Hemispheric asymmetry of pattern reversal visual evoked potentials in healthy subjects

Pattern reversal visual evoked potentials were recorded from temporal leads of both hemispheres in 3 right-handed and 3 left-handed subjects. The stimuli subtended 6 degrees of visual field (full field condition), or 1 degree of visual field (foveal condition), or were restricted to the peripheral portion of the visual field (annular condition). Check sizes varied from 16 to 2.8 min of arc. The stimuli were phase-reversed at 1 or 8 Hz. Remarkable hemispheric asymmetries were found, depending on the portion of the visual field and temporal frequency. In right-handed subjects the amplitude of visual evoked potentials recorded over the left hemisphere was larger for stimuli phase-reversed at 8 Hz in full-field and annular conditions, whereas the amplitude of visual evoked potentials recorded over the right hemisphere was larger for stimuli phase-reversed at 1 Hz in the foveal condition. Different patterns of hemispheric asymmetries were observed in left-handed subjects.     

Facial affect recognition in autism,ADHD and typical development

Introduction: Autism spectrum disorder (ASD) and Attention-Deficit Hyperactivity Disorder (ADHD) have been associated with facial affect recognition (FAR) alterations. Methods: This study examined accuracy and response times for general and specific FAR in whole face and eye-region stimuli. FAR was assessed in matched samples of children and adolescents with ASD (n?=?35), ADHD (n?=?32), and typical development (TD) (n?=?32) aged 8.6–15.9 years (M?=?11.6; SD?=?2.0). Results: Compared to TD, the ASD group performed less accurate and showed longer response times for general and specific FAR, mostly driven by problems in neutral and happy face identification. The ADHD group responded faster than the ASD group for global FAR. No differences between ADHD and TD were found. Attentional distractibility had a significant effect on FAR performance in ASD and ADHD. Conclusions: Findings confirm FAR alterations in ASD, but not ADHD, and endorse effects of attentional distractibility on FAR in ASD and ADHD. FAR and attention function training is clinically meaningful in ASD. Future studies should include control for visual attention and facial configuration skills, use naturalistic FAR material and also investigate implicit FAR.     

Sleep problems in children with autism spectrum disorders, developmental delays, and typical development: a population-based study

This study compared parent-reported sleep characteristics in 2- to 5-year-old children with autism spectrum disorders (ASD) to children with other developmental delays (DD) and typical development (TD). We included 529 children (303 ASD [167 males], 63 DD [46 males], and 163 TD [134 males]) enrolled in the CHARGE study, an ongoing population-based case-control study. The mean age of participants was 3.6 years (standard deviation, 0.8 years). ASD diagnosis was confirmed with Autism Diagnostic Interview-Revised (ADI-R) and Autism Diagnostic Observation Schedules (ADOS). Cognitive and adaptive functioning was assessed using Mullen Scales of Early Learning (MSEL) and Vineland Adaptive Behavior Scales (VABS), respectively. Demographic, medical and sleep history information were ascertained from California birth records, telephone interview, medical assessments at clinic visit, and parent-administered questionnaires. Fifty-three percent of children with ASD had at least one frequent sleep problem, followed by 46% of children with DD, and 32% of the TD group (P < 0.0001). Exploratory factor analyses of sleep history data yielded two factors: sleep onset problems and night waking. Children with ASD had marginally higher sleep onset factor scores and significantly higher night waking factor scores compared with the TD group. Factor scores for children with DD were intermediate between the ASD and TD groups. Cognitive or adaptive development did not predict severity of sleep problems in the ASD group.     

Importance of optic flow for postural stability of male and female young adults

Purpose

A feedback control process based on self-motion perception contributes to postural stability; however, little is known about the visual modulation of postural muscles. The aim of this study was to investigate the effect of optic flow stimuli, presented full field, in the peripheral and foveal visual field, on muscular activation. Then, we assessed the correlation between optic flow, muscle activity and body sway in male and female subjects.

Methods

We used surface electromyography (EMG) and stabilometry on 24 right-handed young adults. We recorded the bilateral activation of tibialis anterior, gastrocnemius medialis, biceps femoris and vastus medialis. EMG and center of pressure (COP) signals were acquired simultaneously. EMG signal amplitude was computed as root mean square normalized by baseline.

Results

We found a significant effect for muscles, gender and an interaction effect of muscle by gender (ANOVA, p < 0.001). Results showed different postural alignments in males and females. The COP spatial variability during peripheral stimuli was generally reduced. The prevalent direction of oscillation evoked by peripheral stimuli was clustered, while foveal and random stimuli induced distributed and randomized directions. Also for muscle activity, we found gender differences in the prevalent oscillation distributions evoked by optic flow.

Conclusion

Visual stimuli always evoke an excitatory input on postural muscles, but the stimulus structure produces different postural effects. Peripheral optic flow stimuli stabilize postural sway, while random and foveal optic flow provoke larger sway variability similar to those evoked in the absence of visual stimulation.     

Effects of Attention on Pattern-Reversal Visual Evoked Potentials: Foveal Field Stimulation Versus Peripheral Field Stimulation

The effects of foveal field attention on pattern reversal visual evoked potential (VEP) were investigated in thirteen normal subjects. Conventional monocular VEP was recorded during the three conditions of control, foveal concentration and reaction time task. Three patterns of checkerboard, which were full field (radius, 0-9 degrees), peripheral field (2.5-9 degrees) and foveal field (0-2.5 degrees), were presented for the stimulation in each condition. The P100 and N145 amplitude of the peripheral field VEP were significantly smaller during the concentration and the reaction time task conditions than that in the control session, while the foveal field VEP amplitudes were enhanced in the concentration and reaction time tasks conditions. The full field VEP amplitudes were not significantly changed by the conditions. We concluded that the act of concentration to the foveal field or the task requiring attention to the foveal field, enhanced the VEP response to foveal field stimulation and suppressed the VEP to the peripheral field. A gating effect in area V1 was speculated, although extra-striate cortex might contribute.     

Atypical visual change processing in children with autism: An electrophysiological Study

Children with Autism Spectrum Disorder (ASD) may display atypical behaviors in reaction to unattended changes that occur in all sensory modalities. Atypical automatic auditory change processing has been highlighted in ASD via the analysis of mismatch negativity (MMN). The present study investigated visual deviancy detection in children with ASD in order to determine whether unusual reactions to change operate in other sensory modalities. Twelve children with ASD were presented with a passive visual oddball paradigm using dynamic stimuli. Compared to controls, children with ASD showed an earlier visual mismatch response, suggesting a hypersensitivity to visual deviancy. This study is thus consistent with the hypothesis of the existence of “general” atypical change detection processing in children with ASD that might contribute to their intolerance of change.     

On the Differentiation of Foveal and Peripheral Early Visual Evoked Potentials

The C1 is one of the earliest visual evoked potentials observed following the onset of a patterned stimulus. The polarity of its peak is dependent on whether stimuli are presented in the upper or lower regions of the peripheral visual field, but has been argued to be negative for stimuli presented to the fovea. However, there has yet to be a systematic investigation into the extent to which the peripheral C1 (pC1) and foveal C1 (fC1) can be differentiated on the basis of response characteristics to different stimuli. The current study employed checkerboard patterns (Exp 1) and sinusoidal gratings of different spatial frequency (Exp 2) presented to the fovea or within one of the four quadrants of the peripheral visual field. The checkerboard stimuli yielded a sizable difference in peak component latency, with the fC1 peaking ~32 ms after the pC1. Further, the pC1 showed a band-pass response magnitude profile that peaked at 4 cycles per degree (cpd), whereas the fC1 was high-pass for spatial frequency, with a cut-off around 4 cpd. Finally, the scalp topographies of the pC1 and fC1 in both experiments differed greatly, with the fC1 being more posterior than the pC1. The results reported here call into question recent attempts to characterize general C1 processes without regard to whether stimuli are placed in the fovea or in the periphery.     

Electrophysiologic assessment of central auditory processing by auditory brainstem responses in children with autism spectrum disorders

In addition to aberrant features in the speech, children with Autism Spectrum Disorder (ASD) may present unusual responses to sensory stimuli, especially to auditory stimuli. We investigated the auditory ability of children with ASD by using Auditory Brainstem Responses (ABR) as they can directly judge both hearing status and the integrity of auditory brainstem pathways. One hundred twenty-one children (71: ASD; M 58/ F 13, mean age; 41.8 months, 50: control group; M 41/ F 9, mean age; 38 months) were included in the study. As compared with the values in the control group, the latency of wave V, wave I-V, and wave III-V inter-peak latencies were significantly prolonged (p<0.05) in the ASD group. The findings indicate that children with ASD have a dysfunction or immaturity of the central auditory nervous system. We suggest any children with prolonged III-V inter-peak latencies, especially high functioning children should be further evaluated for central auditory processing to set up a more appropriate treatment plan.     

Peripheral vision in persons with dyslexia

We compared persons with dyslexia and normal readers with respect to how well they identified letters and short strings of letters briefly presented in the peripheral visual field at the same time that a single letter was presented at the fixation point of gaze. We found that the dyslexic subjects had a markedly wider area in which correct identification occurred in the peripheral field than did the normal readers. However, the dyslexic subjects had a "masking" between letters in the foveal field and letters in the near periphery. It appears that dyslexic persons learn to read outside the foveal field and, more generally, that there are different learned strategies for task-directed vision. Among such strategies are different mutual interactions between foveal and peripheral vision.     

Recognition of dynamic facial expressions in peripheral and central vision

The present study investigated the effects of dynamic information on the recognition of emotional facial expressions across the visual field (i.e., central or peripheral vision). Facial stimuli with three pleasant expressions (excited, happy, and relaxed) and three unpleasant expressions (fearful, angry, and sad) were selected on the basis of valence and activation. The facial stimuli were presented dynamically or statically at either the central or peripheral visual field. Participants evaluated the emotional state of the target facial expression using a forced-choice task (N=34) and an Affect Grid (Russell, Weiss, & Mendelsohn, 1989) (N =39) requiring categorical and dimensional judgments about facial expressions. The results of the forced-choice task showed that only dynamic angry faces in peripheral vision had better recognition than the equivalent faces in the static condition. The results of the Affect Grid indicated that only the pleasant expressions presented in the peripheral field were significantly rated as more strongly pleasant. These findings suggest that an effect of dynamic information is more salient in peripheral vision than in central vision for recognizing certain facial expressions.     

Exploring Visual Perspective Taking and body awareness in children with Autism Spectrum Disorder

Introduction: Recent evidence suggests that impairments in social cognition are associated to the cognitive abilities needed to take several viewpoints in perceptual situations and body awareness. The aim of the current study was to investigate Visual Perspective Taking (VPT) and Body awareness performance in a group of children with Autism Spectrum Disorders (ASD) compared with a group of children with Intellectual Disability (ID) and typically developing (TD) children.

Methods: Our groups were administered an IQ test and a VPT task, and body awareness tests.

Results: Children with ASD or ID were more impaired in body awareness development compared to TD (p?p?Conclusions: The current study provides a framework for considering social impairments in autism on a broader scale, including visuoperceptual and body awareness difficulties as a core contributor to social interaction difficulties.     

基于Lasso特征选择的自闭症预测

目的寻找自闭症(autism spectrum disorders,ASD)的客观生物标记以辅助临床诊断。静息态功能连接(resting-state functional connectivity,RSFC)反映了大脑不同脑区神经活动模式间的时间相关性,研究者常从RSFC中探索识别ASD的生物标记,然而大部分方法还不能有效选出具有识别力的RSFC。本文采用最小绝对值收缩与选择算子(least absolute shrinkage and selection operator,Lasso)来选择ASD组和正常发育组之间具有显著性差异的RSFC特征。方法首先基于Pearson相关分析提取RSFC特征,并进行阈值化处理保留具有较大正相关值的RSFC。然后采用Lasso方法提取有识别能力的RSFC,最后利用支持向量机进行ASD分类,并主要以分类准确率指标对分类性能进行评估。结果基于Lasso方法进行特征选择后,ASD分类准确率为81.52%,同时找出了能显著区分ASD儿童与正常儿童的RSFC。结论基于Lasso特征选择的方法提高了对ASD的识别准确率,识别的生物标记有潜力应用于临床诊断。     

Audio–vocal system regulation in children with autism spectrum disorders

Do children with autism spectrum disorders (ASD) respond similarly to perturbations in auditory feedback as typically developing (TD) children? Presentation of pitch-shifted voice auditory feedback to vocalizing participants reveals a close coupling between the processing of auditory feedback and vocal motor control. This paradigm was used to test the hypothesis that abnormalities in the audio–vocal system would negatively impact ASD compensatory responses to perturbed auditory feedback. Voice fundamental frequency (F ₀) was measured while children produced an /a/ sound into a microphone. The voice signal was fed back to the subjects in real time through headphones. During production, the feedback was pitch shifted (?100 cents, 200 ms) at random intervals for 80 trials. Averaged voice F ₀ responses to pitch-shifted stimuli were calculated and correlated with both mental and language abilities as tested via standardized tests. A subset of children with ASD produced larger responses to perturbed auditory feedback than TD children, while the other children with ASD produced significantly lower response magnitudes. Furthermore, robust relationships between language ability, response magnitude and time of peak magnitude were identified. Because auditory feedback helps to stabilize voice F ₀ (a major acoustic cue of prosody) and individuals with ASD have problems with prosody, this study identified potential mechanisms of dysfunction in the audio–vocal system for voice pitch regulation in some children with ASD. Objectively quantifying this deficit may inform both the assessment of a subgroup of ASD children with prosody deficits, as well as remediation strategies that incorporate pitch training.     

Pictorial depth perception in central and peripheral visual fields

The present study aims to examine whether depth perception based on pictorial cues in the peripheral visual field is improved by compensating for the peripheral reduction of visual sensitivity. Figures that partially overlapped or had apparent transparency over a background figure were presented on a CRT monitor at the central-peripheral retinal regions of 2.5-10 degrees eccentricity under the two conditions of same size or size adjusted for the Cortical Magnification Scale (Virsu & Rovamo, 1979). In Experiment 1 the subjects could discriminate the depth relationship of two cortically magnified figures when these were presented within the retinal eccentricity of 10 degrees, even when solutions for the tasks were not dependent on a single visual attribute (brightness, shape). But discrimination in the peripheral visual field became difficult when the number of visual attributes of the stimuli increased (Experiment 2). We conclude that even for peripheral vision, depth perception based on pictorial cues is possible when cortically magnified stimuli are used. However, it should be further study whether or not the visual acuity is an only determinant for the difference between central and peripheral depth perception.     

How do children with autism spectrum disorder form gist memory during sleep? A study of slow oscillation–spindle coupling

Sleep is assumed to support memory through an active systems consolidation process that does not only strengthen newly encoded representations but also facilitates the formation of more abstract gist memories. Studies in humans and rodents indicate a key role of the precise temporal coupling of sleep slow oscillations (SO) and spindles in this process. The present study aimed at bolstering these findings in typically developing (TD) children, and at dissecting particularities in SO-spindle coupling underlying signs of enhanced gist memory formation during sleep found in a foregoing study in children with autism spectrum disorder (ASD) without intellectual impairment. Sleep data from 19 boys with ASD and 20 TD boys (9–12 years) were analyzed. Children performed a picture-recognition task and the Deese–Roediger–McDermott (DRM) task before nocturnal sleep (encoding) and in the next morning (retrieval). Sleep-dependent benefits for visual-recognition memory were comparable between groups but were greater for gist abstraction (recall of DRM critical lure words) in ASD than TD children. Both groups showed a closely comparable SO-spindle coupling, with fast spindle activity nesting in SO-upstates, suggesting that a key mechanism of memory processing during sleep is fully functioning already at childhood. Picture-recognition at retrieval after sleep was positively correlated to frontocortical SO-fast-spindle coupling in TD children, and less in ASD children. Critical lure recall did not correlate with SO-spindle coupling in TD children but showed a negative correlation (r = −.64, p = .003) with parietal SO-fast-spindle coupling in ASD children, suggesting other mechanisms specifically conveying gist abstraction, that may even compete with SO-spindle coupling.     

Lateralization patterns of verbal stimuli processing assessed by reaction time and event-related potentials in schizophrenic patients

Event-related potentials (ERPs), reaction time (RT), number of errors and number of omissions were recorded by using a visual target detection paradigm in which consonant pairs were presented in a central and in a lateral condition. Fourteen DSM III drug-free schizophrenics and 19 healthy subjects took part in the study. All of them were male and right-handed. Independent principal component analysis and varimax rotation were performed for each condition. Separate ANOVAs were performed on factor scores computed for each rotated principal component. In the central condition, schizophrenic patients showed a reduction of the late positive complex (LPC) peak with respect to normal controls, and this reduction was associated with a predominant negative symptomatology. No pattern of lateral asymmetry was found in either group for behavioural and ERP measures. For the lateral condition, a significant advantage of the right visual field (RVF) presentation (shorter RT and larger LPC peak for RVF stimuli) was observed in normal subjects, while no visual field effect on these two measures was detected in schizophrenics. Significant differences were found between the two groups on both behavioural and ERP measures for the RVF only. Furthermore, two ERP components showed a marked advantage of the left visual field in the patient group, associated with a predominance of positive symptoms in the clinical picture.     

Regional homogeneity of fMRI time series in autism spectrum disorders

Functional magnetic resonance imaging (fMRI) and functional connectivity MRI (fcMRI) studies of autism spectrum disorders (ASD) have suggested atypical patterns of activation and long-distance connectivity for diverse tasks and networks in ASD. We explored the regional homogeneity (ReHo) approach in ASD, which is analogous to conventional fcMRI, but focuses on local connectivity. FMRI data of 26 children with ASD and 29 typically developing (TD) children were acquired during continuous task performance (visual search). Effects of motion and task were removed and Kendall's coefficient of concordance (KCC) was computed, based on the correlation of the blood oxygen level dependent (BOLD) time series for each voxel and its six nearest neighbors. ReHo was lower in the ASD than the TD group in superior parietal and anterior prefrontal regions. Inverse effects of greater ReHo in the ASD group were detected in lateral and medial temporal regions, predominantly in the right hemisphere. Our findings suggest that ReHo is a sensitive measure for detecting cortical abnormalities in autism. However, impact of methodological factors (such as spatial resolution) on ReHo require further investigation.     

Pikachurin interaction with dystroglycan is diminished by defective O-mannosyl glycosylation in congenital muscular dystrophy models and rescued by LARGE overexpression

Visuo-tactile integration occurs in a privileged way in peripersonal space, namely when visual and tactile stimuli are in spatial proximity. Here, we investigated whether crossmodal spatial effects (i.e. stronger crossmodal interactions for spatially congruent compared to incongruent visual and tactile stimuli) are also present when visual stimuli presented near the body are indirectly viewed in a mirror, thus appearing in far space. Participants had to attend to one of their hands throughout a block of stimuli in order to detect infrequent tactile target stimuli at that hand while ignoring tactile targets at the unattended hand, all tactile non-target stimuli, and any visual stimuli. Visual stimuli were presented simultaneously with tactile stimuli, in the same (congruent) or opposite (incongruent) hemispace with respect to the tactile stimuli. In one group of participants the visual stimuli were delivered near the participants' hands and were observed as indirect mirror reflections ('mirror' condition), while in the other group these were presented at a distance from the hands ('far' condition). The main finding was that crossmodal spatial modulations of ERPs recorded over and close to somatosensory cortex were present in the 'mirror' condition but not the 'far' condition. That is, ERPs were enhanced in response to tactile stimuli coupled with spatially congruent versus incongruent visual stimuli when the latter were viewed through a mirror. These effects emerged around 190 ms after stimuli onset, and were modulated by the focus of spatial attention. These results provide evidence that visual stimuli observed in far space via a mirror are coded as near-the-body stimuli according to their known rather than to their perceived location. This suggests that crossmodal interactions between vision and touch may be modulated by previous knowledge of reflecting surfaces (i.e. top-down processing).     

Characterizing sleep in children with autism spectrum disorders: a multidimensional approach

STUDY OBJECTIVES: To relate parentally reported sleep concerns in autism spectrum disorders (ASD) to polysomnographic (PSG) findings and measures of daytime behavior and autism symptomatology. DESIGN: Cross-sectional study involving validated questionnaires, sleep histories and diaries, 2 nights of PSG, and the Autism Diagnostic Observation Schedule (ADOS). SETTING: Vanderbilt University General Clinical Research Center Sleep Core. PARTICIPANTS: 21 children with ASD and 10 typically developing (TD) children, aged 4-10 years. Children were free of psychotropic medications, with no history of mental retardation or epileptic seizures. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Children with ASD were defined as "good sleepers" (10 children) and "poor sleepers" (11 children) on the basis of parental report; the age-comparable TD children were all reported by their parents to be good sleepers. Poor sleepers with ASD showed prolonged sleep latency and decreased sleep efficiency on night 1 of PSG and differed on insomnia-related subscales of the Children's Sleep Habits Questionnaire (CSHQ; increased sleep onset delay and decreased sleep duration). The good sleepers with ASD did not differ from the TD children in sleep architecture or on CSHQ domains. As compared with ASD good sleepers, the ASD poor sleepers also had higher scores related to affective problems on the Child Behavior Checklist and more problems with reciprocal social interaction on the ADOS. CONCLUSIONS: Parentally reported sleep concerns of insomnia in children with ASD are substantiated by validated sleep questionnaires and by PSG. Furthermore, good sleepers with ASD showed fewer affective problems and better social interactions than ASD poor sleepers.