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

Synopsis of my Understanding of Consciousness

 

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

· The objective of the scientific study of consciousness is to understand the biological basis of consciousness, sometimes called the neural correlate of consciousness (NCC).

· Control of movement is the ultimate result of neurological activity. (1) Cognitive activity for prediction, and (2) cognitive, memory and emotional activity for value judgments and decisions comprise the brain contributions to movement control.

· Consciousness serves to assist animals in their struggle for survival in a competitive environment. The brain serves as a reality emulator for prediction and planning.

· Consciousness is the convolution of an instantaneous, transient, synaptically-connected neural pattern (mental image) with lifelong synaptic storehouse memory termed the “core memory” or “autobiographical memory.” Edelman terms this convolution of present mental image with lifelong memory the “Remembered Present.” Input from the senses is not required for consciousness; an imagined image or a restored memory can serve as the image convolved with lifelong memory.

· Consciousness is mediated by a “dynamic core” of ever-changing neural activity in the thalamocortical system and within the cortex itself on a millisecond-by-millisecond basis. Consciousness arises as an emergent property of this neuronal network activity.

· Consciousness is supported by unconscious processes, including Fixed Action Patterns (FAPs) of movement: Innate FAPs of infant sucking, crying, sneeze, hiccups. Learned FAPs of walking, riding bicycle, finger movements of violin, piano, keyboard typing; Emotional FAPs, facial grimace, laugh. FAPs of vocal movements in speech. An infant learning to talk is a process of developing FAPs for speech. FAPs are thought to originate in the basal ganglia and associated neural circuitry.

· It is useful to distinguish two kinds of consciousness: (1) human-type conscious and (2) core consciousness.

· Human-type consciousness includes a sense of time from the distant past to the remote future. The ability to conceive ideas and manipulate ideas for planning of future movements and action is a major distinguishing feature of human-type consciousness. The brain is a reality emulator for planning action. Human-type consciousness also has the capability for a rich language. Human-type consciousness is founded on and includes core consciousness.

· Core consciousness has a sense of awareness of the present, which is based on a sense of self. The sense of self is based on the proto-self, the unconscious functions of such things as the hypothalamus and autonomic nervous system. Through the senses of vision, hearing, touch, taste, smell, core consciousness provides an awareness of the present world.  Cognition and emotion provide basis for motivation for action. Innate and learned FAPs support movement control dictated by motivation.

· Sense of self is the result of evolution. In earliest evolution, a cell boundary provided a container to maintain high concentrations of chemicals for rapid rates of reactions. The evolving cell then came to have a sense of boundary, exemplified by an amoeba, which seeks food and avoids certain chemicals. Further along in evolution, a sea slug neural network can be fear-conditioned. This sense of boundary to protect the self evolved into the autonomic nervous system with hypothalamus, the limbic system, and cortex cognition.

· The dynamic core of consciousness is dependent on activity in a subset of thalamocortical loops together with activity in a subset of the cortex itself, along with a few other possible areas. No specific neurons or loops within the areas are required. The size and spatial distribution of the dynamic core can vary widely with the intensity of momentary thoughts. Neurons and synapses comprising the dynamic core are used and reused in varying arrangements on a basis of about 10 milliseconds as thoughts change. The minimal neural correlate of consciousness is currently unknown but may become more clearly defined in future decades.

· Functionality of the dynamic core is best understood as a dynamic network of gestalts composed of assemblies of neurons. Many gestalts of various sizes are dynamically recruited into a hierarchical assembly mediated by instantaneously active synapses.  This momentary consciousness gestalt varies in time from tens to a few hundred milliseconds.  The consciousness gestalt varies in size from many tiny gestalts during reverie to a large gestalt embracing many smaller gestalts during ponderous thought.

· Consciousness is supported by areas in the brain stem and by the hypothalamus. Damage to certain of these areas leads to loss of consciousness or death. Sleep is a natural loss of consciousness controlled by these areas. General anesthetics influence these areas. Coma is caused by lack of function of certain of these areas. Vegetative state or “brain death” is the result of the residual function of these areas with no activity in the thalamocortical loops or cortex.

· Memory is a central component of the brain mechanisms that lead to consciousness. Memory is not simply recall or readout of information coded in synapses, but rather involves a regeneration of the original episode, semantics or procedure in terms of synaptic changes created by the original experience. The biological mechanisms of memory are currently not well understood, although some aspects now seem clear. The mechanism of long-term potentiation (LTP) alluded to by Donald O. Hebb has provided much insight. Memory can be mediated by circulating neural signals in the prefrontal cortex and association cortices; or by widespread modification in the brain’s synapses, including modifications in ion concentrations, ion channels, neurotransmitters or their receptors; or by structural modifications in dendrites, spines, or receptors. The combinatorics of a million billion (10¹⁵) synapses provides an essentially limitless state-space of mental images. The hippocampus is not required for consciousness, although it is required to form new declarative memories. It seems clear that procedural memory operates unconsciously, and hence does not require the hippocampus. The distinctive mechanisms of working memory, declarative memory (episodic and semantic), and procedural memory together with the effects of time duration and memory consolidation continue to be intensively researched.

· The brain remains continuously active from an early time in the prenatal embryo until a time of accidental trauma, disease, stroke or death when the neurons and synapses no longer function. When the neurobiological basis of the dynamic core ceases to function, consciousness ceases.

 

 

 

Link to — Introduction to Consciousness

Link to — Consciousness Subject Outline

Further discussion -- Covington Theory of Consciousness