Different roles of the parahippocampal place area (PPA) and retrosplenial cortex (RSC) in panoramic scene perception

Abstract

Constructing a rich and continuous visual experience requires computing specific details across views as well as integrating similarities across views. In this paper, we report functional magnetic resonance imaging (fMRI) evidence that these distinct computations may occur in two scene-sensitive regions in the brain, the parahippocampal place area (PPA) and retrosplenial cortex (RSC). Participants saw different snapshot views from panoramic scenes, which represented clearly different views, but appeared to come from the same scene. Using fMRI adaptation, we tested whether the PPA and RSC treated these panoramic views as the same or different. In the panoramic condition, three different views from a single panoramic scene were presented. We did not find any attenuation for panoramic repeats in the PPA, showing viewpoint-specificity. In contrast, RSC showed significant attenuation for the panoramic condition, showing viewpoint-integration. However, when the panoramic views were not presented in a continuous way, both the specificity in the PPA and the integration in RSC were lost. These results demonstrate that the PPA and RSC compute different properties of scenes: the PPA focuses on selective discrimination of different views while RSC focuses on the integration of scenes under the same visual context. These complementary functions of the PPA and RSC enable both specific and integrative representations of scenes across several viewpoints.

Figure 1

a, Panoramic 1st and Panoramic 3rd image were taken from a single panoramic view. Panoramic 1st, 2nd, and 3rd images were sequentially presented one at a time at fixation. The 1st and the 3rd image overlapped in 33% of its physical details. b, A schematic illustration of the panoramic repeat condition, shown with three event trials (TR=2s) and jittered inter trial interval.

Figure 2

The PPA and RSC are shown on a representative participant’s brain. a, The crosshair indicates the right PPA (24, -33, -23). b, The crosshair indicates left RSC (-18, -59, 13).

Figure 3

A schematic illustration of the continuous and non-continuous blocks in Experiment 2. Trials with green underlines indicate the panoramic condition; blue underlines indicated the identical condition; gray underlines indicated the unrelated condition.

Figure 4

Repetition attenuation for panoramic images in RSC but not in the PPA. Mean peak hemodynamic responses for panoramic 1st, 2nd, 3rd and identical 1st, 2nd, 3rd images are shown for each ROI in Experiment 1. Error bars indicate ± SEM. a, Parahippocampal place area (PPA). Paired comparisons between panoramic 1st and 3rd images show no attenuation, while paired comparisons between identical 1st and 3rd images show significant neural attenuation. Differences between the amount of attenuation across the two conditions was significant. b, Retrosplenial cortex (RSC). Paired comparisons between panoramic 1st and 3rd images showed significant neural attenuation. The amount of attenuation in RSC for the panoramic condition was significantly larger than the amount of attenuation in the PPA for the panoramic condition. Differences between the amount of attenuation for the panoramic condition across the PPA and RSC were significant. Paired comparisons between identical 1st and 3rd images showed significant neural attenuation as well. c, Examples of each condition are illustrated. Panoramic repeat condition repeated three different views taken from a single panoramic image; Identical repeat condition repeated three identical images.

Figure 5

Mean peak hemodynamic responses for panoramic 1st, 2nd, 3rd; identical 1st, 2nd, 3rd; unrelated 1st, 2nd, 3rd images are shown separately for the continuous repetition block (left panel) and the non-continuous repetition block (right panel) in Experiment 2. Error bars indicate ± SEM. a, Parahippocampal place area (PPA). b, Retrosplenial cortex (RSC).