Dissociable Roles of Dorsolateral Prefrontal Cortex and Frontal Eye Fields During Saccadic Eye Movements

Abstract

The dorsolateral prefrontal cortex (DLPFC) and the frontal eye fields (FEF) have both been implicated in the executive control of saccades, yet possible dissociable roles of each region have not been established. Specifically, both establishing a “task set” as well as suppressing an inappropriate response have been linked to DLPFC and FEF activity, with behavioral outcome measures of these mechanisms mainly being the percentage of pro-saccade errors made on anti-saccade trials. We used continuous theta-burst stimulation (cTBS) to disrupt FEF or DLPFC function in humans during an anti-saccade task to assess the causal role of these regions in these executive control processes, and in programming saccades towards (pro-saccade) or away (anti-saccade) from visual targets. After right FEF cTBS, as compared to control cTBS to the right primary somatosensory cortex (rS1), anti-saccade amplitude of the first saccade decreased and the number of anti-saccades to acquire final position increased; however direction errors to the visual target were not different. In contrast, after left DLPFC cTBS, as compared to left S1 cTBS, subjects displayed greater direction errors for contralateral anti-saccades; however, there were no impairments on the number of saccades or the saccade amplitude. These results are consistent with the notion that DLPFC is necessary for executive control of saccades, whereas FEF is necessary for visuo-motor aspects of anti-saccade programming.

The effects of individualised intermittent theta burst stimulation in the prefrontal cortex: A TMS‐EEG study

“…In the motor cortex, 30 Hz cTBS resulted in a larger and more consistent decrease in MEP amplitude than 50 Hz cTBS (Goldsworthy et al, 2012). Saccadic delay has also been reported following 50 Hz cTBS over the FEF, however, involvement of executive control of saccades were found following prefrontal stimulation (Cameron, Riddle, & D'Esposito, 2015), suggesting the effect of TBS may be distinct in different brain regions. Beyond the motor cortex, Nyffeler et al targeted the FEF, which is in close proximity to the prefrontal cortex, and found prolonged saccadic delay following 30 Hz cTBS (Nyffeler et al, 2006b).…”

“…Beyond the motor cortex, Nyffeler et al targeted the FEF, which is in close proximity to the prefrontal cortex, and found prolonged saccadic delay following 30 Hz cTBS (Nyffeler et al, 2006b). Saccadic delay has also been reported following 50 Hz cTBS over the FEF, however, involvement of executive control of saccades were found following prefrontal stimulation (Cameron, Riddle, & D'Esposito, 2015), suggesting the effect of TBS may be distinct in different brain regions. As there has been no other study using 30 Hz iTBS in the prefrontal cortex or FEF, future studies are required to confirm and expand these findings.…”

Prenatal maternal cortisol concentrations predict neurodevelopment in middle childhood

“…The involvement of the PFC, especially highly affected regions such as the dorsolateral PFC (Cameron et al, 2015; Leon-Dominguez et al, 2015), in executive functions may account for the association between prenatal maternal cortisol and both verbal and non-verbal measure of cognitive ability. Tests of indirect effects indicated that cortical thickness did not underlie the observed association between prenatal maternal cortisol and child cognitive functioning.…”

Decoding the neural dynamics of free choice in humans

“…However, if a saccade wasn't planned, the latency of the peak of HG activity was correlated with reaction times. This suggests that middle and superior frontal gyri are also involved in the execution of saccades (Cameron et al, 2015).…”