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

Major Concepts in Consciousness

Consciousness is not precisely defined

Consciousness should not be precisely defined at the current state of the science. A common sense definition can be used.

Sense of Self

Sense of self is a subset of neural activity within the dynamic core representing the status of an organism, including unconscious functionality of the autonomic nervous system. Sense of self is rooted in an organism’s innate imperative of self-preservation and continues throughout life as a mental storehouse of conscious and unconscious experiences beginning in late prenatal embryonic life.  Recent experience is rich and varied, fading to dim memories of the distant past.  Emotional experiences are intense and enduring even of the remote past.  Most of the common mammals and some (birds/reptiles?) have a sense of self and core consciousness.

Autobiographical Self

Humans have an elaborated sense of self that includes rich autobiographical details beyond the functional capability of non-human animals.

Mental Object

Bound subset of neural activity within the dynamic core representing the current focus of thought.

Gestalt phenomena

Early 20th-century German psychologists provided the foundation for the modern study of perception. The German term ‘Gestalt’ refers to the “pattern” or “configuration.” Organisms tend to perceive entire patterns or configurations rather than bits and pieces.

Consciousness

Consciousness arises from a momentary (convolution/interaction/conjoining) of a mental object with the sense of self. The dynamic core is the momentary neural activity representing the mental object and the sense of self. Consciousness is an emergent property of the neural activity of the dynamic core.

A person’s self, which contributes to consciousness, is comprised of the entire ensemble of well-worn synaptic connections and strengths, endowed by genetics and modified by neuronal plasticity over a lifetime of experience and interactions in the environment.  The subset of neuronal activity comprising the dynamic core is comprised of a momentary perception as convolved with the active portion of the neuronal synaptic network comprising the self.

Core Consciousness

Mammals and some (birds/reptiles?) have core consciousness.

Human-type Consciousness

Humans have an elaborated sense of self, including rich autobiographical details extending far beyond the core consciousness of nonhuman animals.

Perceptual Categorization

Sensory data are parsed into minute details represented in neural assemblies. The neural assemblies are amalgamated into categories, which are consolidated into synaptic memory as a hierarchy of neural assemblies. The details of this hierarchy continue to be refined in the ongoing process of experience and learning. Widespread neural assemblies throughout the brain’s modular areas are momentarily integrated into the dynamic core to form thoughts.

Bayesian Inference

The brain seems to implement Bayesian inference in many of its functions.  This insight fits well with the notion that the brain functions as a reality emulator, with the occipital, parietal and temporal lobes principally involved in sensory and perceptual categorization functions.

Neurons and Synapses

Neurons are the fundamental functional unit of nervous system physiology. Neurons of the brain can have input dendritic trees with 10⁴ or more synapses and axons with many output synaptic terminals.

Neural Network

The fundamental units of neural network functionality include (1) the functionality of dendritic trees, (2) the functional connections of axon terminations, and (3) neuron assemblies. Information is processed in the neural assemblies with a response to a time of a few tens of milliseconds. The information processing functionality of the neural network can be very complex.

Plasticity of Neural Network

Synapses with their modifiable efficacy (plasticity) form the basis of neural network conduction pathways as well as (hierarchical/representational/combinational?) network patterns that represent memories. The combinatorics of 10¹⁵ synapses in the brain provides a virtually limitless capacity for memory.

Memory as Regeneration of a prior event

Memory is not simply data retrieval. Memory is a regeneration of the neural activity of an original event. The regeneration process does not perfectly reconstruct the original; it is only partial, and it is faulty. The synaptic connections comprising memory are reused again and again as modular assemblies that are modified for subsequent memories; consequently, older memories tend to fade.

Movement as FAPs

Emotion and Limbic

Thalamocortical System

Pulse-like behavior of Neural Network

The neural network functions in pulse-like fashion . Action potential pulses travel down an axon and cause a neurotransmitter to be released in the synapse. The neurotransmitter arrives at its receptor and may be part of a sufficiently large near-simultaneous volley of pulses (spikes) to cause the post-synaptic neuron to fire a spike.

Individual spikes in the neural network hardly have a specific meaning. Volleys of spikes that travel along momentarily efficacious synaptic pathways constitute the information handling functionality of the neural network. Plasticity of synaptic connections mediate memory functions.

Neural pulses, Spikes; Dendritic Trees

Computer Models Required to Gain Insight

Brain functionality is so intricate and complex that it requires computer models to gain insight into the functionality and relationships.  (Computer models to gain insight must not be confused with "brain is a computer."  The brain is vastly different from a digital computer in many ways.) Examples of simulation models include one for the basal ganglia (Frank; Learning and the Basal Ganglia, 154) and one for the stochastic behavior of small populations of neurons (Spike Synchrony in Small Populations of Neurons).

Reentry; Recursive functionality

There is a ceaseless production of new activity states, in early sensory cortices and in motor cortices, across time. It is these successive neural states, one after the other, that can be said to constitute "regresses" for the previous state. Neural assemblies are activated (refreshed) in a pulse-like manner by reentrant signals circulating in the network hierarchy. It is the perpetually recursive property of corticocortical systems that permits this special form of regress. (Domasio; Convergence Zone, 70)   [recursion]  [Bayesian inference]  [Fuster's  perception-action cycle, 6]

Working Memory

Dynamic Core

The subset of neuronal activity Edelman refers to as the dynamic core is comprised of a momentary perception (mental object) convolved with the momentarily active portion of the neuronal synaptic network comprising the self.

Oscillation and Synchronization

The reliability of spike transmission increases steeply for approximately 20 to 40 synchronous thalamic inputs in a time window of 5 milliseconds, when the reliability per spike is most energetically efficient. The optimal range of synchronous inputs is influenced by the balance of background excitation and inhibition in the cortex, which can gate the flow of information into the cortex. Ensuring reliable transmission by spike synchrony in small populations of neurons may be a general principle of cortical function.  (Spike Synchrony in Small Populations of Neurons)

Attention

Sleep and Dreaming

Complexity, Self-Organization, Emergence

Sensory Systems

Cortical Maps

Sensory areas are represented topographically.

Modular areas of functionality

The dynamic core of consciousness is comprised of a subset of neural network signals bound across widespread modular areas. Edelman says the dynamic core is (1) highly differentiated and (2) highly integrated. Perceptual categorization in the modular areas is highly differentiated into minute neural assemblies, thereby permitting exquisite detail. When these minute neural assemblies are selected and amalgamated into a dynamic core, they become highly integrated on a momentary basis to form a conscious thought.

Association Cortices

Brain Stem

 

 

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Link to — Consciousness Subject Outline

Further discussion — Covington Theory of Consciousness