Poster A119, Saturday, March 25, 5:00 – 7:00 pm, Pacific Concourse
Individualized alpha-band rTMS to the inferior frontal junction selectively enhances visual search performance
Bruce Luber1, Greg Appelbaum2, Lysianne Beynel2, Sara H Lisanby1; 1National Institute of Mental Health, 2Duke University
The inferior frontal junction (IFJ) has been implicated in top-down processing during visual search in both human and non-human primate studies. Here we attempt to provide causal evidence for that role by applying repetitive transcranial magnetic stimulation (rTMS) to IFJ during a difficult visual search task using simulated aerial reconnaissance photos. In a within subjects design, subjects were given active or sham rTMS at either 1 Hz or at their individual peak alpha frequency (IAF, mean 11.5 Hz), applied either to right IFJ or right inferior parietal cortex (IPC: an area also implicated in visual search in prior TMS studies). IFJ or IPC were defined individually by selecting the voxel showing the maximal fMRI activation during the visual search task. The TMS coil placement was guided with neuronavigation using the subject’s fMRI image overlaid on their structural MRI. In a group of thirteen healthy young adults, active IAF stimulation to IFJ resulted in significant speeding of reaction time (RT) compared to sham. There were no significant changes in accuracy, or in RT at IPC or with 1 Hz rTMS. The site- and frequency-specific enhancement of performance with excitatory rTMS applied immediately prior to task trials provides direct evidence for the involvement of IFJ in guiding visual search, and is a first step in using rTMS to optimize visual search performance in humans.
Topic Area: PERCEPTION & ACTION: Vision