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.
Consciousness and explicit memory storage may depend on a three-dimensional matrix formed by protoplasmic astrocytes in the brain. Recent anatomical and physiological evidence shows that individual astrocytes occupy separate, non-overlapping tessellating domains that tile cortical gray matter. Each domain encompasses many thousands of synapses, and astrocytes respond to neural activity as rapidly as neurons do, distinguishing inputs from different pathways. Astrocytes in sensory cortex can discriminate sensory details more finely than surrounding neurons. Domains are interconnected by gap junctions, forming syncytial networks that may extend across the entire neocortex. This matrix is proposed to seamlessly bind attended sensory information and encode explicit memories, with the temporal stream of consciousness arising from sequential neural activity.