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The ventral visual pathway is directly involved in the perception and recognition of objects. However, the extent to which the neural representation of objects in this region reflects low-level or high-level properties remains unresolved. A problem in resolving this issue is that only a small proportion of the objects experienced during natural viewing can be shown during a typical experiment. This can lead to an uneven sampling of objects that biases our understanding of how they are represented. To address this issue, we developed a data-driven approach to stimulus selection that involved describing a large number objects in terms of their image properties. In the first experiment, clusters of objects were evenly selected from this multi-dimensional image space. Although the clusters did not have any consistent semantic features, each elicited a distinct pattern of neural response. In the second experiment, we asked whether high-level, category-selective patterns of response could be elicited by objects from other categories, but with similar image properties. Object clusters were selected based on the similarity of their image properties to objects from five different categories (bottle, chair, face, house, and shoe). The pattern of response to each metameric object cluster was similar to the pattern elicited by objects from the corresponding category. For example, the pattern for bottles was similar to the pattern for objects with similar image properties to bottles. In both experiments, the patterns of response were consistent across participants providing evidence for common organising principles. This study provides a more ecological approach to understanding the perceptual representations of objects and reveals the importance of image properties.

Regions in the ventral visual pathway, such as the fusiform face area (FFA) and parahippocampal place area (PPA) are selective for images from specific object categories. Yet images from different object categories differ in their image properties. To investigate how these image properties are represented in the FFA and PPA, we compared neural responses to locally-SCRAMBLED images (in which mid-level, spatial properties are preserved) and globally-SCRAMBLED images (in which mid-level, spatial properties are not preserved). There was a greater response in the FFA and PPA to images from the preferred CATEGORY relative to their non-preferred category for the scrambled conditions. However, there was a greater selectivity for locally-scrambled compared to globally-scrambled images. Next, we compared the magnitude of fMR-adaptation to intact and scrambled images. fMR-adaptation was evident to locally-scrambled images from the preferred category. However, there was no adaptation to globally-scrambled images from the preferred category. These results show that the selectivity to faces and places in the FFA and PPA is dependent on mid-level properties of the image that are preserved by local-scrambling.

Background Musculoskeletal pain research in South African is scant. Hence this study to determine the percentages of nurses with musculoskeletal pain at baseline + at follow-up interview a year later (persistent pain) and occurrence of incident pain (no pain at baseline but pain at follow-up); and to identify risk factors associated with persistent pain. Methods CUPID methodology was used. Nurses in wards with patient handling tasks were selected from two large public-sector hospitals in Gauteng, South Africa. They were interviewed at baseline about the one-month prevalence of site-specific musculoskeletal pain and about a large number of physical, social and psychological variables. Of the 251 baseline nurses, 189 (75%) completed a similar follow-up interview. The baseline nurses and follow-up nurses did not differ by study variables, and having pain at baseline did not influence follow-up participation. Explanatory variables associated with musculoskeletal pain were identified using multivariate logistic regression; a backward hierarchical stepwise approach was used to build final models. Results One-month prevalences of site-specific pain were consistently higher at follow-up than at baseline. For example, low back pain and neck pain were 33.9% and 42.3% and 20.7% and 27.5% respectively. Persistence of pain was common: 77% of nurses reported persistence of neck pain and 70% knee pain with the lowest being wrist/hand pain at 35%. Nearly half, 39/82, of nurses who did not have any pain during the 1-month prior to baseline, developed pain in the 1-month before the follow-up interview. Regarding site specific pain, incident low back pain had the highest (32.8%) and incident elbow pain had the lowest occurrences (8.5%). Only past injuries [OR 7.0, 95% CI: 3.0–16.2] and ≥2 distressing somatic symptoms were associated with persistent pain. Conclusions Persistence of pain was common. A large number of potential determinants of persistent pain were considered, but few identified.

Bistable stimuli, such as the Necker Cube, demonstrate that experience can change in the absence of changes in the environment. Such phenomena can be used to assess stimulus-independent aspects of conscious experience. The current study used resting state functional magnetic resonance imaging (rs-fMRI) to index stimulus-independent changes in neural activity to understand the neural architecture that determines dominance durations during bistable perception (using binocular rivalry and Necker cube stimuli). Anterior regions of the Superior Parietal Lobule (SPL) exhibited robust connectivity with regions of primary sensorimotor cortex. The strength of this region's connectivity with the striatum predicted shorter dominance durations during binocular rivalry, whereas its connectivity to pre-motor cortex predicted longer dominance durations for the Necker Cube. Posterior regions of the SPL, on the other hand, were coupled to associative cortex in the temporal and frontal lobes. The posterior SPL's connectivity to the temporal lobe predicted longer dominance during binocular rivalry. In conjunction with prior work, these data suggest that the anterior SPL contributes to perceptual rivalry through the inhibition of incongruent bottom up information, whereas the posterior SPL influences rivalry by supporting the current interpretation of a bistable stimulus. Our data suggests that the functional connectivity of the SPL with regions of sensory, motor, and associative cortex allows it to regulate the interpretation of the environment that forms the focus of conscious attention at a specific moment in time.