Abstract
People are very good at detecting familiar object categories in briefly presented pictures of complex natural scenes. In 2 experiments, we used fMRI-guided transcranial magnetic stimulation (TMS) to investigate the role of the extrastriate body area (EBA) in the detection of people in complex natural scenes. In experiment 1, subjects indicated - in different blocks - whether people or cars were present in a briefly (50 ms) presented picture. We found that the accuracy of detecting people in natural scenes was decreased after TMS over the right EBA (5 pulses at -200, -100, 0, 100, 200 ms) compared to sham stimulation. Performance on the car detection task was unaffected by TMS. In experiment 2, we investigated at what stage the EBA was crucially involved in the detection of people. We applied TMS either before (-200, -100 ms) or after stimulus onset (100, 200 ms), and found that only TMS post stimulus onset decreased detection performance. These findings demonstrate that a TMS-induced virtual lesion in the EBA results in impaired detection of people in complex natural scenes. They extend previous findings that delayed-match-to-sample discrimination tasks with isolated body stimuli are impaired by TMS over the EBA, and by occipitotemporal brain lesions incorporating the surrounding cortex. We conclude that the EBA plays a causal role in the initial extraction of body-related features from complex visual input.
Meeting abstract presented at VSS 2012