Individuals with autism spectrum disorder show normal responses to a fear potential startle paradigm

Sensory Gating in Neurodevelopmental Disorders: A Scoping Review

This review aimed to explore the current understanding of sensory gating in neurodevelopmental disorders as a possible transdiagnostic mechanism. We applied methods according to the Joanna Briggs Institute Manual for Evidence Synthesis, following the population, concept, and context scoping review eligibility criteria. Using a comprehensive search strategy in five relevant research databases (Medline, EMBASE, CINAHL, PsychInfo, and Scopus), we searched for relevant peer-reviewed, primary research articles and unpublished data. Two independent reviewers screened the titles and abstracts, full-texts, and completed data extraction. We identified a total of 81 relevant articles and used descriptive analyses to summarize the characteristics and outcomes of all identified studies. Literature regarding sensory gating was most common in autistic populations with relatively fewer studies examining attention-deficit/hyperactivity disorder, tic disorders, and childhood-onset fluency disorder (COFD). The methods to assess sensory gating varied widely both within and between groups and included measures such as habituation, prepulse inhibition, affect-modulated inhibition, medication and other intervention trials. Most consistently, when participants complete questionnaires about their sensory experiences, those who have neurodevelopmental disorders report differences in their sensory gating. Affect-modulated inhibition appears to be discrepant between samples with and without neurodevelopmental disorder diagnoses. Habituation was the most commonly reported phenomenon and many differences in habituation have been found in autistic individuals and individuals with tic disorders whereas concerns with inhibition seemed more common in COFD. Overall, the evidence is inconsistent within and between disorders suggesting there is still much to learn about sensory gating in neurodevelopmental disorders.

Trait Anxiety in Individuals on the Autism Spectrum: a Systematic Review

Although anxiety is commonly researched in autism, the focus has predominantly been on anxiety disorders and not upon general levels of anxiousness or trait anxiety. This review summarises research investigating trait anxiety in autism. Systematic searches yielded 1099 records, with 23 studies meeting inclusion criteria. Study participants were mainly males from Western countries, with no representation of older adults or individuals with intellectual disability. All articles used self-report questionnaire trait anxiety measures. Anxiety measure psychometric details were absent in most studies, with 21 using subjective measures that are not validated for use in autism. Results showed higher trait anxiety scores in autism versus control groups, and correlations between trait anxiety scores and other study outcomes.

Fear Potentiated Startle in Children With Autism Spectrum Disorder: Association With Anxiety Symptoms and Amygdala Volume

Atypical responses to fearful stimuli and the presence of various forms of anxiety are commonly seen in children with autism spectrum disorder (ASD). The fear potentiated startle paradigm (FPS), which has been studied both in relation to anxiety and as a probe for amygdala function, was carried out in 97 children aged 9-14 years including 48 (12 female) with ASD and 49 (14 female) with typical development (TD). In addition, exploratory analyses were conducted examining the association between FPS and amygdala volume as assessed with magnetic resonance imaging in a subset of the children with ASD with or without an anxiety disorder with available MRI data. While the startle latency was increased in the children with ASD, there was no group difference in FPS. FPS was not significantly associated with traditional Diagnostic and Statistical Manual (DSM) or "autism distinct" forms of anxiety. Within the autism group, FPS was negatively correlated with amygdala volume. Multiple regression analyses revealed that the association between FPS and anxiety severity was significantly moderated by the size of the amygdala, such that the association between FPS and anxiety was significantly more positive in children with larger amygdalas than smaller amygdalas. These findings highlight the heterogeneity of emotional reactivity associated with ASD and the difficulties in establishing biologically meaningful probes of altered brain function. LAY SUMMARY: Many children with autism spectrum disorder (ASD) have additional problems such as anxiety that can greatly impact their lives. How these co-occurring symptoms develop is not well understood. We studied the amygdala, a region of the brain critical for processing fear and a laboratory method called fear potentiated startle for measuring fear conditioning, in children with ASD (with and without an anxiety disorder) and typically developing children. Results showed that the connection between fear conditioning and anxiety is dependent on the size of the amygdala in children with ASD.

Age- and sex-specific fear conditioning deficits in mice lacking Pcdh10, an Autism Associated Gene

PCDH10 is a gene associated with Autism Spectrum Disorder. It is involved in the growth of thalamocortical projections and dendritic spine elimination. Previously, we characterized Pcdh10 haploinsufficient mice (Pcdh10^+/- mice) and found male-specific social deficits and dark phase hypoactivity. Pcdh10^+/- males exhibit increased dendritic spine density of immature morphology, decreased NMDAR expression, and decreased gamma synchronization in the basolateral amygdala (BLA). Here, we further characterize Pcdh10^+/- mice by testing for fear memory, which relies on BLA function. We used both male and female Pcdh10^+/- mice and their wild-type littermates at two ages, juvenile and adult, and in two learning paradigms, cued and contextual fear conditioning. We found that males at both ages and in both assays exhibited fear conditioning deficits, but females were only impaired as adults in the cued condition. These data are further evidence for male-specific alterations in BLA-related behaviors in Pcdh10^+/- mice and suggest that these mice may be a useful model for dissecting male specific brain and behavioral phenotypes relevant to social and emotional behaviors.

Atypical EEG Responses to Nonverbal Emotionally Charged Stimuli in Children with ASD

This study focused on auditory emotional perception in children with low-functioning autism and investigated the children's response to emotionally charged nonverbal sounds which regularly induced emotional response in typically developing (TD) peers. An EEG was conducted, and emotional reactions were assessed using analog scales and images of presented sounds with additional images during the presentation of emotional stimuli. The results showed that EEG and emotional responses to the fearful sounds were similar in TD children and children with autism spectrum disorders (ASD). Both groups of children showed an increase in peak alpha frequency and power of alpha2-band and a decrease in low-frequency bands. Sounds of crying and laughter induced an atypical EEG response in children with ASD, with no change in alpha-band's power and frequency observed in them; this was contrary to the observation in TD children. The decrease in the fractal dimension detected in children with ASD only for sounds of crying and laughter correlated with the accuracy of assessment of these stimuli.

How are attention, learning, and social cognition related on the non-clinical autistic spectrum?

Autism spectrum disorder (ASD) - and autistic traits more generally - are associated with a heterogeneous pattern of differences in cognitive function. These include differences in associative learning, attention, and processing of social information. All three cognitive functions have importance in clinical, educational, and research contexts. The present study investigates the relationships between these functions in the context of autistic traits in the neurotypical population. In an online study, we asked a group of over 400 people to complete the Autism Spectrum Quotient questionnaire. We also asked participants to complete one of two standard attentional learning paradigms - either a Kamin blocking or an attentional highlighting task. To investigate the relation of attention and learning to social information processing, we incorporated social cues in one of each kind of paradigm. We found Kamin blocking increased with increasing number of autistic traits, in particular the sub-trait attention switching, but only for non-social cues. We found that highlighting decreased with increasing number of traits, in particular the sub-trait communication, but only for social cues. We interpret these findings as evidence of a crucial role for attention in other characteristics of the broader autistic phenotype, and discuss the relevance of these results for cognitive explanations of autistic traits and symptoms.

Enhanced social learning of threat in adults with autism

Background

Recent theories have linked autism to challenges in prediction learning and social cognition. It is unknown, however, how autism affects learning about threats from others “demonstrators” through observation, which contains predictive learning based on social information. The aims of this study are therefore to investigate social fear learning in individual with autism spectrum disorder (ASD) and to examine whether typically developing social cognition is necessary for successful observational learning.

Methods

Adults with ASD (n = 23) and neurotypical controls (n = 25) completed a social fear learning (SFL) procedure in which participants watched a “demonstrator” receiving electrical shocks in conjunction with a previously neutral conditioned stimulus (CS+), but never with a safe control stimulus (CS−). Skin conductance was used to measure autonomic responses of learned threat responses to the CS+ versus CS−. Visual attention was measured during learning using eye tracking. To establish a non-social learning baseline, each participant also underwent a test of Pavlovian conditioning.

Results

During learning, individuals with ASD attended less to the demonstrator’s face, and when later tested, displayed stronger observational, but not Pavlovian, autonomic indices of learning (skin conductance) compared to controls. In controls, both higher levels of attention to the demonstrator’s face and trait empathy predicted diminished expressions of learning during test.

Limitations

The relatively small sample size of this study and the typical IQ range of the ASD group limit the generalizability of our findings to individuals with ASD in the average intellectual ability range.

Conclusions

The enhanced social threat learning in individuals with ASD may be linked to difficulties using visual attention and mental state attributions to downregulate their emotion.

Strengthening risk prediction using statistical learning in children with autism spectrum disorder

Purpose

The purpose of this paper is to investigate the prediction ability in children with ASD in the risk-involving situations and compute the impact of statistical learning (SL) in strengthening their risk knowledge. The learning index and stability with time are also calculated by comparing their performance over three consecutive weekly sessions (session 1, session 2 and session 3).

Design/methodology/approach

Participants were presented with a series of images, showing simple and complex risk-involving situations, using the psychophysical experimental paradigm. The stimuli in the experiment were provided with different levels of difficulty in order to keep the legacy of the prediction and SL-based experiment intact.

Findings

The first phase of experimental work showed that children with ASD accurately discriminated the risk, although performed poorly as compared to neurotypical. The attenuated response in differentiating risk levels indicates that children with ASD have a poor and underdeveloped sense of risk. The second phase investigated their capability to extract the information from repetitive patterns and calculated SL stability value in time. The learning curve shows that SL is intact and stable with time (average session r=0.74) in children with ASD.

Research limitations/implications

The present work concludes that impaired action prediction could possibly be one of the factors underlying underdeveloped sense of risk in children with ASD. Their SL capability shows that risk knowledge can be strengthened in them. In future, the studies should investigate the impact of age and individual differences, by using knowledge from repetitive trials, on the learning rate and trajectories.

Practical implications

SL, being an integral part of different therapies, rehabilitation schemes and intervention systems, has the potential to enhance the cognitive and functional abilities of children with ASD.

Originality/value

Past studies have provided evidence regarding the work on the prediction ability in individuals with ASD. However, it is unclear whether the risk-involving/dangerous situations play any certain role to enhance the prediction ability in children with ASD. Also, there are limited studies predicting risk knowledge in them. Based on this, the current work has investigated the risk prediction in children with ASD.

Altered responses to social chemosignals in autism spectrum disorder

Autism spectrum disorder (ASD) is characterized by impaired social communication, often attributed to misreading of emotional cues. Why individuals with ASD misread emotions remains unclear. Given that terrestrial mammals rely on their sense of smell to read conspecific emotions, we hypothesized that misreading of emotional cues in ASD partially reflects altered social chemosignaling. We found no difference between typically developed (TD) and cognitively able adults with ASD at explicit detection and perception of social chemosignals. Nevertheless, TD and ASD participants dissociated in their responses to subliminal presentation of these same compounds: the undetected 'smell of fear' (skydiver sweat) increased physiological arousal and reduced explicit and implicit measures of trust in TD but acted opposite in ASD participants. Moreover, two different undetected synthetic putative social chemosignals increased or decreased arousal in TD but acted opposite in ASD participants. These results implicate social chemosignaling as a sensory substrate of social impairment in ASD.

Reinforcement Learning in Autism Spectrum Disorder

Early behavioral interventions are recognized as integral to standard care in autism spectrum disorder (ASD), and often focus on reinforcing desired behaviors (e.g., eye contact) and reducing the presence of atypical behaviors (e.g., echoing others' phrases). However, efficacy of these programs is mixed. Reinforcement learning relies on neurocircuitry that has been reported to be atypical in ASD: prefrontal-sub-cortical circuits, amygdala, brainstem, and cerebellum. Thus, early behavioral interventions rely on neurocircuitry that may function atypically in at least a subset of individuals with ASD. Recent work has investigated physiological, behavioral, and neural responses to reinforcers to uncover differences in motivation and learning in ASD. We will synthesize this work to identify promising avenues for future research that ultimately can be used to enhance the efficacy of early intervention.

Sensory processing in autism spectrum disorders and Fragile X syndrome-From the clinic to animal models

Brains are constantly flooded with sensory information that needs to be filtered at the pre-attentional level and integrated into endogenous activity in order to allow for detection of salient information and an appropriate behavioral response. People with Autism Spectrum Disorder (ASD) or Fragile X Syndrome (FXS) are often over- or under-reactive to stimulation, leading to a wide range of behavioral symptoms. This altered sensitivity may be caused by disrupted sensory processing, signal integration and/or gating, and is often being neglected. Here, we review translational experimental approaches that are used to investigate sensory processing in humans with ASD and FXS, and in relevant rodent models. This includes electroencephalographic measurement of event related potentials, neural oscillations and mismatch negativity, as well as habituation and pre-pulse inhibition of startle. We outline robust evidence of disrupted sensory processing in individuals with ASD and FXS, and in respective animal models, focusing on the auditory sensory domain. Animal models provide an excellent opportunity to examine common mechanisms of sensory pathophysiology in order to develop therapeutics.

Atypical Amygdala Response to Fear Conditioning in Autism Spectrum Disorder

BACKGROUND

Anxiety is the most common comorbid psychiatric concern in individuals diagnosed with autism spectrum disorder (ASD) and can cause significant functional impairment. Fear conditioning tasks offer a useful neurodevelopmental model for anxiety, yet there are no published neuroimaging studies of fear conditioning using ASD samples.

METHODS

Twenty adults diagnosed with ASD and 19 healthy adult control subjects completed a standard fear conditioning and extinction paradigm while undergoing functional magnetic resonance imaging scanning. A burst of air on the base of the neck was the unconditioned stimulus. Participants returned 1 day later for scanning during an extinction recall phase. A priori regions of interest were analyzed with a familywise error correction rate < 0.05.

RESULTS

All regions of interest demonstrated significantly greater response to threat than safe conditions during initial fear acquisition. Compared with age-matched control subjects, the ASD group showed a significantly decreased differential response to threat versus safe cues in right amygdala during the initial fear acquisition phase and decreased response in left amygdala during the first run of extinction recall on the second day of scanning.

CONCLUSIONS

Symptoms of severe anxiety in ASD may arise from atypical neural mechanisms especially related to the differentiation of threat versus safe cues. An inability to effectively identify safety contexts may underlie chronically increased levels of anxiety in many individuals diagnosed with ASD.

Autistic Traits Moderate the Impact of Reward Learning on Social Behaviour

A deficit in empathy has been suggested to underlie social behavioural atypicalities in autism. A parallel theoretical account proposes that reduced social motivation (i.e., low responsivity to social rewards) can account for the said atypicalities. Recent evidence suggests that autistic traits modulate the link between reward and proxy metrics related to empathy. Using an evaluative conditioning paradigm to associate high and low rewards with faces, a previous study has shown that individuals high in autistic traits show reduced spontaneous facial mimicry of faces associated with high vs. low reward. This observation raises the possibility that autistic traits modulate the magnitude of evaluative conditioning. To test this, we investigated (a) if autistic traits could modulate the ability to implicitly associate a reward value to a social stimulus (reward learning/conditioning, using the Implicit Association Task, IAT); (b) if the learned association could modulate participants’ prosocial behaviour (i.e., social reciprocity, measured using the cyberball task); (c) if the strength of this modulation was influenced by autistic traits. In 43 neurotypical participants, we found that autistic traits moderated the relationship of social reward learning on prosocial behaviour but not reward learning itself. This evidence suggests that while autistic traits do not directly influence social reward learning, they modulate the relationship of social rewards with prosocial behaviour. Autism Res2016, 9: 471–479. © 2015 The Authors Autism Research published by Wiley Periodicals, Inc. on behalf of International Society for Autism Research

Delayed disengagement of attention from snakes in children with autism

In the visual search task, it is well known that detection of a tilted straight line as the target among vertical lines that act as distractors is easier than vice versa, and that detection of a snake image as the target among flower images is easier than vice versa. In this study, the degree of such search asymmetry was compared between 18 children with autism and 14 typically developing (TD) children. The results revealed that compared to TD children, children with autism were disproportionally slow when asked to detect the flower among the snake images, suggesting the possibility that they experienced difficulty of disengaging their attention from the snake images. This delayed disengagement would serve itself as an enhanced attentional bias toward snakes in children with autism that is similar to characteristics of visual search performance in anxiety patients.

An update on anxiety in youth with autism spectrum disorders

PURPOSE OF REVIEW

Anxiety is one of the most common co-occurring psychiatric conditions in youth with autism spectrum disorders (ASDs). This article reviews recent evidence as well as earlier relevant studies regarding the characteristics, assessment, and treatment of anxiety in youth with ASD.

RECENT FINDINGS

It is well established that the prevalence of anxiety in youth with an ASD is significantly greater than the prevalence of anxiety in the general population. Recent studies have highlighted the importance of informant, method, and instrument when measuring anxiety in this population. Despite the high prevalence, findings to date have been unable to identify any consistent risk factors for anxiety. New psychological treatments, including modified cognitive behavioral therapy for youth with high functioning ASD and co-occurring anxiety, are emerging. Pharmacological data, however, are scant. Existing studies show that youth with ASD are at increased risk for behavioral activation when taking SSRIs.

SUMMARY

Clinicians working with youth with ASD are encouraged to routinely screen for anxiety. Until further data are available, clinical judgment is needed when prescribing treatments, particularly selective serotonin reuptake inhibitors, which require close monitoring of side-effects. Research on risk factors, pathophysiology, and treatment of this condition is needed.

Abnormal emotional learning in a rat model of autism exposed to valproic acid in utero

Autism Spectrum Disorders (ASD) are complex neurodevelopmental disorders characterized by repetitive behavior and impaired social communication and interactions. Apart from these core symptoms, a significant number of ASD individuals display higher levels of anxiety and some ASD individuals exhibit impaired emotional learning. We therefore sought to further examine anxiety and emotional learning in an environmentally induced animal model of ASD that utilizes the administration of the known teratogen, valproic acid (VPA) during gestation. Specifically we exposed dams to one of two different doses of VPA (500 and 600 mg/kg) or vehicle on day 12.5 of gestation and examined the resultant progeny. Our data indicate that animals exposed to VPA in utero exhibit enhanced anxiety in the open field test and normal object recognition memory compared to control animals. Animals exposed to 500 mg/kg of VPA displayed normal acquisition of auditory fear conditioning, and exhibited reduced extinction of fear memory and normal litter survival rates as compared to control animals. We observed that animals exposed to 600 mg/kg of VPA exhibited a significant reduction in the acquisition of fear conditioning, a significant reduction in social interaction and a significant reduction in litter survival rates as compared to control animals. VPA (600 mg/kg) exposed animals exhibited similar shock sensitivity and hearing as compared to control animals indicating the fear conditioning deficit observed in these animals was not likely due to sensory deficits, but rather due to deficits in learning or memory retrieval. In conclusion, considering that progeny from dams exposed to rather similar doses of VPA exhibit striking differences in emotional learning, the VPA model may serve as a useful tool to explore the molecular and cellular mechanisms that contribute to not only ASD, but also emotional learning.

Fear-potentiated startle response is unrelated to social or emotional functioning in adolescents with autism spectrum disorders

It has been suggested that atypical amygdala function contributes to the social impairments characteristic of autism spectrum disorders (ASDs). Previous research has demonstrated that adolescents and adults with ASD generate normal response during a fear-potentiated startle paradigm, suggesting this aspect of amygdala function is intact and may not account for the social dysfunction associated with the condition. The amygdala also plays a crucial role in the expression of anxiety and may contribute to high rates of reported anxiety in individuals with ASD. The present study partially replicates prior work by examining the fear-potentiated startle response in adolescents with ASD, and extends this to investigate the relationship between startle response and anxiety. Eyeblink magnitude and latency (electromyographic activity; EMG) were collected from 20 adolescents with ASD and 19 typically developing (TD) age-matched adolescents during a fear-potentiated startle paradigm. Parent-report and self-report of anxiety and additional psychiatric symptoms were collected. Parental reports indicated higher rates of associated psychopathology in adolescents with ASD compared with TD adolescents. Consistent with previous results, both groups showed normal potentiated startle response, and no group differences in EMG were found. Symptoms of anxiety and level of social impairment were unrelated to startle response. These findings held for all levels of anxiety, suggesting that within the context of the fear-potentiated startle paradigm, amygdala response is not associated with degree of atypical social or emotional functioning in ASD.

Personal space regulation in childhood autism spectrum disorders

People appropriately adjust the distance between themselves and others during social interaction, and they may feel discomfort and move away when another person intrudes on their personal space. In the present study, we investigated personal space in children with persistent difficulties in the domain of social behavior, such as children with autism spectrum disorders (ASD), and in children with typical development (TD). The stop-distance paradigm was used to derive estimates of interpersonal distance, before and after a brief interaction with an unfamiliar adult confederate. The results showed that ASD children felt comfortable at a greater distance compared to TD children. Moreover, personal space shrunk after interaction with the confederate in TD children, but it failed to do so in ASD children. These findings reveal that autism deeply affects the regulation of personal space, influencing both its size and flexibility.

A potentiated startle study of uncertainty and contextual anxiety in adolescents diagnosed with autism spectrum disorder

Background

Beyond the core symptoms of autism spectrum disorder (ASD), associated symptoms of anxiety can cause substantial impairment for individuals affected by ASD and those who care for them.

Methods

We utilized a potentiated startle paradigm with a puff of air to the neck as the unconditioned stimulus in order to investigate differences between response to cued fear and contextual anxiety among cognitively able adolescents diagnosed with ASD and an age- and IQ-matched typically developing group.

Results

In a threat-modulated startle paradigm, response patterns to neutral, predictable, and unpredictable conditions were comparable across typically developing and ASD youth in terms of startle response magnitude and latency. However, the ASD group showed significantly greater absolute startle responsivity at baseline and throughout the experiment, suggesting possibly enhanced general sensitivity to threatening contexts. The ASD group, but not the control group, demonstrated moderate to strong negative correlations between psychophysiological response to unpredictable threats (uncertainty) and questionnaire measures of generalized anxiety, intolerance of uncertainty, and repetitive behavior.

Conclusions

Our data suggest enhanced general reactivity among the ASD group, possibly reflecting greater sensitivity to the threatening context of the startle paradigm. Associations with the response to uncertainty may help explain shared neurobehavioral mechanisms in ASD and anxiety. This task can provide useful targets for future neuroimaging and genetics studies as well as specific avenues for intervention. We emphasize the importance of further basic and clinical research into links among these important constructs.

General developmental health in the VPA-rat model of autism

Autism is a neurodevelopmental condition diagnosed by impaired social interaction, abnormal communication and, stereotyped behaviors. While post-mortem and imaging studies have provided good insights into the neurobiological symptomology of autism, animal models can be used to study the neuroanatomical, neurophysiological and molecular mediators in more detail and in a more controlled environment. The valproic acid (VPA) rat model is an environmentally triggered model with strong construct and clinical validity. It is based on VPA teratogenicity in humans, where mothers who are medicated with VPA during early pregnancy show an increased risk for giving birth to an autistic child. In rats, early embryonic exposure, around the time of neural tube closure, leads to autism-like anatomical and behavioral abnormalities in the offspring. Considering the increasing use of the VPA rat model, we present our observations of the general health of Wistar dams treated with a single intraperitoneal injection of 500 or, 600 mg/kg VPA on embryonic day E12.5, as well as their male and female offspring, in comparison to saline-exposed controls. We report increased rates of complete fetal reabsorption after both VPA doses. VPA 500 mg/kg showed no effect on dam body weight during pregnancy or, on litter size. Offspring exposed to VPA 500 mg/kg showed smaller brain mass on postnatal days 1 (P1) and 14 (P14), in addition to abnormal nest seeking behavior at P10 in the olfactory discrimination test, relative to controls. We also report increased rates of physical malformations in the offspring, rare occurrences of chromodacryorrhea and, developmentally similar body mass gain. Further documentation of developmental health may guide sub-grouping of individuals in a way to better predict core symptom severity.

Cued and contextual fear conditioning in BTBR mice is improved with training or atomoxetine

The BTBR T+tf/J (BTBR) strain of mice is a model for autism spectrum disorders (ASDs). These mice display reduced social behavior, altered communication, and high levels of repetitive behavior. BTBR mice have shown a deficit in learning cued and contextual fear conditioning. In this study, experiments were conducted to determine if either changes in training or drug administration would improve learning in BTBR mice when compared to C57BL/6 (B6) mice in contextual and cued fear conditioning. The first experiment examined the effects of three conditioned stimulus-unconditioned stimulus (CS-US) training paradigms; a 1P (1 CS-US pairing), 4P (4 CS-US pairings), and 10P (10 CS-US pairings). Increasing the number of CS-US pairings to 10 caused an increase in freezing behavior by the BTBR mice in contextual and cued conditioning indicating that more training facilitated BTBR learning. B6 mice had a more complex reaction to the increased training; the mice increased freezing behavior in the cued fear conditioning but not contextual fear conditioning. The second experiment determined whether atomoxetine, a noradrenergic reuptake inhibitor that has been shown to improve attention and decrease hyperactivity, impulsivity, and social withdrawal, would enhance learning. There was a significant increase in freezing behavior in contextual fear conditioning following atomoxetine administration in BTBR mice but not in B6 mice. Our data demonstrates that contextual and cued learning in BTBR mice is facilitated by increased training. Furthermore, contextual learning is improved in BTBR mice with use of atomoxetine, which helps to improve attention. Both increased training and pharmacological intervention improved learning in the BTBR mice suggesting a role for the combination of the two.

The Interplay between Emotion and Cognition in Autism Spectrum Disorder: Implications for Developmental Theory

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that is clinically defined by abnormalities in reciprocal social and communicative behaviors and an inflexible adherence to routinised patterns of thought and behavior. Laboratory studies repeatedly demonstrate that autistic individuals experience difficulties in recognizing and understanding the emotional expressions of others and naturalistic observations show that they use such expressions infrequently and inappropriately to regulate social exchanges. Dominant theories attribute this facet of the ASD phenotype to abnormalities in a social brain network that mediates social-motivational and social-cognitive processes such as face processing, mental state understanding, and empathy. Such theories imply that only emotion related processes relevant to social cognition are compromised in ASD but accumulating evidence suggests that the disorder may be characterized by more widespread anomalies in the domain of emotions. In this review I summarize the relevant literature and argue that the social-emotional characteristics of ASD may be better understood in terms of a disruption in the domain-general interplay between emotion and cognition. More specifically I will suggest that ASD is the developmental consequence of early emerging anomalies in how emotional responses to the environment modulate a wide range of cognitive processes including those that are relevant to navigating the social world.

Emotional face processing in neurotypicals with autistic traits: implications for the broad autism phenotype

The present study investigated emotional face processing in neurotypicals selected for autistic traits (AT). Participants (N=81), who obtained scores one standard deviation above or below average on the Autism Spectrum Quotient, were tested using observational fear conditioning (FC), a face version of the attention probe task, and the "Reading the Mind in the Eyes" test. The results indicated that high AT participants displayed enhanced observational FC, no attentional bias to fearful faces, and increased latency (but normal accuracy) to recognizing the mental state of another. To a certain extent, this pattern resembles the social-emotional phenotype that was previously described in autism spectrum disorders. Therefore, these results may contribute to the broad autism phenotype perspective.

Oxytocin reduces background anxiety in a fear-potentiated startle paradigm: peripheral vs central administration

Oxytocin is known to have anti-anxiety and anti-stress effects. Using a fear-potentiated startle paradigm in rats, we previously demonstrated that subcutaneously administered oxytocin suppressed acoustic startle following fear conditioning compared with startle before fear conditioning (termed background anxiety), but did not have an effect on cue-specific fear-potentiated startle. The findings suggest oxytocin reduces background anxiety, an anxious state not directly related to cue-specific fear, but sustained beyond the immediate threat. The goal of the present study was to compare the effects of centrally and peripherally administered oxytocin on background anxiety and cue-specific fear. Male rats were given oxytocin either subcutaneously (SC) or intracerebroventricularly (ICV) into the lateral ventricles before fear-potentiated startle testing. Oxytocin doses of 0.01 and 0.1 μg/kg SC reduced background anxiety. ICV administration of oxytocin at doses from 0.002 to 20 μg oxytocin had no effect on background anxiety or cue-specific fear-potentiated startle. The 20 μg ICV dose of oxytocin did reduce acoustic startle in non-fear conditioned rats. These studies indicate that oxytocin is potent and effective in reducing background anxiety when delivered peripherally, but not when delivered into the cerebroventricular system. Oxytocin given systemically may have anti-anxiety properties that are particularly germane to the hypervigilance and exaggerated startle typically seen in many anxiety and mental health disorder patients.

Impaired social interactions and motor learning skills in tuberous sclerosis complex model mice expressing a dominant/negative form of tuberin

Tuberous sclerosis complex (TSC) is a genetic disorder characterized by the development of hamartomas in multiple organs. Neurological manifestation includes cortical dysplasia, epilepsy, and cognitive deficits such as mental impairment and autism. We measured the impact of TSC2-GAP mutations on cognitive processes and behavior in, ΔRG transgenic mice that express a dominant/negative TSC2 that binds to TSC1, but has mutations affecting its GAP domain and its rabaptin-5 binding motif, resulting in inactivation of the TSC1/2 complex. We performed a behavioral characterization of the ΔRG transgenic mice and found that they display mild, but significant impairments in social behavior and rotarod motor learning. These findings suggest that the ΔRG transgenic mice recapitulate some behavioral abnormalities observed in human TSC patients.

The intense world theory - a unifying theory of the neurobiology of autism

Autism covers a wide spectrum of disorders for which there are many views, hypotheses and theories. Here we propose a unifying theory of autism, the Intense World Theory. The proposed neuropathology is hyper-functioning of local neural microcircuits, best characterized by hyper-reactivity and hyper-plasticity. Such hyper-functional microcircuits are speculated to become autonomous and memory trapped leading to the core cognitive consequences of hyper-perception, hyper-attention, hyper-memory and hyper-emotionality. The theory is centered on the neocortex and the amygdala, but could potentially be applied to all brain regions. The severity on each axis depends on the severity of the molecular syndrome expressed in different brain regions, which could uniquely shape the repertoire of symptoms of an autistic child. The progression of the disorder is proposed to be driven by overly strong reactions to experiences that drive the brain to a hyper-preference and overly selective state, which becomes more extreme with each new experience and may be particularly accelerated by emotionally charged experiences and trauma. This may lead to obsessively detailed information processing of fragments of the world and an involuntarily and systematic decoupling of the autist from what becomes a painfully intense world. The autistic is proposed to become trapped in a limited, but highly secure internal world with minimal extremes and surprises. We present the key studies that support this theory of autism, show how this theory can better explain past findings, and how it could resolve apparently conflicting data and interpretations. The theory also makes further predictions from the molecular to the behavioral levels, provides a treatment strategy and presents its own falsifying hypothesis.

Affective modulation of the startle eyeblink and postauricular reflexes in autism spectrum disorder

Eyeblink and postauricular reflexes to standardized affective images were examined in individuals without (n = 37) and with (n = 20) autism spectrum disorders (ASDs). Affective reflex modulation in control participants replicated previous findings. The ASD group, however, showed anomalous reflex modulation patterns, despite similar self-report ratings of pictures. Specifically, the ASD group demonstrated exaggerated eyeblink responses to pleasant images and exaggerated postauricular responses to unpleasant images. Although ASD is often conceptualized in terms of specific deficits in affective responding in the social domain, the present results suggest a domain-general pattern of deficits in affective processing and that such deficits may arise at an early phase in the stream of information processing.

Amygdala engagement in response to subthreshold presentations of anxious face stimuli in adults with autism spectrum disorders: preliminary insights

Current theoretical models of autism spectrum disorders (ASD) have proposed that impairments in the processing of social/emotional information may be linked to amygdala dysfunction. However, the extent to which amygdala functions are compromised in ASD has become a topic of debate in recent years. In a jittered functional magnetic resonance imaging study, sub-threshold presentations of anxious faces permitted an examination of amygdala recruitment in 12 high functioning adult males with ASD and 12 matched controls. We found heightened neural activation of the amygdala in both high functioning adults with ASD and matched controls. Neither the intensity nor the time-course of amygdala activation differed between the groups. However, the adults with ASD showed significantly lower levels of fusiform activation during the trials compared to controls. Our findings suggest that in ASD, the transmission of socially salient information along sub-cortical pathways is intact: and yet the signaling of this information to structures downstream may be impoverished, and the pathways that facilitate subsequent processing deficient.

Brief report: Attenuated emotional suppression of the attentional blink in Autism Spectrum Disorder: another non-social abnormality?

Twenty-five individuals with Autism Spectrum Disorder and 25 typically developed individuals participated in an Attentional Blink paradigm to determine whether emotional words would capture attention similarly in the two groups. Whilst the emotionality of words facilitated attention in typical comparison participants, this effect was attenuated in the ASD group. The magnitude of the emotional modulation of attention in ASD also correlated significantly with participants' VIQ, which was not observed for the comparison group. Together these observations replicate and extend the findings of Corden et al. (J Autism Develop Disord 38:1072-1080, 2008) and implicate abnormalities in emotional processes outside the broader context of social cognition in ASD. We discuss our findings in relation to possible abnormalities in amygdala function that may underlie the disorder.

Illusory memories of emotionally charged words in autism spectrum disorder: further evidence for atypical emotion processing outside the social domain

Recent evidence suggests that individuals with ASD may not accumulate distinct representations of emotional information throughout development. On the basis of this observation we predicted that such individuals would not be any less likely to falsely remember emotionally significant as compared to neutral words when such illusory memories are induced by asking participants to study lists of words that are orthographically associated to these words. Our findings showed that typical participants are far less likely to experience illusory memories of emotionally charged as compared to neutral words. Individuals with ASD, on the other hand, did not exhibit this emotional modulation of false memories. We discuss this finding in relation to the role of emotional processing atypicalities in ASD.

Enhanced long-term microcircuit plasticity in the valproic Acid animal model of autism

A single intra-peritoneal injection of valproic acid (VPA) on embryonic day (ED) 11.5 to pregnant rats has been shown to produce severe autistic-like symptoms in the offspring. Previous studies showed that the microcircuitry is hyperreactive due to hyperconnectivity of glutamatergic synapses and hyperplastic due to over-expression of NMDA receptors. These changes were restricted to the dimensions of a minicolumn (<50 μm). In the present study, we explored whether Long Term Microcircuit Plasticity (LTMP) was altered in this animal model. We performed multi-neuron patch-clamp recordings on clusters of layer 5 pyramidal cells in somatosensory cortex brain slices (PN 12-15), mapped the connectivity and characterized the synaptic properties for connected neurons. Pipettes were then withdrawn and the slice was perfused with 100 μM sodium glutamate in artificial cerebrospinal fluid in the recording chamber for 12 h. When we re-patched the same cluster of neurons, we found enhanced LTMP only at inter-somatic distances beyond minicolumnar dimensions. These data suggest that hyperconnectivity is already near its peak within the dimensions of the minicolumn in the treated animals and that LTMP, which is normally restricted to within a minicolumn, spills over to drive hyperconnectivity across the dimensions of a minicolumn. This study provides further evidence to support the notion that the neocortex is highly plastic in response to new experiences in this animal model of autism.

Startle modulation in autism: positive affective stimuli enhance startle response

Behavioral evidence suggests that emotion processing deficits in individuals with autism spectrum disorders (ASD) may occur at the level of basic (early, rapid, automatic) affective processes. Consistently, neurological evidence indicates that key brain areas associated with basic affective processing are atypical in ASD. The current study sought to better specify these deficits by comparing different components of basic affective processing in 14 adolescents and adults with ASD and 14 typical controls matched for age and verbal ability. Participants viewed affective pictures, and their responses were assessed with (i) affective eyeblink startle modulation, an indicator of the brain's aversive motivational system; (ii) facial electromyography, an online indicator of implicit valence appraisal; and (iii) self-report, an indicator of overt valence appraisal. The results show that in contrast to the typical pattern, in which exposure to negative stimuli increases startle whereas exposure to positive stimuli decreases startle, individuals with ASD showed startle potentiation to both positive and negative stimuli. Atypical potentiation during positive stimuli occurred despite individuals with ASD demonstrating appropriate implicit valence appraisals, reflected in their facial EMG responses, and appropriate overt appraisals, reflected in their self-reported ratings of the stimuli. Potentiation of startle to both positive and negative stimuli suggests a disruption in basic affective processes in ASD at the level of the early motivational response. This atypical pattern of responses has implications for understanding social and emotion deficits in ASD and calls for further investigation of basic affective processes.

Free recall and forgetting of emotionally arousing words in autism spectrum disorder

Since the earliest descriptions of individuals with autism spectrum disorders (ASDs) abnormalities in affective behaviours have been considered a prominent feature in their clinical manifestations. What remains unclear, however, is whether these altered emotional behaviours are a mere facet of abnormalities in socio-cognitive processes or whether they constitute a primary feature of the condition. A number of studies now indicate that emotional processing atypicalities in ASD extend to domains outside the broader context of social cognition leading us to suggest that the disorder may be characterised by basic abnormalities in how psychophysiological and cognitive emotional responses modulate one another [Gaigg, S. B. & Bowler, D. M. (2007). Differential fear conditioning in Asperger's syndrome: Implications for an amygdala theory of autism. Neuropsychologia, 45, 2125-2134]. In the current study, we show that although individuals with ASD, like typical individuals, exhibit a free recall advantage for emotionally arousing and semantically related neutral as compared to unrelated neutral words, they do not show reduced forgetting rates for arousing stimuli as do typical individuals. These observations provide further support for the view that psychophysiological emotional responses do not modulate cognitive processes normally in ASD and further implicate abnormalities of amygdala connectivity (in particular with the hippocampus) in the neuropathology underlying this disorder.

Fine cuts of empathy and the amygdala: dissociable deficits in psychopathy and autism

In the current paper, the "fine cuts" approach advocated by Uta Frith is applied to our understanding of empathy and amygdala dysfunction in two disorders, psychopathy and autism. A fine cut is made between cognitive (i.e., Theory of Mind) and emotional empathy. The literature with respect to psychopathy and autism and these two functions is then considered. A fine cut is also made between the amygdala's role in stimulus-reinforcement association and specific aspects of social cognition. Again the literature with respect to psychopathy and autism and these two functions of the amygdala is considered. It is concluded that while both conditions can be considered disorders of social cognition, fine cuts can be made dissociating the impairments associated with each.

Abnormal fear conditioning and amygdala processing in an animal model of autism

A core feature of autism spectrum disorders is the impairment in social interactions. Among other brain regions, a deficit in amygdala processing has been suggested to underlie this impairment, but whether the amygdala is processing fear abnormally in autism, is yet not clear. We used the valproic acid (VPA) rat model of autism to (a) screen for autism-like symptoms in rats, (b) test for alterations in amygdala-dependent fear processing, and (c) evaluate neuronal reactivity and synaptic plasticity in the lateral amygdala by means of in vitro single-cell electrophysiological recordings. VPA-treated animals displayed several symptoms common to autism, among them impaired social interactions and increased repetitive behaviors. Furthermore, VPA-treated rats were more anxious and exhibited abnormally high and longer lasting fear memories, which were overgeneralized and harder to extinguish. On the cellular level, the amygdala was hyperreactive to electrical stimulation and displayed boosted synaptic plasticity as well as a deficit in inhibition. We show for the first time enhanced, overgeneralized and resistant conditioned fear memories in an animal model of autism. Such hyperfear could be caused by the hyperreactivity and hyperplasticity found in the lateral amygdala, which may in turn be due to a deficit in the inhibitory system of the amygdala. We hypothesize an 'aversive world' syndrome that could, even if not a primary cause of the disorder itself, underlie some core symptoms in autism, such as impairments in social interactions and resistance to rehabilitation.

Intact emotion facilitation for nonsocial stimuli in autism: is amygdala impairment in autism specific for social information?

Atypical amygdala development may play a key role in the emergence of social disability and other symptoms of autism (Baron-Cohen et al., 2000; Schultz, 2005). The mechanisms by which this may occur have received little attention, however, and most support from behavioral and imaging studies has been concerned with socially relevant stimuli such as faces. Given the complexity of amygdala function and its known role in many other emotional tasks, we examined whether individuals with autism would demonstrate impaired performance on several tasks that have been shown to require activation of the amygdala but that do not have any explicit social meaning. Relative to a typical comparison group matched for age and IQ, our sample of 37 adolescents and adults with autism (mean age=19.7 years) demonstrated equivalent facilitation for perception and learning of emotionally relevant stimuli. On each of four tasks, there were significant main effects of emotion condition on performance for both groups. Future research regarding atypical amygdala function and emotion processing in autism should consider whether the response to nonsocial emotion factors (including negative valence or high arousal) may be intact, despite difficulties in responding to socially relevant stimuli.

The intense world syndrome--an alternative hypothesis for autism

Autism is a devastating neurodevelopmental disorder with a polygenetic predisposition that seems to be triggered by multiple environmental factors during embryonic and/or early postnatal life. While significant advances have been made in identifying the neuronal structures and cells affected, a unifying theory that could explain the manifold autistic symptoms has still not emerged. Based on recent synaptic, cellular, molecular, microcircuit, and behavioral results obtained with the valproic acid (VPA) rat model of autism, we propose here a unifying hypothesis where the core pathology of the autistic brain is hyper-reactivity and hyper-plasticity of local neuronal circuits. Such excessive neuronal processing in circumscribed circuits is suggested to lead to hyper-perception, hyper-attention, and hyper-memory, which may lie at the heart of most autistic symptoms. In this view, the autistic spectrum are disorders of hyper-functionality, which turns debilitating, as opposed to disorders of hypo-functionality, as is often assumed. We discuss how excessive neuronal processing may render the world painfully intense when the neocortex is affected and even aversive when the amygdala is affected, leading to social and environmental withdrawal. Excessive neuronal learning is also hypothesized to rapidly lock down the individual into a small repertoire of secure behavioral routines that are obsessively repeated. We further discuss the key autistic neuropathologies and several of the main theories of autism and re-interpret them in the light of the hypothesized Intense World Syndrome.

Tactile sensitivity of normal and autistic children

Many children with autistic spectrum disorders have unusual reactions to certain sensory stimuli. These reactions vary along a hyper- to hypo-responsivity continuum. For example, some children overreact to weak sensory input, but others do not respond negatively to even strong stimuli. It is typically assumed that this deviant responsivity is linked to sensitivity, although the particular stage of sensory processing affected is not known. Psychophysical vibrotactile thresholds of six male children (age: 8-12) who were diagnosed to have autistic spectrum disorders and six normal male children (age: 7-11) were measured by using a two-alternative forced-choice task. The tactile stimuli were sinusoidal displacements and they were applied on the terminal phalanx of the left middle finger of each subject. By using a forward-masking paradigm, 40- and 250-Hz thresholds of the Pacinian tactile channel and 40-Hz threshold of the Non-Pacinian I tactile channel were determined. There was no significant difference between the thresholds of autistic and normal children, and the autistic children had the same detection and masking mechanisms as the normal children. The sensory responsivity of each subject was tested by clinical questionnaires, which showed again no difference between the two subject groups. Furthermore, no significant correlations could be found between the questionnaire data and the psychophysical thresholds. However, there was a high correlation between the data from the tactile and emotional subsets of the questionnaires. These results support the hypothesis that the hyper- and hypo-responsivity to touch, which is sometimes observed in autistic spectrum disorders, is not a perceptual sensory problem, but may probably be emotional in origin.

Brief Report: Emotional Processing in High-Functioning Autism—Physiological Reactivity and Affective Report

This study examined physiological response and affective report in 10 adult individuals with autism and 10 typically developing controls. An emotion induction paradigm using stimuli from the International Affective Picture System was applied. Blood pressure, heart and self-ratings of experienced valence (pleasure), arousal and dominance (control) were assessed during the experiment. Physiological response profiles correlated low to significantly negative between groups. Individuals with autism experienced less arousal when viewing sad pictures but higher arousal while processing neutral stimuli. In addition, they reported more control than the normative group when viewing fearful and sad stimuli. Findings indicate altered physiological reactivity and affective report in autism, which may be related to more general impairments in socio-emotional functioning.

Impaired recognition of negative basic emotions in autism: a test of the amygdala theory

Autism and Asperger Syndrome are autism spectrum conditions (ASC) characterized by deficits in understanding others' minds, an aspect of which involves recognizing emotional expressions. This is thought to be related to atypical function and structure of the amygdala, and performance by people with ASC on emotion recognition tasks resembles that seen in people with acquired amygdala damage. In general, emotion recognition findings in ASC have been inconsistent, which may reflect low numbers of participants, low numbers of stimuli and trials, heterogeneity of symptom severity within ASC groups, and ceiling effects on some tasks. The present study tested 39 male adults with ASC and 39 typical male controls on a task of basic emotion recognition from photographs, in two separate experiments. On a control face discrimination task the group with ASC were not impaired. People with ASC were less accurate on the emotion recognition task compared to controls, but only for the negative basic emotions. This is discussed in the light of similar findings from people with damage to the amygdala.