Extended Data Fig. 4: The time course of the activity of thalamic units recorded in dLGN in response to static gratings is similar across spatial phases.
From: Cortical direction selectivity emerges at convergence of thalamic synapses
a, Example thalamic unit with transient response to static gratings during cortical silencing. Top, spatiotemporal receptive field. Bottom, PSTHs in response to each phase of the static grating used to construct the spatiotemporal receptive field illustrated above. The PSTH at the preferred phase is highlighted by a thicker trace. The preferred phase is defined as the phase closest to the vector average of the response at each phase. The brackets show the time windows over which the early (30–110 ms) and late (110–230 ms) firing rates were averaged (Re and Rl, respectively) to compute the early/late index [(Re − Rl)/(Re + Rl)]. This unit has an early/late index of 1 for static gratings presented at the preferred phase and of 0.88 and 1 for gratings presented at phases of ±45° from the preferred phase. b, As in a but for an example thalamic unit with sustained response. The arrows illustrate the preferred spatial phase and the phases separated by ±45°. This unit has an early/late index of −0.3 for static gratings presented at the preferred phase and of −0.08 and 0.22 for gratings presented at phases of ±45° from the preferred phase. c, Heat maps of responses to static gratings for 177 thalamic units (24 mice) during cortical silencing. Left, each row is the amplitude of the PSTH of one of the thalamic units in response to the preferred phase of the static grating. The units are ordered according to their early/late index in response to the preferred phase. Middle, same as left but in response to a static grating, the phase of which is 45° below the preferred phase. The order of the units has not been changed; that is, it is the same as on the left. Right, same as left but in response to a static grating with a phase 45° above the preferred phase. The order is the same as on the left. Note that transient and sustained units maintain their characteristic firing dynamics even in response to static gratings presented at phases of ±45° from the preferred phase. d, Scatter plots of the early/late index computed in response to static gratings presented at the preferred phase and at phases of ±45° from the preferred phase. Note that in all plots the data are close to the unity line. e, Distribution of direction selectivity indexes of the firing rates (DSI F0) of the 177 thalamic units in d. The vertical dotted line is DSI F0 = 0.3. In 22 units DSI F0 was greater than 0.3. f, As in d but specifically for those thalamic units with DSI F0 values greater than 0.3. Colours indicate the value of DSI F0, according to the colour scale on the right.
