Figure 3. Orientation tuning of thalamic excitation.

a, Example cell: Top, Isolated thalamic excitation (EPSC_Thal) in response to drifting gratings of various orientations (average of 8 trials per direction). Gray rectangle, visual stimulus (1.7 s). Blue bar, LED illumination (2.6 s). Bottom, F1 modulation of EPSC_Thal. Cycle average (blue) and best-fitting sinusoid (green) at the grating temporal frequency (2 Hz). The y-offset was removed to aid comparison of F1 amplitude across different orientations. Right, EPSC_Thal and cycle average in response to 330 degree grating at expanded time scale showing how Q_Thal and F1_Thal are determined. b, Orientation tuning curves of Q_Thal (dashed line) and F1_Thal (solid line) for the neuron in (a). c, Population tuning curves of Q_Thal (dashed line) and F1_Thal (solid line). Left, Population tuning curves in which Q_Thal and F1_Thal tuning curves for each cell were equally shifted so that the preferred direction of F1_Thal occurred at 0 degrees (F1_Thal reference). Right, Population tuning curves in which Q_Thal and F1_Thal tuning curves for each cell were independently shifted so that preferred direction of Q_Thal and F1_Thal both occurred at 0 degrees (self reference). d, Orientation selectivity index (OSI) of Q_Thal plotted against OSI of F1_Thal for each cell. e, Direction selectivity index (DSI) of Q_Thal plotted against DSI of F1_Thal for each cell. Filled red markers in d and e denote the OSI and DSI values of the example cell. Data in c–e are from n = 42 cells from 33 mice. Error bars, mean ± s.e.m.