Fig. 4

Examples of mTI on spiking activity in the superior colliculus (SC) in the awake, behaving macaque A) Effects of mTI during a period of stable visual fixation. mTI did not influence eye position (horizontal gaze position, top row), but the activity of this SC neuron significantly after mTI (red rasters and spike density functions; means and SEM) compared to after either no-stimulation trials (grey/black combined, p = 0.0001) or after SHAM stimulation trials (blue, p = 0.005). There was no significant difference in activity after the SHAM vs no-stimulation conditions (p = 0.87; spike-counts tested in a response window of 250 to 350 ms after target onset Wilcoxon-rank-sum-test corrected for multiple comparison [α = 0.0167]). In addition, mTI induced pupil dilation (middle row) that was absent in no-stimulation trials and more prominent than on SHAM stimulation trials. Contours show mean subtended by the standard error of the mean. B Effects of mTI delivered before a visually-guided saccade on single-unit activity. When delivered just before the arrival of visual information in the SC in a visually-guided saccade task, mTI provoked significantly higher functionally-related activity (red rasters and spike density functions showing mean subtended by standard error) compared to no-stimulation trials (black rasters and spike density functions, p < 0.001; Wilcoxon rank-sum test corrected for multiple comparisons of activity spanning from 50 to 80 ms after target onset, α = 0.0167). This increase in activity on TI vs SHAM (blue rasters and spike density functions) approached significance (p = 0.02)