Movement preparation in high-functioning autism and Asperger disorder: a serial choice reaction time task involving motor reprogramming

Using computerized games to teach face recognition skills to children with autism spectrum disorder: the Let's Face It! program

BACKGROUND

An emerging body of evidence indicates that relative to typically developing children, children with autism are selectively impaired in their ability to recognize facial identity. A critical question is whether face recognition skills can be enhanced through a direct training intervention.

METHODS

In a randomized clinical trial, children diagnosed with autism spectrum disorder were pre-screened with a battery of subtests (the Let's Face It! Skills battery) examining face and object processing abilities. Participants who were significantly impaired in their face processing abilities were assigned to either a treatment or a waitlist group. Children in the treatment group (N = 42) received 20 hours of face training with the Let's Face It! (LFI!) computer-based intervention. The LFI! program is comprised of seven interactive computer games that target the specific face impairments associated with autism, including the recognition of identity across image changes in expression, viewpoint and features, analytic and holistic face processing strategies and attention to information in the eye region. Time 1 and Time 2 performance for the treatment and waitlist groups was assessed with the Let's Face It! Skills battery.

RESULTS

The main finding was that relative to the control group (N = 37), children in the face training group demonstrated reliable improvements in their analytic recognition of mouth features and holistic recognition of a face based on its eyes features.

CONCLUSION

These results indicate that a relatively short-term intervention program can produce measurable improvements in the face recognition skills of children with autism. As a treatment for face processing deficits, the Let's Face It! program has advantages of being cost-free, adaptable to the specific learning needs of the individual child and suitable for home and school applications.

A preliminary transcranial magnetic stimulation study of cortical inhibition and excitability in high-functioning autism and Asperger disorder

AIM

Controversy surrounds the distinction between high-functioning autism (HFA) and Asperger disorder, but motor abnormalities are associated features of both conditions. This study examined motor cortical inhibition and excitability in HFA and Asperger disorder using transcranial magnetic stimulation (TMS).

METHOD

Participants were diagnosed by experienced clinicians strictly according to DSM-IV criteria. Participants with HFA (nine males, two females; mean age 16y 8mo, SD 4y 5mo) or Asperger disorder (11 males, three females; mean age 19y 1mo, SD 4y 2mo) and neurotypical participants (eight males, three females; mean age 19y 0mo, SD 3y 1mo) were administered a paired-pulse TMS paradigm intended to assess motor cortical inhibition and excitability. Responses to TMS were recorded by electromyography.

RESULTS

Cortical inhibition was significantly reduced in the HFA group compared with both the Asperger disorder (p<0.001) and neurotypical (p<0.001) groups, suggesting disruption of activity at gamma-aminobutyric acid A (GABA(A)) receptors. There was no group difference in cortical excitability.

INTERPRETATION

Cortical inhibition deficits may underlie motor dysfunction in autism, and perhaps even relate to specific clinical symptoms (e.g. repetitive behaviours). These findings provide novel evidence for a possible neurobiological dissociation between HFA and Asperger disorder based on GABAergic function.

Motor response programming and movement time in children with heavy prenatal alcohol exposure

The present experiment assessed motor response programming and movement time in children with histories of heavy prenatal alcohol exposure (PEA). Alcohol-exposed children between the ages of 7 and 17 years were classified into two groups: Fetal Alcohol Syndrome (FAS: n=9) and children with PEA (PEA: n=19) but who did not have the defining characteristics of FAS. The FAS and PEA children were compared with non-alcohol-exposed children (NC: n=23) when completing two tasks: a simple reaction time task (RT alone condition) and a reaction plus movement task (RT+Move condition). The movement involved responding to an imperative stimulus signal and depressing three target buttons in a set sequence. Participants completed 24 trials each for the RT alone and RT+Move response conditions. Results indicated no significant differences in performance among FAS, PEA, and NC groups during the RT alone condition. However, during the RT+Move condition, the FAS group produced significantly longer and more variable RTs than the PEA and NC groups, which produced comparable RTs. The FAS group also produced significantly slower movement times when moving to all three targets, whereas movement time variability did not significantly differ as a function of group. The observed results indicate children with FAS experience deficits in response programming and movement time production.

Vision in developmental disorders: is there a dorsal stream deficit?

The main aim of this review is to evaluate the proposal that several developmental disorders affecting vision share an impairment of the dorsal visual stream. First, the current definitions and common measurement approaches used to assess differences in both local and global functioning within the visual system are considered. Next, studies assessing local and global processing in the dorsal and ventral visual pathways are reviewed for five developmental conditions for which early to mid level visual abilities have been assessed: developmental dyslexia, autism spectrum disorders, developmental dyspraxia, Williams syndrome and Fragile X syndrome. The reviewed evidence is broadly consistent with the idea that the dorsal visual stream is affected in developmental disorders. However, the potential for a unique profile of visual abilities that distinguish some of the conditions is posited, given that for some of these disorders ventral stream deficits have also been found. We conclude with ideas regarding future directions for the study of visual perception in children with developmental disorders using psychophysical measures.

Begleitsymptomatik bei tief greifenden Entwicklungsstörungen

Fragestellung: Kinder und Jugendliche mit tief greifenden Entwicklungsstörungen zeigen neben der Kernsymptomatik eine Vielzahl assoziierter Erkrankungen i. S. von genetischen Syndromen oder neurologischen Erkrankungen, die für die Behandlung und den Verlauf der Störung von Bedeutung sind. In der vorliegenden Arbeit wird die Art und Häufigkeit dieser somatischen Begleiterscheinungen in Relation zur Intelligenz der Patienten analysiert. Methodik: Die Stichprobe besteht aus 601 Patienten, bei denen zwischen 1997 und 2007 in der Abteilung für Entwicklungsstörungen des Heckscher-Klinikums die Diagnose einer tief greifenden Entwicklungsstörung gestellt wurde. Neben genetischen Syndromen wurden auch neurologische Störungen erfasst. Ergebnisse: 373 (62 %) der Patienten hatten eine, 121 (20 %) zwei Diagnosen auf der Achse IV des multiaxialen Klassifikationsschemas. Genetische Störungen wurden bei insgesamt 6 % (N = 37) der Stichprobe festgestellt. Die häufigsten neurologischen Diagnosen waren Bewegungsstörungen (N = 214; 35.6 %) und Epilepsien (N = 98; 16.3 %). Patienten mit einer Intelligenzminderung zeigen häufiger somatische Begleiterscheinungen als Patienten ohne Intelligenzminderung. Schlussfolgerungen: Tief greifende Entwicklungsstörungen sind komplexe Störungsbilder, die überzufällig häufig einhergehen mit neurologischen Störungen und einem breiten Spektrum an genetischen Syndromen. Kinder mit autistischen Störungen und einer Intelligenzminderung zeigen mehr Begleiterkrankungen und sind in der psychosozialen Anpassung deutlicher beeinträchtigt als Kinder mit autistischen Störungen ohne Intelligenzminderung.

Divided attention capacity in adults with autism spectrum disorders and without intellectual disability

Earlier research showed that divided attention, an aspect of executive function, is limited in both children and adults with autism spectrum disorders (ASDs). The current study explored divided attention capacity in adults with ASD and without intellectual disability (n = 36). Divided attention was tested using a computerized variant of a well-known memory recognition test, with two levels of cognitive load. The effect of cognitive load on reaction time performance is considered to be inversely proportional to divided attention capacity. The study failed to provide a relationship between divided attention and ASD, contrary to earlier research. Findings indicated that only the adults with ASD who used medication had a divided attention deficit, and that this group had specific difficulty reaching a binary decision in a memory search task. An additional finding was that the participants with ASD were overall slow. Possible causes and implications of these findings are discussed.

Movement planning and reprogramming in individuals with autism

Two experiments explored how individuals with and without autism plan and reprogram movements. Participants were given partial or complete information regarding the location of the upcoming manual movement. In Experiment 1, direct information specified the hand or direction of the upcoming movement. These results replicated previous reports that participants with autism utilize advance information to prepare their movements in the same manner as their chronologically age matched peers. Experiment 2 examined how individuals respond to an unexpected change in the movement requirements. Participants received advance information about the hand and direction of the upcoming movement. On 20% of the trials participants needed to adjust either the hand or direction they had prepared. Overall, the individuals with autism had difficulty reprogramming already planned movements, particularly if a different effector was required.

Impairment in movement skills of children with autistic spectrum disorders

AIM

We undertook this study to explore the degree of impairment in movement skills in children with autistic spectrum disorders (ASD) and a wide IQ range.

METHOD

Movement skills were measured using the Movement Assessment Battery for Children (M-ABC) in a large, well defined, population-derived group of children (n=101: 89 males,12 females; mean age 11y 4mo, SD 10mo; range 10y-14y 3mo) with childhood autism and broader ASD and a wide range of IQ scores. Additionally, we tested whether a parent-completed questionnaire, the Developmental Coordination Disorder Questionnaire (DCDQ), was useful in identifying children who met criteria for movement impairments after assessment (n=97 with complete M-ABCs and DCDQs).

RESULTS

Of the children with ASD, 79% had definite movement impairments on the M-ABC; a further 10% had borderline problems. Children with childhood autism were more impaired than children with broader ASD, and children with an IQ less than 70 were more impaired than those with IQ more than 70. This is consistent with the view that movement impairments may arise from a more severe neurological impairment that also contributes to intellectual disability and more severe autism. Movement impairment was not associated with everyday adaptive behaviour once the effect of IQ was controlled for. The DCDQ performed moderately well as a screen for possible motor difficulties.

INTERPRETATION

Movement impairments are common in children with ASD. Systematic assessment of movement abilities should be considered a routine investigation.

A pilot study: coordination of precision grip in children and adolescents with high functioning autism

PURPOSE

This pilot study compared temporal coordination during a precision grip task between 13 children and adolescents with autism spectrum disorders (ASD) who were high functioning and 13 peers with typical development.

METHODS

Temporal coordination between grip and load forces was measured using latency between onset of grip and load forces, grip force at onset of load force, peak grip force (PGF), and time to PGF.

RESULTS

Compared with peers with typical development, participants with ASD demonstrated prolonged latency between grip and load forces, elevated grip force at onset of load force, and increased movement variability. PGF and time to PGF were not significantly different between the 2 groups.

CONCLUSIONS

These findings indicate temporal dyscoordination in participants with ASD. The findings also enhance our understanding of motor coordination deficits in persons with ASD and have theoretical as well as clinical implications.

Functional brain organization for visual search in ASD

Although previous studies have shown that individuals with autism spectrum disorder (ASD) excel at visual search, underlying neural mechanisms remain unknown. This study investigated the neurofunctional correlates of visual search in children with ASD and matched typically developing (TD) children, using an event-related functional magnetic resonance imaging design. We used a visual search paradigm, manipulating search difficulty by varying set size (6, 12, or 24 items), distractor composition (heterogeneous or homogeneous) and target presence to identify brain regions associated with efficient and inefficient search. While the ASD group did not evidence accelerated response time (RT) compared with the TD group, they did demonstrate increased search efficiency, as measured by RT by set size slopes. Activation patterns also showed differences between ASD group, which recruited a network including frontal, parietal, and occipital cortices, and the TD group, which showed less extensive activation mostly limited to occipito-temporal regions. Direct comparisons (for both homogeneous and heterogeneous search conditions) revealed greater activation in occipital and frontoparietal regions in ASD than in TD participants. These results suggest that search efficiency in ASD may be related to enhanced discrimination (reflected in occipital activation) and increased top-down modulation of visual attention (associated with frontoparietal activation).

Patterns of visual sensory and sensorimotor abnormalities in autism vary in relation to history of early language delay

Visual motion perception and pursuit eye movement deficits have been reported in autism. However, it is unclear whether these impairments are related to each other or to clinical symptoms of the disorder. High-functioning individuals with autism (41 with and 36 without delayed language acquisition) and 46 control subjects participated in the present study. All three subject groups were matched on chronological age and Full-Scale IQ. The autism group with delayed language acquisition had bilateral impairments on visual motion discrimination tasks, whereas the autism group without delay showed marginal impairments only in the left hemifield. Both autism groups showed difficulty tracking visual targets, but only the autism group without delayed language acquisition showed increased pursuit latencies and a failure to show the typical rightward directional advantage in pursuit. We observed correlations between performance on the visual perception and pursuit tasks in both autism groups. However, pursuit performance was correlated with manual motor skills only in the autism group with delayed language, suggesting that general sensorimotor or motor disturbances are a significant additional factor related to pursuit deficits in this subgroup. These findings suggest that there may be distinct neurocognitive phenotypes in autism associated with patterns of early language development.

Acquisition of internal models of motor tasks in children with autism

Children with autism exhibit a host of motor disorders including poor coordination, poor tool use and delayed learning of complex motor skills like riding a tricycle. Theory suggests that one of the crucial steps in motor learning is the ability to form internal models: to predict the sensory consequences of motor commands and learn from errors to improve performance on the next attempt. The cerebellum appears to be an important site for acquisition of internal models, and indeed the development of the cerebellum is abnormal in autism. Here, we examined autistic children on a range of tasks that required a change in the motor output in response to a change in the environment. We first considered a prism adaptation task in which the visual map of the environment was shifted. The children were asked to throw balls to visual targets with and without the prism goggles. We next considered a reaching task that required moving the handle of a novel tool (a robotic arm). The tool either imposed forces on the hand or displaced the cursor associated with the handle position. In all tasks, the children with autism adapted their motor output by forming a predictive internal model, as exhibited through after-effects. Surprisingly, the rates of acquisition and washout were indistinguishable from normally developing children. Therefore, the mechanisms of acquisition and adaptation of internal models in self-generated movements appeared normal in autism. Sparing of adaptation suggests that alternative mechanisms contribute to impaired motor skill development in autism. Furthermore, the findings may have therapeutic implications, highlighting a reliable mechanism by which children with autism can most effectively alter their behaviour.

Childhood and current autistic features in adolescents with schizotypal personality disorder

The diagnostic boundaries between autistic- and schizophrenia-spectrum disorders have varied over the years, and some overlap in diagnostic criteria persists. The present study examined childhood and current signs of autistic disorder (AD) in adolescents with schizotypal personality disorder (SPD) or other personality disorders, as well as healthy controls. A structured interview was administered to rate participants' current symptoms. Participants' guardians were interviewed with the Autism Diagnostic Inventory-Revised (ADI-R), a clinical assessment of childhood and current autistic signs. Compared to both the other personality-disordered and healthy groups, adolescents with SPD were rated as having significantly more impairment on childhood and current social functioning, and having more unusual interests and behaviors. For the entire sample, impaired childhood social functioning and unusual interests and behaviors were associated with higher negative symptom scores. Current impairments in social functioning, unusual interests and behaviors, and communication were also linked with greater negative symptoms. However, neither childhood nor current autistic features significantly predicted later conversion to an Axis I psychotic disorder over the course of three years of follow-up. The findings indicate that past and current autistic signs are more common in adolescents with SPD, but neither current nor childhood autistic features are linked with conversion to psychosis.

Towards development of biomechatronic tools for early diagnosis of neurodevelopmental disorders

This paper introduces Neurodevelopmental Engineering, a new interdisciplinary research area at the intersection of developmental neuroscience and bioengineering. Specifically, it presents current results of the design and development process of a set of instrumented toys equipped with a variety of sensors for behavioral analysis of infants in minimally structured environmental conditions. First the multidisciplinary design approach is presented, then the detailed functional and technical specifications of the proposed biomechatronic toys and of their scenarios of use are described. Finally, a clear picture of ongoing implementation of the proposed technology is provided together with preliminary results of verification tests.

A novel technological approach towards the early diagnosis of neurodevelopmental disorders

In this work, a novel technological approach to the early diagnosis of neuro-developmental disorders is presented. Disorders such as Autism are typically diagnosed after language development, i.e. after the 2-3 years of age. In this paper, three different typologies of instruments are presented which are designed to assess infants behavior in different perceptual and motor domains. The first is an instrumented toy embedding kinematic and force sensors for studying grasping and manipulation in infants as young as 6 months old. The second is a wearable device for sensing the kinematics of the upper and lower limbs of infants, designed to assess spontaneous movements in premature babies. The third is a multimodal audio-visuo-vestibular cap which was designed to assess infants orienting behaviors in social situations in response to audio and visual stimuli.

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.

Atypical involvement of frontostriatal systems during sensorimotor control in autism

Autism is a neurodevelopmental disorder involving dysmaturation of widely distributed brain systems. Accordingly, behaviors that depend on distributed systems, such as higher level cognition and sensorimotor control, are compromised in the disorder. The current study investigated alterations in neural systems underlying sensorimotor disturbances in autism. An fMRI investigation was conducted using saccadic and pursuit eye movement paradigms with 13 high functioning individuals with autism and 14 age- and IQ-matched typically developing individuals. Individuals with autism had reduced activation in cortical eye fields and cerebellar hemispheres during both eye movement tasks. When executing visually guided saccades, individuals with autism had greater activation bilaterally in a frontostriatal circuit including dorsolateral prefrontal cortex, caudate nucleus, medial thalamus, anterior and posterior cingulate cortex, and right dentate nucleus. The increased activation in prefrontal-striatal-thalamocortical circuitry during visually guided saccades indicates that systems typically dedicated to cognitive control may need to compensate for disturbances in lower-level sensorimotor systems. Reduced activation throughout visual sensorimotor systems may contribute to saccadic and pursuit disturbances that have been reported in autism. These findings document that neurodevelopmental disturbances in autism affect widely distributed brain systems beyond those mediating language and social cognition.

Movement interference in autism-spectrum disorder

Movement interference occurs when concurrently observing and executing incompatible actions and is believed to be due to co-activation of conflicting populations of mirror neurons. It has also been suggested that mirror neurons contribute towards the imitation of observed actions. However, the exact neural substrate of imitation may depend on task demands: a processing route for goal-directed meaningful actions may be distinct from one for non-goal-directed actions. A more controversial role proposed for these neurons is in theory of mind processing, along with the subsequent suggestion that impairment in the mirror neuron circuit can contribute to autism-spectrum disorder (ASD) where individuals have theory of mind deficits. We have therefore examined movement interference in nine ASD participants and nine matched controls while performing actions congruent and incongruent with observed meaningless arm movements. We hypothesised that if the mirror neuron system was impaired, reduced interference should be observed in the ASD group. However, control and ASD participants demonstrated an equivalent interference effect in an interpersonal condition, with greater movement variability in the incongruent compared to the congruent condition. A component of movement interference which is independent of congruency did differ between groups: ASD participants made generally more variable movements for the interpersonal task than for biological dot-motion task, while the reverse was true for the control participants. We interpret these results as evidence that the ASD participant group either rely to a greater extent on the goal-directed imitation pathway, supporting claims that they have a specific deficit of the non-goal-directed imitation pathway, or exhibit reduced visuomotor integration.

A neurobehavioral examination of individuals with high-functioning autism and Asperger's disorder using a fronto-striatal model of dysfunction

The repetitive, stereotyped, and obsessive behaviors that characterize autism may in part be attributable to disruption of the region of the fronto-striatal system, which mediates executive abilities. Neuropsychological testing has shown that children with autism exhibit set-shifting deficiencies on tests such as the Wisconsin Card Sorting task but show normal inhibitory ability on variants of the Stroop color-word test. According to Minshew and Goldstein's multiple primary deficit theory, the complexity of the executive functioning task is important in determining the performance of individuals with autism. This study employed a visual-spatial task (with a Stroop-type component) to examine the integrity of executive functioning, in particular inhibition, in autism (n = 12) and Asperger's disorder (n = 12) under increasing levels of cognitive complexity. Whereas the Asperger's disorder group performed similarly to age- and IQ-matched control participants, even at the higher levels of cognitive complexity, the high-functioning autism group displayed inhibitory deficits specifically associated with increasing cognitive load.

Quantitative assessment of neuromotor function in adolescents with high functioning autism and Asperger Syndrome

BACKGROUND

Motor impairment in children with Asperger Syndrome (AS) or High functioning autism (HFA) has been reported previously. This study presents results of a quantitative assessment of neuromotor skills in 14-22 year old HFA/AS.

METHODS

16 HFA/AS and 16 IQ-matched controls were assessed by the Zurich Neuromotor Assessment (ZNA).

RESULTS

The HFA/AS group showed strongest impairments of dynamic balance skills and diadochokinesis. Motor abilities were associated with degree of social withdrawal in the full sample and severity of current autistic symptoms in the HFA/AS group.

CONCLUSION

Similar motor patterns as in younger children were found in the older adolescents. The association of autistic symptoms with motor performance points towards an essential role of motor impairment in autism spectrum disorders.

Decreased GAD67 mRNA levels in cerebellar Purkinje cells in autism: pathophysiological implications

The recent identification of decreased protein levels of glutamate decarboxylase (GAD) 65 and 67 isoforms in the autistic cerebellar tissue raises the possibility that abnormal regulation of GABA production in individual neurons may contribute to the clinical features of autism. Reductions in Purkinje cell number have been widely reported in autism. It is not known whether the GAD changes also occur in Purkinje cells at the level of transcription. Using a novel approach, the present study quantified GAD67 mRNA, the most abundant isoform in Purkinje cells, using in situ hybridization in adult autistic and control cases. The results indicate that GAD67 mRNA level was reduced by 40% in the autistic group (P < 0.0001; two-tailed t test), suggesting that reduced Purkinje cell GABA input to the cerebellar nuclei potentially disrupts cerebellar output to higher association cortices affecting motor and/or cognitive function. These findings may also contribute to the understanding of previous reports of alterations in the GABAergic system in limbic and cerebro-cortical areas contributing to a more widespread pathophysiology in autistic brains.

Temporal judgements of internal and external events in persons with and without autism

When participants make judgments about the onset of self-initiated movements they typically report the movement occurred earlier than it had [Obhi, S. S., & Haggard, P. (2004). Free will and free won't. American Scientific, 92, 358-365.]. One interpretation is that feed-forward processes lead to awareness of the movement prior to execution. Because individuals with autism experience reduced preparatory activity prior to a voluntary movement, the present study sought to determine whether these anticipatory biases are exhibited by persons with autism. Participants watched a dot move in a circle and pressed the spacebar any time after one revolution. A tone either followed the participants' voluntary movement or was computer generated. Participants in both groups made anticipatory judgements regarding movement initiation ( approximately 100 ms). When the movement and tone occurred together this anticipatory bias was also present, regardless of which event participants focused on. Individuals with autism appear to have access to a similar representation of voluntary movements, however this representation may be more variable.

How do Individuals with Autism Plan Their Movements?

Two experiments investigated how persons with and without autism plan manual aiming movements when advance information is direct and when strategic planning is required. In Experiment 1 advance information about hand, direction, and/or movement amplitude was manipulated. Reaction times suggested both groups adopted a hierarchical pattern of movement planning. In Experiment 2, participants performed aiming movements to one of two targets that were the same or different size. Participants without autism varied the starting location in anticipation of specific target stimuli whereas participants with autism consistently selected the midpoint. Overall, individuals with autism used advance information to plan their movements when this information was direct. However, their performance became stereotyped when strategies were self-generated.

An examination of movement kinematics in young people with high-functioning autism and Asperger's disorder: further evidence for a motor planning deficit

This paper examines upper-body movement kinematics in individuals with high-functioning autism (HFA) and Asperger's disorder (AD). In general, the results indicate that HFA is more consistently associated with impaired motoric preparation/initiation than AD. The data further suggest that this quantitative difference in motor impairment is not necessarily underpinned by greater executive dysfunction vulnerability in autism relative to AD. Quantitative motoric dissociation between autism and AD may have down-stream effects on later stages of movement resulting in qualitative differences between these disorder groups, e.g. "motor clumsiness" in AD versus "abnormal posturing" in autism. It will be important for future research to map the developmental trajectory of motor abnormalities in these disorder groups.

Motor signs distinguish children with high functioning autism and Asperger's syndrome from controls

While many studies of motor control in autism have focused on specific motor signs, there has been a lack of research examining the complete range of subtle neuromotor signs. This study compared performance on a neurologic examination standardized for children (PANESS, Physical and Neurological Exam for Subtle Signs, Denckla [1974 Developmental Medicine and Child Neurology, 16(6), 729-741]) between a group of 40 boys aged 6-17 with autism and average range IQs and a group of 55 typically developing boys. The Autism group was shown to have significant impairment on several measures of motor control compared to the Control group. Regression analyses revealed that a model including four PANESS variables offered a high level of discrimination in distinguishing boys with high-functioning autism from controls.

Atypically diffuse functional connectivity between caudate nuclei and cerebral cortex in autism

Background

Autism is a neurodevelopmental disorder affecting sociocommunicative behavior, but also sensorimotor skill learning, oculomotor control, and executive functioning. Some of these impairments may be related to abnormalities of the caudate nuclei, which have been reported for autism.

Methods

Our sample was comprised of 8 high-functioning males with autism and 8 handedness, sex, and age-matched controls. Subjects underwent functional MRI scanning during performance on simple visuomotor coordination tasks. Functional connectivity MRI (fcMRI) effects were identified as interregional blood oxygenation level dependent (BOLD) signal cross-correlation, using the caudate nuclei as seed volumes.

Results

In the control group, fcMRI effects were found in circuits with known participation of the caudate nuclei (associative, orbitofrontal, oculomotor, motor circuits). Although in the autism group fcMRI effects within these circuits were less pronounced or absent, autistic subjects showed diffusely increased connectivity mostly in pericentral regions, but also in brain areas outside expected anatomical circuits (such as visual cortex).

Conclusion

These atypical connectivity patterns may be linked to developmental brain growth disturbances recently reported in autism and suggest inefficiently organized functional connectivity between caudate nuclei and cerebral cortex, potentially accounting for stereotypic behaviors and executive impairments.

Neuropsychological Characteristics of School-Age Children with High-Functioning Autism: Performance on the Nepsy

Utilizing standardization and validation data from the NEPSY, this study presents a reanalysis of the High-Functioning Autism (HFA) versus Typical samples using IQ as a covariate. The reanalysis in the present paper should prove important to clinicians and researchers by (1) determining if the original findings can be replicated for the HFA sample when controlling for IQ, and (2) providing neuropsychological description for children with HFA versus Typical children across the NEPSY variables. The sample included 23 children with HFA who ranged in age from 5 years 5 months to 12 years 11 months (Mean = 9.59 years). The HFA Group comprised 19 males, 22 Caucasians, and was 87% right handed. All of the parents had between 12 to 15 years of education. A Typical Group was selected from the standardization sample of the NEPSY and matched on the variables of chronological age, race, gender, parental education, and region of the country. A MANCOVA revealed significant group differences on 8 of the 14 core subtests of the NEPSY, with the HFA Group performing lower than the Typical Group. While these findings significantly overlapped with those from the original validation study, significant group differences also were uncovered for the subtests of Phonological Processing, Auditory Attention and Response Set, and Speeded Naming; Comprehension of Instructions and Narrative Memory were no longer significant after controlling for IQ. When the groups were compared with respect to the number of cases falling below the 10th percentile, the HFA Group showed a higher rate of occurrence on each subtest, but only significantly so on the Arrows Subtest. These findings provide additional support for the phenotypic neurocognitive presentation of individuals with HFA, and they suggest that the NEPSY can contribute to the neuropsychological description of children with HFA.

Neural dynamics of autistic behaviors: cognitive, emotional, and timing substrates

What brain mechanisms underlie autism, and how do they give rise to autistic behavioral symptoms? This article describes a neural model, called the Imbalanced Spectrally Timed Adaptive Resonance Theory (iSTART) model, that proposes how cognitive, emotional, timing, and motor processes that involve brain regions such as the prefrontal and temporal cortex, amygdala, hippocampus, and cerebellum may interact to create and perpetuate autistic symptoms. These model processes were originally developed to explain data concerning how the brain controls normal behaviors. The iSTART model shows how autistic behavioral symptoms may arise from prescribed breakdowns in these brain processes, notably a combination of underaroused emotional depression in the amygdala and related affective brain regions, learning of hyperspecific recognition categories in the temporal and prefrontal cortices, and breakdowns of adaptively timed attentional and motor circuits in the hippocampal system and cerebellum. The model clarifies how malfunctions in a subset of these mechanisms can, through a systemwide vicious circle of environmentally mediated feedback, cause and maintain problems with them all.

Gait function in high-functioning autism and Asperger's disorder : evidence for basal-ganglia and cerebellar involvement?

Gait abnormalities have been widely reported in individuals with autism and Asperger's disorder. There is controversy as to whether the cerebellum or the basal-ganglia frontostriatal regions underpin these abnormalities. This is the first direct comparison of gait and upper-body postural features in autism and Asperger's disorder. Clinical and control groups were matched according to age, height, weight, performance, and full scale IQ. Consistent with Hallet's (1993) cerebellar-gait hypothesis, the autistic group showed significantly increased stride-length variability in their gait in comparison to control and Asperger's disorder participants. No quantitative gait deficits were found for the Asperger's disorder group. In support of Damasio and Maurer's (1982) basal-ganglia frontostriatal-gait hypothesis, both clinical groups were rated as showing abnormal arm posturing, however, only the Asperger's group were rated as significantly different from controls in terms of head and trunk posturing. While DSM-IV-TR suggests that Asperger's disorder, but not autism, is associated with motoric clumsiness, our data suggest that both clinical groups are uncoordinated and lacking in motor smoothness. Gait differences in autism and Asperger's disorder were suggested to reflect differential involvement of the cerebellum, with commonalities reflecting similar involvement of the basal-ganglia frontostriatal region.

Partially enhanced thalamocortical functional connectivity in autism

Based on evidence for thalamic abnormalities in autism, impairments of thalamocortical pathways have been suspected. We examined the functional connectivity between thalamus and cerebral cortex in terms of blood oxygen level dependent (BOLD) signal cross-correlation in 8 male participants with high-functioning autism and matched normal controls, using functional MRI during simple visuomotor coordination. Both groups exhibited widespread connectivity, consistent with known extensive thalamocortical connectivity. In a direct group comparison, overall more extensive connectivity was observed in the autism group, especially in the left insula and in right postcentral and middle frontal regions. Our findings are inconsistent with the hypothesis of general underconnectivity in autism and instead suggest that subcortico-cortical connectivity may be hyperfunctional, potentially compensating for reduced cortico-cortical connectivity.

Development in infants with autism spectrum disorders: a prospective study

BACKGROUND

Autism is rarely diagnosed before three years of age despite evidence suggesting prenatal abnormalities in neurobiological processes. Little is known about when or how development becomes disrupted in the first two years of life in autism. Such information is needed to facilitate early detection and early intervention.

METHODS

This prospective study of autism spectrum disorders (ASD) examined development using the Mullen Scales of Early Learning (MSEL) in 87 infants tested at target ages 6, 14, and 24 months. Participants came from infants at high risk (siblings of children with autism) and low risk (no family history of autism) groups. Based on language test scores, Autism Diagnostic Observation Schedule, and clinical judgment at 24 months of age, participants were categorized as: unaffected, ASD, or language delayed (LD). Longitudinal linear regression and ANOVA models were applied to MSEL raw scores, and estimates were compared between the three diagnostic groups.

RESULTS

No statistically significant group differences were detected at 6 months. By 14 months of age, the ASD group performed significantly worse than the unaffected group on all scales except Visual Reception. By 24 months of age, the ASD group performed significantly worse than the unaffected group in all domains, and worse than the language delayed group in Gross Motor, Fine Motor, and Receptive Language. The developmental trajectory of the ASD group was slower than the other groups', and showed a significant decrease in development between the first and second birthdays.

CONCLUSIONS

Variations from typical and language delayed development are detectable in many children with ASD using a measure of general development by 24 months of age. Unusual slowing in performance occurred between 14 and 24 months of age in ASD.

Pseudo-random number generation in children with high-functioning autism and Asperger's disorder: further evidence for a dissociation in executive functioning?

The repetitive, stereotyped and obsessive behaviours, which are core diagnostic features of autism, are thought to be underpinned by executive dysfunction. This study examined executive impairment in individuals with autism and Asperger's disorder using a verbal equivalent of an established pseudo-random number generating task. Different patterns of disinhibition emerged in the autism (n = 12) and Asperger's disorder (n = 12) groups. Consistent with previous research, the autism group repeated single numbers (e.g. 2, 2, 2) more frequently than the control group. In contrast to past research suggesting intact executive abilities, this study found that the Asperger's disorder group generated more repetitive number patterns (e.g. 45, 45) than the controls. Executive functioning in children with Asperger's disorder may be particularly vulnerable to a lack of visual cueing and concrete rules. Qualitative differences in executive dysfunction between these groups may implicate differential disruption within the fronto-striatal circuitry.

Response monitoring, the error-related negativity, and differences in social behavior in autism

Children with autism not only display social impairments but also significant individual differences in social development. Understanding the source of these differences, as well as the nature of social impairments, is important for improved diagnosis and treatments for these children. Current theory and research suggests that individual differences in response monitoring, a specific function of the anterior cingulate cortex (ACC), may contribute to social-emotional and social-cognitive impairments and individual differences in autism. To examine this hypothesis, we used a modified flanker task to assess an ERP index of response monitoring, the error-related negativity (ERN), in a sample of higher function children with autism (HFA) and an IQ-matched control sample. The results revealed a significant Diagnostic group by Verbal IQ interaction on ERN amplitude indicating that the most verbally capable HFA children displayed significantly larger ERN amplitudes than did the control children. Within the HFA sample, greater ERN amplitude was also related to parent reports of fewer symptoms of social interaction impairments, fewer internalizing problems, but more externalizing problems, although these associations were reduced to nonsignificance when medication status was controlled. The latter results complement previous observations from imaging studies of a significant association between ACC activity and social symptoms and impairments in autism. The implications of these results for future research on brain-behavior relations, as well as treatment related research with children with autism are discussed.

Autism and Asperger's disorder: Are they movement disorders involving the cerebellum and/or basal ganglia?

Autism and Asperger's disorder (AD) are childhood developmental disorders of unknown aetiology. Autism and AD share several behavioural features, and it is not clear whether they are distinct disorders or variants of the same disorder. Recent studies indicate that disordered movement may be another feature of autism and AD, and that this may reflect dysfunction within the frontostriatal and/or cerebellar motor circuits. While disordered movement in autism and AD has been examined in a variety of ways, it is relatively under-researched compared to the cognitive, affective, and behavioural disturbances seen in these disorders. This review examines the role of the frontostriatal and cerebellar motor systems in the behavioural features of autism and AD, with gait as a proxy, and discusses difficulties with their diagnosis and their possible pathogenesis.

The Application of Short Forms of the Wechsler Intelligence Scales in Adults and Children with High Functioning Autism

We evaluated the predictive accuracy of short forms of the Wechsler intelligence scales for individuals with high functioning autism. Several short forms were derived from participants who had received the full procedure. Stepwise multiple regression analyses were performed to determine the strength of association between the subtests included in the short form and IQ scores based upon the full test. These analyses were performed for all participants, and also for autism participants with atypical subtest profiles. In all analyses the percentages of explained variance were typically in the .8-.9 range. It was concluded that short forms may be used with good predictive accuracy in individuals with high functioning autism, even when the subtest profile is atypical.

Behavioural aspects of cerebellar function in adults with Asperger syndrome

Aside from social deficits, Asperger and autistic individuals also exhibit motor control abnormalities such as impaired gait, balance, manual dexterity and grip. One brain area that has consistently been reported on autopsy and imaging studies to be abnormal in such individuals is the cerebellum. As the cerebellum controls sensorimotor coordination and lesions here typically cause hypotonia, dysmetria and dyscoordination, we performed a series of quantitative tests aimed at investigating cerebellar function in Asperger individuals. Tests examining visually guided movement (rapid pointing), speeded complex movement (finger tapping, rapid hand turning), muscle tone (catching dropped weight), prediction, coordination and timing (balance, grip force and interval timing) were conducted on 12 Asperger subjects and 12 age and IQ matched controls. In comparison to control subjects, Asperger subject's demonstrated: (i) decreased pointing accuracy and rate, (ii) increased postural instability, and (iii) decreased timing accuracy. IQ was found to co-vary with some parameters of each of these tasks and no further impairments were found on the remaining tests. We suggest that these specific deficits reflect impairment in the ability to integrate sensory input with appropriate motor commands and are consistent with cerebellar dysfunction in Asperger syndrome.

Impairment of a cortical event-related desynchronisation during a bimanual load-lifting task in children with autistic disorder

In autism, the abilities of communication are affected, associated with abnormalities of cognitive, sensorial and motor development. In a previous study based on a load-lifting task, we showed impairment of anticipation in children with autism as evidenced by kinematics and eletromyographic recordings [Neurosci. Lett. 348 (2003) 17]. In the present study, we assessed the cortical counterparts of the use of anticipatory postural adjustments in a group of control children and in a group of children with autism. The tasks required maintaining a stable forearm position despite imposed or voluntary lifting of an object placed either on the controlateral forearm or on a support. We investigated the differences between the two groups of children on the Event-Related Desynchronisation (ERD) which precedes movement onset in adults [Electroencephalogr. Clin. Neurophysiol. 46 (1979) 138]. Electroencephalogram (EEG) power evolution of a 6-8-Hz frequency band was averaged before and after imposed or voluntary movement onset. EEG reactivity of control and autistic children did not differ during the imposed unloading condition, but significant differences appeared in the voluntary unloading situations. Before lifting the object, control children showed an ERD above the left motor areas. An ERD also occurred above the right motor areas when the object was placed on their forearm. This indicates that the ERD can also translate the use of anticipatory postural adjustments. By contrast, children with autism did not show an ERD in the two voluntary situations. This suggests a central deficit of anticipation in both postural and motor control in children with autism.

Abnormal activity patterns in premotor cortex during sequence learning in autistic patients

BACKGROUND

Evidence for frontal abnormality in autism has accumulated in recent years. Our own studies have shown abnormal activation in prefrontal cortex during finger tapping and visuomotor coordination. Studies in healthy adults suggest reduced premotor and increased prefrontal activity during advanced learning stages. We examined hemodynamic changes during visuomotor learning in autistic patients.

METHODS

We studied eight high-functioning autistic patients and eight control subjects during learning of an 8-digit sequence over a period of 8 min, using functional magnetic resonance imaging.

RESULTS

Autistic patients showed overall less prefrontal activation during late visuomotor learning; however, the main finding was a complementary one of enhanced activation in right pericentral and premotor cortex. In the autism group, Brodmann areas 3, 4, and 6 of the right hemisphere became more involved during late learning stages (trials 25-48), compared with early stages (trials 1-24). This effect was not seen in the control group.

CONCLUSIONS

Our findings suggests that in autistic patients 1) primary sensorimotor and premotor cortex, which is normally predominant in early stages of visuomotor learning, plays an atypical role in later stages, even when learning is evident; and 2) handedness and side of execution interact with asymmetry of visuomotor learning activations, contrary to what is seen in normal adults.

Cerebellar function in autism: functional magnetic resonance image activation during a simple motor task

BACKGROUND

The cerebellum is one of the most consistent sites of neuroanatomic abnormality in autism, yet it is still unclear how such pathology impacts cerebellar function. In normal subjects, we previously demonstrated with functional magnetic resonance imaging (fMRI) a dissociation between cerebellar regions involved in attention and those involved in a simple motor task, with motor activation localized to the anterior cerebellum ipsilateral to the moving hand. The purpose of the present investigation was to examine activation in the cerebella of autistic patients and normal control subjects performing this motor task.

METHODS

We studied eight autistic patients and eight matched normal subjects, using fMRI. An anatomic region-of-interest approach was used, allowing a detailed examination of cerebellar function.

RESULTS

Autistic individuals showed significantly increased motor activation in the ipsilateral anterior cerebellar hemisphere relative to normal subjects, in addition to atypical activation in contralateral and posterior cerebellar regions. Moreover, increased activation was correlated with the degree of cerebellar structural abnormality.

CONCLUSIONS

These findings strongly suggest dysfunction of the autistic cerebellum that is a reflection of cerebellar anatomic abnormality. This neurofunctional deficit might be a key contributor to the development of certain diagnostic features of autism (e.g., impaired communication and social interaction, restricted interests, and stereotyped behaviors).

Annotation: The similarities and differences between autistic disorder and Asperger's disorder: a review of the empirical evidence

BACKGROUND

The ongoing controversy over the distinction between autistic disorder and Asperger's disorder is important to resolve because of the implications regarding an understanding of the aetiology and prognosis, and the diagnostic and clinical practices relating to these conditions. This paper provides a critical evaluation of current published research evidence.

METHOD

Databases, such as PsychINFO and Medline, as well as book chapters, reference lists from relevant articles, and recent editions of key journals were searched for all relevant studies (until 2002) which incorporated participants diagnosed with high-functioning autism and Asperger's disorder using either cluster analysis or comparative approaches to examine similarities and differences between these groups. Keywords used in the searches included autistic disorder, Asperger's disorder, autism, high-functioning autism, and pervasive developmental disorder.

RESULTS

On the basis of the available evidence, there seem to be few qualitative differences between autistic disorder and Asperger's disorder.

CONCLUSION

There is currently insufficient evidence to establish the validity of Asperger's disorder as a syndrome distinct from high-functioning autism. The findings are consistent with the view that these disorders belong on an autism spectrum.

Annotation: the neural basis of social impairments in autism: the role of the dorsal medial-frontal cortex and anterior cingulate system

BACKGROUND

The fundamental social disturbance of autism is characterized, in part, by problems in the acquisition of joint attention skills in the first years of life, followed by impairments in the development of social cognition, as assessed on theory of mind (ToM) measures. Recently, studies have indicated that a system involving the dorsal medial-frontal cortex (DMFC), and the anterior cingulate (AC), may contribute to the development of the tendency to initiate joint attention in infancy. Similarly, research has implicated the DMFC/AC system in ToM performance in typical and atypical individuals. These data suggest it may be useful to consider the functions associated with this system in the developmental psychopathology of autism.

METHOD

A review of the studies of the connections between the DMFC/AC system, joint attention and ToM task performance.

RESULTS AND CONCLUSIONS

This review raises the hypothesis that the DMFC/AC may be involved in the basic disturbance in social orienting in autism. The DMFAC/AC may also play a role in the capacity to monitor proprioceptive information concerning self-action and integrate this self-related information with exteroceptive perceptual information about the behavior of other people. A disturbance in these functions of the DMFC/ AC may contribute to the atypical development of intersubjectivity, joint attention and social cognition that may impair the lives of people with autism. Thus, impairment in the development of this system may constitute a neural substrate for socio-cognitive deficits in autism.

Motor performance and anatomic magnetic resonance imaging (MRI) of the basal ganglia in autism

This study was conducted to examine the volume of the basal ganglia in individuals with autism and to evaluate whether performance on specific motor tasks correlated with the volume of these structures. Volumetric measurements of the caudate nucleus and putamen were obtained from magnetic resonance images (MRI) of 40 non-mentally retarded individuals with autism and 41 healthy controls. Motor performance was assessed in these subjects by using the Finger Tapping Test, the Grooved Pegboard Test, and the measurement of Grip Strength. No volumetric differences of the basal ganglia were found between the two groups after adjusting for brain volume. The autistic subjects' performance was slower on the Grooved Pegboard Test and weaker on Grip Strength. Our findings suggest that the motor deficits observed in autism may not be related to structural abnormalities of the basal ganglia, and other brain regions, such as the cerebellum and the frontal lobe, may be involved in the pathophysiology of motor disturbances in autism.

A clinical and neurobehavioural review of high-functioning autism and Asperger's disorder

OBJECTIVE

To compare, contrast and review clinical and neuropsychological studies of high-functioning autism and Asperger's disorder.

METHOD

This paper reviews past and contemporary conceptualizations of autism and Asperger's disorder, together with epidemiological information, genetic and neurobehavioural findings. This paper focuses on neurobehavioural studies, in particular, executive functioning, lateralization, visual-perceptual and motor processing, which have provided an important source of information about the potential neurobiological dissociation that may exist between autism and Asperger's disorder.

RESULTS

The clinical profiles of autism and Asperger's disorder contain a mixture of psychiatric and neurological symptoms: for example, movement abnormalities (i.e. stereotyped behaviours, hand flapping, toe walking, whole-body movements), atypical processing of parts and wholes, verbal and non-verbal deficits, ritualistic/compulsive behaviour, disturbances in reciprocal social interaction and associated depression and anxiety. The considerable clinical overlap between autism and Asperger's disorder has led many to question whether Asperger's disorder is merely a mild form of autism, or whether it should be considered as a separate clinical entity.

CONCLUSION

In light of the growing body of epidemiological information, genetic, and neurobehavioural evidence that distinguishes autism from Asperger's disorder, it is premature to rule out the possibility that these disorders may be clinically, and possibly neurobiologically separate.

Efficacy of sensory and motor interventions for children with autism

Idiosyncratic responses to sensory stimuli and unusual motor patterns have been reported clinically in young children with autism. The etiology of these behavioral features is the subject of much speculation. Myriad sensory- and motor-based interventions have evolved for use with children with autism to address such issues; however, much controversy exists about the efficacy of such therapies. This review paper summarizes the sensory and motor difficulties often manifested in autism, and evaluates the scientific basis of various sensory and motor interventions used with this population. Implications for education and further research are described.