Connections between neurons strengthen or break during brain development. Unexpectedly, key cell-surface proteins involved in immunity seem to regulate some of this plasticity.
Carla Shatz of Stanford University in Palo Alto, California, and her colleagues found that two members of the family of major histocompatibility complex class I (MHC I) proteins limit the 'tuning up' of circuitry involved in visual processing. Mice in which the genes for these two proteins had been deleted performed better in a visual task involving the blocking of one eye than did normal mice. The MHC I proteins curb the retuning of circuitry that enables the functioning eye to compensate for the blocked one, the authors say.