Figure 5.

Combined condition responses are well approximated by linear weighted summation. (a) Predicted responses from weighted linear summation were strongly correlated with measured responses in the combined condition (R=0.99, p<<0.001). Each datum represents the response of one neuron at one heading angle; spontaneous activity was subtracted. (b) A correlation coefficient was computed, for each neuron, from a linear regression fit to the predicted and measured responses. The median R² value was 0.83 and 89 cases (69%) were significant (p<0.05). Three cases with negative (but not significant) R² values are not shown. (c) Visual and vestibular weights derived from the best fit of the linear weighted sum model for each neuron with significant R² values (black bars in panel b). Median weights for vestibular and visual inputs were 0.6 and 0.76, respectively, which are significantly smaller than 1 (p<<0.001, t-tests). There is a significant negative correlation between vestibular and visual weights (R=−0.40, p<0.001, spearman rank correlation). Circles: monkey A; Triangles: monkey C.