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

Human-type Consciousness

My term “human-type consciousness” encompasses Gerald Edelman’s term “higher-order consciousness” (Edelman; Universe of Consciousness, 102), and Antonio Damasio’s term “extended consciousness” (Damasio; Feeling of What Happens, 16).

Consciousness at any instant is an emergent property of the information represented in the activated thalamocortical networks at that instant. That includes an activated neural subnetwork representing the sense of self, which includes an awareness of body; and a mental object representing an awareness of the world, be it real or fictive.  (Hobson; Consciousness, 141)   [Edelman's dynamic core]

Human-type consciousness is closely allied with a number of functionalities of the brain. Consciousness is an emergent property of neural activity in the dynamic core, which is closely related to the functionality of working memory and attentionEmergence is a typical property of complex systems. Underlying consciousness and forming a major part its functionality are emotion and motivation, which forms what LeDoux calls the traditional tripartite amalgam: cognition, emotion, and motivation.

Although consciousness has no formal definition at the current state of the science, and we should leave it this way for now, it is useful to distinguish between human consciousness and the consciousness of other animals.

The uniqueness of our species may arise from a combination of two factors --   (1) a theory of mind (the ability to imagine the mind of others)    and (2) a conscious global workspace (an internal buffer where the infinite variety of ideas can be recombined). (Dehaene; Reading in the Brain, 9)

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

 

Human consciousness is mediated by a greatly expanded brain facility compared with other animals. Most prominent among these is a greatly expanded frontal cortex and the uniquely human Broca and Wernicke language areas. The hugely expanded frontal cortex, facilitating cognitive reasoning, thinking, planning and decision making has coevolved with the special language areas. The human brain also has a special area for processing and recognizing the visual images of human faces. Humans can quickly see, remember and recognize a human face. (Within some time limits, however. I must confess that at my high school reunion I was embarrassed more than once when failing to recognize a classmate!)

Neurons; Synapses; Glial Cells

All functions of consciousness are mediated by neurons and synapses and their supporting cells and structures. The dynamic core of active neurons mediates the emergent property of consciousness.

Information flow in neurons and neuronal networks is not instantaneous.  It takes time for action potential to propagate along axons and for neurotransmitters to span the synaptic cleft and activate the postsynaptic neuron.

A neuron will fire whenever a quorum of input signals on its ~10,000 dendrite tree synapses is achieved in a ~2 ms time window. Generally, the input signals comprising the quorum can occur on the synapses in any combination; no particular combination is required. Consequently, a neuron's functionality is stochastic, not deterministic.

 

Consciousness — Interaction between The Self and a Mental Object

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

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)

Global mappings involve large parts of the brain and various combinations of local maps for different modalities. (Edelman; Remembered Present, 143)

Bayesian inference and the Perception-Action cycle can provide insight for how the brain mediates the neural activity of consciousness.

Mirror Neurons allow you to Empathize with Another Person

Mirror neurons fire not only when you perform an action,     but also when you watch someone else    perform the same action. (Ramachandran; Tell-Tale Brain, 22)

What mirror neurons do is effectively allow you to empathize with another person     and read their intentions. (Ramachandran; Tell-Tale Brain, 22)

Mirror neurons may well be central to social learning,    imitation,    and cultural transmission    of skills and attitudes. (Ramachandran; Tell-Tale Brain, 23)

 

Sense of Self

A person' s individuality as a person is represented in the neurons and synapses, forming the molecular signature, or "the self," of the person.

Although the self is comprised of the nervous system’s entire ensemble of synapses whose efficacies are the legacy of genetic endowment together with life experiences ingrained in synaptic patterns,  the sense of self arises from the momentary neural activity pattern in a portion of the network.

In the normal waking conscious state, our orientation makes us aware of where we are, the date and approximate time, who is present in our surroundings, the goal or direction of our behavior. (Hobson; Consciousness, 135)

The main role of the orbitofrontal cortex in autobiographical memory lies in the mediation between specific memories,    memory-related emotions    and a feeling of self-awareness or autonoetic consciousness. (Zald & Rauch; Orbitofrontal Cortex, 300)

Critical elements of our autobiography arise from a continuously reactivated network based on convergence zones, which are located in the temporal and frontal higher-order cortices, as well as in subcortical nuclei such as those in the amygdala. (Damasio; Feeling of What Happens, 221)

 

Mental Object

Sensory input, memory

Mental object is identified as the physical state created by correlated, transient activity, both electrical and chemical, in a large population or 'assembly' of neurons in several specific cortical areas. (Changeux, Neuronal Man, 137)

Behavioral Responses

A person’s behavioral responses are strongly influenced by emotion in the immediate term, but by perception, cognition, and intelligence in the longer term.

Sensory Input

Sensory input for the neural network is a multimodal input of the five senses activating millions of neurons in ever changing spatial and temporal patterns.

Vision, Auditory, Somatosensory, Gustatory, and Olfactory sensory data provide continuous updates for the synaptic efficacies of memory, resulting in the neural representation of The Self.

A sensory input pattern propagates into the brain's established synaptic efficacies pattern, activating a pattern of synaptic efficacies closely conforming to the sensory input pattern.

The valence of a stimulus can range from rewarding (pleasant) to punishing (aversive). (Zald & Rauch; Orbitofrontal Cortex, 268)

Sensory Inputs Not Required for Consciousness

Sensory inputs are not required for consciousness. Blind people and deaf people have consciousness.

 

Memory — Working Memory, Short-Term memory, Long-Term Memory

By the associative property of memory, neural assemblies aggregate into the sparse but widespread neural assemblies of the dynamic core of consciousness.

The brain fills-in the details of a perception or memory using Gestalt properties.

Working memory is an intimately related part of the ongoing neural activity of the thalamocortical system related to attention, the dynamic core, and consciousness.

There are many local short-term memory circuits in the brain. Consolidation to long-term memory continues persistently.

Plasticity of Synapses Mediates Memory. Biochemical changes in the synapses mediate memory in the relative near-term, whereas gene expression and protein changes in synapses and dendritic tree structures are consolidated over time for hippocampus-independent long-term memory. Neural signals activate a widespread but sparse  memory trace that most closely conforms to a synaptic efficacy pattern established by prior neural activity.

 

Human-type Consciousness builds upon Core Consciousness

Nervous systems evolved in animals as a way of providing command signals for the control of movement in a competitive environment. Higher, non-human primates may have some aspects of human-type consciousness. Human-type consciousness as I am using the term here probably arose about the time hominoids migrated out of Africa, or perhaps somewhat later, about 50 thousand years ago.

 Human-type consciousness is dependent upon the function of Core Consciousness.

 In general, Mammals have Core consciousness. Also, I believe Birds have some aspects of consciousness.

 Reptiles have a few characteristics of Core consciousness.

 Lower animals such as Insects and Lobsters do not have consciousness. Although some have the capability for simple learned behaviors and many can be fear-conditioned, most are innately-wired automatons. A spider building a web has no idea what it is doing; the nervous system is innately wired to do its thing.

Emotions

Consciousness and emotion are not separable. (Damasio; Feeling of What Happens, 16)

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)

Although there is no consensus among experts about the definition of emotions, primary emotions are sometimes listed as Happiness, Sadness, Fear, Anger, Surprise, Disgust.

Secondary or social emotions such as Embarrassment, Jealousy, Guilt, Pride.

Emotions provide immediate responses for behavioral actions, before the cognitive brain has had time to provide a more thoughtful and reasoned plan of action.

The valence of an emotion can range from Fear-to-Pleasure.

Like bodily affects, the positive or negative hedonic tone of an emotion provides the necessary value system for learning to adapt to rapidly changing aspects of the environment. (Johnston; Why We Feel, 86)

Intensity of affects and emotions can be viewed as amplifications of the reproductive consequences of current physical or social circumstances. (Johnston; Why We Feel, 87)

 

Limbic System Mediates Emotions

The limbic system together with FAPs behavior patterns mediate emotional responses.

The limbic system, although not precisely defined, typically includes the amygdala and hypothalamus.

Subjective Feel of Emotions Guides Choices for Survival

The feel of different emotions might be important in guiding choices and thus in aiding survival. (Greenfield; Private Life of Brain, 49)

Feelings, in Susan Greenfield's hypothesis, are the most basic form of consciousness. (Greenfield; Private Life of Brain, 163)

In evolutionary terms, we can view emotions as processes where a person is highly interactive with the environment.  If you are interacting with the environment, you are focusing on your senses. (Greenfield; Private Life of Brain, 49)

The ultimate question: How do subjective sensations -- different states of consciousness -- occur as a result of the shifting neuronal network activity within the physical brain? (Greenfield; Private Life of Brain, 163)

Music and Emotion

I believe that music interacts with the oscillation and synchronizations of the neural network signals in the brain to produce resonances in the neural signal loops.  The oscillations, synchronizations and resonances somehow excite the limbic system to release neurotransmitters, such as dopamine, which then interact with the nucleus accumbens and frontal cortex circuits to produce a euphoria.

Perhaps music creates a resonance in the brain between neurons firing in synchrony with a sound wave and a natural oscillation in the emotion circuits? (Pinker; How the Mind Works, 538)

 

Brain’s Neural Networks Emulate Reality

Brains evolved as a way to emulate reality for predicting movements required to locate and compete for mates, forage for food, chase prey, and avoid predators. Human-type consciousness includes characteristics such as:

 Time sense (see below) -- Distant Past to Future Planning.

 Ideas -- mental representation of hypothetical episodes and relationships, planning. Ideas hallmark: (1) observe the world, (2) conjure desired arrangement. Squirrel-with-nuts behavior is innate, no ideas.

 Language -- helpful for manipulating and communicating ideas, but not necessary for consciousness. Core consciousness can survive damage to the Broca and Wernicke areas.

 Creativity -- logically connecting ideas and mental objects to fashion desirable relationships.

 Abstract thinking -- examples include mathematics, symbolic representation of ideas and external objects.

 Moral behavior -- sense of right and wrong, good and evil. (Orbitofrontal cortex)

The human mind can conjure all manner of fantasies to trying to understand nature and the world. As a specific example for prior millennia, humans conjured all kinds of mythical figures and tales about the star patterns in the night sky. With the advent of the scientific method, humans attempted to assure that their neural emulations of reality corresponded to the real world.

 

Research study — Brain Functions as a Reality Emulator

Research study — Qualia as a Master Organ

Research study — Bayesian Inference in Brain Functionality

 

Working Memory is Essential for Human-type Consciousness

Extended consciousness requires working memory and explicit long-term memory (including both semantic and episodic memories). (Damasio & Meyer; Consciousness Overview, 9)

Key elements of our autobiography correspond to our identity, to our recent experiences, and to the experiences that we anticipate, especially those in the near future. (Damasio; Feeling of What Happens, 221)

Working memory is the gateway to subjective experiences, emotional and nonemotional ones, and is indispensable in the creation of a conscious emotional feeling. (LeDoux; Emotional Brain, 296)

Active consciousness has its major activity involved with anterior cortical, related thalamic, and basal ganglia neural sites, which are known to be crucially involved with actions of either direct motor action or of thought, planning. (Baars; Neuronal Mechanisms of Consciousness, 274)

Nearest we may come to sharing someone else's consciousness is via poetry, paintings, and music. (Greenfield; Private Life of Brain, 180)

Attention

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)

 

Language — a Major Contributor to Human-type Consciousness

Language is a major contributor to extended consciousness. (Damasio; Feeling of What Happens, 108)

Language facilitates the perceptual categorization of detailed thoughts and the communication of perceptions and memories.

Verbal working memory (Phonological Loop) can be regarded as the neural computational space in which the meaning of a sentence is derived, taking account of syntactic, semantic, contextual, and pragmatic information. (Philip Lieberman; Human Language, 62)

The neural substrate that supports verbal working memory is a distributed system involving Wernicke's area, Broca's area, other cortical areas, and subcortical structures. (Philip Lieberman; Human Language, 77)

 

 

Research study — Social Learning

 

Neural Network Provides the Facility for the Dynamic Core within the Thalamocortical System

The neural network provides the facility for the dynamic core to operate within the thalamocortical system. Hierarchical circuits, reentry with recursion, and Bayesian inference functionality link the brain’s many specialized local circuitry modules to combine at hierarchical convergence zones, abstracting the most significant information for frontal cortex and working memory decisions to control movement crucial for survival.

Brain’s Three Topological Networks

At the brain’s higher levels of anatomical order, it is possible to distinguish important principles of organization. Three major topological arrangements in the brain appear to be essential to understanding the brain’s global functioning. (Edelman; Universe of Consciousness, 42)

The brain's neural network can be considered in terms of three topological networks, closely interworking together: (1) the thalamocortical system, which mediates the dynamic core of consciousness, (2) the parallel unidirectional pathways through the basal ganglia, cerebellum, hippocampus and (3) the network of diffusely projecting modulatory neurons emanating from the brain stem.

Modular Areas of the Brain Provide Specialized Processing

According to Gazzaniga's model of consciousness, specialized neural circuitry in hundreds, if not thousands, of the brain’s modular functional areas enable the processing and mental representation of a specific aspect of conscious experience, and these circuits are widely distributed throughout the brain. (Gazzaniga; Left Hemisphere/Right Hemisphere, 262-266)

Consciousness is best conceived as the brain's awareness of its own activity, including such modular functions as perception, memory, thinking, and feeling, each of which has some degree of anatomical localization or functional specialization. (Hobson; Dream Drugstore, 88)

Brodmann's cortical maps and his regional classification remains an important reference system for cortical localization. (Sporns; Networks of the Brain, 54)

Neural Network Oscillatory Electrical Signals

Neural network activity with its ubiquitous recurrent and reentrant circuitry generates oscillatory electrical signals that can be detected on the scalp (Electroencephalogram EEG) and by invasive probes into the brain.  The spectral frequencies of these neural signals have a power law characteristic, displaying an inverse linear relationship on a log-log plot.  This kind of relationship is called "pink noise." (Buzsáki - Rhythms of the Brain, 119)

Gamma-Band Oscillations Associated with Consciousness

Synchronous gamma-band oscillations have been shown to correlate with consciousness in humans and animals. (Revonsuo; Inner Presence, 95)

 

Neuromodulatory Systems

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

Major neuromodulatory systems of the brain. (1) noradrenergic, (2) adrenergic, (3) dopaminergic, (4) serotonergic, (5) cholinergic, (6) histaminergic. (Kandel; Principles of Neural Science, 890)

Five well-established biogenic amine neurotransmitters -- three catecholamines -- (1) dopamine, (2) (noradrenaline), (3) epinephrine (adrenaline) -- and (4) histamine and (5) serotonin. (Purves; Neuroscience, 147)

 

Unconsciousness Neural Activity Supports Consciousness

Much activity of the brain is unconscious. The autonomic nervous system provides much functionality for the sense of self. Abnormal states such as pain or immune responses such as fever can rise to the level of consciousness.

In the mechanisms of the mind, unconscious action enters largely into all its processes. (Mlodinow; Subliminal, 32)

Neurons in the upper cortical layers, are mainly concerned with unconscious processing. (Koch and Crick; Neuronal Basis, 109)

Sleep and Dreaming

No one knows why we need sleep.

“If sleep does not serve an absolutely vital function, then it is the biggest mistake the evolutionary process has ever made,” Sleep Necessity

In humans, at least five stages of sleep with progressively higher wakening thresholds can be distinguished, with the deepest stage being a rapid eye movement (REM) phase. (Buzsáki; Rhythms of the Brain, 187)

 

Abnormal Function of the Brain

Analyzing the abnormal functioning of the brain can be a way to gain insight about brain functions underlying consciousness.

 

Sense of Time — Past and Present

Human sense of time spans a logarithmic scale, i.e. we remember things as the occurring at times such as: a few minutes ago, earlier today, yesterday, last week, about a month ago, last year, several years ago, etc.

Recency effect is what provides the reference on which our location in the present and projection into the future can be founded. (Baddeley; Working Memory, 115)

Retrieval memory and inference allow a 14 month old to detect logical connection between past and present. (Hobson; Consciousness, 100)

Knowledge of Ultimate Death

Human-type consciousness subsumes a knowledge of ultimate death.

People who are resuscitated from near death often report strange sensory phenomena, such as memories flashing before their eyes or white light or tunnel. (Horstman; Healthy Aging Brain, 199)

The jolts of EEG activity lasted 30 to 180 seconds and displayed properties that are normally associated with consciousness, such as extremely fast electrical oscillations in the brain known as gamma waves. (Horstman; Healthy Aging Brain, 199)

An anesthesiologist posits that the predeath spikes are most likely brief "last hurrah" seisures originating in brain areas that were irritable or unstable from oxygen starvation. (Horstman; Healthy Aging Brain, 200)

Consciousness Departs

At the very end, as death takes hold, everything stops for us as we know it. Consciousness departs. (Horstman; Healthy Aging Brain, 197)

At the moment of death, most of the body's cells are still alive. Unaware of what has just happened, they carry out, to the best of their abilities, the business of living: the metabolic functions that support life, procuring oxygen and nutrients from the surrounding environment, and using them to generate the energy needed to make and power the activities of proteins and other component of cells. (Horstman; Healthy Aging Brain, 197)

In a short while, starved of oxygen, the cells will die, and with their death, something of immense antiquity will come to its own quiet end. (Horstman; Healthy Aging Brain, 197)

Every one of the cells in your body that just died could trace its ancestry through an unbroken chain of cell divisions backward in time an almost unimaginable 4 billion years to the emergence of the earliest form of cellular life on this planet. (Horstman; Healthy Aging Brain, 197)

With no immune system functioning, the bacteria in the body take over and consume the body, producing a gaseous odor and leaving dust and non-consumable bones.

 

    Excerpts from science experts

Higher-order consciousness leads to the construction of an imaginative domain, one of feeling, emotion, thought, fantasy, self, and will. (Edelman; Bright Air, 151)

Higher-order consciousness is built on the foundations provided by primary consciousness and is accompanied by a sense of self and the ability in the waking state explicitly to construct past and future scenes. Higher-order consciousness requires a semantic capability, and in its most developed form, a linguistic capability. (Edelman; Universe of Consciousness, 102)

Extended consciousness is also present in some nonhumans at simple levels; it only attains its highest levels in humans where it is also enhanced by language. (Damasio; Feeling of What Happens, 16)

Prefrontal cortices probably participate only in extended consciousness. (Damasio; Feeling of What Happens, 181)

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

Only the part of consciousness called self-awareness is capable of observing brains states. (Hobson; Dreaming as Delirium, 12)

Only human beings can engage in reflective thinking:  "That's a good idea"; "That's nonsense"; "I want to do that", (Greenspan; First Idea, 17)

Humans have very poor facial recall ability. Humans are experts as facial recognition. Babies will look at faces in preference to any other visual image. (Johnston; Why We Feel, 40-41)

Perception without awareness - The Hidden Persuaders, 'subliminal perception', Message "DRINK COKE" flashed briefly during a movie. (Edelman; Universe of Consciousness, 67)

 

      Research study — Theory of Mind Independent of Episodic Memory

 

I have provided much further discussion indexed alphabetically.

              Index of Topics Discussed

I have included paraphrases of recent research reports in sidebar discussions on a number of specific topics.

         Sidebar Discussions

Here are links to titles of more than 120 reference books for which I have provided nearly 20 thousand paraphrases.

         Reference Book Paraphrases

 

 

 

 

Link to — Core Consciousness

Link to — Fear —- Pleasure

Link to — Consciousness Subject Outline

Further discussion — Covington Theory of Consciousness