CONDITIONED CHANGES IN THE BASAL FOREBRAIN - RELATIONS WITH LEARNING-INDUCED CORTICAL PLASTICITY

Simultaneous recordings were performed in the auditory cortex and in t he basal forebrain (BF) of rats subjected to habituation, conditioning (tone followed by a footshock), extinction, and reconditioning. Quant ification of myographic activity from the neck muscles revealed behavi oral conditioning in 10-20 trials. Short-latency, increased discharges of the BF neurons were observed within the first 5 conditioning trial s, whereas tone-evoked responses above the level of the first habituat ion trials only started to occur between the 5th and the 10th trial in the auditory cortex. Increased discharges persisted in the BF during extinction; the cortical responses returned to their habituation level . Relative to conditioning, pseudoconditioning induced much smaller in creased discharges in both structures. The role of the BF neurons in p romoting learning-induced cortical plasticity is discussed in light of these results.