Saccadic Eye Movement Cortical Regions

Participants were screened for contraindications related to fMRI and to single-pulse TMS and cTBS according to common safety guidelines (Rossi et al., 2009 (link); Oberman et al., 2011 (link)). Resting motor thresholds (RMTs) and active motor thresholds (AMTs) were established for the first dorsal interosseous muscle of the subject’s right hand using electromyography. TMS was applied using a hand-held biphasic figure-eight coil with a 75 mm outer winding diameter (MagVenture), connected to a MagProX100 System (MagVenture). Coil orientation was chosen to induce a posterior–anterior electrical field in the brain (45° from the mid-sagittal axis).
Subjects performed five runs of an interleaved pro-saccade (look toward)/anti-saccade (look away) task to identify the cortical regions of interest (ROIs; Fig. 2B). An interleaved task was used as evidence suggests an important role for DLPFC (Everling and DeSouza, 2005 (link); Johnston et al., 2014 (link)) as well as for FEF (DeSouza and Everling, 2010 (link)) in task or preparatory set and thus could not simply default to an anti-saccade task set on each trial. Two target positions (13° or 9°) in the left and right directions were included so that subjects would have to rely on spatial information to calculate the saccade vector. In this way, we could be sure that the paradigm required DLPFC, FEF, and PPC processes.