Functional relevance of the lateral occipito-temporal cortex in body perception

Abstract

An important node of the brain network underlying body perception is the Extrastriate Body Area (EBA), which is located in the lateral occipito-temporal cortex of the human brain. Previous functional Magnetic Resonance Imaging (fMRI) research has revealed the selective role of EBA in both the visual and haptic processing of body parts. However, it remains unanswered as to whether this region is essential and necessary to identify body parts or merely epiphenomenal, which is a common criticism in neuroimaging studies. In order to address the issue, I conducted a preliminary transcranial magnetic stimulation (TMS) experiment on four healthy subjects by utilizing continuous Theta Burst Stimulation (cTBS) that creates a disruption in the cortical region. The experimental design involves the four factors: sensory modality (vision-fast, vision-slow, and haptics), TMS target (left EBA, right EBA, and V1), object category (hand, car, and teapot), and time (before and after cTBS). The preliminary experiment revealed that the majority of the subjects (75% of the subjects) displayed an EBA-specific effect (i.e., effect relative to V1) in the comparison between the hand category and the car category for the vision-fast condition. This EBA-specific hand effect was, however, relatively much weaker in the vision-slow and haptics condition. Similarly, the EBA-specific hand effect was not readily evident in the comparison between the hand category and teapot category. The implications are further discussed and a research design for the actual experiment was introduced.