The Global Workspace (GW) Theory of Consciousness and Epilepsy

Conscious processing arises from coherent neuronal activity across widely distributed brain regions, particularly fronto-parietal associative cortices, according to global workspace theory. Transitions between conscious and non-conscious states involve abrupt, non-linear changes in neural coherence. Epileptic seizures, which often cause brutal alterations of consciousness, provide a test of this hypothesis. Recent findings show that sudden loss of consciousness during seizures coincides with non-linear increases in neural synchrony within distant cortico-cortical and cortico-thalamic networks. Excessive synchrony may prevent the distributed network from achieving the differentiation and complexity needed for conscious representation. These observations confirm predictions of the global workspace model and define a physiological window of neural coherence associated with conscious processing.

Study at a glance

Abstract

The global workspace (GW) theory proposes that conscious processing results from coherent neuronal activity between widely distributed brain regions, with fronto-parietal associative cortices as key elements. In this model, transition between conscious and non conscious states are predicted to be caused by abrupt non-linear massive changes of the level of coherence within this distributed neural space. Epileptic seizures offer a unique model to explore the validity of this central hypothesis. Seizures are often characterized by the occurrence of brutal alterations of consciousness (AOC) which are largely negatively impacting patients' lives. Recently, we have shown that these sudden AOC are contemporary to non-linear increases of neural synchrony within distant cortico-cortical and cortico-thalamic networks. We interpreted these results in the light of GW theory, and suggested that excessive synchrony could prevent this distributed network to reach the minimal level of differentiation and complexity necessary to the coding of conscious representations. These observations both confirm some predictions of the GW model, and further specify the physiological window of neural coherence (minimum and maximum) associated with conscious processing.