Figure 4.
Activating vLGN reduces activity in mSC
(A) Schematic of the experimental setup for Neuropixels (NPXs) recordings in the mSC during optogenetic stimulation of ChR2-expressing GABAergic vLGN neurons in awake, head-fixed mice.
(B) Mean spike rates of an example single unit in the mSC in response to three consecutive looming stimuli of different contrasts (gray bars) during vLGN stimulation (red) and in control trials (black). Background shading shows the laser stimulation period. Shading shows the 95% confidence interval of the mean across trials.
(C) Mean spike rate of the single unit shown in (B) during a 3-s window from stimulus onset in control (black) and laser trials (red), normalized to the mean response to 99%-contrast looming stimuli in control trials. Shading shows the 95% confidence interval of the mean across trials. The dashed line represents the normalized mean pre-stimulus spike rate of the single unit.
(D) Mean population spike rate of all recorded units in the mSC during looming stimuli of different contrasts in control (black) and laser trials (red), normalized to the response to 99%-contrast looming stimuli; n = 6 mice. Pale dots represent data from single animals. Shading shows SEM across mice. Dashed line represents the normalized mean pre-stimulus activity.
(E) Mean suppressive effect of vLGN stimulation on the population spike rate of all recorded units in the mSC during a 99%-contrast looming stimulus, n = 6 mice. Error bars represent SEM across mice. Pale dots represent data from single animals; p = 1.70 × 10−3, one-sample t test.
(F) Mean suppressive effect of vLGN stimulation on the population-spike rate of recorded units in superficial (Superf., yellow), intermediate (Interm., orange), or deep (Deep, red) layers in the mSC during 99%-contrast looming stimulus presentation. Superficial-intermediate, p = 0.0126; intermediate-deep, p = 0.257; superficial-deep, p = 0.191. Tukey’s honest significance test preceded by repeated-measures, one-way analysis of variance, p = 0.0161).
(G) Median suppressive effect of vLGN stimulation during spontaneous activity on single units responding to either looming or grating stimuli (visual, red, n = 84 units), and on single units not responding to any visual stimulus (non-visual, orange, n = 34 units) in intermediate and deep layers of the mSC. Pale dots represent data from single units. Error bars represent IQR across single units. Single units from 11 recordings in six animals. p = 0.0121, Wilcoxon rank-sum test.
(H) Median suppressive effect of vLGN stimulation during spontaneous activity on single units responding to either looming or grating stimuli, but not to sounds (visual-only, dark red, n = 62 units) and on single units not responding to any visual stimulus, but showing a significant response to sounds (sound-only, dark orange, n = 14 single units) in intermediate and deep layers of the mSC. Single units from 11 recordings in six animals. p = 0.0240, Wilcoxon rank-sum test.