LEARNING-INDUCED DYNAMIC RECEPTIVE-FIELD CHANGES IN PRIMARY AUDITORY-CORTEX OF THE UNANESTHETIZED MONGOLIAN GERBIL

Learning-induced changes of the spectro-temporal characteristics of pr imary auditory cortex (AI) units were studied by response plane analys is of recordings from the AI in unanaesthetized Mongolian gerbils. Usi ng response planes obtained prior to and after auditory discrimination training bins of significant change were identified and their spectre -temporal distribution was studied. Bins of significant changes were g enerally found to be distributed over the entire spectro-temporal rece ptive field but occurred most frequently within the first 100 ms of re sponse in the spectral neighbour-hood (1.5 octaves) of the frequency o f the reinforced conditioned stimulus. Training-induced response decre ases occurred early after 10 ms for reinforced conditioned tones and t ones in the frequency neighbourhood. Response increases occurred so ea rly only for non-reinforced tones in the neighbourhood of the reinforc ed frequency and occurred later (after 40 ms) for the reinforced tones . The results are discussed in the light of dynamic disinhibition.