SUBCORTICAL ADAPTIVE FILTERING IN THE AUDITORY-SYSTEM - ASSOCIATIVE RECEPTIVE-FIELD PLASTICITY IN THE DORSAL MEDIAL GENICULATE-BODY

Highly specific subcortical receptive field (RF) plasticity was found in the dorsal division of the guinea pig medial geniculate body during cardiac conditioning to a tonal frequency. There was increased response to the conditioned-stimulus (CS) frequency, and there were decreased responses to adjacent frequencies, especially at the pretraining best frequency (BF), which often resulted in a shift of tuning such that the CS became the new BF. Moreover, 1 hr later the effects were stronger, more sharply tuned, and centered on the CS frequency. A sensitization paradigm produced only broad, general increases of response across the RF. These findings reveal that the analysis of sensory RF dynamics is a valuable approach to understanding the neural mechanisms of information processing in learning and memory.