The occipital place area represents the local elements of scenes

Neuroimaging studies have identified three scene-selective regions in human cortex: parahippocampal place area (PPA), retrosplenial complex (RSC), and occipital place area (OPA). However, precisely what scene information each region represents is not clear, especially for the least studied, more posterior OPA. Here we hypothesized that OPA represents local elements of scenes within two independent, yet complementary scene descriptors: spatial boundary (i.e., the layout of external surfaces) and scene content (e.g., internal objects). If OPA processes the local elements of spatial boundary information, then it should respond to these local elements (e.g., walls) themselves, regardless of their spatial arrangement. Indeed, we found that OPA, but not PPA or RSC, responded similarly to images of intact rooms and these same rooms in which the surfaces were fractured and rearranged, disrupting the spatial boundary. Next, if OPA represents the local elements of scene content information, then it should respond more when more such local elements (e.g., furniture) are present. Indeed, we found that OPA, but not PPA or RSC, responded more to multiple than single pieces of furniture. Taken together, these findings reveal that OPA analyzes local scene elements - both in spatial boundary and scene content representation - while PPA and RSC represent global scene properties.National Institutes of Health (U.S.) (Grant EY013455

Representational similarity precedes category selectivity in the developing ventral visual pathway

© 2019 Many studies have investigated the development of face-, scene-, and body-selective regions in the ventral visual pathway. This work has primarily focused on comparing the size and univariate selectivity of these neural regions in children versus adults. In contrast, very few studies have investigated the developmental trajectory of more distributed activation patterns within and across neural regions. Here, we scanned both children (ages 5–7) and adults to test the hypothesis that distributed representational patterns arise before category selectivity (for faces, bodies, or scenes) in the ventral pathway. Consistent with this hypothesis, we found mature representational patterns in several ventral pathway regions (e.g., FFA, PPA, etc.), even in children who showed no hint of univariate selectivity. These results suggest that representational patterns emerge first in each region, perhaps forming a scaffold upon which univariate category selectivity can subsequently develop. More generally, our findings demonstrate an important dissociation between category selectivity and distributed response patterns, and raise questions about the relative roles of each in development and adult cognition

Scene Recognition: How and Why?

Presented on December 4, 2017 at 11:15 a.m. in the Krone Engineered Biosystems Building, Room 1005.Daniel D. Dilks received his Ph.D. in Cognitive Science from Johns Hopkins University in 2005, after which he became a Postdoctoral Fellow, and later a Research Fellow, in the Kanwisher Laboratory at MIT. He joined the Emory faculty in September 2013. His research focuses on three big questions about human vision: i) How is the visual cortex functionally organized?, ii) How does this functional organization get wired up in development?, and iii) Once wired up, how does visual cortex change in adulthood?Runtime: 51:35 minutesOur ability to perceive the visual environment is remarkable: we can recognize a place or “scene” (e.g., a kitchen, a beach, Georgia Tech) within a fraction of a second – even if we have never seen that particular place before (Potter, 1976) – and almost simultaneously use that information to seamlessly navigate. Given the ecological importance of scene recognition, it is perhaps not surprising then that particular regions of the human brain are specialized for processing visual scene information: the parahippocampal place area (PPA) (Epstein & Kanwisher, 1998), the retrosplenial complex (RSC) (Aguirre & D’Esposito, 1999), and the occipital place area (OPA) (Dilks et al., 2013). While the exact function each of these regions plays in scene processing remains unknown, it is currently believed that the scene processing system as a whole (comprised of the three scene-selective cortical regions) is a monolithic system in the service of navigation. However, in this talk, I will present multiple lines of evidence challenging the pervasive theory that all three scene-selective cortical regions serve the purpose of navigation. Instead, I propose that scene processing is comprised of two distinct pathways: one responsible for navigation, including RSC and OPA, and another responsible for scene categorization (e.g., recognizing a scene as a kitchen, a beach, Georgia Tech), including PPA

A critical review of the development of face recognition: Experience is less important than previously believed

Historically, it has been argued that face individuation develops very slowly, not reaching adult levels until adolescence, with experience being the driving force behind this protracted improvement. Here, we challenge this view based on extensive revie

Referred Visual Sensations: Rapid Perceptual Elongation after Visual Cortical Deprivation

Visual perceptual distortion (i.e., elongation) has been demonstrated in a single case study after several months of cortical deprivation after a stroke. Here we asked whether similar perceptual elongation can be observed in healthy participants after deprivation and, crucially, how soon after deprivation this elongation occurs. To answer this question, we patched one eye, thus noninvasively and reversibly depriving bottom-up input to the region of primary visual cortex (V1) corresponding to the blind spot (BS) in the unpatched eye, and tested whether and how quickly elongation occurs after the onset of deprivation. Within seconds of eye patching, participants perceived rectangles adjacent to the BS to be elongated toward the BS. We attribute this perceptual elongation to rapid receptive field expansion within the deprived V1 as reported in electrophysiological studies after retinal lesions and refer to it as "referred visual sensations" (RVS). This RVS is too fast to be the result of structural changes in the cortex (e.g., the growth of new connections), instead implicating unmasking of preexisting connections as the underlying neural mechanism. These findings may shed light on other reported perceptual distortions, as well as the phenomena of "filling-in.

Reorganization of Visual Processing in Age-Related Macular Degeneration Depends on Foveal Loss

Purpose: When individuals with central vision loss due to macular degeneration (MD) view stimuli in the periphery, most of them activate the region of retinotopic cortex normally activated only by foveal stimuli—a process often referred to as reorganization. Why do some show this reorganization of visual processing whereas others do not? We reported previously that six individuals with complete bilateral loss of central vision showed such reorganization, whereas two with bilateral central vision loss but with foveal sparing did not, and we hypothesized that the effect occurs only after complete bilateral loss of foveal vision. Here, we conduct a stronger test of the dependence of reorganization of visual processing in MD on complete loss of foveal function, by bringing back one (called MD6) of the two participants who previously did not show reorganization and who showed foveal sparing. MD6 has now lost all foveal function, and we predicted that if large-scale reorganization of visual processing in MD individuals depends on complete loss of foveal input, then we will now see such reorganization in this individual. Methods: MD6 and two normally sighted control subjects were scanned. Stimuli were gray-scale photographs of objects presented at either the fovea or a peripheral retinal location (i.e., the MD participant’s preferred retinal locus or the control participants’ matched peripheral location). Results: In MD6, visual stimulation at the preferred retinal locus significantly activated not only the expected “peripheral” retinotopic cortex but also the deprived “foveal” cortex. Crucially, MD6 exhibited no such large-scale reorganization 5 years earlier when she had some foveal sparing. By contrast, in the control participants, stimulation at the matched peripheral location produced significant activation in peripheral retinotopic cortex only. Conclusions: We conclude that complete loss of foveal function may be a necessary condition for large-scale reorganization of visual processing in individuals with MD.National Institutes of Health (U.S.) (Grant EY016559)National Institutes of Health (U.S.) (Grant EY13455

Reorganization of Visual Processing in Macular Degeneration Is Not Specific to the "Preferred Retinal Locus"

Recent work has shown that foveal cortex, deprived of its normal bottom-up input as a result of macular degeneration (MD), begins responding to stimuli presented to a peripheral retinal location. However, these studies have only presented stimuli to the "preferred retinal location," or PRL, a spared part of the peripheral retina used by individuals with MD for fixating, face recognition, reading, and other visual tasks. Thus, previous research has not yet answered a question critical for understanding the mechanisms underlying this reorganization: Does formerly foveal cortex respond only to stimuli presented at the PRL, or does it also respond to other peripheral locations of similar eccentricity? If foveal cortex responds to stimuli at PRL because it is the long-term habitual use of this region as a functional fovea that drives the formerly foveal cortex to respond to stimuli presented at the PRL (the "use-dependent reorganization" hypothesis), then foveal cortex will not respond to stimuli presented at other locations. Alternatively, it may be that foveal cortex responds to any peripheral retinal input, independent of whether input at that retinal location has been chronically attended for months or years (the "use-independent reorganization" hypothesis). Using fMRI, we found clear activation of formerly foveal cortex to stimuli presented at either the PRL or an isoeccentric non-PRL location in two individuals with MD, supporting the use-independent reorganization hypothesis. This finding suggests that reorganization is driven by passive, not use-dependent mechanisms