title: Stimulation of the human frontal eye fields modulates sensitivity of extrastriate visual cortex.
abstract: The precise role of frontal eye fields (FEF) in vision independent of their role in eye movements remains a matter of debate. One proposal is that the FEF exert top-down influences on the extrastriate visual cortex prior to eye movement preparation. Here we establish, by use of transcranial magnetic stimulation (TMS), that activity in the human FEFs has a direct effect on the sensitivity of extrastriate visual area MT/V5, and that the spatial organization of this top-down effect is lateralized in the human brain. We show that phosphene threshold-the TMS intensity required to elicit a visual perception-for MT/V5 stimulation changes as a function of the delay between the application of TMS over FEF and MT/V5. The effects were specific to the location and time of stimulation. Stimulation of FEF 20-40 ms prior to stimulation of MT/V5 decreased the intensity of MT/V5 stimulation required to elicit phosphenes: TMS of the right FEF changed the sensitivity of left and right MT/V5 whereas TMS of the left FEF changed the sensitivity only of the left MT/V5. Thus, the sensitivity of human extrastriate cortex is modulated by activity in the FEF.
authors.affiliation: Institute of Cognitive Neuroscience and Department of Psychology, University College London, 17 Queen Square, London, WC1N 3AR, United Kingdom. juha.silvanto@ucl.ac.uk
authors.forename: Juha
authors.initials: J
authors.lastname: Silvanto
authors.forename: Nilli
authors.initials: N
authors.lastname: Lavie
authors.forename: Vincent
authors.initials: V
authors.lastname: Walsh
mesh_terms: D001931:Brain Mapping; D007839:Functional Laterality; D006801:Humans; D010719:Phosphenes; D050781:Transcranial Magnetic Stimulation; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields / Q000502:physiology*