Event-related alpha suppression in response to facial motion

This article has been made available through the Brunel Open Access Publishing Fund.While biological motion refers to both face and body movements, little is known about the visual perception of facial motion. We therefore examined alpha wave suppression as a reduction in power is thought to reflect visual activity, in addition to attentional reorienting and memory processes. Nineteen neurologically healthy adults were tested on their ability to discriminate between successive facial motion captures. These animations exhibited both rigid and non-rigid facial motion, as well as speech expressions. The structural and surface appearance of these facial animations did not differ, thus participants decisions were based solely on differences in facial movements. Upright, orientation-inverted and luminance-inverted facial stimuli were compared. At occipital and parieto-occipital regions, upright facial motion evoked a transient increase in alpha which was then followed by a significant reduction. This finding is discussed in terms of neural efficiency, gating mechanisms and neural synchronization. Moreover, there was no difference in the amount of alpha suppression evoked by each facial stimulus at occipital regions, suggesting early visual processing remains unaffected by manipulation paradigms. However, upright facial motion evoked greater suppression at parieto-occipital sites, and did so in the shortest latency. Increased activity within this region may reflect higher attentional reorienting to natural facial motion but also involvement of areas associated with the visual control of body effectors. © 2014 Girges et al

Categorisation in infants and adults : Perceptual saliency as a function of timing

Concepts mentally represent categories of entities in the world. They are thought to be fundamental to thinking. Of primary concern is whether conceptual information is at the core of infants' representations of categories, or if infants first learn to classify on a purely perceptual basis. The relationship between perceptual and conceptual categorisation has been conceived of in terms of a dichotomy. I argue, however, that both perceptual and conceptual information are constrained by the amount of time the cognitive system has to process information. In this thesis, I investigate the relative weighting of perceptual information under time pressure at the beginning of conceptual development, in infants, and when conceptual development is complete, in adults. The effects of timing on categorisation were investigated in 16 experiments with infants and adults. Experiments 1 to 3 utilised the familiarisation/novelty preference procedure with 4-month-old infants. The experiments demonstrated that when processing time is limited, infants show a marked preference for the highly-diagnostic information. With increased looking time, less diagnostic information is incorporated into the object representation. Experiments 4 to 16 revealed that the properties adults use in rapid categorisation tasks correspond to those of infants, and are therefore not a function of age. Rather, how subjects perceive, process and assign relative weighting to different properties in categorising objects is dependent on timing constraints

A preliminary comparison of volumetric changes between dyslexia and Asperger syndrome

Although shared neuropsychological characteristics between dyslexia and autistic spectrum disorder have been identified, no comparisons at anatomical brain level have been reported. In this study, we examined global and regional grey and white matter changes in adults with dyslexia and patients with Asperger syndrome (AS) in comparison to healthy controls, using voxel-based-morphometry. Results revealed higher levels of global grey matter volume in the Asperger syndrome group in comparison to normal controls but not dyslexia. Further comparisons of grey and white matter could not detect any regional differences between the three groups. From the current data, the hypothesis that regional anatomical abnormalities are strongly implicated in AS and dyslexia could not be supported with the technique used

Comparison of form and motion coherence processing in autistic spectrum disorders and dyslexia

A large body of research has reported visual perception deficits in both people with dyslexia and autistic spectrum disorders. In this study, we compared form and motion coherence detection between a group of adults with high-functioning autism, a group with Asperger’s disorder, a group with dyslexia, and a matched control group. It was found that motion detection was intact in dyslexia and Asperger. Individuals with high-functioning autism showed a general impaired ability to detect coherent form and motion. Participants with Asperger’s syndrome showed lower form coherence thresholds than the dyslexic and normally developing adults. The results are discussed with respect to the involvement of the dorsal and ventral pathways in developmental disorders

Snapshot series demonstrating part of a facial motion sequence.

<p>Snapshot series demonstrating part of a facial motion sequence.</p

Grand averaged amplitude and latency data for facial motion at PO and O sites.

<p>*Baseline amplitudes are considered the initial values of alpha.</p

Significant main effects and interactions at PO and O electrodes.

<p>*Results taken from multivariate tests (Pillai’s Trace) due to a significant Mauchly’s test indicating that sphericity cannot be assumed.</p

Latency of mid-point peak and minimum amplitudes at PO and O electrodes.

<p>*Mauchly’s test indicated that the assumption of sphericity had been violated. Degrees of freedom were therefore corrected using Greenhouse-Geisser estimates of sphericity.</p

Low copy numbers of complement and deficiency are risk factors for myositis, its subgroups and autoantibodies

BACKGROUND: Idiopathic inflammatory myopathies (IIM) are a group of autoimmune diseases characterised by myositis-related autoantibodies plus infiltration of leucocytes into muscles and/or the skin, leading to the destruction of blood vessels and muscle fibres, chronic weakness and fatigue. While complement-mediated destruction of capillary endothelia is implicated in paediatric and adult dermatomyositis, the complex diversity of complement in IIM pathology was unknown. METHODS: We elucidated the gene copy number (GCN) variations of total , and and in 1644 Caucasian patients with IIM, plus 3526 matched healthy controls using real-time PCR or Southern blot analyses. Plasma complement levels were determined by single radial immunodiffusion. RESULTS: The large study populations helped establish the distribution patterns of various GCN groups. Low GCNs of (=2+3) and deficiency (=0+1) were strongly correlated with increased risk of IIM with OR equalled to 2.58 (2.28-2.91), p=5.0×10 for , and 2.82 (2.48-3.21), p=7.0×10 for deficiency. Contingency and regression analyses showed that among patients with deficiency, the presence of became insignificant as a risk factor in IIM except for inclusion body myositis (IBM), by which 98.2% had with an OR of 11.02 (1.44-84.4). Intragroup analyses of patients with IIM for C4 protein levels and IIM-related autoantibodies showed that those with anti-Jo-1 or with anti-PM/Scl had significantly lower C4 plasma concentrations than those without these autoantibodies. CONCLUSIONS: deficiency is relevant in dermatomyositis, is important in IBM and both deficiency and contribute interactively to risk of polymyositis