Representation of averaging saccades in the superior colliculus of the monkey.

We tested the hypothesis that averaging saccades occur when two different saccades are prepared and executed simultaneously. The activity of saccade-related burst neurons (SRBNs) in the primate superior colliculus was recorded while monkeys made both non-averaging saccades to single targets and averaging saccades which directed the gaze between two simultaneously presented visual targets. For movements of comparable direction and amplitude, the activity measured during averaging and non-averaging saccades was statistically indistinguishable. These results are not consistent with the hypothesis that averaging saccades result from the simultaneous execution of two different saccades at the level of the collicular SRBNs. Instead, these findings indicate that averaging saccades are represented as single intermediate movements within the topographically organized map of these collicular cells.