More than just channeling: The role of subcortical mechanisms in executive functions - Evidence from the Stroop task.

The literature has long emphasized the role of the cerebral cortex in executive functions. Recently, however, several researchers have suggested that subcortical areas might also be involved in executive functions. The current study explored the possibility that subcortical mechanisms have a functional role in adaptive resolution of Stroop interference. We asked 20 participants to complete a cued task-switching Stroop task with variable cue-target intervals (CTI). Using a stereoscope, we manipulated which eye was shown the relevant dimension and which was shown the irrelevant dimension. This technique allowed us to examine the involvement of monocularly segregated - subcortical - regions of the visual processing stream. The interference effect was modulated by this eye-of-origin manipulation in the 0 CTI condition. This finding provides a novel indication for the notion that subcortical regions have a functional role in the resolution of Stroop interference. This indication suggests that cortical regions are not solely involved and that a dynamic interaction between cortical and subcortical regions is involved in executive functions.