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

Synthesis of the Covington Theory of Consciousness

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My objective in this website has been to bring together salient features of interpretations by science experts into a synthesis of my own understanding of consciousness.

I have gleaned information from reference books, recent reports and articles in the journals Science and Nature, as well as sources on the Internet.  My statements and the interpretations I show are based upon authoritative statements by mature scientists whose specialties include neurology, physiology, medicine, psychology, and perhaps others.  I do not delve into the realms of philosophy or mysticism.

Consciousness is an emergent property of a biological network of neurons resulting from billions of years of evolution.

The intricacies of the neural network and system require that conceptual models and eventually mathematical models describing information flows in the neural network must be employed to help gain an understanding of the neural basis of consciousness.

Scientific examinations of brain functions typically observe brain operation from varied perspectives.  The differences in observations resulting from these varied perspectives must be resolved into a coherent whole.  Most significantly, the neural oscillations observable in the EEG must be resolved with the understanding of logical functions performed by the excitatory and inhibitory synapses of neurons, along with the population statistics implied by network degeneracy, redundancy, and failure tolerance. Information theory must be used, together with spectral analysis, and population statistics of neuron functions.

In my view, the thoughts of Damasio, LeDoux, Llinás, Rolls, Buzsáki, Greenfield, Fuster, Kandel, et al., lead to the dynamic core of consciousness hypothesized by Edelman.


‘The Self,’ Emotion, Stereotyped Movements, Consciousness

Antonio Damasio

Consciousness is a momentary creation of neural patterns, which describes a relation between the organism, on the one hand, and an object or event, on the other. (Damasio & Meyer; Consciousness Overview, 6)

 Core consciousness is the process of achieving a neural and mental pattern that brings together, in about the same instant, the pattern for the object, the pattern for the organism, and the pattern for the relationship between the two. (Damasio; Feeling of What Happens, 194)

 All that core consciousness requires is a very brief, short-term memory. (Damasio; Feeling of What Happens, 113)

 Core consciousness is created in pulses, each pulse triggered by an object we interact with or that we recall. Each new object triggers the process of changing the proto-self. Proto-self modified by the first object becomes the inaugural proto-self for the new object. Continuity of consciousness is based on the steady generation of consciousness pulses, which correspond to the endless processing of myriad objects, whose interaction, actual or recalled, constantly modifies the proto-self. (Damasio; Feeling of What Happens, 176)

  Sense of self is a critical component in any notion of consciousness. (Damasio; Feeling of What Happens, 89)

 Machinery of feelings is a contributor to the process of consciousness, namely to the creation of self. (Damasio; Looking for Spinoza, 110)

What gives the brain a natural means to generate the singular and stable reference we call self? The functionality in the brain representing the self is, biologically speaking, based on a collection of nonconscious neural patterns representing the body proper. (Damasio; Feeling of What Happens, 134)

  Biological antecedents of the sense of self -- a single, bounded, living organism bent on maintaining stability to maintain its life. Survival, a boundary, regulation of internal states, maintain life within a narrow range of the internal states. (Damasio; Feeling of What Happens, 136)

 Sense of self brings orientation -- sense of self introduces the notion that all the current activity represented in brain and mind pertain to a single organism whose auto-preservation needs are the basic cause of most events currently represented. (Damasio; Looking for Spinoza, 208)

 Limbic system is not precisely defined; it remains a catchall for a number of evolutionarily old structures; many neuroscientists resist using it. (Damasio; Descartes’ Error, 28)


Joseph LeDoux

Every human brain has billions of neurons that together make trillions of synaptic connections among one another. During wakefulness and during sleep, during thoughtfulness and during boredom -- at any one moment, billions of synapses are active. (LeDoux; Synaptic Self, 49)

 The self is the totality of what an organism is physically, biologically, psychologically, socially, and culturally. (LeDoux; Synaptic Self, 31)

Synapses are ultimately the key to the brain's many functions, and thus to the self. (LeDoux; Synaptic Self, 64)

Self is created and maintained by arrangements of synaptic connections. (LeDoux; Synaptic Self, 12)

 Our life's experiences contribute to who we are; implicit and explicit memory storage constitute key mechanisms through which the self is formed and maintained. The way we characteristically walk and talk, the way we think and feel, all reflect the workings of systems that function on the basis of past experience, but their operation takes place outside of awareness. (LeDoux; Synaptic Self, 28)

 Some emotional systems in the brain are essentially the same in many vertebrates, including mammals, reptiles, birds and possibly amphibians and fishes. Evolution stubbornly maintains emotional functions across species. (LeDoux; Emotional Brain, 107)


Levitin, Schneck & Berger, Sacks


Rudolfo Llinás

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)

 Consciousness is a noncontinuous event determined by simultaneity of activity in the thalamocortical system. (Llinás; I of the Vortex, 124)

 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)

 Emotions are among the very oldest of our brain properties. (Llinás; I of the Vortex, 156)


Gerald Edelman

Consciousness is an outcome of a recursively comparative memory in which previous self-nonself categorizations (Remembered) are continually related to ongoing present perceptual categorizations (Present) and their short-term succession. (Edelman; Remembered Present, 155)

"The Remembered Present" - dynamic interaction between memory and ongoing perception that gives rise to consciousness. Activity of the reticular thalamic nucleus gates various activity combinations of specific thalamic nuclei corresponding to different sensory modalities. Intralaminar thalamic nuclei, which send diffuse connections to most areas of the cortex, help to synchronize thalamocortical responses and regulate the overall levels of activity in these multiple reentrant systems. (Edelman; Wider than the Sky, 55)

  Conscious experience is associated with the activity of populations of neurons that are widely distributed in the thalamocortical system. The distributed groups of neurons must engage in strong and rapid reentrant interactions. (Edelman; Universe of Consciousness, 62)

 Signals from "self" systems begin even before birth and remain a central feature of primary consciousness. (Edelman; Wider than the Sky, 57)

 Two systems, limbic-brain stem and thalamocortical, were linked during evolution.  The later-evolving cortical system served learning behavior that was adapted to increasingly complex environments. (Edelman; Bright Air, 118)

 Memories are necessarily associative and never identical. (Edelman; Wider than the Sky, 53)

Three Major Topological Arrangements in the Brain  (1) Thalamocortical system, (2) Parallel, unidirectional pathways through the basal ganglia, (3) Fan-out meshwork of diffusely projecting neurotransmitter modulatory neurons emanating from brain stem nuclei.  (Edelman; Wider than the Sky, 26)

  Dynamic core of consciousness --  a large cluster of neuronal groups that together constitute, on a time scale of hundreds of milliseconds, a unified neural process of high complexity. (Giulio Tononi, Gerald Edelman; Consciousness and Complexity)



Neural Network, Neural Pattern, Mental Image

Edmund Rolls

mathematical models of network functionality

recurrent connections

associative networks

Emotion and motivation are linked by the property that both involve rewards and punishers. (Rolls; Emotion Explained, 1)


 György Buzsáki

1/f distribution, Pink Noise

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. (Buzsáki; Rhythms of the Brain, 292)

 The computational properties of recursive organization, such as the extensive CA3 recurrent system, meet the requirements of an "autoassociator." (Buzsáki; Rhythms of the Brain, 289)


 Susan Greenfield

According to Susan Greenfield's hypothesis, the most rudimentary consciousness is a pure emotion associated with fast interactions with the outside world. (Greenfield; Private Life of Brain, 175)

 Neuronal gestalt -- a highly variable aggregation of neurons which is temporarily recruited around a triggering epicenter. (Greenfield; Centers of Mind, 99)


 Joaquín Fuster

Perception-action cycle

Emotion domain of the prefrontal cortex extends mainly through the medial and orbital aspects. (Fuster; Prefrontal Cortex, 345)

 The informational content of memory networks resides in the associative relationships among the neuronal elements.  It is not so much that a memory trace is contained in the network; rather, the memory trace is the network. (Fuster; Memory in Cerebral Cortex, 11)

 It is a reasonable presumption that all types of short-term memory as well as long-term memory essentially share the same cortical substrate.  The basic differences between them would lie in the degree and distribution of neuronal activity within the substrate. (Fuster; Memory in Cerebral Cortex, 16)


Eric Kandel

Two types of circuits in the brain.   (1) mediating circuits produce behaviors, (2) modulatory circuits act on the mediating circuits, regulating the strength of their synaptic connections. (Kandel; Search of Memory, 224)

  Selective attention is widely recognized as a powerful factor in perception, action, and memory -- and the unity of conscious experience. (Kandel; Search of Memory, 311)

 Amygdala is the part of the limbic system most specifically involve with emotional experience. (Kandel; Principles of Neural Science, 988)

  Brain stem contains the locus ceruleus, crucial for attention and for cognitive functions.  Fully half of all noradrenergic neurons of the brain are clustered together in this small nucleus. (Kandel; Principles of Neural Science, 871)


 Doya, et al - Bayesian Brain

Bayesian Inference in Brain Functionality

Reentry and Recursion


Refining Features of the Theory of Consciousness

Michael Gazzaniga

Sense of self is constructed by the left hemisphere interpreter on the basis of input from distributed networks. (Gazzaniga; Human, 308)

Sense of self arises out of distributed networks in both hemispheres. (Gazzaniga; Human, 308)

Both hemispheres have processing specializations that contribute to a sense of self. (Gazzaniga; Human, 308)

  In the biased competition model, with reciprocal suppression of activity in visual regions that encode non-relevant stimuli, suppression occurs due to competition of multiple stimuli for limited visual processing resources. (Gazzaley; Top-down WM, 198)

 Humans have an innate ability to understand that other humans have minds. First called Theory of Mind (TOM) by David Premack. (Gazzaniga; Human, 48-49)

 For speech, each hemisphere is concerned with different aspects.  Wernicke's area in the left hemisphere recognizes distinctive parts of speech, and an area in the right auditory cortex recognize prosody, the metric structure of speech. (Gazzaniga; Human, 28)

 Neocortex recalls patterns autoassociatively, which means it can recall a complete pattern when given only a partial one.   (Gazzaniga; Human, 367)




Each individual brain has multiple representations of itself at different levels, extending from the basic subcortical homeostatic mechanisms through the representation of the body at a somatic, kinesthetic and motor level, up to the personal representation of a concept of our bodies and faces, and such long-term memory representations as autobiographical and episodic memories. (Baddeley; Working Memory, 314)

Attention is necessary for consciousness. (Baddeley; Working Memory, 311)

Consciousness serves as a mental workspace, a very powerful mechanism for registering the environment and relating it to past experience, which can in turn be used to model the present, and using that model, to simulate and hence to predict the future and plan further action. (Baddeley; Working Memory, 314)

Visuospatial sketch pad as the seat of phenomenological experience of visual imagery, and the central executive as the attentional controller. (Baddeley; Working Memory, 315)


David LaBerge


Francis Crick

"You" are the behavior of a vast assembly of nerve cells and their associated molecules. (Crick; Astonishing Hypothesis, 3)

 A language system of the type found in humans is not essential for consciousness. (Crick; Astonishing Hypothesis, 23)


Christof Koch

The form of awareness associated with focal attention is caused by the firing of a temporally coordinated assembly of neurons firing in some special manner for at least 100 or 200 msec. This special form of neuronal activity induces short-term memory. (Koch and Crick; Neuronal Basis, 109)


Allan Hobson

Consciousness at any instant is simply the integrated product of the information represented in the activated thalamocortical networks at that instant. That includes sense of self; awareness of body; and awareness of the world, be it real or fictive. (Hobson; Consciousness, 141)

 Primary components of consciousness are those experienced by all mammals, including human infants: sensation, perception, attention, emotion, instinct, movement. (Hobson; Consciousness, 16)

 Secondary components of consciousness are those experienced only by adult humans: memory, thought, language, intention, orientation, volition. (Hobson; Consciousness, 17)

 Consciousness is determined by the neurochemical modulatory systems of the brainstem core. (Hobson; Consciousness, 73)

  Allan Hobson’s AIM Sleep Model


Giulio Tononi

The only conclusion that can be drawn for sure about the neural substrate of consciousness is that it includes parts of the corticothalamic system. (Tononi & Laureys; Neurology of Consciousness, 390)


Further Refinements


Conscious experiences are an emergent property of the nervous system. (Johnston; Why We Feel, 119)

 The dopamine pathway to the nucleus accumbens is closely associated with motivation and the control of motor behavior and is correlated with hedonic tone that is a fundamental aspect of all feeling states. (Johnston; Why We Feel, 119)

 Neural processing of emotions begins with the limbic system, a number of interconnected subcortical regions around the hypothalamus. One major pathway from the limbic system via the hypothalamus is responsible for physiological adjustments to the body, such as changes in heart rate or blood pressure. A second output pathway, common to all feelings, is the pleasure pathway, which ultimately releases dopamine onto the nucleus accumbens. The dopamine pathway to the nucleus accumbens is closely associated with the control of motor behavior and is correlated with hedonic tone that is a fundamental aspect of all feeling states. Limbic system outputs influence two major arousal systems of the brain, and these pathways provide a mechanism by which feelings can modulate cortical arousal. (Johnston; Why We Feel, 119)



Language is probably not required for consciousness. (Zeman; Consciousness, 285)


Orbitofrontal cortex (OFC) and the insular; two major components of the paralimbic belt. (Miller; Human Frontal Lobes, 59)


Speech involves not only the communication of vocabulary and grammatical content but also social and emotional content. (Miller; Human Frontal Lobes, 74)


Brain uses its motor components to move our lips and tongue and palate so that the speech is well articulated, as our auditory system listens to what is being said and prepares the other components to make modifications. (Andreasen, Creating Brain, 64)

 Howard Gardner

Multiple intelligences --  theory of multiple intelligences was developed in 1983 by Howard Gardner, professor of education at Harvard University.



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