意識を創発するワーキングメモリ

Abstract

Consciousness plays an essential role in high-level cognition, which includes a long list of tasks such as perception, language comprehension, self-recognition, representation of other's mind, mental operations, complex reasoning and problem solving. Despite its importance, the neural basis of consciousness have not yet been revealed. Functional magnetic resonance imaging (fMRI) is an established technique for the study of neural correlates of consciousness (NCC) that involve high-level cognition by measuring cardiovascular responses. These works have indicated that the conscious mind emerges from the interaction of multiple neural networks. Among these networks, the working (executive) memory (WM) network coupled with the default mode network and dorsal attentional-network have been recently recognized to play a major role. We show evidences from cognitive social neuroscience experiments that indicate neural mechanisms supporting WM play a critical role in generating consciousness through executive functions such as updating, shifting and inhibiting incoming information. These executive works function in the dorsolateral and ventrolateral prefrontal cortex (PFC) and anterior cingulate cortex, with coordination across these and other brain areas being related to task dependent processes. WM's capacity limitation also plays a critical for active consciousness. Theoretical modeling of consciousness using graph theory, with which we can quantify large-scale networks of the brain, supports our WM-based consciousness. We propose a three-layered model of consciousness consisting of vigilance-, awareness-, and recursive-consciousness, which correspond to biological-, sensory-motor-, and self-consciousness, respectively. Among these layers, self-consciousness is likely critical for social interaction, which involves working together with other minds. Consistently, modular brain areas that bind multiple minds have been found in the medial PFC using fMRI. By introducing a false believe task, we confirmed high-level intentionality and meta-representation could also be involved in WM's executive function working on the dorsolateral PFC, which makes inference of another's mind possible.