachandran;
Phantoms in the Brain |
153 |
|
Repression -- |
|
0 |
Ramachandran;
Phantoms in the Brain |
153 |
|
Reaction formation -- the
propensity to assert the exact opposite of what one suspects to be true of
oneself. |
|
0 |
Ramachandran;
Phantoms in the Brain |
154 |
|
Rationalization -- |
|
1 |
Ramachandran;
Phantoms in the Brain |
154 |
|
Humor -- |
|
0 |
Ramachandran;
Phantoms in the Brain |
154 |
|
Projection -- when, wanting to
avoid confronting a malady or disability, we conveniently attributed to
someone else. |
|
0 |
Ramachandran;
Phantoms in the Brain |
158 |
|
"The Unbearable Lightness
of Being" |
|
4 |
Ramachandran;
Phantoms in the Brain |
162 |
|
When specific portions of that
what pathway are damaged, patients lose the ability to recognize faces, even
those of close friends and relatives. |
|
4 |
Ramachandran;
Phantoms in the Brain |
162 |
|
Face recognition areas (found on
both sides of the brain) relay information to the limbic system, down deep in
the middle of the brain, which then helps generate emotional responses to
particular faces. |
|
0 |
Ramachandran;
Phantoms in the Brain |
162 |
|
A disconnection could exist
between the temporal lobe facial recognition area and the amygdala in the
limbic system. |
|
0 |
Ramachandran;
Phantoms in the Brain |
164 |
|
The dampness
of your hands is a sure
giveaway of how you
feel toward a person. |
|
2 |
Ramachandran;
Phantoms in the Brain |
164 |
|
You can measure the emotional
reaction very easily by placing electrodes on your palm and recording changes
in the electrical resistance of your skin. |
|
0 |
Ramachandran;
Phantoms in the Brain |
164 |
|
Call the galvanic skin response
or GSR, this simple little test of skin resistance of your palms forms the
basis of the lie detector test. |
|
0 |
Ramachandran;
Phantoms in the Brain |
164 |
|
When you tell a fib, your palms
sweat ever so slightly. |
|
0 |
Ramachandran;
Phantoms in the Brain |
174 |
|
God and the Limbic System |
|
10 |
Ramachandran;
Phantoms in the Brain |
175 |
|
It has been reported that a man in Canada stimulated his temporal lobe and experienced God. |
|
1 |
Ramachandran;
Phantoms in the Brain |
175 |
|
What would happen if you tried
the stimulation device on an atheist brain? Would he experience God? Maybe we should try the
stimulation device on Francis
Crick. |
|
0 |
Ramachandran;
Phantoms in the Brain |
175 |
|
Scientists have suspected that
the temporal lobes, especially with the left lobe, are somehow involved in religious experience. |
|
0 |
Ramachandran;
Phantoms in the Brain |
175 |
|
Every medical
student is taught that patients with epileptic seizures originating in the temporal lobe can have intense, spiritual
experiences
during the seizure and sometimes become preoccupied with religious and moral issues even during the seizure-free periods. |
|
0 |
Ramachandran;
Phantoms in the Brain |
176 |
|
Many traits
make us uniquely human,
but none is more enigmatic than religion -- our propensity to believe in God or in some higher power that transcends mere appearances. |
|
1 |
Ramachandran;
Phantoms in the Brain |
177 |
|
Limbic system
gets its input from all sensory systems -- vision, touch, hearing, taste and smell. |
|
1 |
Ramachandran;
Phantoms in the Brain |
177 |
|
The smell
sense in is directly
wired to the limbic
system,
going straight to the amygdala. |
|
0 |
Ramachandran;
Phantoms in the Brain |
177 |
|
The amygdala serves as a gateway into the limbic system. |
|
0 |
Ramachandran;
Phantoms in the Brain |
177 |
|
In lower
mammals, smell is intimately linked with emotion, territorial
behavior, aggression and sexuality. |
|
0 |
Ramachandran;
Phantoms in the Brain |
177 |
|
The limbic system's output is geared primarily toward the experience and expression of emotions. |
|
0 |
Ramachandran;
Phantoms in the Brain |
177 |
|
The experience
of emotion is a mediated by back-and-forth connections with
the frontal lobes, and much of the richness of your inner emotional life probably depends on these interactions. |
|
0 |
Ramachandran;
Phantoms in the Brain |
177 |
|
The outward
expression of emotions
requires the participation of the hypothalamus, a control center with three major outputs. |
|
0 |
Ramachandran;
Phantoms in the Brain |
177 |
|
First, hypothalamic
nuclei send hormonal and neural signals to the pituitary gland, which is often described as the conductor of the endocrine orchestra. Hormones released through the endocrine
system influence almost every part of the human body. |
|
0 |
Ramachandran;
Phantoms in the Brain |
177 |
|
Second, the hypothalamus sends commands to the autonomic
nervous system,
which controls various vegetative and bodily functions, including the
production of tears, saliva and sweat and the control of blood pressure,
heart rate, body temperature, respiration, bladder function, defecation, etc. |
|
0 |
Ramachandran;
Phantoms in the Brain |
177 |
|
Third, hypothalamus output drives actual
behaviors, often remembered by the mnemonic the "four F's" -- fighting, fleeing, feeding
and sexual
behavior. |
|
0 |
Ramachandran;
Phantoms in the Brain |
179 |
|
Much of our knowledge about the functions of the limbic system come from patients
who had epileptic seizures originating in this part of the brain. |
|
2 |
Ramachandran;
Phantoms in the Brain |
179 |
|
When you hear the word epilepsy you think of someone
having fits or a seizure -- a powerful involuntary contraction
of all muscles of the body -- called a grand mal seizure. |
|
0 |
Ramachandran;
Phantoms in the Brain |
179 |
|
It seems ironic that this sense of enlightenment, this absolute conviction that truth is revealed at last, should
derive from limbic structures concerned with emotions rather than from the thinking,
rational parts of the brain that take so much pride in their ability to discern truth and falsehood. |
|
0 |
Ramachandran;
Phantoms in the Brain |
179 |
|
Seizures
usually last only a
few seconds each episode, but these brief temporal lobe storms can
sometimes permanently alter the patient's
personality
so that even between seizures he is different from other people. |
|
0 |
Ramachandran;
Phantoms in the Brain |
180 |
|
Epileptic changes give rise to what some neurologists call "temporal lobe personality." Patients have heightened emotions and see cosmic significance in trivial events. |
|
1 |
Ramachandran;
Phantoms in the Brain |
180 |
|
Epileptic patients have on occasion given neurologists hundreds of pages of written text filled with mystical symbols and notations. |
|
0 |
Ramachandran;
Phantoms in the Brain |
180 |
|
Every medical
student is taught that they should never expect to see a "textbook case" in the wards, for these are
merely composites
concocted by the authors of the medical tomes. |
|
0 |
Ramachandran;
Phantoms in the Brain |
180 |
|
A patient relates, "I had
my first seizure when I was eight years old. I remember seeing a bright light before I fell to the ground and wondered where it came from." |
|
0 |
Ramachandran;
Phantoms in the Brain |
181 |
|
A paradoxical
combination of loss of libido and preoccupation with sexual rituals is not
unusual in patients with temporal lobe epilepsy. |
|
1 |
Ramachandran;
Phantoms in the Brain |
183 |
|
Evolutionary psychology used to be called sociobiology, a term that fell into disrepute for political reasons. |
|
2 |
Ramachandran;
Phantoms in the Brain |
183 |
|
According to evolutionary
psychology,
many human
traits and propensities, even ones we might ordinarily be tempted
to attribute to
culture,
may in fact have been specifically chosen by the guiding hand of natural selection because of their adaptive value. |
|
0 |
Ramachandran;
Phantoms in the Brain |
183 |
|
One good example of evolutionary psychology is the tendency for men to be polygamous and promiscuous whereas women tend to be more monogamous. |
|
0 |
Ramachandran;
Phantoms in the Brain |
183 |
|
A woman invests a good deal more time and effort in each offspring, so that she has to be very discerning in her choice of sexual partners. |
|
0 |
Ramachandran;
Phantoms in the Brain |
183 |
|
For a man, the optimal evolutionary
strategy is to disseminate
his genes as widely
as possible, given his few
seconds of investment in
each encounter. |
|
0 |
Ramachandran;
Phantoms in the Brain |
184 |
|
We must be careful not to carry
these evolutionary psychology
arguments too far. |
|
1 |
Ramachandran;
Phantoms in the Brain |
184 |
|
Just because a trait is universal -- present in all cultures including cultures that have
never been in contact -- it doesn't follow that the trait is genetically specified. |
|
0 |
Ramachandran;
Phantoms in the Brain |
184 |
|
You would never argue that there
is a cooking module in the brain specified by cooking genes. |
|
0 |
Ramachandran;
Phantoms in the Brain |
184 |
|
How would an evolutionary
psychologist account
for the origins of religion? |
|
0 |
Ramachandran;
Phantoms in the Brain |
184 |
|
The universal human tendency to
seek authority figures -- giving rise to an organized priesthood, the
anticipation and rituals, chanting and dancing, sacrificial rites and
adherence to a moral code -- encourages conformist behavior and attributes
and contributes to the stability of the social group. |
|
0 |
Ramachandran;
Phantoms in the Brain |
184 |
|
Temporal lobe epilepsy patients experience a sense
of omnipotence and grandeur, as if to say,
"I am the chosen one. It is my
duty and privilege to transmit God's work to you lesser beings." |
|
0 |
Ramachandran;
Phantoms in the Brain |
184 |
|
Certain parts of the temporal
lobe play a more direct role in the genesis of omnipotence and grandeur
experiences than any other part of the brain. |
|
0 |
Ramachandran;
Phantoms in the Brain |
184 |
|
As far as the patient is
concerned, whatever changes that have occurred as a result of the omnipotence
and grandeur experiences are authentic -- and sometimes even desirable -- and
the physician has no right to attribute a value label to such esoteric embellishments
of personality. |
|
0 |
Ramachandran;
Phantoms in the Brain |
185 |
|
Most animals don't have the receptors or neural machinery for color vision. |
|
1 |
Ramachandran;
Phantoms in the Brain |
185 |
|
Our goal as scientists is to
discover how and why a religious sentiments originate in the brain, but this
has no bearing one way of the other on whether God really exists or not. |
|
0 |
Ramachandran;
Phantoms in the Brain |
185 |
|
Temporal lobe personality -- the
symptoms of this syndrome -- hyper Ingrassia, spiritual leanings and an
obsessive need to talk about their feelings and about religious and
metaphysical topics. |
|
0 |
Ramachandran;
Phantoms in the Brain |
186 |
|
Not every temporal
lobe epilepsy patient becomes religious. |
|
1 |
Ramachandran;
Phantoms in the Brain |
186 |
|
There are many parallel neural
connections between the temporal cortex and the amygdala. |
|
0 |
Ramachandran;
Phantoms in the Brain |
186 |
|
Some temporal lobe epilepsy
patients may have their personalities skewed in other directions, becoming
obsessed with writing, drawing, arguing philosophy, or being preoccupied with
sex. |
|
0 |
Ramachandran;
Phantoms in the Brain |
189 |
|
The Victorian era witnessed a
vigorous intellectual debate between two brilliant biologist -- Charles
Darwin and Alfred Russel Wallace. |
|
3 |
Ramachandran;
Phantoms in the Brain |
190 |
|
Most organisms evolve to become
more and more specialized as they take up new environmental bases make use
Métis. |
|
1 |
Ramachandran;
Phantoms in the Brain |
190 |
|
Humans have evolved an organ, a
brain, that gives us the capacity to eBay and specialization. |
|
0 |
Ramachandran;
Phantoms in the Brain |
191 |
|
Both Neanderthal and Cro-Magnon
on grid cranial capacities were actually larger than ours, and it's not
inconceivable that their latent potential intelligence may have been equal to
or greater than that of Homo sapiens. |
|
1 |
Ramachandran;
Phantoms in the Brain |
191 |
|
Darwin resolutely maintained
that natural selection was the prime force in evolution and could account for
the emergence of even the most esoteric mental traits, without the helping
hand of a supreme being. |
|
0 |
Ramachandran;
Phantoms in the Brain |
191 |
|
Esoteric and advanced human
traits like musical and mathematical ability are spaz specific manifestations
of what is usually called Gen. intelligence -- the culmination of a runaway
brain that exploded in size and complexity within the last 3 million years. |
|
0 |
Ramachandran;
Phantoms in the Brain |
192 |
|
Once this intelligence was in
place, you could use it for all sorts of other things, like the calculus,
music and the design of scientific instruments to extend the reach of our
senses. |
|
1 |
Ramachandran;
Phantoms in the Brain |
192 |
|
"Savants" are persons whose mental capacity or general intelligence is abysmally low, yet who have islands of astonishing talent. |
|
0 |
Ramachandran;
Phantoms in the Brain |
192 |
|
They are sometimes on record
with an IQ of less than 50, barely able to function in normal society, yet
they could eat with these generate an eight digit prime number. |
|
0 |
Ramachandran;
Phantoms in the Brain |
192 |
|
The realms of art and music are
punctuated with so that's who's talents have amazed and delighted audience
audiences through the ages. |
|
0 |
Ramachandran;
Phantoms in the Brain |
193 |
|
Signs of severe autism --
ritualistic behavior, inability to relate to others and limited language. |
|
1 |
Ramachandran;
Phantoms in the Brain |
193 |
|
Most geniuses are more like
idiots of eyes than they would care to admit -- extraordinarily talented in a
few domains are quite ordinary in other respects. |
|
0 |
Ramachandran;
Phantoms in the Brain |
197 |
|
Most savants are not truly
creative. |
|
4 |
Ramachandran;
Phantoms in the Brain |
198 |
|
Creative
spark of genius -- that universal "why didn't I think of that?" quality that characterizes the most beautiful and creative insights. |
|
1 |
Ramachandran;
Phantoms in the Brain |
199 |
|
The Woman Who Died Laughing |
|
1 |
Ramachandran;
Phantoms in the Brain |
201 |
|
The abnormal activity or damage
that sets people giving is almost always located in portions of the limbic
system, a set of structures including the hypothalamus, mammillary bodies and
cingulate gyrus that are involved in emotions. |
|
2 |
Ramachandran;
Phantoms in the Brain |
201 |
|
A relatively small cluster of
brain structures is involved in the phenomenon of laughter -- a sort of
"laughter circuit." |
|
0 |
Ramachandran;
Phantoms in the Brain |
201 |
|
Identifying the location of a
laughter circuit doesn't tell us why laughter exists or what its biological
function might be. |
|
0 |
Ramachandran;
Phantoms in the Brain |
201 |
|
Asking why a given trait evolve
(be it yawning, laughing, crying or dancing) is absolutely vital for
understanding its biological function. |
|
0 |
Ramachandran;
Phantoms in the Brain |
201 |
|
The brain was shaped by natural selection just as any other organ in the
body. |
|
0 |
Ramachandran;
Phantoms in the Brain |
201 |
|
The central tenet of
evolutionary psychology is that many salient aspects of human behavior are
mediated by specialized modules (mental organs) that are specifically shaped
by natural selection. |
|
0 |
Ramachandran;
Phantoms in the Brain |
201 |
|
As our Pleistocene ancestors
romped across ancient savannas in small bands, their brains evolve solutions
to their everyday problems -- things like recognizing kin, seeking healthy
sexual partners or eschewing foul-smelling food. |
|
0 |
Ramachandran;
Phantoms in the Brain |
202 |
|
Disgust for feces is probably hardwired in your brain. |
|
1 |
Ramachandran;
Phantoms in the Brain |
202 |
|
Dung beetles probably find the
bouquet of feces irresistible. |
|
0 |
Ramachandran;
Phantoms in the Brain |
202 |
|
Feces infected with cholera,
salmonella or shigella are especially foul smelling. |
|
0 |
Ramachandran;
Phantoms in the Brain |
202 |
|
The notion that there might be
genes are mental organs for cooking is silly, even though cooking is a
universal human trait. |
|
0 |
Ramachandran;
Phantoms in the Brain |
206 |
|
To an ethologist, any stereotyped vocalization almost always implies that the organism is trying to communicate something to others in the social group. |
|
4 |
Ramachandran;
Phantoms in the Brain |
206 |
|
Suggestion that the main purpose of laughter might be to allow the individual to alert others of the social
group (usually kin) that the detected anomaly is trivial, nothing to
worry about. |
|
0 |
Ramachandran;
Phantoms in the Brain |
206 |
|
Laughter is
so notoriously contagious, for the value of any such signal would be amplified as it spread through the social group. |
|
0 |
Ramachandran;
Phantoms in the Brain |
206 |
|
Once a mechanism
is in place, it could be easily exploited for other purposes. |
|
0 |
Ramachandran;
Phantoms in the Brain |
206 |
|
Feathers
evolved in birds
originally to provide insulation but were later adapted for flying. |
|
0 |
Ramachandran;
Phantoms in the Brain |
206 |
|
The ability to reinterpret events in the light of
new information may
have been refined through the generations to help people playfully juxtapose larger ideas
or concepts -- that
is, to be creative. |
|
0 |
Ramachandran;
Phantoms in the Brain |
207 |
|
Given the well-known role of the
limbic system and producing
an orienting response
to a potential threat or
alarm, it is not
altogether surprising that is that it is also involved in the aborted orienting reaction in
response to a false
alarm -- laughter. |
|
1 |
Ramachandran;
Phantoms in the Brain |
210 |
|
Three little bones in our middle ear -- the malleus,
incus and stapes -- are used for hearing. Two of these bones (malleus and incus) were originally part of the
lower jaw of our reptilian
ancestors, who use them for chewing. |
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3 |
Ramachandran;
Phantoms in the Brain |
210 |
|
Reptiles needed flexible,
multielement and multihinged jaws so they could swallow giant prey, whereas
mammals preferred a single strong bone for cracking nuts and chewing tough
substances like grains. |
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0 |
Ramachandran;
Phantoms in the Brain |
210 |
|
The smile takes the particular form that it does not because of natural
selection alone but because it evolved from the very opposite -- the threat grimace. |
|
0 |
Ramachandran;
Phantoms in the Brain |
212 |
|
"You Forgot to Deliver the
Twin" |
|
2 |
Ramachandran;
Phantoms in the Brain |
227 |
|
The Martians See Red? |
|
15 |
Ramachandran;
Phantoms in the Brain |
234 |
|
Francis Crick
and Christof Koch
have made the ingenious suggestion that qualia arise from a set of neurons in the lower layers of the primary sensory areas, because these are the ones that project to the frontal lobes where many of the higher functions are carried out. |
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7 |
Ramachandran;
Phantoms in the Brain |
234 |
|
Other researchers have suggested
that the patterns of nerve impulses (spikes) from widely separated brain
regions become synchronized when you pay attention to something and become
aware of it. It is the synchronization itself that leads to conscious awareness. |
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0 |
Ramachandran;
Phantoms in the Brain |
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