Testing the role of spontaneous activity in visuospatial perception with patterned optogenetics
Fig 5
A. Various configurations of locations of the Gabor patches will be presented and coupled with optogenetic inactivation. Bilateral configurations will be used to answer to test the theories’ predictions (cf. Fig 6). In order to make the experiment feasible, we have selected a set of configurations for which the theories under scrutiny yield the most distinct predictions (cf. Fig 6). Importantly, some additional configurations (shaded in blue) are necessary to maintain a proper balance between stimuli rewarded with left vs. right licks – to prevent the insurgence of a response bias to either side. Two bilateral configurations will be coupled with optogenetic inactivation of background activity (here indicated with a striped shading). Probe trials will be used to estimate false alarm rates and any effect of optogenetic illumination on it. Finally, unilateral configurations will be used to test if optogenetic inactivation induces any bias in response side, in the absence of a stimulus being presented in the inactivated hemifield of view. Fractions and number of trials for each category are only an estimate that will depend on animals’ performance and on the actual number of trials in each experimental session. B. Diagram indicating the positions of the Gabor patches that will be used in the actual experimental sessions. Compared to the outline shown in Fig 1, we will have to adjust the locations where the Gabor patches are shown based on the actual coverage of the visual field by the screen where visual stimuli are displayed within the experimental setup. Specifically, while the visual field extends up to 140 deg beyond the midline, the screens only reach 110 deg. This introduces a possible confounding factor. Specifically, the line splitting each hemifield of view in half (dashed line) does not overlap with the line splitting the portion of the screen visible within each hemifield of view in two (dotted line). Under the assumption that optogenetic inactivation will induce a hemineglect-like deficit, we cannot predict if mice will respond based on the position of the still-perceived Gabor patch with respect to either the dashed or dotted line, i.e., based on the position of the Gabor on the screen or on the field of view. For this reason, to avoid possible confounding factors, we will avoid displaying Gabor patches in the portion of the visual field (shaded in blue) between these two lines, where no prediction can be made about the behavioral responses of mice.