Abstract
Previous work indicates that learning of spatial locations relative to environmental boundaries and the learning of spatial locations relative to discrete landmarks are dissociable processes supported by different neural systems (Wang & Spelke, 2002; Doeller & Burgess, 2008). However, the perceptual systems that provide the inputs to these learning mechanisms are not well understood. We hypothesized that the Occipital Place Area (OPA), a scene-selective region located near the transverse occipital sulcus, might play a critical role in boundary-based learning, by extracting boundary information from visual scenes during navigation. To test this idea, we used transcranial magnetic stimulation (TMS) to interrupt processing in the OPA while subjects performed a virtual navigation task that required them to learn locations of test objects relative to boundaries and landmarks. The environment consisted of a circular chamber, which was limited by a boundary wall, contained a rotationally symmetric landmark object, and was surrounded by distal cues for orientation (mountains, rendered at infinity). The relative position of the landmark and boundary changed across testing blocks. Test objects were tethered to either the landmark or the boundary, thus allowing learning of object location relative to each cue to be independently assessed. Prior to each block, transcranial magnetic continuous theta burst stimulation (cTBS) was applied to either the functionally-defined right OPA or a Vertex control site. Consistent with our prediction, we found that cTBS to the OPA impaired learning of object locations relative to boundaries, but not relative to landmarks. These results provide the first evidence that OPA is causally involved in visually-guided navigation. Moreover, they indicate that the OPA is essential for the coding of environmental boundary information.
Meeting abstract presented at VSS 2015