Figure 4.

Magnitude and synchrony of thalamic input drive cortical response properties. A, Air-puff stimulation of the full whisker array leads to a greater spatial spread of the cortical response in the onset frame, but the variability of the response amplitude does not peak at threshold stimulus amplitudes (n = 2 animals). Inset depicts all variability data binned into three equally sized groups to demonstrate variability trends (* indicates p < 0.05, two-sided t test with unequal variances). B, Sensory stimulation with an air puff after trimming all but one whisker shows spatial and amplitude variability responses similar to those seen with single whisker stimulation using a piezoelectric actuator (n = 2 animals). Inset depicts all variability data binned into three equally sized groups to demonstrate variability trends (* indicates p < 0.05, two-sided t test with unequal variances). C, Activity from pairs of single neurons residing in the same barreloid were recorded simultaneously in response to whisker deflections. The jitter, calculated as the SD of the first spike latency, was strongly correlated with the synchrony of firing between the two neurons (n = 15 pairs). D, Increasing intensity of optical stimulation of ChR-expressing VPm neurons reduced jitter. E, Beyond the optical threshold response, the jitter in response to optical stimulation was significantly lower than the minimum jitter achieved using whisker stimulation (n = 7 cells).