The occipital place area is causally and selectively involved in scene perception

Abstract

Functional magnetic resonance imaging has revealed a set of regions selectively engaged in visual scene processing: the parahippocampal place area (PPA), the retrosplenial complex (RSC), and a region around the transverse occipital sulcus (previously known as "TOS"), here renamed the "occipital place area" (OPA). Are these regions not only preferentially activated by, but also causally involved in scene perception? Although past neuropsychological data imply a causal role in scene processing for PPA and RSC, no such evidence exists for OPA. Thus, to test the causal role of OPA in human adults, we delivered transcranial magnetic stimulation (TMS) to the right OPA (rOPA) or the nearby face-selective right occipital face area (rOFA) while participants performed fine-grained perceptual discrimination tasks on scenes or faces. TMS over rOPA impaired discrimination of scenes but not faces, while TMS over rOFA impaired discrimination of faces but not scenes. In a second experiment, we delivered TMS to rOPA, or the object-selective right lateral occipital complex (rLOC), while participants performed categorization tasks involving scenes and objects. TMS over rOPA impaired categorization accuracy of scenes but not objects, while TMS over rLOC impaired categorization accuracy of objects but not scenes. These findings provide the first evidence that OPA is causally involved in scene processing, and further show that this causal role is selective for scene perception. Our findings illuminate the functional architecture of the scene perception system, and also argue against the "distributed coding" view in which each category-selective region participates in the representation of all objects.

Figure 1.

TMS target sites. A, rOPA. B, rOFA. C, rLOC.

Figure 2.

In Experiment 1, TMS was delivered to rOPA or vertex while participants were required to discriminate fine-grained differences in scene layout or face shape. A, Example trial where participants performed a delayed 2AFC match-to-sample task on either scenes or faces with TMS delivered for 500 ms during the presentation of the second stimulus. B, Example morph continua for scenes and faces. C, TMS over rOPA impaired discrimination of scenes but not faces, while TMS over rOFA impaired discrimination of faces but not scenes.

Figure 3.

In Experiment 2, TMS was delivered to rOPA, rLOC, or vertex while participants performed a categorization task on scenes or objects. A, Example trial where participants performed a 4AFC categorization task on either scenes or objects with TMS delivered for 500 ms during the presentation of the stimulus. B, Example stimuli from each category. For ease of seeing the category in this figure, the stimuli pictured here are less degraded than those actually presented to the participant. For exact details on the level of degradation, please refer to Materials and Methods. C, TMS over rOPA impaired categorization accuracy of scenes but not objects, while TMS over rLOC impaired categorization accuracy of objects but not scenes.