Astrocytes as a Bridging Mechanism: From Circuits to Cortex in Consciousness

Abstract

This article reviews the currently reported coupling properties of astrocytes in neural circuits, as well as the potentially promising functional structures and molecular mechanisms associated with astrocytic specialized domains and the spatiotemporal specificity of calcium levels. It proposes a model of astrocytes as a bridging mechanism—from microcircuit specialization to the functional connectivity of brain regions and nuclei—that addresses what signals are involved, how integration is achieved, and how these processes act on long-term memory and the “brain-body” characteristics of consciousness. The model posits that, in the formation of consciousness and cognition, astrocytes and their functional structures bridge the neuronal encoding of multimodal embodied perception, integrate and transmit it, and generate delayed, low-frequency calcium waves corresponding to the current state of consciousness or cognition. Through a relatively global signal, they direct the dynamics of the cortical connectome, thereby acting, at the level of brain dynamics, as a downstream bridging router for memory and shaping the inertial circuits of consciousness over long time domains. At the microenvironmental level, astrocytes and their subtypes in different regions shape neural circuits through metabolic coupling based on layer-specific spatial transcriptomes, reversibly shaping the cellular and synaptic basis of long-term memory. By virtue of their broad receptor repertoire expression, astrocytes serve as terminal receptors for perceptual information. At the circuit level, through syncytium-based global calcium waves, they form a global signal, thereby locally and specifically influencing and globally regulating cortical activity and coordinating the cortical connectivity and spatial transcription of consciousness. In terms of embodied consciousness, astrocytes bridge, through neurovascular coupling and global signals, the bidirectional communication between consciousness as “brain-body synchrony” and bodily rhythms such as blood flow and respiration.