Abstract
Neuroimaging studies have revealed two separate classes of category-selective regions specialized in optic flow (egomotion-compatible) processing and in scene/place perception. Despite the importance of both optic flow and scene/place recognition to estimate changes in position and orientation within the environment during self-motion, the possible functional link between egomotion- and scene-selective regions has not yet been established. Here we reanalyzed functional magnetic resonance images from a large sample of participants performing two well-known “localizer” fMRI experiments, consisting in passive viewing of navigationally relevant stimuli such as buildings and places (scene/place stimulus) and coherently moving fields of dots simulating the visual stimulation during self-motion (flow fields). After interrogating the egomotion-selective areas with respect to the scene/place stimulus and the scene-selective areas with respect to flow fields, we found that the egomotion-selective areas V6+ and pIPS/V3A responded bilaterally more to scenes/places compared to faces, and all the scene-selective areas (parahippocampal place area or PPA, retrosplenial complex or RSC, and occipital place area or OPA) responded more to egomotion-compatible optic flow compared to random motion. The conjunction analysis between scene/place and flow field stimuli revealed that the most important focus of common activation was found in the dorsolateral parieto-occipital cortex, spanning the scene-selective OPA and the egomotion-selective pIPS/V3A. Individual inspection of the relative locations of these two regions revealed a partial overlap and a similar response profile to an independent low-level visual motion stimulus, suggesting that OPA and pIPS/V3A may be part of a unique motion-selective complex specialized in encoding both egomotion- and scene-relevant information, likely for the control of navigation in a structured environment.
Highlights
Optic flow is an important cue for monitoring our movements in the surrounding environment
In a recent paper (Serra et al 2019), we showed that while the most posterior areas V6+, posterior segment of the intraparietal sulcus (pIPS)/ V3A, and IPSmot/VIP are involved in the visual analysis of scenes, the most anterior areas posterior cingulate sulcus area (pCi), posterior insular cortex (PIC) and cingulate sulcus visual area (CSv) are mainly implicated in motor control during locomotion, being activated by a motor task requiring long-range leg movements
To test whether egomotion-selective regions are sensitive to navigationally relevant information in the absence of visual motion, and whether scene-selective regions are sensitive to coherent visual motion in the absence of navigational scene, we analyzed the response profile of V6+, pIPS/V3A, IPSmot/VIP, CSv, pCi, PIC during the scene/place stimulus and the response profile of aPPA, pPPA, retrosplenial complex (RSC), occipital place area (OPA) during the flow field stimulus, respectively
Summary
Optic flow is an important cue for monitoring our movements in the surrounding environment. Optic flow processing simulating self-motion (egomotion; Gibson 1950) has been ascribed to a network of dorsal higher-level visual and multisensory cortical regions (egomotion-selective regions) including the medial parietooccipital areas V6 and V6Av (V6 complex or V6+; Pitzalis et al 2006, 2010, 2013b; Cardin and Smith 2010), the posterior segment of the intraparietal sulcus (pIPS), a location remarkably coincident with the dorsal part of retinotopic area V3A (Tootell et al 1997; Pitzalis et al 2010), the cingulate sulcus visual areas (CSv and pCi; Wall and Smith 2008; Serra et al 2019), the posterior insular cortex (PIC; Frank et al 2014), and a parietal motion region located in a region similar to that of the putative human area VIP (IPSmot, Pitzalis et al 2013c; Bremmer et al 2001; Sereno and Huang 2006; Cardin and Smith 2010). Responses to optic flow have been found in the lateral occipitotemporal MT complex (MT+; Cardin and Smith 2010; Serra et al 2019) and in the dorsal margin of the postcentral sulcus, in a portion of cortex likely corresponding to the human homolog of the macaque vestibular area 2v (putative 2v or p2v; Guldin and Grüsser 1998; Cardin and Smith 2010), i.e., a multisensory area, containing neurons that respond to both vestibular and optokinetic stimulation (Buttner and Buettner 1978)
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