Having to identify a target reduces latencies in p

Authors: Nathalie Guyader Jennifer Malsert Christian Marendaz

Publish Date: 2008/12/23

Volume: 74, Issue: 1, Pages: 12-20

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Abstract

In a princeps study Trottier and Pratt 2005 showed that saccadic latencies were dramatically reduced when subjects were instructed to not simply look at a peripheral target reflexive saccade but to identify some of its properties According to the authors the shortening of saccadic reactions times may arise from a topdown disinhibition of the superior colliculus SC potentially mediated by the direct pathway connecting frontal/prefrontal cortex structures to the SC Using a “cue paradigm” a cue preceded the appearance of the target the present study tests if the task instruction Identify vs Glance also reduces the latencies of antisaccades AS which involve prefrontal structures We show that instruction reduces latencies for prosaccade but not for AS An AS requires two processes the inhibition of a reflexive saccade and the generation of a voluntary saccade To separate these processes and to better understand the task effect we also test the effect of the task instruction only on voluntary saccades The effect still exists but it is much weaker than for reflexive saccades The instruction effect closely depends on task demands in executive resources

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