The Astroglia Syncytial Theory of Consciousness.

A novel hypothesis proposes that astrocytes, which form a global syncytium throughout the neocortex, are the locus of consciousness by integrating synaptic signals. Earlier criticism noted that intercellular calcium waves are too slow for consciousness but ideal for memory formation. Recent technical advances have overcome the challenge of separating syncytial electrical responses from neuronal activity, revealing that the astroglia syncytium is isoelectric with minimal impedance and conducts electricity as rapidly as neural networks. This suggests the syncytium can transmit integrated local synaptic signaling globally across the neocortex in the timeframe required for consciousness, potentially binding all functional brain areas.

Study at a glance

Abstract

The neurological basis of consciousness remains unknown despite innumerable theories proposed for over a century. The major obstacle is that empirical studies demonstrate that all sensory information is subdivided and parcellated as it is processed within the brain. A central region where such diverse information combines to form conscious expression has not been identified. A novel hypothesis was introduced over two decades ago that proposed astrocytes, with their ability to interconnect to form a global syncytium within the neocortex, are the locus of consciousness based on their ability to integrate synaptic signals. However, it was criticized because intercellular calcium waves, which are initiated by synaptic activity, are too slow to contribute to consciousness but ideal for memory formation. Although astrocytes are known to exhibit rapid electrical responses in active sensory pathways (e.g., vision), it was technically impossible to determine electrical activity within the astroglia syncytium because of the challenge of separating syncytial electrical responses from simultaneous neuronal electrical activity. Therefore, research on astroglia syncytial electrical activity lagged for over sixty years, until recently, when an ingenuous technique was developed to eliminate neuronal electrical interference. These technical advances have demonstrated that the astroglia syncytium, although massive and occupying the entire neocortex, is isoelectric with minimal impedance. Most importantly, the speed of electrical conductance within the syncytium is as rapid as that of neural networks. Therefore, the astroglia syncytium is theoretically capable of transmitting integrated local synaptic signaling globally throughout the entire neocortex to bind all functional areas of the brain in a timeframe required for consciousness.