Astrocyte heterogeneity and hierarchical information flow: reframing glial computation.

Astrocytes are active elements in the brain; they exhibit complex, highly branched processes that contact neurons and blood vessels to regulate neuronal activity and vasoactive responses. Distal processes receive information that is integrated in the soma; however, rather than uniform units, astrocytes display structural and functional heterogeneity across their processes. Furthermore, it remains unclear whether all the distal processes serve as input sites, output sites, or whether specific domains contribute more strongly to somatic responses. In this Perspective article, we discuss this hierarchical organization of information flow, with specialized compartments acting as input and output elements while others play integrating roles. Here, we discuss that astrocyte polarity depends on the local circuit and is dynamically reshaped by development, aging, and disease. Graph-theoretical approaches support hierarchical network structures within astrocytes for processing information and open the door to their contribution to brain computation in physiological and pathological reconfiguration.