Consciousness and the dynamical core

Primary consciousness is the holy grail of neuroscience. Unlike high level consciousness which concerns aspects such as the notion of self and consciousness of consciousness, primary consciousness is concerned with phenomenal qualia. In brief, why do we have a subjective phenomenal experience of something such as the redness of something red. This refers to the ‘what it is like’ to experience something. The philosophical problem of zombies is often used to illustrate some issues involved. Is it possible to have a zombie like creature that can respond and behave in exactly the same way as we do but that does not have a subjective experience? If so then why do we have one? Further to this, why should a mechanistic device such our brain produce experience but the zombie or even a thermostat not? How can something material produce something phenomenal?

The problem is a big question as we do not really understand at any level how phenomenal experience can arise. We can however deduce some properties that a system must satisfy to enable it and also identify neural correlates of consciousness. Both of these still leave an explanatory gap of say ‘why is the activation of this group of neurons accompanied by an experience of red?’.

William James noted that consciousness is a process, and although it undeniably forms an aspect of what primary consciousness is, I have trouble with people who use such a claim as an answer to the problem. A process is an abstract concept that only bestows meaning to an intelligent observer of a situation, as such its ontological status is vaguer than something such as for example a chair. Although hard to define, I don’t feel that primary consciousness suffers from this ontological ambiguity. This is probably because consciousness is the closest thing to us, it is us, and as a result although difficult to tie down conceptually due to its subjective nature, its being is direct, immediate and definitely not ambiguous or even interpretational. This may highlight a difference in ontological category between process and consciousness that has to be clarified.

Pursuing the process aspect of consciousness Gerald Edelman and Giulio Tononi present the dynamical core hypothesis as an explanation.

‘First, consciousness experience appears to be associated with neural activity that is distributed simultaneously across neuronal groups in many different regions of the brain. Consciousness is therefore not the prerogative of any one brain area; instead, its neural substrates are widely dispersed throughout the so-called thalamocortical system, and associated regions. Secondly, to support conscious experience, a large number of groups of neurons must interact rapidly and reciprocally through the process called reentry’.

The dynamic core relies upon the notion of complexity in a neural system. A neural system is highly integrated if it constituent clusters are well connected so that functionally their behaviour can synchronize. A highly integrated system although able to bind information in different parts cannot contain much information as everything ends up doing the same thing so the number of possible states is limited. A differentiated system is the opposite in which there is little communication to bind parts but the number of possible states is large. Complexity is defined as a balance between integration and differentiation in which many states are possible and desperate parts can communicate and bind. Given this, consciousness through the dynamic core is defined as follows:

1. A group of neurons can contribute directly to the conscious experience only if it is part of a distributed functional cluster that, through reentrant interactions in the thalamocortical system, achieves high integration in hundreds of milliseconds.

2. To sustain conscious experience, it is essential that this functional cluster be highly differentiated, as indicated by high levels of complexity.

A curious question that this model raises relates to the fact that different neuronal groups can be members of the dynamic core at different times allowing for the possibility that at two different moments in time the dynamic core may be constituted from totally different members. If this is the case what binds the continuity of consciousness? Is it just the process and if so how does this evade the problem of ontological status mentioned above?

For more on the dynamical core hypothesis read ‘A Universe Of Consciousness’ by Gerald Edelman and Giulio Tononi.