Naturalizing consciousness: A theoretical framework

Inasmuch as this theory of neuronal group selection (TNGS) abandons the basic computational notions of logic and a clock,  a means for spatiotemporal coordination must be put in place. This is provided by a process called reentry, the operation  of which is central to the emergence of consciousness. Reentry is an ongoing process of recursive signaling among neuronal  groups taking place across massively parallel reciprocal fibers that link mapped regions such as those found in the cortex.  Reentry is a selectional process occurring in parallel; it differs from feedback, which is instructional and involves an error  function that is serially transmitted over a single pathway. As a result of the correlations that reentry imposes on the interactions  of competing neuronal groups, synchronously active circuits across widely distributed brain areas are selectively favored.  This provides a solution to the so-called binding problem: how do functionally segregated areas of the brain correlate their  activities in the absence of an executive program or superordinate map?

I have put forth arguments elsewhere (12) that a theory based on the notion that the brain is a computer or an instructional system is not tenable. Instead, I have  indicated that the brain is a selectional system, one in which large numbers of variant circuits are generated epigenetically,  following which particular variants are selected over others during experience (12–14).

This functional cluster has been called the reentrant dynamic  core (8) to emphasize its central properties as a complex system capable of yielding differentiated yet unitary states. In a recent  paper, Crick and Koch (17) essentially agree with this formulation; their coalitions correspond roughly to core states.

A scientific view that assumes that consciousness arises from reentrant interactions among neural populations must therefore  conclude that it is the neural activity of the dynamic core that is causal. If we call that activity C′ and the qualia it  entails C, then it is C′ that is the cause of our actions and further C′ events (Fig. 2).

Figure 2    

Causal chains in the world, body, and brain affect the reentrant dynamic core. Core activities (C′) in turn affect further  neural events and actions. Core processes confer the ability to make high-order distinctions. The entailed qualia (C) consist  of those distinctions. The shaded area labeled “phenomenal transform” has no causal efficacy but consistently reflects the  C′ states, which are causal. The boundary of the dynamic core in the figure should not be interpreted too strictly, because  in real brains it fluctuates in time. 

According to the framework proposed here (Fig. 2), consciousness arises as a result of integration of many inputs by reentrant interactions in the dynamic core. This integration  occurs in periods of <500 ms. Selection occurs among a set of circuits in the core repertoire; given their degeneracy, a number  of different circuits can carry out similar functions.