Chieko Kanai

Alterations of local spontaneous brain activity and connectivity in adults with high-functioning autism spectrum disorder

BackgroundPrevious autism research has hypothesized that abnormalities of functional connectivity in autism spectrum disorder (ASD) may vary with the spatial distance between two brain regions. Although several resting-state functional magnetic resonance imaging (rsfMRI) studies have extensively examined long-range (or distant) connectivity in the adult ASD brain, short-range (or local) connectivity has been investigated in less depth. Furthermore, the possible relationship between functional connectivity and brain activity level during the resting state remains unclear.MethodsWe acquired rsfMRI data from 50 adults with high-functioning ASD and 50 matched controls to examine the properties of spontaneous brain activity using measures of local and distant connectivity together with a measure of the amplitude of brain activity, known as fractional amplitude of low-frequency fluctuation (fALFF). The two connectivity measures were calculated using a common graph-theoretic framework. We also examined the spatial overlaps between these measures and possible relationships of these disrupted functional measures with autistic traits assessed by the Autism-Spectrum Quotient (AQ).ResultsCompared to the controls, participants with ASD exhibited local over-connectivity in the right superior frontal gyrus and middle frontal gyrus, accompanied by local under-connectivity in the bilateral fusiform gyri (FG) and right middle temporal gyrus (MTG). On the other hand, we did not find any significant alterations in distant connectivity. Participants with ASD also exhibited reduced fALFF in the right middle occipital gyrus, lingual gyrus, and FG. Further conjunction and spatial overlap analyses confirmed that the spatial pattern of reduced fALFF substantially overlapped with that of local under-connectivity, demonstrating the co-occurrence of disrupted connectivity and spontaneous activity level in the right inferior occipital gyrus, posterior MTG (pMTG), and FG. Finally, within the ASD group, disrupted local connectivity in the right pMTG significantly correlated with the “social interaction” subscale score of the AQ.ConclusionsThese findings revealed local functional disruptions in the occipital and temporal regions, especially the right FG and pMTG, in the form of co-occurrence of spontaneous brain activity level and local connectivity, which may underline social and communicative dysfunctions in adult ASD.

Recognition of Facial Expressions and Prosodic Cues with Graded Emotional Intensities in Adults with Asperger Syndrome.

This study investigated the ability of adults with Asperger syndrome to recognize emotional categories of facial expressions and emotional prosodies with graded emotional intensities. The individuals with Asperger syndrome showed poorer recognition performance for angry and sad expressions from both facial and vocal information. The group difference in facial expression recognition was prominent for stimuli with low or intermediate emotional intensities. In contrast to this, the individuals with Asperger syndrome exhibited lower recognition accuracy than typically-developed controls mainly for emotional prosody with high emotional intensity. In facial expression recognition, Asperger and control groups showed an inversion effect for all categories. The magnitude of this effect was less in the Asperger group for angry and sad expressions, presumably attributable to reduced recruitment of the configural mode of face processing. The individuals with Asperger syndrome outperformed the control participants in recognizing inverted sad expressions, indicating enhanced processing of local facial information representing sad emotion. These results suggest that the adults with Asperger syndrome rely on modality-specific strategies in emotion recognition from facial expression and prosodic information.

An fMRI study of reduced perceptual load-dependent modulation of task-irrelevant activity in adults with autism spectrum conditions.

Recent studies on selective attention have demonstrated that the perceptual load of a task determines the processing stage at which irrelevant sensory stimuli are filtered out. Although individuals with autism spectrum conditions (ASC) have been repeatedly reported to display several kinds of abnormal behavior related to attention deficits, the neural mechanisms underlying these deficits have not been well investigated within the framework of the load dependency of selective attention. The present study used functional magnetic resonance imaging (fMRI) to examine the brain responses of adults with high-functioning ASC to irrelevant visual distractors while performing a visual target detection task under high or low perceptual load. We observed that the increased perceptual load activated regions of the fronto-parietal attention network of controls and ASC comparably. On the other hand, the visual cortex activity evoked by visual distractors was less modulated by the increased perceptual load in ASC than in controls. Simple regression analyses showed that the degree of the modulation was significantly correlated with the severity of the autistic symptoms. We also observed reduced load-dependent modulation of the functional connectivity between the intraparietal and visual regions in the ASC group. These results revealed neural correlates for abnormal perceptual load-dependent engagement of visual attention in ASC, which may underlie aspects of cognitive and behavioral characteristics of these disorders.

Functional alterations in neural substrates of geometric reasoning in adults with high-functioning autism.

Individuals with autism spectrum condition (ASC) are known to excel in some perceptual cognitive tasks, but such developed functions have been often regarded as “islets of abilities” that do not significantly contribute to broader intellectual capacities. However, recent behavioral studies have reported that individuals with ASC have advantages for performing Ravens (Standard) Progressive Matrices (RPM/RSPM), a standard neuropsychological test for general fluid intelligence, raising the possibility that ASC′s cognitive strength can be utilized for more general purposes like novel problem solving. Here, the brain activity of 25 adults with high-functioning ASC and 26 matched normal controls (NC) was measured using functional magnetic resonance imaging (fMRI) to examine neural substrates of geometric reasoning during the engagement of a modified version of the RSPM test. Among the frontal and parietal brain regions involved in fluid intelligence, ASC showed larger activation in the left lateral occipitotemporal cortex (LOTC) during an analytic condition with moderate difficulty than NC. Activation in the left LOTC and ventrolateral prefrontal cortex (VLPFC) increased with task difficulty in NC, whereas such modulation of activity was absent in ASC. Furthermore, functional connectivity analysis revealed a significant reduction of activation coupling between the left inferior parietal cortex and the right anterior prefrontal cortex during both figural and analytic conditions in ASC. These results indicate altered pattern of functional specialization and integration in the neural system for geometric reasoning in ASC, which may explain its atypical cognitive pattern, including performance on the Ravens Matrices test.

Altered functional organization within the insular cortex in adult males with high-functioning autism spectrum disorder: evidence from connectivity-based parcellation

BackgroundThe insular cortex comprises multiple functionally differentiated sub-regions, each of which has different patterns of connectivity with other brain regions. Such diverse connectivity patterns are thought to underlie a wide range of insular functions, including cognitive, affective, and sensorimotor processing, many of which are abnormal in autism spectrum disorder (ASD). Although past neuroimaging studies of ASD have shown structural and functional abnormalities in the insula, possible alterations in the sub-regional organization of the insula and the functional characteristics of each sub-region have not been examined in the ASD brain.MethodsResting-state functional magnetic resonance imaging (rs-fMRI) data were acquired from 36 adult males with ASD and 38 matched typically developed (TD) controls. A data-driven clustering analysis was applied to rs-fMRI data of voxels in the left and right insula to automatically group voxels with similar intrinsic connectivity pattern into a cluster. After determining the optimal number of clusters based on information theoretic measures of variation of information and mutual information, functional parcellation patterns in both the left and the right insula were compared between the TD and ASD groups. Furthermore, functional profiles of each sub-region were meta-analytically decoded using Neurosynth and were compared between the groups.ResultsWe observed notable alterations in the anterior sector of the left insula and the middle ventral sub-region of the right insula in the ASD brain. Meta-analytic decoding revealed that whereas the anterior sector of the left insula contained two functionally differentiated sub-regions for cognitive, sensorimotor, and emotional/affective functions in TD brain, only a single functional cluster for cognitive and sensorimotor functions was identified in the anterior sector in the ASD brain. In the right insula, the middle ventral sub-region, which is primarily specialized for sensory- and auditory-related functions, showed a significant volumetric increase in the ASD brain compared with the TD brain.ConclusionsThe results indicate an altered organization of sub-regions in specific parts of the left and right insula of the ASD brain. The alterations in the left and right insula may constitute neural substrates underlying abnormalities in emotional/affective and sensory functions in ASD.

Ocular Fixation Abnormality in Patients with Autism Spectrum Disorder.

We examined the factors that influence ocular fixation control in adults with autism spectrum disorder (ASD) including sensory information, individuals’ motor characteristics, and inhibitory control. The ASD group showed difficulty in maintaining fixation especially when there was no fixation target. The fixational eye movement characteristics of individuals were consistent regardless of the presence or absence of a fixation target in the controls, but not in the ASD group. Additionally, fixation stability did not correlate with an ability to suppress reflexive saccades measured by an antisaccade task. These findings suggest that ASD adults have deficits in converting alternative sensory information, such as retinal signals in the peripheral visual field or extraretinal signals, to motor commands when the foveal information is unavailable.

Attitudes toward risk and ambiguity in patients with autism spectrum disorder

Although the ability to make optimal decisions under uncertainty is an integral part of everyday life, individuals with autism spectrum disorder (ASD) frequently report that they experience difficulties with this skill. In behavioral economics, researchers distinguish two types of uncertainty to understand decision-making in this setting: risk (known probabilities) and ambiguity (unknown probabilities). However, it remains unclear how individuals with ASD behave under risk and ambiguity, despite growing evidence of their altered decision-making under uncertainty. We therefore extended previous research by studying the attitudes of those with ASD toward risk and ambiguity in both positive and negative contexts (i.e., gain and loss). In gain contexts, no significant difference was observed between the groups in risk attitudes, but ambiguity aversion was attenuated in ASD. In loss contexts, ambiguity attitudes did not significantly differ between the groups, but the ASD participants were less risk-seeking compared with the controls. In addition, insensitivity to the context change under risk and ambiguity in ASD was both significantly associated with poor social skills. These results improve our understanding of altered decision-making under uncertainty by disentangling the attitudes toward risk and ambiguity in ASD individuals. Applying behavioral economic tools may provide insights into the mechanisms underlying behavioral disturbances in ASD.

Clinical and psychosocial characteristics in adults with pervasive development disorders: a survey in Japan

Abstract Background: In spite of the relatively high prevalence of pervasive development disorders (PDD), the medical and educational services for persons with PDD are insufficient in Japan. The present study investigated the clinical and psychosocial characteristics of adults with PDD in Japan. Methods: We selected 111 individuals with PDD out of the 257 subjects attending an outpatient clinic for adult PDD at Showa University Karasuyama Hospital, between the period of July 2008 and June of 2009. Sociodemographic factors, psychosocial characteristics, and medication status of the subjects were investigated. Results: The mean age of subjects at the initial visit to a medical organization was 21.4 years; however, only 34.2% were diagnosed as having PDD. These results indicated that persons with PDD are apt to be misdiagnosed. Most of the persons with PDD were unmarried, and lived with their parents. This may be partly due to economic reasons, because the unemployment rate was high in this group. More than 45% of the subjects with PDD were taking psychoactive medications, which indicated that they carried a high-risk for co-existing mental health problems. Conclusions: The results of the present study indicated that many persons with PDD are socially isolated, in spite of their relatively high level of education, and that these individuals require additional medical and educational services.

Inflexible daily behaviour is associated with the ability to control an automatic reaction in autism spectrum disorder

Inflexible behaviours in people with autism spectrum disorder (ASD) broadly obstruct social communication. Meanwhile, flexibility implicates cognitive control to resolve socially conflicting situations; however, it remains unclear how people with ASD behave in the face of these conflicts in this respect. We used the ultimatum game (UG) and the implicit-association test (IAT) to examine goal-directed/economic flexibility, both of which involve conflict and cognitive control. In addition, we used the Detail and Flexibility Questionnaire (DFlex) to measure inflexible everyday behaviour with diminished cognitive control and attention shifting. We observed the decreased flexibility in participants with ASD (DFlex and IAT); further, their IAT scores positively correlated with DFlex. However, in the UG, contrary to our prediction, participants with ASD accepted unfair offers more frequently than TD. These results suggest that assessing the automatic/attention processing level with the IAT could be a useful approach to study behavioural flexibility among ASD compared with the UG, which might comprise multiple response strategies besides economic rationality. Overall, the severity of inflexible daily behaviours in people with ASD may be associated with a reduced flexible attitude at an automatic level, altered attention processing and decreased cognitive control.

Social Skills in Autism Spectrum Disorders

Autism spectrum disorders children with (ASD), having core problems associated with social deficits, have recently attracted significant attention because the number of ASD is increasing in these days. Clarifying the difference between ASD and typically developing (TD) children in earlier developmental stages is difficult. The core difficulties of ASD are mainly manifest in social interaction and social skills development, verbal and nonverbal communication, and behavioral issues (e.g., stereotyped behaviors). Studies show that social skills development strongly involves learning to execute complex movements. One part of this chapter emphasizes the importance of sensory and motor development and their role to enhance social skills development in individuals with ASD. The more physical (motor learning and motor skills) and social interaction is used during the early years of development, the more fundamental social skills (e.g., eye gaze, joint attention, imitation, gestures, etc.) can be developed and encouraged.