Figure 9. Optogenetic suppression of PV neurons increases responses of pyramidal neurons in a condition-dependent manner. A, Example traces from a pyramidal neuron. Responses to the Oddball protocol (top) were enhanced in the presence of light (bottom). Blue and red patches mark the timing of standard and deviant tones, respectively. Green bars mark the timing of light pulses. B, Peristimulus time histograms of the responses of the example neuron from F to tone f2 without (left) and with (right) PV suppression. Light gray patch marks the stimulus timing, and green bar shows the light pulse. C, Scatter plots for the responses of pyramidal neurons to standard (left) and deviant (right) tones, with and without light, at the lowest range of light intensities used. Responses are mean firing rates in the range of 0–40 ms after tone onset. Data points represent the responses to each tone in each of the protocol sets played to different neurons (a few neurons were presented with two protocol sets with light intensities falling within the same bin—see numbers below the intensity range titles). Numbers on the plot areas show counts of responses enhanced by light (above diagonal) and responses reduced or unchanged (below diagonal). D, E, Same as C, for the medium (D) and high (E) light intensity ranges. F, Bars showing the average difference between responses of pyramidal neurons with and without light for the different conditions, in the same light intensity range as H. Error bars show SEMs over all responses. G, H, Same as F, for the medium (G) and high (H) light intensity ranges. I, J, These panels follow the analysis performed in the study by Natan et al. (2015, their Fig. 4). I, Top row, Peristimulus time histograms for the responses of pyramidal neurons in protocols using our highest light intensity range, normalized to the maximum firing rate (FR) of each neuron in response to the deviant condition under no light. Showing responses with (lighter colored curves and patches) and without light (darker colors) to the deviant (left), standard (middle), and silence (right) conditions. The latter is taken from the silent trials in the Rare sequences. Bottom row, The change in normalized FR because of the light (Light – No Light FRs), for the deviant, standard, and silence conditions (left, middle, and right panels, respectively). Light gray patch marks the tone duration, and green bars marks the light pulse. Bands around the traces show SEM. J, Top row, The mean normalized FR along the 0–40 ms range (left) and the 0–150 ms range (right) after tone onset, showing responses to silence (Sil), standard (Std), and deviant (Dev) conditions under no light and under light, with the same color code as in I. Bottom row, Mean change in normalized FR because of light (Light – No Light FRs) along the same time ranges as the top row. Error bars are SEMs.