Scientific Understanding of Consciousness
Major Concepts in Consciousness
Consciousness an Emergent Property
Consciousness is an emergent property of a biological network of neurons resulting from billions of years of evolution.
Basis of contemporary neural science is that all mental processes are biological. (Kandel; Principles of Neural Science, 1275)
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.
The Self and Sense-of-Self
A person's individuality and personality are represented in the Self, the brain’s neural network established by genetics and connected by synapses whose synaptic efficacies are updated via the neural activity experienced in the environment. Synapses have short-term plasticity via biochemical changes and longer-term plasticity over weeks and longer via (consolidation) gene expression and protein synthesis.
Multimodal sensory patterns interact with the engraved synaptic efficacies of the Self, resulting in perception, consciousness, and via the plasticity of the synapses, both short-term and long-term memory.
Within the total ensemble of synaptic efficacies of the Self, the sense-of-self is a subset of neural activity within the dynamic core representing the status of the organism. The sense-of-self is supported by the unconscious functionality of the autonomic nervous system.
Sense-of-self is based upon ‘the self’ comprised of the entire neural network connected via synapses molecularly (engraved/encrusted/ingrained/imprinted) by genetics and by ongoing experience in the environment. 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.
Humans have an elaborated sense of self that includes rich autobiographical details beyond the functional capability of non-human animals.
Bound subset of neural activity within the dynamic core representing the current focus of thought.
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 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.
Mammals and some (birds/reptiles?) have core consciousness.
Humans have an elaborated sense of self, including rich autobiographical details extending far beyond the core consciousness of nonhuman animals. Human-type consciousness overlays core consciousness.
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.
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. Projection neurons of the brain can have input dendritic trees with 104 or more synapses, and axons with many output synaptic terminals. Rich networks of inhibitory interneurons interconnect with the dendritic trees of projection neurons, and by experience-inscripted synaptic efficacies, provide intricate precision functionality.
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.
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.
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
The most rudimentary consciousness is a pure emotion associated with fast interactions with the outside world. Neural processing of emotions begins with the limbic system, a number of interconnected subcortical regions around the hypothalamus.
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), one for the stochastic behavior of small populations of neurons (Spike Synchrony in Small Populations of Neurons), and one for the Large-scale Model of mammalian Thalamocortical System (Computer Simulation of Thalamocortical System).
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]
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.
Patterns of neural signal traces in the dendritic trees of neurons, dynamically connected momentarily by efficacious synapses, sculptured by genetics and experience, mediate neural network activity, an ever-changing subset of which forms the dynamic core of consciousness.
Oscillation and Synchronization
Simultaneity of neuronal activity arising from intrinsic oscillatory electrical activity, resonance, and coherence are at the root of cognition. Simultaneity of neuronal activity is the most pervasive mode of operation of the brain. Neuronal groups that oscillate in phase, i.e. coherently, support simultaneity of activity.
The term ‘synchronization’ should be interpreted broadly to mean ‘coherence of neuronal assemblies’ at the group level, not necessarily synchronized individual neuronal firing.
Sleep and Dreaming
Complexity, Self-Organization, Emergence
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.
The foundations for the processes of consciousness are the unconscious processes in charge of life regulation -- the blind dispositions that regulate metabolic functions and are housed in brainstem nuclei and hypothalamus. (Damasio; Self Comes to Mind, 119)
Link to — Sidebars Table of Contents
Link to — Reference Paraphrases Book List
Link to — Consciousness Subject Outline
Further discussion — Covington Theory of Consciousness