Functional selection of adaptive auditory space map by GABA(A)-mediated inhibition

The external nucleus of the inferior colliculus in the barn owl contains an auditory map of space that is based on the tuning of neurons for interaura l differences in the timing of sound. In juvenile owls, this region of the brain can acquire alternative maps of interaural time difference as a resul t of abnormal experience. It has been found that, in an external nucleus th at is expressing a learned, abnormal map, the circuitry underlying the norm al map still exists but is functionally inactivated by inhibition mediated by gamma-aminobutyric acid type A (GABA(A)) receptors. This inactivation re sults from disproportionately strong inhibition of specific input channels to the network. Thus, experience-driven changes in patterns of inhibition, as well as adjustments in patterns of excitation, can contribute critically to adaptive plasticity in the central nervous system.