To measure the effect of each device (Fig.
Effects of the VVM on the VOR. (a) Representation of mice wearing the three different types of devices used in the protocol; Pattern (left), No-pattern (middle) and Sham (right). (b) Depiction of the set-up to test VOR; the mouse is head-fixed and secured in a plexiglas tube during horizontal rotations of the turntable at a fixed peak velocity (30º/s) and variable frequencies (0.2-2 Hz). 3D renderings (a and b) were obtained using Paint 3D (Microsoft Corporation). (c) Example raw traces of VOR responses recorded on day 0 at 0,5 Hz for Sham (grey), No-pattern (green) and Pattern (orange). Head rotations in the dark evoked compensatory eye movements in the opposite direction. VVM-exposed mice showed altered eye movements. (d) Sham (n = 8), No-pattern (n = 16) and Pattern (n = 15) mean VOR gain along the entire protocol (20 days). The mean VOR (e) gain and (f) phase are at all tested days are plotted for the different frequencies of stimulation. The significance of the gain and phase changes compared to Sham are indicated next to each point in the graph. Horizontal lines represent intra-group significant differences between the tested days. Error bars represent ± SEM; Newman Keuls post-hoc test *p < 0.05; **p < 0.01; ***p < 10–3.
Effects of the VVM on OKR. (a) Representation of the set-up used to test OKR. A dotted background was projected into a mirror while the mouse was kept head-fixed. 3D model obtained using Paint 3D (Microsoft Corporation). (b) Example raw traces of the OKR response to a stimulation at 0.33 Hz at peak velocity of 10°/s for each condition; Sham (grey), No-pattern (green) and Pattern (orange). The eye position smoothly follows the optokinetic stimulus. (c) Kinematics of the mean OKR gain of Sham (n = 6), No-pattern (n = 8) and Pattern (n = 12) during the tested days. Horizontal lines represent intra-group significant differences between the tested days. OKR gain (d) and phase (e) at each of the different frequencies tested along each day. The significance of both gain and phase are indicated on top of each point in the graph for No-pattern (first line, green) and Pattern (second line, orange). Error bars represent ± SEM; Newman Keuls post-hoc test *p < 0.05; **p < 0.01; ***p < 10–3.
Effects of the VVM on OKR nystagmus. (a) Example raw traces for each group (Sham n = 8, grey; No-pattern n = 16, green; Pattern n = 15, orange) of the OKR response to the 60 s-long stimulation at 7.5º/s in temporo-nasal direction (black line). The grey rectangles mark the segments that were not considered in the analysis of the eye movements (quick phases or recording artefacts). Only slow phases were computed to characterize the response over the duration of the visual stimulation. (b) To illustrate the dynamic of responses over the stimulation period, the individual slow phases gains were plotted over time for 7.5°/s constant velocity stimulation in temporo-nasal direction. In the VVM-treated groups, the first response after stimulus onset (the first slow phase), appears lower after the VVM protocol. To quantify this difference, the gains of the first and last slow phases in response to all velocities and directions were averaged (c). When computed, the difference between the first and last SP gains reveals that before the VVM, the three groups had similar first and last gains while, on day 0, VVM-treated groups had lower first slow phase gains. On day 1, these gains have increased and at day 2, they are identical to Sham. The significant differences compared to Sham are indicated on top of each point in the graphs for No-pattern (green asterisks) and Pattern (orange asterisks) groups, respectively. Error bars represent ± SEM; Newman Keuls post-hoc test *p < 0.05; **p < 0.01; ***p < 10–3.
Comparison of the amplitude and dynamics of VOR and OKR gain changes over time. Global gain changes in VOR (purple diamonds) and OKR (blue triangles) over time were compared by subtracting the mean responses of the Sham group from those of the VVM-exposed mice (ΔGain). Differences between VOR and OKR responses of both VVM-exposed groups are represented with black asterisks. Error bars represent ± SEM; Newman Keuls post-hoc test *p < 0.05; **p < 0.01; ***p < 10–3.