Fig. 6.

Discrimination (Dis) and reward (Rew) periods are associated with facilitated firing rate modulations in the lemniscal pathway. The figure depicts peristimulus time histograms (PSTHs) of single neurons recorded from layer IV (A), layers V/VI (B), and VPM (C). The red boxes indicate the discrimination (0–250 ms) and reward periods (1,000–2,000 ms). A: PSTHs of the neurons presented in this column were all recorded in the same session. Increases in the firing rate that correspond to intense whisker stimulation are generally present during both discrimination and reward periods. B: PSTHs of the neurons presented in this column were all recorded in the same session. Note that increases and decreases in firing rate occur at multiple time periods that may or may not match the discrimination and reward periods. C: PSTHs of the neurons presented in this column were all recorded in the same session. As observed in layer IV of S1, discrimination and reward periods were characterized by intense whisker stimulation, which was associated with increases in the firing rate of a large fraction of neurons in VPM.