Frontal eye field modulation of visual oscillations; an online TMS EEG study

Grosbras, M.-H., Lauder, J. and Hoogenboom, N. (2009) Frontal eye field modulation of visual oscillations; an online TMS EEG study. In: Vision Sciences Society: 9th Annual Meeting, Naples, Italy, 8-13 May 2009,

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A single pulse of transcranial magnetic stimulation (TMS) applied over the frontal eye field (FEF) can facilitate the subsequent detection of near-threshold stimuli (Grosbras and Paus, 2003) or can increase the excitability of other visual regions (Silvanto et al., 2005). How FEF TMS influences cortical processes remains elusive, however. We aim to combine electro-encephalography (EEG) and single pulse TMS to explore the timing of the modulation of EEG as well as changes in the oscillatory activity. Five subjects viewed gratings briefly flashed in their lower left or right half visual field while we recorded EEG. In some trials we applied single-pulse TMS over the right FEF or a control site (vertex) at three latencies relative to visual onset: -100, 0 and 50ms. In some trials we applied TMS without any visual stimulation. We excluded from the analysis the 30ms during which TMS artifact occurred. We analyzed (1) Event-Related Potentials (2) Power in alpha, beta, lower gamma and upper gamma frequency bands during the 500ms before and after visual stimulus onset. We observed higher P300 amplitude for FEF than for vertex TMS. When no visual stimulation was present we observed a decrease in alpha power after TMS, larger for FEF stimulation than vertex and for the right hemisphere. No effect was observed in other frequency bands. When a visual stimulus was present, FEF TMS applied 50 ms after a left target specifically increased alpha synchronization. The TMS-induced changes in evoked visual response occurred at the same time as effects of attention have been observed, and are similar to what Taylor and al observed with FEF repetitive TMS. The TMS reduction in alpha synchronization in visual cortex during background activity is reminiscent of similar desynchronization during attention orienting and in line with a role of FEF in top-down visual control.

Item Type:Conference Proceedings
Glasgow Author(s) Enlighten ID:Hoogenboom, Dr Nienke and Lauder, Mr Jason and Grosbras, Dr Marie-Helene
Authors: Grosbras, M.-H., Lauder, J., and Hoogenboom, N.
Subjects:R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
College/School:College of Science and Engineering > School of Psychology
College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
429501Top down control of visual processing and awareness - studies with transcranial magnetic stimulation and electroencephalographyMarie-Helene GrosbrasBiotechnology and Biological Sciences Research Council (BBSRC)BB/E003699/1Cognitive Neuroimaging & Neuroengineering Technologies