Transcranial Magnetic Stimulation to the Transverse Occipital Sulcus Affects Scene but not Object Processing

摘要

Traditionally, it was theorized that the human visual system identifies and classifies scenes in a bottom-up, object-centered approach, such that scene processing can only occur once the objects within a scene are identified. Conversely, recent research suggests a more top-down approach, such that the global image features of a scene are sufficient for the recognition and categorization of a scene. Moreover, we have shown that disrupting object processing with repetitive transcranial magnetic stimulation (rTMS) actually enhances scene processing possibly through a release of inhibitory mechanisms (Mullin & Steeves, 2011). The present study examines the effects of rTMS to the left transverse occipital sulcus (TOS), an area implicated in scene perception. In two separate sessions, we performed online functionally-guided rTMS to the left TOS and the vertex (control site) while participants performed an object and scene classification task. Each session included no rTMS trials. Participants were presented with a stream of scene and object images and were asked to indicate as quickly and accurately as possible whether they were manmade or natural. Preliminary results suggest that unlike rTMS to object areas, which produces a release of inhibition on scene processing, inhibiting the TOS does not affect object categorization. This suggests that there is not a mutual release of inhibition from scenes to objects in this top-down approach to image processing. However, transiently interrupting the TOS resulted in longer latencies and lower accuracy rates for scene processing compared to the control conditions. Given that the parahippocampal place area (PPA), a key region in the scene processing network, presumably remains intact with rTMS to the TOS, this suggests that the TOS must nonetheless play an important role in this network.