Modulation of cognitive control levels via manipulation of saccade trial type probability assessed with event-related BOLD fMRI.

J Neurophysiol. 2015 Nov 25;:jn.00776.2015

Authors: Pierce JE, McDowell JE

Abstract
Cognitive control supports flexible behavior adapted to meet current goals and can be modelled through investigation of saccade tasks with varying cognitive demands. Basic prosaccades (rapid glances towards a newly appearing stimulus) are supported by neural circuitry including occipital and posterior parietal cortex, frontal and supplementary eye fields, and basal ganglia. These trials can be contrasted with complex antisaccades (glances towards the mirror image location of a stimulus), which are characterized by greater functional MRI BOLD signal in the aforementioned regions and recruitment of additional regions such as dorsolateral prefrontal cortex. The current study manipulated the cognitive demands of these saccade tasks by presenting three rapid event-related runs of mixed saccades with a varying probability of antisaccade versus prosaccade trials (25, 50, or 75%). Behavioral results showed an effect of trial type probability on reaction time, with slower responses in runs with a high antisaccade probability. Imaging results exhibited an effect of probability in bilateral pre- and post-central gyrus, bilateral superior temporal gyrus, and medial frontal gyrus. Additionally, the interaction between saccade trial type and probability revealed a strong probability effect for prosaccade trials, showing a linear increase in activation parallel to antisaccade probability in bilateral temporal/occipital, posterior parietal, medial frontal, and lateral prefrontal cortex. In contrast, antisaccade trials showed elevated activation across all runs. Overall, this study demonstrated that improbable performance of a typically simple prosaccade task led to augmented BOLD signal to support changing cognitive control demands, resulting in activation levels similar to the more complex antisaccade task.

PMID: 26609113 [PubMed - as supplied by publisher]