Evidencing a place for the hippocampus within the core scene processing network.

Functional neuroimaging studies have identified several "core" brain regions that are preferentially activated by scene stimuli, namely posterior parahippocampal gyrus (PHG), retrosplenial cortex (RSC), and transverse occipital sulcus (TOS). The hippocampus (HC), too, is thought to play a key role in scene processing, although no study has yet investigated scene-sensitivity in the HC relative to these other "core" regions. Here, we characterised the frequency and consistency of individual scene-preferential responses within these regions by analysing a large dataset (n = 51) in which participants performed a one-back working memory task for scenes, objects, and scrambled objects. An unbiased approach was adopted by applying independently-defined anatomical ROIs to individual-level functional data across different voxel-wise thresholds and spatial filters. It was found that the majority of subjects had preferential scene clusters in PHG (max = 100% of participants), RSC (max = 76%), and TOS (max = 94%). A comparable number of individuals also possessed significant scene-related clusters within their individually defined HC ROIs (max = 88%), evidencing a HC contribution to scene processing. While probabilistic overlap maps of individual clusters showed that overlap "peaks" were close to those identified in group-level analyses (particularly for TOS and HC), inter-individual consistency varied across regions and statistical thresholds. The inter-regional and inter-individual variability revealed by these analyses has implications for how scene-sensitive cortex is localised and interrogated in functional neuroimaging studies, particularly in medial temporal lobe regions, such as the HC. Hum Brain Mapp 37:3779-3794, 2016. © 2016 Wiley Periodicals, Inc.

The effect of personal grooming on self-perceived body image.

OBJECTIVE: Grooming behaviours, including the application of fragranced products, are thought to reflect a means of managing social impressions and self-image. Although application of deodorants has previously been shown to make individuals appear more confident to others, few studies have specifically examined the psychological effects of such rituals on the wearer. Here, we investigated how grooming behaviours affect self-perceived body image, a central component of an individual's self-image. METHODS: In two separate experiments, using a psychophysical forced choice task, male and female participants with a normal Body Mass Index (BMI) indicated whether projected life-size images of their own body were bigger or smaller than their actual size. In the experimental condition, participants applied a fragranced deodorant before performing the task, whereas in the control condition, no product was applied. Our dependent measures were the point of subjective equality (PSE), the size at which participants report their body is subjectively equal to their actual body size, and the difference limen (DL), the amount of change in body size distortion necessary for it to be reliably detected. These measurements provide an index of attitudinal and perceptual components of body image, respectively. RESULTS: Both male and female participants who, at baseline, overestimated their body size, made significantly more accurate judgments about their body size, as measured by the PSE, following application of a fragranced deodorant or antiperspirant than they did in the control condition. This effect was seen in the absence of differences in perceptual sensitivity to changes in body size (DL) across groups and conditions. People who underestimated their body size did not show this effect. Of note, both male and female overestimators had a significantly larger BMI than underestimators. CONCLUSION: These results demonstrate that the attitudinal component of body image is malleable and can be influenced by everyday grooming routines, suggesting such behaviours have psychological benefits for both genders, beyond their basic hygiene function. However, there are individual differences in people's susceptibility to these effects, perhaps reflecting variability in self-esteem.

Extrastriate cortex and medial temporal lobe regions respond differentially to visual feature overlap within preferred stimulus category.

It has been proposed that domain-specific regions in extrastriate cortex, parahippocampal cortex and the medial temporal lobe (MTL, particularly the hippocampus, HC, and perirhinal cortex, PrC) may respond differently to the degree of feature complexity present in sets of visual stimuli, with the latter two regions tuned to represent the differences among stimuli with a high degree of visual overlap or featural ambiguity (Graham, Barense, & Lee, 2010; Cowell, Bussey, & Saksida, 2010a). To test this prediction, healthy participants viewed blocks containing visually similar or visually different exemplars from four stimulus categories (scenes, faces, inanimate objects and animate objects). Independent functional regions of interest were identified in extrastriate and MTL regions that were preferentially responsive to one or more of these visual categories, and the main experimental data interrogated for any evidence of an interaction between visual category and degree of feature overlap. In PrC and posterior HC (PostHC) viewing sets of stimuli with a large number of overlapping features resulted in greater activity than blocks containing items that were more visually distinct. The opposite pattern was found in fusiform face area (FFA), parahippocampal place area (PPA) and lateral occipital complex (LOC). The increased response in the HC and PrC to high visual similarity was seen only for visual categories that effectively activate these regions (PrC-faces and objects; PostHC-scenes). This study confirms that regions throughout the visual ventral stream, parahippocampal cortex and MTL are engaged differentially by visual complexity, consistent with recent lesion experiments in which MTL damage affects discrimination and learning of, as well as recognition memory for, exemplars with a high degree of visual feature overlap.

Domain specificity in visual cortex.

We investigated the prevalence and specificity of category-selective regions in human visual cortex. In the broadest survey to date of category selectivity in visual cortex, 12 participants were scanned with functional magnetic resonance imaging while viewing scenes and 19 different object categories in a blocked-design experiment. As expected, we found selectivity for faces in the fusiform face area (FFA), for scenes in the parahippocampal place area (PPA), and for bodies in the extrastriate body area (EBA). In addition, we describe 3 main new findings. First, evidence for the selectivity of the FFA, PPA, and EBA was strengthened by the finding that each area responded significantly more strongly to its preferred category than to the next most effective of the remaining 19 stimulus categories tested. Second, a region in the middle temporal gyrus that has been reported to respond significantly more strongly to tools than to animals did not respond significantly more strongly to tools than to other nontool categories (such as fruits and vegetables), casting doubt on the characterization of this region as tool selective. Finally, we did not find any new regions in the occipitotemporal pathway that were strongly selective for other categories. Taken together, these results demonstrate both the strong selectivity of a small number of regions and the scarcity of such regions in visual cortex.

A cortical area selective for visual processing of the human body.

Despite extensive evidence for regions of human visual cortex that respond selectively to faces, few studies have considered the cortical representation of the appearance of the rest of the human body. We present a series of functional magnetic resonance imaging (fMRI) studies revealing substantial evidence for a distinct cortical region in humans that responds selectively to images of the human body, as compared with a wide range of control stimuli. This region was found in the lateral occipitotemporal cortex in all subjects tested and apparently reflects a specialized neural system for the visual perception of the human body.

Interactions between visual working memory and selective attention.

The relationship between working memory and selective attention has traditionally been discussed as operating in one direction: Attention filters incoming information, allowing only relevant information into short-term processing stores. This study tested the prediction that the contents of visual working memory also influence the guidance of selective attention. Participants held a sample object in working memory on each trial. Two objects, one matching the sample and the other novel, were then presented simultaneously. As measured by a probe task, attention shifted to the object matching the sample. This effect generalized across object type, attentional-probe task, and working memory task. In contrast, a matched task with no memory requirement showed the opposite pattern, demonstrating that this effect is not simply due to exposure to the sample. These results confirm a specific prediction about the influence of working memory contents on the guidance of attention.

fMRI evidence for objects as the units of attentional selection.

Contrasting theories of visual attention emphasize selection by spatial location, visual features (such as motion or colour) or whole objects. Here we used functional magnetic resonance imaging (fMRI) to test key predictions of the object-based theory, which proposes that pre-attentive mechanisms segment the visual array into discrete objects, groups, or surfaces, which serve as targets for visual attention. Subjects viewed stimuli consisting of a face transparently superimposed on a house, with one moving and the other stationary. In different conditions, subjects attended to the face, the house or the motion. The magnetic resonance signal from each subject's fusiform face area, parahippocampal place area and area MT/MST provided a measure of the processing of faces, houses and visual motion, respectively. Although all three attributes occupied the same location, attending to one attribute of an object (such as the motion of a moving face) enhanced the neural representation not only of that attribute but also of the other attribute of the same object (for example, the face), compared with attributes of the other object (for example, the house). These results cannot be explained by models in which attention selects locations or features, and provide physiological evidence that whole objects are selected even when only one visual attribute is relevant.

The line-motion illusion: attention or impletion?

When a brief lateral cue precedes an instantaneously presented horizontal line, observers report a sensation of motion in the line propagating from the cued end toward the uncued end. This illusion has been described as a measure of the facilitatory effects of a visual attention gradient (O. Hikosaka, S. Miyauchi, & S. Shimojo, 1993a). Evidence in the present study favors, instead, an account in which the illusion is the result of an impletion process that fills in interpolated events after the cue and the line are linked as successive states of a single object in apparent motion.