Neurological disorders and the structure of human consciousness

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Abstract

Recent studies that identify distinct neural correlates of perceptual awareness offer a promising step towards improved understanding of the neurological underpinnings of conscious experience. Such studies indicate that perceptual awareness is modular in nature, with neural correlates of awareness consisting of the specialized structures involved in perceptual processing. However, the integrative, multimodal nature of conscious experience appears to require a functional architecture that overcomes this modular segregation of function. We propose a model in which experience emerges from the dynamic interactions of specialized component processes via a distributed neural network. Such a model offers a mechanism to explain several empirical observations of the neural correlates of perceptual awareness, cognitive function, and symptoms of neurological damage.

Section snippets

Modularity of perceptual awareness

Neurophysiological evidence for the modular organization of perceptual awareness is strong. Rather than functioning as a general-purpose computing device, the brain consists of a network of adaptive systems 2, 11. Functional neuroimaging experiments, single-cell recordings and neuropsychological dissociations of function indicate that neural circuits segregate into functionally specialized systems on both cognitive and cellular levels, and reveal a robust correlation between the performance of

Integrated awareness emerges from modular interactions within a neuronal workspace

Although evidence for the modularity of information processing is strong, a modular architecture is not, in itself, sufficient to account for the majority of cognitive tasks that occur within the realm of conscious experience. The presence of a large-scale network, whose long-range connectivity provides a neural workspace through which the outputs of numerous, specialized, brain regions can be interconnected and integrated, provides a promising solution to this need for integration, and fits

Interpreting a post-lesion world

When considered within a framework of modular, interpreted consciousness, a variety of seemingly bizarre neurological syndromes reveal a rational pattern of symptoms. Although phenomenally distinct, such syndromes may be mechanistically related, with symptoms falling into place as the logical results of an interpretive system that is striving to make sense of an altered set of available information.

Conclusions

Data from a wide range of functional, physiological and clinical studies support a model of consciousness in which subjective awareness emerges from the interactions of specialized, modular components in a distributed neural network. In addition, the activity of such components is united cognitively by an interpretive process that occurs in the left hemisphere of the human brain. The dynamic, self-modifying nature of the interactions between these components is driven solely by the range of

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