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Weston Pack, Thom Carney, Stanley Klein; Bilateral Involvement of the Right Frontal Eye Field in Saccade Production. Journal of Vision 2010;10(7):504. doi: 10.1167/10.7.504.
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© ARVO (1962-2015); The Authors (2016-present)
Transcranial magnetic stimulation (TMS) has been used to stimulate the frontal eye fields (FEFs) to study their functional role in saccade generation. Assorted tasks such as memory guided, auditory triggered and anti-saccades have been investigated previously using TMS. While results varied, the primary effects of TMS have been delayed contralateral saccades and degraded accuracy. We decided to examine the time-course and laterality of right FEF TMS effects on saccade generation during exogenous and endogenous visual attention tasks. For the exogenous task, targets appeared to the left or right of fixation at 10° eccentricity. In the endogenous task the same targets were continuously present, but a cue presented at fixation indicated when and where to make the saccade.
In the exogenous saccade task, TMS increased ipsilateral saccade latency by 43, 33, 35, 27, and 32ms when delivered 60, 70, 80, 90, and 176ms prior to predicted saccade onset, respectively. For the same TMS delivery times the contralateral latencies increased by 51, 20, 56, 34, and 53ms, respectively. In the endogenous saccade task, TMS increased ipsilateral latencies by 43 and 87ms at 45 and 250ms prior to predicted saccade onset. Contralateral saccade latencies increased by 29, 51, 79, and 39ms when TMS was delivered 43, 132, 250, and 315ms prior to the predicted saccade onset. All reported latency increases were significant, p<.01. Control sham TMS conditions produced no significant latency effects. For both tasks, when TMS was presented just 20ms prior to saccade onset, no latency changes occurred.
The time course of TMS based saccadic disruption appears to be broad and begins between 20 and 60ms prior to saccade onset. The results indicate consistent bilateral disruptive effects for single pulse TMS applied to the right FEF. These results are consistent with reports of the bilateral fronto-parietal attention network involved with saccade generation.
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