The developmental profile of visual cortex astrocytes

Airi Watanabe; Connie Guo; Per Jesper Sjöström

doi:10.1016/j.isci.2023.106828

The developmental profile of visual cortex astrocytes

iScience. 2023 May 6;26(6):106828. doi: 10.1016/j.isci.2023.106828. eCollection 2023 Jun 16.

Authors

Airi Watanabe^{1

2}, Connie Guo^{1

3}, Per Jesper Sjöström¹

Affiliations

¹ Centre for Research in Neuroscience, Brain Repair and Integrative Neuroscience Program, Department of Medicine, The Research Institute of the McGill University Health Centre, Montreal General Hospital, Montreal, QC H3G 1A4, Canada.
² Integrated Program in Neuroscience, Irving Ludmer Building, McGill University, 1033 Pine Avenue West, Montreal, QC H3A 1A1, Canada.
³ Department of Anatomy and Cell Biology, Faculty of Science, McGill University, Strathcona Anatomy and Dentistry Building, 3640 University Street, Montreal, QC H3A 0C7, Canada.

Abstract

We investigated how astrocytes in layer 5 mouse visual cortex mature over postnatal days (P) 3-50. Across this age range, resting membrane potential increased, input resistance decreased, and membrane responses became more passive with age. Two-photon (2p) and confocal imaging of dye-loaded cells revealed that gap-junction coupling increased starting ∼P7. Morphological reconstructions revealed increased branch density but shorter branches after P20, suggesting that astrocyte branches may get pruned as tiling is established. Finally, we visualized spontaneous Ca²⁺ transients with 2p microscopy and found that Ca²⁺ events decorrelated, became more frequent and briefer with age. As astrocytes mature, spontaneous Ca²⁺ activity thus changes from relatively cell-wide, synchronous waves to local transients. Several astrocyte properties were stably mature from ∼P15, coinciding with eye opening, although morphology continued to develop. Our findings provide a descriptive foundation of astrocyte maturation, useful for the study of astrocytic impact on visual cortex critical period plasticity.

Keywords: Cellular neuroscience; Developmental neuroscience; Neuroscience; Sensory neuroscience.