Astrocytes are a type of glial cell and are essential for the maintenance of many neurological functions. Now, a new study (Science doi:10.1126/science.1222381) reveals that astrocytes are localized to specific domains in the central nervous system, with potential consequences for understanding region-specific brain functions.

Using reporter fate mapping in mice, Hui-Hsin Tsai et al. found that astrocytes migrate radially from the ventricular zone, forming distinct domains that are determined by their embryonic sites of origin in this zone. The astrocytes did not undergo secondary tangential migration later in development, in adulthood or after injury, suggesting that the restricted astrocyte domains remain stable.

The authors then investigated how astrocyte distribution influences interactions with neighboring neurons by selectively removing astrocytes from part of the ventral ventricular zone (the motor neuron progenitor domain). This depletion altered the numbers of certain types of synapses, and astrocytes from adjacent regions could not migrate into the depleted area to rescue the synaptic dysfunction.

Thus, these results indicate that regional astrocyte allocation might be important for the development and maintenance of localized brain functions. The findings could also have implications for understanding brain regeneration, as they show that there are limitations in the astrocyte response to injury.