Figure 4.

Neuronal responses to a weak stimulus after pairing with a strong stimulus in the presence of CCK in anesthetized rats. (A) An unresponsive neuron in the auditory cortex became responsive after 10 pairings (P10) of f₁ (18 kHz) and f_B (14 kHz). Raster plots and raw traces show neuronal responses to f₁before (t0) and after stimulus pairings (t1, t2). Z-scores were calculated based on differences between average neuronal firing during a 30-ms period after stimulus onset and spontaneous firing during a 30-ms period before stimulus onset. ^**P < 0.01, paired t-test (stimulus-evoked vs spontaneous firing); ^##P < 0.01, one-way ANOVA. A frequency-response function was acquired at the beginning of the experiment (T). (B) Pairing of f₁ and f_B after local infusion of PBS did not induce a change in neuronal responses. Raster plots and raw traces show neuronal responses to f₁ at different times before and after pairings of f₁ and f_B during three blocks of 10 trials (P10, P10', and P10”). Z-scores were calculated based on differences between average neuronal firing during a 90-ms period after stimulus onset and spontaneous firing during a 90-ms period before stimulus onset. N.S., not significant, one-way ANOVA.