Fig. 5: Vestibulo-ocular and spino-ocular motor signal integration depends on the swim frequency.

a Movements of the left (Leye) and right eye (Reye) during horizontal sinusoidal head rotation (green) and swim-related tail undulations (blue) at stage 52 (a₁); note that the spontaneously reduced swim frequency within the illustrated episode (marked by the red dashed line in a₂) produced two different types of resultant ocular motion. b Representative example of ocular motion of the left eye during a single horizontal head rotation cycle and concurrent tail undulations (b₁), depicting the variation in eye motion magnitude (b₂) and change of eye position eccentricity (= angular position of the eye relative to the longitudinal axis of the head; b₃). c Quantification of ocular motion parameters as scatter plots of Δ motion magnitude (c₁) and Δ position eccentricity (c₂) as function of the swimming frequency (n = 32 swimming episodes from N = 15 animals at different developmental stages). Two-tailed p values were calculated to estimate the Pearson coefficient correlation (R) significance (p = 0.3023 for the Δ motion magnitude plot and p = 0.0023 for the Δ motion eccentricity plot). d Box plots of Δ motion magnitude (d₁) and Δ position eccentricity (d₂) as function of the vestibular stimulus frequency at 0.5 Hz (n = 10 swimming episodes), 1 Hz (n = 13 swimming episodes) and 2 Hz (n = 14 swimming episodes) from N = 4 animals. Upper and lower error bars of box plots represent, respectively, maximum and minimum values. Bounds of box and center lines represent, respectively, the values of 50% of the central region (75 and 25% percentile) and the median values. Superimposed full circles/squares represent mean values. p-values, calculated using the Kruskal-Wallis test were equal to 0.6754 and 0.0423 respectively for box plots (d₁) and (d₂). e Histogram of Δ magnitude (e₁) and Δ eccentricity (e₂) variations during spino-ocular motor coupling at stage 49 (N = 5), stage 52 (N = 5), and stage 58 (N = 5). The Kruskal-Wallis test was performed to test the significance and resulted in p = 0.1829 in e₁ and p = 0.0343 in e₂. f Relative occurrence of eccentricity modulation during ocular motion (left axis) and average swim frequency (black dots and spheres, right axis) between stage 49 and stage 58 (Kruskal-Wallis test, p = 0.0007). Data are presented as mean values ± SEM and statistical significance is indicated as *** p < 0.001, ** p < 0.01, * p < 0.05, ns non-significant in (c–f). Source data are provided as a Source Data file.