Reduced Face Aftereffects in Autism Are Not Due to Poor Attention

This study aimed to determine why face identity aftereffects are diminished in children with autism, relative to typical children. To address the possibility that reduced face aftereffects might reflect reduced attention to adapting stimuli, we investigated the consequence of controlling attention to adapting faces during a face identity aftereffect task in children with autism and typical children. We also included a size-change between adaptation and test stimuli to determine whether the reduced aftereffects reflect atypical adaptation to low- or higher-level stimulus properties. Results indicated that when attention was controlled and directed towards adapting stimuli, face identity aftereffects in children with autism were significantly reduced relative to typical children. This finding challenges the notion that atypicalities in the quality and/or quantity of children’s attention during adaptation might account for group differences previously observed in this paradigm. Additionally, evidence of diminished face identity aftereffects despite a stimulus size change supports an adaptive processing atypicality in autism that extends beyond low-level, retinotopically coded stimulus properties. These findings support the notion that diminished face aftereffects in autism reflect atypicalities in adaptive norm-based coding, which could also contribute to face processing difficulties in this group.     

Face Orientation and Motion Differently Affect the Deployment of Visual Attention in Newborns and 4-Month-Old Infants

Orienting visual attention allows us to properly select relevant visual information from a noisy environment. Despite extensive investigation of the orienting of visual attention in infancy, it is unknown whether and how stimulus characteristics modulate the deployment of attention from birth to 4 months of age, a period in which the efficiency in orienting of attention improves dramatically. The aim of the present study was to compare 4-month-old infants’ and newborns’ ability to orient attention from central to peripheral stimuli that have the same or different attributes. In Experiment 1, all the stimuli were dynamic and the only attribute of the central and peripheral stimuli to be manipulated was face orientation. In Experiment 2, both face orientation and motion of the central and peripheral stimuli were contrasted. The number of valid trials and saccadic latency were measured at both ages. Our results demonstrated that the deployment of attention is mainly influenced by motion at birth, while it is also influenced by face orientation at 4-month of age. These findings provide insight into the development of the orienting visual attention in the first few months of life and suggest that maturation may be not the only factor that determines the developmental change in orienting visual attention from birth to 4 months.     

Event-related Potential Study of Novelty Processing Abnormalities in Autism

To better understand visual processing abnormalities in autism we studied the attention orienting related frontal event potentials (ERP) and the sustained attention related centro-parietal ERPs in a three stimulus oddball experiment. The three stimulus oddball paradigm was aimed to test the hypothesis that individuals with autism abnormally orient their attention to novel distracters as compared to controls. A dense-array 128 channel EGI electroencephalographic (EEG) system was used on 11 high-functioning children and young adults with autism spectrum disorder (ASD) and 11 age-matched, typically developing control subjects. Patients with ASD showed slower reaction times but did not differ in response accuracy. At the anterior (frontal) topography the ASD group showed significantly higher amplitudes and longer latencies of early ERP components (e.g., P100, N100) to novel distracter stimuli in both hemispheres. The ASD group also showed prolonged latencies of late ERP components (e.g., P2a, N200, P3a) to novel distracter stimuli in both hemispheres. However, differences were more profound in the right hemisphere for both early and late ERP components. Our results indicate augmented and prolonged early frontal potentials and a delayed P3a component to novel stimuli, which suggest low selectivity in pre-processing and later-stage under-activation of integrative regions in the prefrontal cortices. Also, at the posterior (centro-parietal) topography the ASD group showed significantly prolonged N100 latencies and reduced amplitudes of the N2b component to target stimuli. In addition, the latency of the P3b component was prolonged to novel distracters in the ASD group. In general, the autistic group showed prolonged latencies to novel stimuli especially in the right hemisphere. These results suggest that individuals with autism over-process information needed for the successful differentiation of target and novel stimuli. We propose the potential application of ERP evaluations in a novelty task as outcome measurements in the biobehavioral treatment (e.g., EEG biofeedback, TMS) of autism.     

Behavior of larval Hemigrapsus sanguineus (de Haan) in response to gravity and pressure

Hemigrapsus sanguineus is an invasive species of crab (family: Grapsidae) in the north Atlantic basin. The species has spread rapidly since it was first discovered in North America in the late 1980s; however, the mechanisms of this range expansion remain unclear. This study attempts to predict the vertical distribution and, thus, ultimate transport of H. sanguineus larvae by examining larval responses to gravity and pressure. Geotaxis was determined by measuring the response of individual larvae to gravity in the absence of other tactic stimuli. Barokinesis was determined by measuring changes in swimming speed of larvae upon step-wise changes in pressure. Geotactic response of the larvae changes ontogenetically; early stage larvae are negatively geotactic (orienting towards the surface), while late stage larvae are positively geotactic (orienting towards the bottom). Larvae show a response to pressure that would aid in depth regulation. Early-stage larvae increase activity upon a change in pressure and orient their movement to gravity. However, the larvae show a relatively low sensitivity to pressure change. The evidence predicts an export-and-return model of larval transport, similar to that of Uca spp. in the Middle Atlantic Bight. This model supports the hypothesis that H. sanguineus larvae have the potential for high dispersal and will continue to invade new regions through larval transport.     

Control of spindle polarity and orientation in Saccharomyces cerevisiae

Control of mitotic spindle orientation represents a major strategy for the generation of cell diversity during development of metazoans. Studies in the budding yeast Saccharomyces cerevisiae have contributed towards our present understanding of the general principles underlying the regulation of spindle positioning in an asymmetrically dividing cell. In S. cerevisiae, the mitotic spindle must orient along the cell polarity axis, defined by the site of bud emergence, to ensure correct nuclear division between the mother and daughter cells. Establishment of spindle polarity dictates this process and relies on the concerted control of spindle pole function and a precise program of cues originating from the cell cortex that directs cytoplasmic microtubule attachments during spindle morphogenesis. These cues cross talk with the machinery responsible for bud-site selection, indicating that orientation of the spindle in yeast cells is mechanistically coupled to the definition of a polarity axis and the division plane. Here, we propose a model integrating the inherently asymmetric properties of the spindle pathway with the program of positional information contributing towards orienting the spindle in budding yeast. Because the basic machinery orienting the spindle in higher-eukaryotic cells appears to be conserved, it might be expected that similar principles govern centrosome asymmetry in the course of metazoan development.     

Visually inexperienced chicks exhibit spontaneous preference for biological motion patterns

When only a small number of points of light attached to the torso and limbs of a moving organism are visible, the animation correctly conveys the animal's activity. Here we report that newly hatched chicks, reared and hatched in darkness, at their first exposure to point-light animation sequences, exhibit a spontaneous preference to approach biological motion patterns. Intriguingly, this predisposition is not specific for the motion of a hen, but extends to the pattern of motion of other vertebrates, even to that of a potential predator such as a cat. The predisposition seems to reflect the existence of a mechanism in the brain aimed at orienting the young animal towards objects that move semi-rigidly (as vertebrate animals do), thus facilitating learning, i.e., through imprinting, about their more specific features of motion.     

Impaired Perception of Facial Motion in Autism Spectrum Disorder

Facial motion is a special type of biological motion that transmits cues for socio-emotional communication and enables the discrimination of properties such as gender and identity. We used animated average faces to examine the ability of adults with autism spectrum disorders (ASD) to perceive facial motion. Participants completed increasingly difficult tasks involving the discrimination of (1) sequences of facial motion, (2) the identity of individuals based on their facial motion and (3) the gender of individuals. Stimuli were presented in both upright and upside-down orientations to test for the difference in inversion effects often found when comparing ASD with controls in face perception. The ASD group’s performance was impaired relative to the control group in all three tasks and unlike the control group, the individuals with ASD failed to show an inversion effect. These results point to a deficit in facial biological motion processing in people with autism, which we suggest is linked to deficits in lower level motion processing we have previously reported.     

Origin of the blood hyperserotonemia of autism

Background  

Research in the last fifty years has shown that many autistic individuals have elevated serotonin (5-hydroxytryptamine, 5-HT) levels in blood platelets. This phenomenon, known as the platelet hyperserotonemia of autism, is considered to be one of the most well-replicated findings in biological psychiatry. Its replicability suggests that many of the genes involved in autism affect a small number of biological networks. These networks may also play a role in the early development of the autistic brain.     

Structure-independent cross-validation between residual dipolar couplings originating from internal and external orienting media

Lanthanide-substituted calcium binding proteins are known to partially orient in high magnetic fields. Orientation provides residual dipolar couplings (rdc's). Two of these systems, Tm³⁺- and Dy³⁺-substituted calbindin D_9k, dissolved in an external orienting medium (nonionic liquid crystalline phase) provide rdc values which are the sum of those induced by the lanthanides and by the liquid crystalline phase on the native calcium binding protein. This structure-independent check shows the innocence of the orienting medium with respect to the structure of the protein in solution. Furthermore, the simultaneous use of lanthanide substitution and external orienting media provides a further effective tool to control and tune the orientation tensor.     

Using Effort to Measure Reward Value of Faces in Children with Autism

According to one influential account, face processing atypicalities in autism reflect reduced reward value of faces, which results in limited attention to faces during development and a consequent failure to acquire face expertise. Surprisingly, however, there is a paucity of work directly investigating the reward value of faces for individuals with autism and the evidence for diminished face rewards in this population remains equivocal. In the current study, we measured how hard children with autism would work to view faces, using an effortful key-press sequence, and whether they were sensitive to the differential reward value of attractive and unattractive faces. Contrary to expectations, cognitively able children with autism did not differ from typically developing children of similar age and ability in their willingness to work to view faces. Moreover, the effort expended was strongly positively correlated with facial attractiveness ratings in both groups of children. There was also no evidence of atypical reward values for other, less social categories (cars and inverted faces) in the children with autism. These results speak against the possibility that face recognition difficulties in autism are explained by atypical reward value of faces.     

Comparison of the Hunting Behavior of Four Piscine Predators Attacking Schooling Prey

Four piscine predator species were observed repeatedly attacking large (> 100,000) schools of flat-iron herring, Harengula thrissina. The predators could be categorized into two groups. Stalking predators (two species) were slow-moving, predominantly solitary hunters attacking from positions beneath the school. Attacks were directed at individual prey and the sequence of events was orient-approach-strike. Although the stalking species were seen most often and were responsible for the majority of the attacks, capture success was low. The remaining two species were fast-moving, pelagic hunters regularly occurring in groups of up to 8 individuals. These predators were extremely proficient at capturing prey, either by orienting on individuals (stragglers) or accelerating into the school and ramming their prey (impact attacks). Group size was positively associated with capture success, but not significantly so. Because stalking predators orient towards individual prey, they may suffer from the effect of confusion when attacking schooling prey. Use of the impact strategy, by comparison, may allow predators to overcome the confusion effect either by attacking prey already separated from the school, or by orienting towards aggregated prey rather than particular individuals.     

The effects of long-chain alcohols on membrane lipids and the (Na+ + K+)-ATPase

The (Na⁺ + K⁺)-ATPase obtained from sheep kidney outer medulla is irreversibly denatured by long-chain aliphatic alcohols. The denaturation proceeds by causing a change in the structure of the membrane lipids rather than by binding directly to the protein. The alcohols decrease the ability of the membrane lipid bilayer to orient the spin label 3-(4′,4′-dimethyloxazolidinyl)-5α-androstan-17β-ol. For the low molecular weight alcohols the ability of the membrane to orient the label is completely lost while for alcohols with more than five carbons only partial loss of the orienting ability of the membrane occurs. The alcohol concentrations necessary to denature the enzyme correspond to the concentrations that produce the maximal change in the ability of the membrane to orient the label, and correlate well with the hydrophobicity of the alcohols as measured by their water-octanol partition coefficients.     

Aberrant auditory system and its developmental implications for autism

Most infants who are later diagnosed with autism show delayed speech and language and/or atypical language profile. There is a large body of research on abnormal speech and language in children with autism. However, auditory development has been relatively under-investigated in autism research, despite its inextricable relationship with language development and despite researchers' ability to detect abnormalities in brain development and behavior in early infancy. In this review, we synthesize research on auditory processing in the prenatal period through infancy and childhood in typically developing children, children at high risk for autism, and children diagnosed with autism. We conclude that there are clear neurobiological and behavioral links between abnormal auditory development and the deficits in social communication seen in autism. We then offer perspectives on the need for a systematic characterization of early auditory development in autism, and identified questions to be addressed in future research on the development of autism.     

Socioeconomic Inequality in the Prevalence of Autism Spectrum Disorder: Evidence from a U.S. Cross-Sectional Study

Background

This study was designed to evaluate the hypothesis that the prevalence of autism spectrum disorder (ASD) among children in the United States is positively associated with socioeconomic status (SES).

Methods

A cross-sectional study was implemented with data from the Autism and Developmental Disabilities Monitoring Network, a multiple source surveillance system that incorporates data from educational and health care sources to determine the number of 8-year-old children with ASD among defined populations. For the years 2002 and 2004, there were 3,680 children with ASD among a population of 557 689 8-year-old children. Area-level census SES indicators were used to compute ASD prevalence by SES tertiles of the population.

Results

Prevalence increased with increasing SES in a dose-response manner, with prevalence ratios relative to medium SES of 0.70 (95% confidence interval [CI] 0.64, 0.76) for low SES, and of 1.25 (95% CI 1.16, 1.35) for high SES, (P<0.001). Significant SES gradients were observed for children with and without a pre-existing ASD diagnosis, and in analyses stratified by gender, race/ethnicity, and surveillance data source. The SES gradient was significantly stronger in children with a pre-existing diagnosis than in those meeting criteria for ASD but with no previous record of an ASD diagnosis (p<0.001), and was not present in children with co-occurring ASD and intellectual disability.

Conclusions

The stronger SES gradient in ASD prevalence in children with versus without a pre-existing ASD diagnosis points to potential ascertainment or diagnostic bias and to the possibility of SES disparity in access to services for children with autism. Further research is needed to confirm and understand the sources of this disparity so that policy implications can be drawn. Consideration should also be given to the possibility that there may be causal mechanisms or confounding factors associated with both high SES and vulnerability to ASD.     

Unaffected perceptual thresholds for biological and non-biological form-from-motion perception in autism spectrum conditions

Background

Perception of biological motion is linked to the action perception system in the human brain, abnormalities within which have been suggested to underlie impairments in social domains observed in autism spectrum conditions (ASC). However, the literature on biological motion perception in ASC is heterogeneous and it is unclear whether deficits are specific to biological motion, or might generalize to form-from-motion perception.

Methodology and Principal Findings

We compared psychophysical thresholds for both biological and non-biological form-from-motion perception in adults with ASC and controls. Participants viewed point-light displays depicting a walking person (Biological Motion), a translating rectangle (Structured Object) or a translating unfamiliar shape (Unstructured Object). The figures were embedded in noise dots that moved similarly and the task was to determine direction of movement. The number of noise dots varied on each trial and perceptual thresholds were estimated adaptively. We found no evidence for an impairment in biological or non-biological object motion perception in individuals with ASC. Perceptual thresholds in the three conditions were almost identical between the ASC and control groups.

Discussion and Conclusions

Impairments in biological motion and non-biological form-from-motion perception are not across the board in ASC, and are only found for some stimuli and tasks. We discuss our results in relation to other findings in the literature, the heterogeneity of which likely relates to the different tasks performed. It appears that individuals with ASC are unaffected in perceptual processing of form-from-motion, but may exhibit impairments in higher order judgments such as emotion processing. It is important to identify more specifically which processes of motion perception are impacted in ASC before a link can be made between perceptual deficits and the higher-level features of the disorder.     

The pathogenesis of autism: insights from congenital blindness

There is substantial heterogeneity in the aetiology and clinical presentation of autism. So how do we account for homogeneity in the syndrome? The answer to this question will be critical for any attempt to trace the links between brain pathology and the psychological disabilities that characterize autism. One possibility is that the source of homogeneity in autism is not to be found ''in the child'', but rather in dysfunction of the system constituted by child-in-relation-to-other. We have been exploring this hypothesis through the study of congenitally blind children, among whom features of autism, and the syndrome of autism itself, are strikingly common. To justify such an approach, one needs to establish that the clinical features in blind children have qualities that are indeed ''autistic-like''. We conducted systematic observations of the social interactions of two matched groups of congenitally blind children who do not have autism, rating their social engagement, emotional tone, play and language during three sessions of free play in the school playground. The qualities of social impairment in the more disabled children were similar to those in sighted children with autism. Additional evidence came from independent ratings of the children in a different play setting: on the childhood autism rating scale (CARS), the socially impaired children had ''autistic-like'' abnormalities in both social and non-social domains. If we can determine the way in which congenital blindness predisposes to features of autism, we shall be in a better position to trace the developmental pathways that lead to the syndrome in sighted children.     

Effect of 5,6-dihydroxytryptamine and 6-hydroxydopamine on the maze behavior of the snail Helix lucroum

One-trial Y-maze test in snails did not reveal any predominance of the right or left alley choice. The choice of the right alley (but not of the left one) was accompanied by a slowing down of forward motion. After the administration of 10 mg/kg of 6-hydroxydopamine 24 hr before the test, right alley choice without slowing down became more frequent. Administration of 5,6-dihydroxytrypamine (10 mg/kg) caused a reduction of motion rate along all parts of the maze and an increase in frequency of the orienting head movements towards the alley to be chosen.