Abstract
Prior evidence has shown that cue-mediated spatial attentional orienting has the potential to modulate several aspects of visual performance such as spatial frequency and contrast discriminations. Similarly, Transcranial Magnetic Stimulation (TMS) on attentional areas has yielded short-lasting visual performance modulations. We explored the effects of TMS on the right Frontal Eye Field (FEF), an attentional orienting relevant area, alone or in conjunction with visuospatial cueing, and gauged its ability to enhance perception of low-contrast near-threshold Gabor stimuli. Three groups of participants took part in the three experiments of this study. In every trial, participants were required, after the presentation of a Gabor stimulus, to perform two tasks: (1) A forced choice categorization task, consisting of determining the orientation of the Gabor lines (Left or Right?) and (2) a detection task (Did you see the stimulus? Where?). In Experiment 1, the Gabor was preceded by a spatially predictive visuospatial cue. In Experiment 2, the Gabor was preceded by a single TMS pulse delivered on the right FEF. Finally, in Experiment 3 the Gabor was preceded by both, the cue and the TMS pulse. In Experiment 1, we replicated previous findings demonstrating enhancements of visual perception at locations indicated by a predictive visuospatial cue. In Experiment 2, time-locked isolated TMS pulses showed a very mild potential to modulate any of the two tasks. Interestingly, the combination of a single TMS pulse on the right FEF with a visuospatial cue in Experiment 3 resulted in significant bilateral enhancements of conscious visual detection, beyond the levels achieved using the cue alone. Our results suggest an important role of the FEF in conscious visual perception. More importantly, they reveal the potential and limitations of TMS pulses alone or combined with visuospatial cueing to punctually boost conscious visual performance, setting up a path for further explorations.
Funded by the Marie Curie Postdoctoral Fellowship (AC), FP6 & ANR eraNET Neuron “BEYONDVIS” (AVC) and Predoctoral Fellowship by the École des Neurosciences de Paris (ENP, Paris School of Neuroscience) (LC).