Functional interactions between oculomotor regions during prosaccades and antisaccades.

Human behavior reflects a continual negotiation of automatic and directed actions. The oculomotor network is a well-characterized neural system in which to study this balance of behavioral control. For instance, saccades made toward and away from a flashed visual stimulus (prosaccades and antisaccades, respectively) are known to engage different cognitive processes. Brain regions important for such controlled execution include the presupplementary motor area (pre-SMA), frontal eye fields (FEF), and intraparietal sulcus (IPS). Recent work has emphasized various elements of this network but has not explored the functional interactions among regions. We used event-related fMRI to image human brain activity during performance of an interleaved pro/antisaccade task. Since traditional univariate statistics cannot address issues of functional connectivity, a multivariate technique is necessary. Coherence between fMRI time series of the pre-SMA with the FEF and IPS was used to measure functional interactions. The FEF, but not IPS, showed significant differential coherence between pro- and antisaccade trials with pre-SMA. These results suggest that the pre-SMA coordinates with FEF to maintain a controlled, preparatory set for task-appropriate oculomotor execution. Copyright 2005 Wiley-Liss, Inc.