Transcranial Magnetic Stimulation of Frontal Oculomotor Regions during Smooth Pursuit

Abstract

Both the frontal eye fields (FEFs) and supplementary eye fields (SEFs) are known to be involved in smooth pursuit eye movements. It has been shown recently that stimulation of the smooth-pursuit area of the FEF [frontal pursuit area (FPA)] in monkey increases the pursuit response to unexpected changes in target motion during pursuit. In the current study, we applied transcranial magnetic stimulation (TMS) to the FPA and SEF in humans during sinusoidal pursuit to assess its effects on the pursuit response to predictable, rather than unexpected, changes in target motion. For the FPA, we found that TMS applied immediately before the target reversed direction increased eye velocity in the new direction, whereas TMS applied in mid-cycle, immediately before the target began to slow, decreased eye velocity. For the SEF, TMS applied at target reversal increased eye velocity in the new direction but had no effect on eye velocity when applied at mid-cycle. TMS of the control region (leg region of the somatosensory cortex) did not affect eye velocity at either point. Previous stimulation studies of FPA during pursuit have suggested that this region is involved in controlling the gain of the transformation of visual signals into pursuit motor commands. The current results suggest that the gain of the transformation of predictive signals into motor commands is also controlled by the FPA. The effect of stimulation of the SEF is distinct from that of the FPA and suggests that its role in sinusoidal pursuit is primarily at the target direction reversal.

Inactivation and stimulation of the frontal pursuit area change pursuit metrics without affecting pursuit target selection

“…The deficits to pursuit metrics and predictive pursuit are observed for pursuit in all directions but are most strongly expressed for pursuit ipsiversive to the lesion. Similar results have recently been reproduced in humans: transcranial magnetic stimulation of the area during ongoing pursuit reduces eye velocity (Gagnon et al 2006).…”

Human Middle Temporal Cortex, Perceptual Bias, and Perceptual Memory for Ambiguous Three-Dimensional Motion

“…TMS effects on eye movements are not uncommon, but are usually associated with stimulating other brain areas than we did, like the frontal eye fields, and only if eye movement preparation or execution falls within a relatively narrow time window (up to 150 ms) around the TMS pulse (Gagnon et al, 2006;Drew and Donkelaar, 2007;Walker et al, 2009). In our case, visual stimulation did not start until several hundred milliseconds after TMS was applied, and then lasted for another second (see below).…”

Refining the Predictive Pursuit Endophenotype in Schizophrenia

“…In support of this view, several imaging studies have shown reduced FEF activation in schizophrenia patients or their relatives during SPEM (23)(24)(25). In addition, transcranial magnetic stimulation of FEFs at the time of change in pursuit direction results in acceleration of the eye in the expected target direction (26), suggesting that poor predictive acceleration may be subjected to behavioral improvement using interventions to enhance FEF function. Zaksas and Pasternak (27) illustrated a close interaction between FEF and MT in maintaining oculomotor working memory, which may provide a new framework to unify the findings of abnormal motion perception (4;6) and abnormal predictive pursuit in schizophrenia.…”