Fig. 2: Temporal delay of audiovisual information is encoded in superior colliculus neurons.

A Distribution of response latency for visual (blue left) and auditory (orange right) unisensory responses. B Schematic of stimulation protocol. C Anatomical distribution of neurons modulated by AV delay. Left: ML; Centre: AP; Right: DV axes. D Raster plots and PSTHs for two example neurons to unisensory and multisensory stimuli presented at variable delays. E AV delay tuning curve for neurons shown in D. Data are represented as mean values ± SEM. F Distribution of preferred AV delay across the population of delay-selective neurons. Distribution of specificity index (G); firing rate modulation (H) and reliability index (I) for delay-selective neurons. J Correlation between the neurons’ preferred AV delay and the difference in latency between visual and auditory response peak time. Only delay neurons that were responsive during both visual and auditory stimulation were included (N = 123). P value from two-sided LMM. The bold line represents the fitted regression (mean predicted values), while the shaded grey area denotes the 95% confidence interval. K Unisensory and multisensory responses for three example neurons and corresponding synthetic multisensory response obtained from the addition of auditory and visual instantaneous firing rates. Responses are represented as mean values ± SEM. Numbers indicate multisensory interaction index (MII). L Distribution of difference between observed and predicted AV delay preference for AV delay-selective neurons. M Cumulative distribution of multisensory interaction index. Green tone indicates AV delay; magenta corresponds to MII calculated at the preferred delay of each individual neuron. N Proportion of neurons exhibiting supra- and sublinear multisensory interaction, normalised by the number of neurons exhibiting supra- or sublinear multisensory interactions at AV delay 0 ms (supralinear = 8.9%; sublinear = 1.2%). Proportions are shown for each AV delay tested, as well for the preferred delay condition and as the mean value across all conditions (all).