Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity

Parapharse Highlights — Rudolfo Llinás


Brain is a closed system modulated by the senses. (Llinás; I of the Vortex, 56)

Brain operates as a reality emulator. (Llinás; I of the Vortex, 13)

Consciousness is a product of thalamocortical activity. (Llinás; I of the Vortex, 131)

Nervous system is primarily self activating and capable of generating a cognitive representation of the external environment even in the absence of sensory input, as for example in dreams. (Llinás & Paré; Brain Modulated by Senses, 4)

Self-activating system is capable of emulating reality, even in the absence of input from reality, as occurs in dream states and daydreaming. (Llinás; I of the Vortex, 57)

Dreaming and wakefulness are so similar from electrophysiological and neurological points of view that wakefulness may be described as a dreamlike state modulated by sensory input. (Llinás & Paré; Brain Modulated by Senses, 6)

Nervous systems of animals evolved to provide a plan of action, one composed of goal-oriented, mostly short-lived prediction verified by moment-to-moment sensory input. The ability to predict evolved in tandem with increasingly complex movement strategies. (Llinás; I of the Vortex, 18, 25)


Evolution of Brain

Central nervous system must have developed over evolutionary time as a neuronal network that initially mediated simple reflex relations between sensory-motor connectivity. (Llinás & Paré; Brain Modulated by Senses, 5)

Brains are an evolutionary prerequisite for guided movement in primitive animals. (Llinás; I of the Vortex, 18)

Neurons came into existence to facilitate and orchestrate the ever-growing complexity of sensorimotor transformations. (Llinás; I of the Vortex, 82)

Cognition and consciousness probably evolved from the emotional states that trigger FAPs. (Llinás; I of the Vortex, 168)

Brain function implements what natural selection has found to be the most beneficial in terms of species survivability. (Llinás; I of the Vortex, 202)


Embryonic Development

Embryos generate continuous bouts of muscle tremor, not unlike small epileptic fits. Epileptic activity may be among the most primitive of all functional states -- a bit like sneezing. (Llinás; I of the Vortex, 63)


Oscillation, Coherence, Resonance

Simultaneity of neuronal activity is the most pervasive mode of operation of the brainNeuronal groups that oscillate in phase, i.e. coherently, support simultaneity of activity. (Llinás; I of the Vortex, 10)

Simultaneity of neuronal activity arising from intrinsic oscillatory electrical activity, resonance, and coherence are at the root of cognition. (Llinás; I of the Vortex, 12)


Gamma (~40 Hz) Oscillations

The 40-Hz oscillation is a candidate mechanism to produce temporal conjunction of rhythmic activity over a large ensemble of neurons. (Llinás; I of the Vortex, 124)

Experiments using magnetoencephalography (MEG) has demonstrated that the coherence and oscillations at 40 Hz may be centrally related to cognition. In a research environment, magnetoencephalography (MEG) can measure human brain function with a temporal resolution comparable to the central nervous system itself. Frequency response of the MEG instruments -- 1 kHz -- ensures that the electrical events coexisting with cognition may be measured in real time. (Llinás & Paré; Brain Modulated by Senses, 7)

In alert subjects, continuous 40-Hz oscillations can be recorded over large areas of the surface of the head.  These oscillations are not in phase, but exhibit a 12- to 13-ms phase shift between the rostral and caudal parts of the brain. (Llinás & Paré; Brain Modulated by Senses, 7)

Oscillation of the inferior olive results in a slight tremor that we all have at close to 10 Hz, even when we are not moving. (Llinás; I of the Vortex, 48)

No one can move faster than they can tremble. (Llinás; I of the Vortex, 48)

Regardless of training or personal effort, we cannot make movements faster than 10 Hz. (Llinás; I of the Vortex, 55)


Reentry and Recursion

Thalamic input from the cortex is far larger than from the peripheral sensory systems. This suggests that thalamocortical iterative activity is a main mechanism of brain function. (Llinás; I of the Vortex, 124)


Motor Patterns and FAPs

The brain's control of organized movement gave birth to the generation and nature of the mind. (Llinás; I of the Vortex, 50)

Sensory experience leading to active movement (motricity) through the function of prediction is the ultimate reason for the very existence of the central nervous system. (Llinás; I of the Vortex, 127)

Most  motor processing is handled by the cerebellum and its associated incoming and outgoing systems. (Llinás; I of the Vortex, 50)

Fixed Action Patterns (FAPs)  Automatic brain modules that make complex movements; well defined motor patterns, (walking, swallowing) (Llinás; I of the Vortex, 133)

Compare FAPs, which include the brain, with spinal reflexes in which the brain is not involved. (Llinás; I of the Vortex, 133)

FAPS group simple reflexes and lower FAPs into functional modules capable of more complex goal-oriented behavior. (Llinás; I of the Vortex, 134)

Central Pattern Generators (CPGs) generate neuronal patterns of activity that drive FAPs such as the walking FAP. (Llinás; I of the Vortex, 134)

When a soloist plays a concerto with a symphony orchestra, the concerto is played purely from memory. This highly specific motor pattern FAP is stored somewhere in the brain during practice sessions and is released during the performance. (Llinás; I of the Vortex, 169)

It is believed that the more complex FAPs are generated centrally by the basal ganglia. (Llinás; I of the Vortex, 136)

The basal ganglia represent some of the least understood areas of the brain, particularly in regard to their functional organization and architecture. (Llinás; I of the Vortex, 136)

Expression of FAPs is supported by the interplay among a number of vastly different parts of the nervous system and the basal ganglia. (Llinás; I of the Vortex, 136)

Majority of connections within the basal ganglia are inhibitory. (Llinás; I of the Vortex, 138)

Basal ganglia's intrinsic, reciprocal inhibitory activity keeps all potential FAPs from becoming active. (Llinás; I of the Vortex, 138)

When a FAP is executed, we say that it has been "liberated" into action. (Llinás; I of the Vortex, 138)

FAPs are most probably implemented at the level of the basal ganglia and put into context by the reentry of the basal ganglia output into the ever-cycling thalamocortical system. (Llinás; I of the Vortex, 144)

Language itself is a FAP. (Llinás; I of the Vortex, 151)

Scherzo of Schubert's Piano Quartet No.8 requires repetitive hand movements at approximately 8 Hz, which approaches the upper limit for finger movements by professional pianists. (Llinás; I of the Vortex, 30)

The spinal cord is capable of sustaining a rhythmic movement -- like a decapitated chicken -- but it cannot organize and generate a directed movement. (Llinás; I of the Vortex, 44)

Most movement control processing occurs in the cerebellum. (Llinás; I of the Vortex, 46)

Climbing fibers, which are some of the most powerful synaptic inputs in the vertebrate central nervous system, play an important role in motor control. (Llinás; I of the Vortex, 46)

Emotions are examples of internally generated intrinsic events that are premotor templates in primitive forms. (Llinás & Paré; Brain Modulated by Senses, 5)

Emotions are linked to the motor aspects of FAPs by access through the amygdala and the hypothalamus and their connectivity with the brain stem. (Llinás; I of the Vortex, 161)


Thalamocortical System

The thalamocortical system, by its hublike organization, allows radial communication of the thalamic nuclei with all aspects of the cortex. These cortical regions include the sensory, motor, and associational areas. These areas subserve a feedforward/feedback, reverberating flow of information. (Llinás; I of the Vortex, 126)

Perception at a given moment is represented by a small percentage of coherently oscillating cellular elements over the whole thalamocortical system. (Llinás & Paré; Brain Modulated by Senses, 14)



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