Supplementary Figure 7: Simulated response of otolith afferents.

We simulated the response of five otolith afferents whose preferred directions correspond to RED tilt with an angle of 0, 15, 30, 45 and 60° respectively. Otolith afferents are cosine tuned: their firing rate is represented by FR=1+cos(α), where α is the angle between gravity and the preferred direction and the baseline firing rate is assumed to be 1. (a) Two-dimensional tuning curves exhibit a peak (white diamond), but tuning curves are far broader than those typically observed in anterior thalamus cells. (b) Simulated responses to yaw rotation around tilted axes, similar to our experimental protocols. In all cells, the amplitude of modulation always increases when the tilt angle increases. This contrasts with the responses reported here (e.g. Fig. 3b and Supplementary Fig. 8). We conclude that the gravity responses observed in anterior thalamus cells don't reflect unprocessed otolithic signals.