PMC

A) Shifts in saccade endpoints relative to the injection site for 199 separate targets from all experiments. B) Shifts in saccade endpoints relative to the optrode site from all experiments. C) Schematic of optogenetic influence of laser illumination on saccade-related neuronal activity in the SC. The gray ellipse is the proposed extent of the injection. The solid circle is the presumed population of neurons active during a saccade to a target about 12° to the right. The green superimposed on both shows the region supposedly illuminated by the laser. D) Schematic of optogenetic influence in one dimension. The regions from C are now shown as Gaussian curves. When the laser (green curve) is positioned between the injection site (black curve) and the active neurons (blue curve), a sub-population of neurons are inactivated, resulting in the neuronal activity represented by the dashed red curve, shifted away from the injection. E) Distal placement of the laser still results in shifts away from the injection. See also in Supplemental Data.

A) Locations of the six targets in the visual field (small squares) along with the location of the injection site and the optrode site. Arrows show the shift in mean saccade endpoint when the SC was exposed to light. Significant shifts are plotted in black (gray otherwise). B) Location on the collicular map of the injection (hexagon) and optrode (starburst) from the locations in . Bars subtending 6° of visual angle are shown for central and peripheral visual field locations to illustrate magnification within the SC map. C) Region of interest on the SC map showing the injection, optrode, saccade targets, and shifts in saccade endpoints. Significant shifts are shown in black, gray otherwise. D) Shift magnitude plotted against distance from injection. Both quantities are expressed as mm in the SC. Black points denote significant shifts. The solid black line is the least-squares linear fit to all the data. E) Shift magnitude plotted against distance from optrode. Symbols are the same as in panel D.

The suppression of neuronal activity at several sites in the SC is shown for monkey OZ (A) and monkey RO (B). The injection site and optrode locations are shown as the hexagon and the starbursts, respectively. Axes indicate distance in mm along the SC. The color bar to the right shows how greater suppression is indicated by darker blue. Lighter regions in the interpolated area denote little change. The black ellipse shows the estimated extent of light sensitivity in monkey OZ determined by a 2D Gaussian fit to the data. The red ellipse in B shows the extent of the injection in Monkey RO determined from subsequent histological analysis. C) For each of 11 histological sections from monkey RO we constructed marginal density plots (see ) representing the degree of transfection over the X and Y dimensions. Sections are aligned to the centers of their marginal distributions. The extents of transfection from each section have been combined in sequence in the center of the plot, with adjacent sections connected. This wireframe structure represents the spread of transfection in three dimensions. See also in Supplemental Data.

A) Saccades with and without laser stimulation directed to a visual target at 11.5°, 8.0°. Saccade endpoints are shown without (gray) and with (green) laser stimulation. Laser light was introduced into the intermediate layers of the SC on randomly interleaved trials. This was done by opening and closing a fast shutter placed in the path of the laser, which remained on throughout the experiment. Green and black crosses indicate the mean saccade endpoints (± 1SE) with and without light, respectively. This example was chosen as a clear demonstration, but most results were based on fewer trials. B) Cumulative distribution of saccade latencies. Black are latencies without light, green are in the presence of laser light. C) Cumulative distributions of peak saccade velocity. The green trace shows peak velocity in the presence of laser light, and the black trace is without light. D) Multiunit neuronal activity with and without laser stimulation. Neuronal responses are shown as spike density histograms aligned to saccade onset at time zero and smoothed with a Gaussian filter with a 5ms SD. E) Distribution of saccadic endpoint shifts from photostimulation for 28 experiments in two monkeys (21 on monkey OZ, 7 in monkey Om). F) Distribution of changes in saccade latency due to photostimulation. G) Distribution of changes in peak saccade velocity due to photostimulation. H) Distribution of changes in neuronal response due to photostimulation.