Figure 8.

Responsive neurons have higher frequencies of spontaneous PSCs. A, Individual traces in responsive and unresponsive neurons showing sPSCs occurring before and after laser onset. This is shown before (above) and after application of the GABA_A-R antagonist, picrotoxin (100 μm, below), indicating that most synaptic events are GABAergic. B, Frequency of sPSCs with WHH > 5 ms before and after picrotoxin indicating mediation by GABA_A-Rs. Experiments with 0 Hz frequency after picrotoxin application are indicated by the dashed line intersecting the x-axis. C, Frequency of all sPSCs before and after picrotoxin indicating that nonGABAergic events are also occurring. D, sPSC frequency and amplitude plotted and divided into groups of responsive and unresponsive neurons. White and black bars indicate day and night data, respectively. Gray bars indicate that day and night data are pooled. Cell numbers are indicated below each bar; * and # refer to responsive/unresponsive and VIP+/VIP− comparisons, respectively. Statistical significance is determined with a two-factor ANOVA followed by multiple-comparisons applied to each group of four bars separately. E, mPSC frequency plotted for responsive and unresponsive neurons (cell numbers: n = 10,8 and n = 13,5 for VIP+ and VIP−, respectively). F, Evoked PSC amplitude at the location with the strongest response (best location) plotted as a function of sIPSC amplitude. For panels B,D,E, and F, only sPSCs >5 ms WHH are examined (Materials and Methods and Results); *p < 0.05, **p < 0.01, ***p < 0.001. Twenty-five percent of data in D and F were obtained in Ai27 mice.