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

Core consciousness


Core Consciousness -- Convolution of a Mental Image with the Sense of Self

Consciousness is a ‘convolution’ (my choice of word; it's hard to precisely convey the concept) of a current mental image with a neural network image of the self.

I have chosen the words in this paragraph title carefully, although it is difficult in a few words to characterize the concept of core consciousness. I’ll expand briefly to try to characterize some salient facets:

Core consciousness refers to the here-and-now, a continuously advancing interval of perhaps a tenth of a second.

Core consciousness is fundamentally connected with the sense of self, that mostly unconscious mental image of organism individuality that is ingrained in synapses, beginning early in prenatal embryonic life.

Mental image relates to a subset of neural activity defining the current thought-topic of consciousness.

Convolution is my groping attempt to convey a superposition and processing of the mental image together with the sense of self.


I use the term “core” consciousness coined by Antonio Damasio to apply to a similar concept Gerald Edelman calls “primary” consciousness, and still another slight variation Rodolfo Llinás calls I of the Vortex.” Terminology can be very confusing when various researchers use their own ad hoc terms for similar concepts. In future years as the neuroscience of consciousness matures, the terminology will coalesce into widely accepted terms.

Core consciousness provides the organism with a sese of self about the here and now. (Damasio; Neurobiology for Consciousness, 112)

From an evolutionary perspective, core consciousness came to exist when second-order maps first brought together the representation of the organism modified by perceptual engagement with the representation of the object. Damasio & Meyer; Consciousness Overview, 12)

Core consciousness is a simple biological phenomenon, having one level of organization; it is stable across the lifetime of an organism. (Damasio; Neurobiology for Consciousness, 112)

Extended consciousness (human-type consciousness) is a complex biological phenomenon, having several levels of organization, and it evolves across the lifetime of the organism. (Damasio; Neurobiology for Consciousness, 113)


Perception and Memory Tightly Entwined

Perception and memory are tightly entwined in the function of consciousness.  All memory is associative.  Neural signaling for a new perception activates a highly-similar sparse neural pathway engraved by past experiences into the synaptic efficacies of memoryActivation of portions of past memories engenders comparisons and similarities (associations), providing cues for portions of neural assemblies of past memories to expand activity, thereby forming a new perception .  The new perception forms an addendum to and embellishment of past memories.

Long-term memory links past value-category associations to present categorized input in a way to yield the basis of primary consciousness. (Edelman; Remembered Present, 133)

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)

Short term memory that is fundamental to primary consciousness reflects previous categorical and conceptual experiences. The interaction of the memory system with current perception occurs over periods of fractions of a second.  (Edelman; Universe of Consciousness, 109)

Consciousness a Convolution of the Perceptual Mental Image with the Sense-of-Self

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)

To relate neural systems to complex cognitive functions, we must focus on neural circuits, discerning how patterns of activity in different circuits merge to form a coherent representation. (Kandel; Science of Mind, 70)

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)

The event of awareness requires that attention be directed to the regions where the self is expressed at the same time that attention is directed to the cortical regions where the object is expressed. (LaBerge; Attention, the Triangular Circuit, 311)

Neural activity does not produce an awareness event unless the prefrontal area amplifies that activity to a particular level and sustains it there for some minimum duration. (LaBerge; Attention, the Triangular Circuit, 312)


Active short-term memory can be considered the quintessential conscious phenomenon. (Fuster; Memory in Cerebral Cortex, 294)

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)

Primary consciousness comprises sensation, perception, emotion, learning, geographic orientation, instinct, primary intention; all of these can be operationally defined in lower animals. (Hobson; Consciousness, 84)

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

Sensory awareness is a basic form of phenomenal consciousness that humans have in common with many other species, including most other higher mammals.  (8 Temporal Binding and Consciousness, 126)


Dreamlike state modulated by the senses

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)

The brain is essentially a closed system capable of self-generated oscillatory activity that determines the functionality of events specified by the sensory stimuli. (Llinás; Perception as Oneiric-like, 113)

The brain functions as a reality emulator to assist the animal with prediction and decisions to enhance survival. 


A confluence of thoughts of experts can provide insight

Edelman uses the term ‘remembered present’ to convey the concept of a sense of self combined and processed with a present mental image.

Primary consciousness is a kind of "remembered present". (Edelman; Bright Air, 120)

Primary consciousness results from the interaction in real time between memories of past value-category correlations and present world input as it is categorized by global mappings. (Edelman; Remembered Present, 155)

Memory is the key element in consciousness. (Edelman; Bright Air, 167)

Consciousness is about 300 million years old. (Edelman; Bright Air, 123)

Remembered present -- a scene that adaptively links immediate or imagined contingences to that animal's previous history of value-driven behavior. (Edelman; Universe of Consciousness, 103)

Edelman's outer loop including the fornix connecting the hippocampus and cingulate gyrus is important for primary consciousness. (Edelman; Remembered Present, 130)

Wakefulness is a dreamlike state modulated by specific sensory inputs. (Llinás; Perception as Oneiric-like, 113)

Core consciousness is mediated by a dynamic core of neural activity along with much unconscious neural activity in a supporting role.

Consciousness as we commonly think of it, from the basic levels to the most complex, is the unified mental pattern that brings together the object and the self. (Damasio; Feeling of What Happens, 11)

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)

Consciousness involves the interaction between the organism and an object. A second-order map represents the relationship of the object with the organism. (Damasio; Feeling of What Happens, 169)

The stuff we are conscious of is the stuff working memory is working on. (LeDoux; Synaptic Self, 191)


Consciousness requires brief, short-term memory; not extensive memory

Memory is the key element in consciousness. (Edelman; Bright Air, 167)

Memory is a central functionality that brings together learning, understanding, and consciousness. (Ratey; User's Guide to Brain, 185)

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

Core consciousness is not founded on extensive memory. Core consciousness is not founded on working memory. Working memory is required for extended consciousness. Do not require access to vast stores of past personal memories to have core consciousness. (Damasio; Feeling of What Happens, 112-3)

Continuity of Consciousness

Arousal and gestalt formation act in concert to generate consciousness. (Greenfield; Centers of Mind, 111)

Our continuity of consciousness occurs as a chain of associations devolved around an epicenter. "Ripples" on one gestalt spread out to ever more remote associations, so a new epicenter starts to recruit neurons into a gestalt. This new gestalt supplants the original, and our consciousness subtly shifts. (Greenfield; Centers of Mind, 105)



Allan Hobson’s components of consciousness


                                     (paraphrase of Allan Hobson, Consciousness, 16ff)


Building Blocks of Consciousness







Input sources


Reception of input data



Representation of input data



Selection of input data



Feelings about representations



Innate propensities to act





Elaborative processing


Retrieval of stored representations



Reflection upon representations



Symbolization of representations



Representations of goals



Representations of time, place, and persons



Automatic recording of experience





Output actions


Decisions to act



Motor acts and behaviors




Primary components of consciousness (Level 1) are those experienced by all mammals, including human infants: sensation, perception, attention, emotion, instinct, movement. (Hobson; Consciousness, 16)

Secondary components of consciousness (Level 2) are those experienced only by adult humans: memory, thought, language, intention, orientation, volition. (Hobson; Consciousness, 17)

Consciousness is graded across species as they develop over evolutionary time (phylogenesis). Consciousness is graded within species over each individual's lifetime (ontogenesis). Consciousness is modulated in everyone over the course of each 24-hour day. (Hobson; Consciousness, 17)


Emotion --  the Most Basic Form of Consciousness

Emotion is the most basic form of consciousness. (Greenfield; Private Life of Brain, 181)

Consciousness characterized by the raw senses is indicative of consciousness at its most minimal. (Greenfield; Private Life of Brain, 182)

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)

The more the mind predominates over raw emotion, the deeper the consciousness. (Greenfield; Private Life of Brain, 182)

Quandary of how a sequence of objective neural events translates into a subjective sensation. (Greenfield; Private Life of Brain, 180)


No Scientific Definition of Consciousness – So What Is It?

Consciousness is not precisely defined – and we should leave it undefined until the science of the field matures much further than it is today. Consequently, we will have questions about which animals have consciousness, which do not, etc. Do birds have consciousness? Do human infants/fetuses have consciousness? Does consciousness depend upon an existing store of long-term memories? For what stages of concussion, hypnosis, anesthesia, coma and brain death does consciousness still exist? With questions such as these remaining, we will always have implied caveats associated with any statements we make.

As a practical matter, we can use a ‘common sense’ definition that consciousness is what we experience from the time we wake up in the morning until we go to sleep at night.

Consider some different states of consciousness

Core consciousness depends on wakefulness. (Damasio & Meyer; Consciousness Overview, 7)

Varied cell groups in the brainstem modulate wakefulness by ascending projections to the cerebral cortex. (Damasio & Meyer; Consciousness Overview, 7)

Core consciousness can best be understood by contrasting the state of consciousness with the state of being unconscious. (Baddeley; Working Memory, 302)

Normal, Wake-time Consciousness

For normal humans, wake-time consciousness includes both human-type consciousness and core consciousness.

Dream State Consciousness

Consciousness could be defined to include the dreams of REM sleep.

Two forms of consciousness: (1) waking and (2) dreaming. (Hobson; Consciousness, 74)

Infant Consciousness

If consciousness is defined to require some accumulation of memory, human infants would have a gradual transition to consciousness in the early postnatal time. Such definitions are likely to be contentious and not widely accepted.

Non-human Primate Consciousness

Non-human primates have core consciousness and perhaps some aspects of human-type consciousness, depending on how consciousness is defined.

Animal consciousness

Consciousness could be defined to include core consciousness for non-human animals, from non-human primates down to perhaps reptiles, but not insects, crustaceans, etc.

Vegetative states consciousness?

Extreme borders of consciousness might include some vegetative states?

Concussion, anesthesia, stroke, coma, etc.

Many abnormal states can result in impaired or no consciousness. Definitions would require many explicit details.

Locked-in Syndrome

Locked-in syndrome (LIS) (Internet) is a condition in which a patient is aware but cannot move or communicate verbally due to complete paralysis of nearly all voluntary muscles in the body except for the eyes. Locked-in syndrome can be caused by stroke at the level of the basilar artery denying blood to the pons,


Core Consciousness in Animals

Primary consciousness comprises sensation, perception, emotion, learning, geographic orientation, instinct, primary intention; all of these can be operationally defined in lower animals. (Hobson; Consciousness, 84)

Primary consciousness is seen in animals with certain brain structures similar to hours. These animals appear to be able to construct a mental scene but have limited semantic or symbolic capabilities and no true language. Primary consciousness emerged in evolution when, through the appearance of new circuits mediating reentry, posterior areas of the brain that are involved in perceptual categorization were dynamically linked to anterior areas that are responsible for a value-based memory. (Edelman; Universe of Consciousness, 102)

Primary consciousness - the ability to generate a mental scene in which a large amount of diverse information is integrated for the function of directing present or immediate behavior -- occurs in animals with brain structures similar to ours. Structures and mechanisms must be described to account for the consciousness that we ascribe both to dogs and to ourselves. (Edelman; Universe of Consciousness, 103-104)

There may exist primitive levels of consciousness, especially involving the passive awareness of events as opposed to the active use of on-line information to guide decision-making and behavior. These kinds of mental states may typify consciousness in organisms that have less or no prefrontal cortex. (LeDoux; Synaptic Self, 192)


Nervous systems evolved in animals as a way of providing command signals for the control of movement in a competitive environment.

Consciousness helps to select appropriate actions in an unpredictable world, actions we choose from a ample repertoire on the basis of fine perceptual distinctions. (Zeman; Consciousness, 296)


‘Core consciousness’ is the kind of consciousness non-human mammals have and should be distinguished from ‘Human-type consciousness.’

A few characteristics of Core Consciousness

An emergent characteristic of evolution-produced neural networks that provides command signals for movement and behavior of animals in a competitive environment. I think of core consciousness as a characteristic of mammals, although birds may have it as well. Core consciousness in the sense I am using it here appeared about the time of the reptile-bird or reptile-mammal transition about 300 million years ago.

Provides a foundation for human-type consciousness

No capability for ideas, planning for future

Functionality for consciousness is widely distributed in the brain. A few small areas in the brain stem and hypothalamus are absolutely critical in a supporting role for consciousness. The fleeting dynamic core of neural network connectivity that constitutes individual thoughts is not dependent on any particular neurons and any particular brain modular areas. Core consciousness of stroke patients can survive damage to portions of a great number of brain modular areas.

Consciousness requires a biological brain resulting from billions of years of evolution of the molecular structures and cellular mechanisms. A computer simulation of the brain can never have consciousness.

Movement control is facilitated by an hierarchical network of Fixed Action Patterns (FAPs). Some FAPs are innate (infant sucking, crying, hiccups), some are learned (leg movements to walk or ride a bicycle; finger movements to play a piano). Brain is not required for some reflexive movements (flapping wings of a decapitated chicken).

Core consciousness is mediated by the brain’s neurons and their synapses

For the most part, the anatomical layout of the neurons is determined genetically with axon growth cones guided by chemotactic signals and by structure scaffolds laid out in early embryonic development. A superabundance of synapses is formed in the embryonic and early postnatal stages, which is then “pruned” by subsequent prenatal and postnatal neural activity on a “use it or lose it” basis. In this way, both genetics and the environment influence the adult neural network. The neural network, both conscious and unconscious, contributes to a “sense of self,” which interacts with mental images, either input from the senses or recreated from memory, to create consciousness. Early emotional relationships between infant and caregiver are especially influential in the developing neural connections between cognitive and limbic areas. These emotional and cognitive relationships continue to experience refinements through adolescence and into adulthood.

Nervous system, network of nerve cells that communicate at synapses; transforms patterns of sensory input into patterns of motor output; adapt behavior to experience, present and past. (Zeman; Consciousness, 73)

Neural Structures of Core Consciousness

Second-order neural patterns of core consciousness - ensemble playing of the superior colliculi and the cingulate under the coordination of the thalamus. Cingulate and thalamus are likely to have the major roles. (Damasio; Feeling of What Happens, 181)

The coordinated activity within the thalamus, anterior cingulate cortex (ACC), the ventral lateral prefrontal cortex (VLPFC), posterior parietal cortex (PPC), and the brain stem probably regulate the content of consciousness through mechanisms of executive attention. (Vogt; Cingulate Neurobiology, 384)


Research study — Intracranial Markers of Conscious Access


Thalamocortical System

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)

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

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)

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)

Mental and behavioral characteristics are functions of the brain, and synaptically connected circuits underlie brain functions. (LeDoux; Synaptic Self, 65)


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

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)

We remain agnostic with respect to the relevance of gamma oscillations to conscious perception. (Crick & Koch; Consciousness and Neuroscience, 46)

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)

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)

Synchronized Oscillations in Consciousness

If synchronized oscillations are required for consciousness, intrinsic rhythmicity of neuronal discharge allows for the rhythmic pacing of brain activity. (Zeman; Consciousness, 294)

Synchronous firing of neurons involved in a common activity is often rhythmic, in the gamma band, 25-100 Hz. (Zeman; Consciousness, 294)

Ubiquitous, bidirectional connections between related brain regions facilitates synchronization. (Zeman; Consciousness, 294)

Rhythmic, synchronous firing of intricately-connected neuronal feedforward and feedback networks generate the gamma-band electrical and magnetic signals measured externally near the brain. Intricately-connected neuronal  feedforward and feedback networks, with reentry and recursion, result in coherent firing and the generation of gamma-band electrical and magnetic signals.

Dynamic core

In the never-ending activity of the dynamic core, the sense of self is “convolved” with the current percept to produce what Edelman calls the ‘remembered present’.

Sense of Self

The sense of self interacts with current perceptual categorization via the dynamic core to yield the emergent property of core consciousness.


Emotion is a component of core consciousness.


Reentry is the central organizing principle that governs the spatiotemporal coordination among multiple selectional networks of the brain. Reentry solves the binding problem. Through reentry, for example, the color, orientation and movement of a visual object can be integrated. Various individual maps that are functionally segregated can be coordinated by communicating directly with each other via reentry. Consequence of this dynamic process is the widespread synchronization of the activity of widely distributed neuronal groups. Binds their functionally segregated activities into coherent output. (Edelman; Wider than the Sky, 41)

Reentry - recursive interchange of parallel signals among brain areas, coordinate the activities of different brain areas in space and time. Unlike feedback, reentry is not a sequential transmission of an error signal in a simple loop. Instead, it simultaneously involves many parallel reciprocal paths and has no prescribed error function. (Edelman; Wider than the Sky, 39, 41)

Reentry - during development, large numbers of reciprocal connections are established both locally and over long distances. This provides a basis for signaling between mapped areas across reciprocal fibers. (Edelman; Wider than the Sky, 39)

Global mapping is a dynamic structure containing various sensory maps, each with different functionally segregated properties, linked by reentry. (Edelman; Wider than the Sky, 49)

Value systems

In higher vertebrates, a series of diffusely projecting neural value systems have evolved that are capable of continually signaling to neurons and synapses all over the brain. (Edelman; Universe of Consciousness, 88) Value systems are perfectly poised to signal the occurrence of important events to the entire brain. (Edelman; Universe of Consciousness, 89)

Neurons in the locus coeruleus fire whenever an animal enters a novel environment or something unexpected happens. When they fire they release the neurotransmitter noradrenaline. Locus coeruleus consists of only a few thousand neurons in the brainstem. These neurons give rise to a vast meshwork of axons that blanket the cortex, hippocampus, basal ganglia, cerebellum, and spinal cord. (Edelman; Universe of Consciousness, 89) Diffuse ascending value systems of the brain are known to be richly connected to the concept-forming regions of the brain, notably the frontal and temporal cortex. (Edelman; Universe of Consciousness, 105)

Human feelings appear to provide the important value system that underlies all human decisions. The shared element of feelings -- hedonic tone -- allows many different feelings to be combined and hence supply an overall assessment of the value associated with the various possible outcomes of a decision problem. (Johnston; Why We Feel, 179)

Diagram of a value system -- Noradrenergic system originating in the locus coeruleus projects diffusely to the entire brain and releases the neuromodulator noradrenaline. (Edelman; Universe of Consciousness, 89)

Value systems - memories of reward and punishment acquired during past behavior. (Edelman; Universe of Consciousness, 109)

Modulator neurotransmitters

Clusters of neurons in the midbrain and rostral pontine reticular formation participate in the modulation of conscious states. (Purves; Neuroscience, 398)

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

Neurochemical modulatory systems confer a second kind of unity on the brain, a metabolic one, which complements electrical synchrony and activation. (Hobson; Consciousness, 73)

Neurotransmitters dopamine, norepinephrine, and serotonin, as well as neuromodulators can also change how we feel about ourselves. (Damasio; Descartes' Error, 160)



Memory is a central component of the brain mechanisms that lead to consciousness. (Edelman; Universe of Consciousness, 93)

Understanding of memory is essential for formulating a theory of consciousness. (Edelman; Wider than the Sky, 50)

Memory is the key element in consciousness. (Edelman; Bright Air, 167)

Primary consciousness is achieved by the reentry of a value-category memory to current ongoing perceptual categorizations that are carried out simultaneously in many modalities. (Edelman; Bright Air, 149)

Short term memory that is fundamental to primary consciousness reflects previous categorical and conceptual experiences. The interaction of the memory system with current perception occurs over periods of fractions of a second. (Edelman; Universe of Consciousness, 109)

Working memory affects extended consciousness but not core consciousness. (Damasio; Feeling of What Happens, 269)


Unconscious support

Reticular core of the brainstem via the thalamus to the cortex is responsible for arousal or alert wakefulness. (Raichle; NCC Cognitive Skill Learning, 655)

Once alert wakefulness has been achieved, we are much less certain which cortical systems are responsible for the content of our consciousness. (Raichle; NCC Cognitive Skill Learning, 655)

Many non-conscious cognitive, attentional and emotional processes occur in support of our conscious experiences. (Raichle; NCC Cognitive Skill Learning, 655)



Consciousness Models

Much too soon for detailed models.

Caveat:  I show these diagrams (cartoons) to try to convey some idea I have in my mind. The structure and workings of the neural network are INTRICATE and VERY vaguely understood by the experts at this time. Interpreted literally, these cartoons will appear ridiculous.

             Link to — Modeling Brain Functionality of Consciousness

             Link to — Hobson’s AIM Model for Consciousness


Map, Neural Pattern, Image, Object . . . What is all this?

Map of nerves of periphery.

Mental image – integration of perceived and/or remembered neural network patterns(?).

Humans experience primary [core] consciousness as a "picture" or "mental image" of ongoing categorized events. No actual image in the brain; "image" is a correlation between different kinds of categorizations. (Edelman; Bright Air, 119)


Edelman’s “Remembered Present”

During normal wakefulness, images established via the five senses interacts with the neural patterns of memory and self to create what Gerald Edelman calls “The Remembered Present,” which is what I call core consciousness.

              Edelman’s  Core Consciousness Diagram

Damasio has a similar concept when he states that consciousness as we commonly think of it, from the basic levels to the most complex, is the unified mental pattern that brings together the object and the self. (Damasio; Feeling of What Happens, 11)


Value-category memory -- synaptic alterations that combine to develop various individual memories are essential to a model of primary consciousness. (Edelman; Universe of Consciousness, 105)






Perceptual categorization



Primary consciousness is supposed to arise as a result of reentrant circuits connecting special memory functions to those mediating current perceptual categorizations. (Edelman; Remembered Present, 64)

Reentrant integration obviates the need for a higher-level command center. (Edelman; Remembered Present, 72)

Consciousness is a process; it depends upon the particular organization of certain parts of the brain, and not upon the whole brain. (Edelman; Remembered Present, 91)



Link to — Human-type Consciousness

Link to — Consciousness Subject Outline

Further discussion — Covington Theory of Consciousness