Signatures of Conscious Processing

Neural_Correlates_Of_Consciousness

Today I went to a lecture with the eminent cognitive scientist Stanislas Dehaene, which is visiting Oslo today on November 6, giving a public lecture on his research into consciousness. The lecture was hosted by The Norwegian Academy of Science and LettersForum for bevissthetsforskning and SERTA CDAB and turned out to be really interesting.

Understanding how brain activity leads to a conscious experience still remains a major experimental challenge, but Dehaene tried to describe a series of experiments that probe the signatures of conscious processing. In these experiments, he and his colleagues asked whether a specific type of brain activity can be detected when a person suddenly becomes aware of a piece of information. They created minimal contrasts whereby the very same visual stimulus was sometimes undetected, and sometimes consciously seen. Then they used time-resolved methods of electro- and magnetoencephalography to follow the time course of brain activity. He claim that results showed that conscious access relates to a global burst of late synchronized activity (a cortical “ignition”), distributed through many cortical areas, and propose a theory of a global neuronal workspace. According to this theory, which is what we experience as a consciousness, is the global availability of information in a large-scale network of pyramidal neurons with long-distance axons.

The so-called hard problem of consciousness, where consciousness is often thought to be a unique brain state that occurs independently of function, should not cripple our attempts for further research and better our understanding of this mysterious concept. But as Cohen and Dennet (2011) points out in their paper, psychophysical and neurophysiological findings pointing to the distinction between visual attention and consciousness, concludes that attention is necessary but not sufficient for consciousness. And they argue that no experimental results exclusively support the existence of consciousness independent of function and access. There are several theorists claiming that there are neural correlates of conscious experience that are separate from the neural correlates of cognitive functions, like winning coalitions, microconsciousness, recurrent processing, etc., which should give a global availability of information. But by isolating conscious experience from cognitive functions one removes the experience in question from any further scientific testing. Even though such theories might offer substantial insight into the formation of internal representations of the sensory and perceptual world, I still do not think it’s sufficient to explain personal awareness. But I look forward to further research which might provide answers about the elusive functional role of consciousness and the neural correlates of conscious experience and cognitive function.

References:

Dehaene, S., & Changeux, J. P. (2011). Experimental and theoretical approaches to conscious processing. Neuron, 70, 200-227.

Cohen M. A., Dennett D. C. (2011). Consciousness cannot be separated from function. Trends in Cognitive Science. 15, 358–364.

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