Figure 1: Associative learning produces tuning shifts. An example of a complete shift of frequency tuning of a single cell in A1 of the guinea pig from a pre-training best frequency (BF) of 0.75 kHz to the CS frequency of 2.5 kHz after 30 trials of tone – shock pairing, during which the guinea pig developed a cardiac conditioned response. Inset shows pre- and post-training cellular responses (rasters) for the pre-training BF and the CS frequencies. Note the marked increase in neuronal discharges to the signal frequency of 2.5 kHz and the pronounced decrease in neuronal responses to the pre-training best frequency of 0.75 kHz.