Secondary consciousness

Secondary consciousness is an individual's accessibility to their history and plans. The ability allows its possessors to go beyond the limits of the remembered present of primary consciousness. Primary consciousness can be defined as simple awareness that includes perception and emotion. As such, it is ascribed to most animals. By contrast, secondary consciousness depends on and includes such features as self-reflective awareness, abstract thinking, volition and metacognition. The term was coined by Gerald Edelman.

Since Descartes's proposal of dualism, it became a general consensus that the mind had become a matter of philosophy and that science was not able to penetrate the issue of consciousness- that consciousness was outside of space and time. However, over the last 20 years, many scholars have begun to move toward a science of consciousness. Such notable neuroscientists that have led the move to neural correlates of the self and of consciousness are Antonio Damasio and Gerald Edelman. Damasio has demonstrated that emotions and their biological foundation play a critical role in high level cognition, and Edelman has created a framework for analyzing consciousness through a scientific outlook. The current problem consciousness researchers face involves explaining how and why consciousness arises from neural computation. In his research on this problem, Edelman has developed a theory of consciousness, in which he has coined the terms primary consciousness and secondary consciousness. The author puts forward the belief that consciousness is a particular kind of brain process; linked and integrated, yet complex and differentiated.

Edelman argues that the evolutionary emergence of consciousness depended on the natural selection of neural systems that gave rise to consciousness, but not on selection for consciousness itself. He is noted for his theory of neuronal group selection, also known as Neural Darwinism, which posits that consciousness is the product of natural selection. He believes consciousness is not something separate from the real world, thus the attempt to eliminate Descartes’ "dualism" as a possible consideration. He also rejects theories based on the notion that the brain is a computer or an instructional system. Instead, he suggests that the brain is a selectional system, one in which large numbers of variant circuits are generated epigenetically. He claims the potential connectivity in the neural net "far exceeds the number of elementary particles in the universe"

Dynamic core hypothesis

Edelman elaborates on the dynamic core hypothesis (DCH), which describes the thalamocortical region- the region believed to be the integration center of consciousness. The DCH reflects the use and disuse of interconnected neuronal networks during stimulation of this region. It has been shown through computer models that neuronal groups existing in the cerebral cortex and thalamus interact in the form of synchronous oscillation. The interaction between distinct neuronal groups forms the "dynamic core" and may help explain the nature of conscious experience.

Re-entry

Edelman integrates the DCH hypothesis into Neural Darwinism, in which metastable interactions in the thalamocortical region cause a process of selectionism through re-entry, a host of internal feedback loops. "Re-entry", as Edelman states, "provides the critical means by which the activities of distributed multiple brain areas are linked, bound, and then dynamically altered in time during perceptual categorization. Both diversity and re-entry are necessary to account for the fundamental properties of conscious experience." These re-entrant signals are reinforced by areas Edelman calls "degenerate". Degeneracy doesn't imply deterioration, but instead redundancy as many areas in the brain handle the same or similar tasks. With this brain structure emerging in early humans, selection could favor certain brains and pass their patterns down the generations. Habits once erratic and highly individual ultimately became the social norm.

While animals with primary consciousness have long-term memory, they lack explicit narrative, and, at best, can only deal with the immediate scene in the remembered present. While they still have an advantage over animals lacking such ability, evolution has brought forth a growing complexity in consciousness, particularly in mammals. Animals with this complexity are said to have secondary consciousness. Secondary consciousness is seen in animals with semantic capabilities, such as the four great apes. It is present in its richest form in the human species, which is unique in possessing complex language made up of syntax and semantics. In considering how the neural mechanisms underlying primary consciousness arose and were maintained during evolution, it is proposed that at some time around the divergence of reptiles into mammals and then into birds, the embryological development of large numbers of new reciprocal connections allowed rich re-entrant activity to take place between the more posterior brain systems carrying out perceptual categorization and the more frontally located systems responsible for value-category memory. The ability of an animal to relate a present complex scene to its own previous history of learning conferred an adaptive evolutionary advantage. At much later evolutionary epochs, further re-entrant circuits appeared that linked semantic and linguistic performance to categorical and conceptual memory systems. This development enabled the emergence of secondary consciousness.