Interaction between visual- and goalrelated neuronal signals on the trajectories of saccadic eye movements. J Cogn Neurosci, 24(3):707–717. [Citée page(s) 48, 49

■ During natural viewing, the trajectories of saccadic eye move-ments often deviate dramatically from a straight-line path be-tween objects. In human studies, saccades have been shown to deviate toward or away from salient visual distractors depending on visual- and goal-related parameters, but the neurophysiologi-cal basis for this is not well understood. Some studies suggest that deviation toward is associated with competition between simultaneously active sites within the intermediate layers of the superior colliculus (SC), a midbrain structure that integrates sen-sory and goal-related signals for the production of saccades. In contrast, deviation away is hypothesized to reflect a higher-level process, whereby the neural site associated with the distractor isactively suppressed via a form of endogenous, top–down in-hibition. We tested this hypothesis by measuring presaccadic distractor-evoked activation of SC visuomotor neurons while monkeys performed a simple task configured specifically to in-duce a high degree of saccades that deviate away. In the SC, cog-nitive processes such as top–down expectation are represented as variation in the sustained, low-frequency presaccadic dis-charge. We reasoned that any inhibition at the distractor-related locus associated with saccade deviation should affect the excit-ability of the neuron, thereby affecting the discharge rate. We found that, although the task produced robust deviation away, there was no evidence of a relationship between saccade devia-tion and distractor-evoked activation outside a short perisaccadic window that began no earlier than 22msec before saccade onset. This indicates that deviation away is not adequately explained by a form of sustained, top–down inhibition at the distractor-related locus in the SC. The results are discussed in relation to the pri-mary sources of inhibition associated with saccadic control.