Enhanced Perceptual Functioning in Autism: An Update, and Eight Principles of Autistic Perception

We propose an "Enhanced Perceptual Functioning" model encompassing the main differences between autistic and non-autistic social and non-social perceptual processing: locally oriented visual and auditory perception, enhanced low-level discrimination, use of a more posterior network in "complex" visual tasks, enhanced perception of first order static stimuli, diminished perception of complex movement, autonomy of low-level information processing toward higher-order operations, and differential relation between perception and general intelligence. Increased perceptual expertise may be implicated in the choice of special ability in savant autistics, and in the variability of apparent presentations within PDD (autism with and without typical speech, Asperger syndrome) in non-savant autistics. The overfunctioning of brain regions typically involved in primary perceptual functions may explain the autistic perceptual endophenotype.     

Perception metamorphosis phenomenon in autism

Abstract  It is well known that various perceptual abnormalities exist in autism. However, because perceptual phenomena are intersubjective, a phenomenological approach is required for getting hold of the reality of the modes of perception involved in autism. From this standpoint, the author has proposed the concept of 'perception metamorphosis phenomenon' (PMP) as the mode of perception peculiar to autistics. This mode of perception is notable to some degree in infancy and adolescence, and points to the appearance of behavior that is indicative of the environmental world being perceived in a manner different from before by the autistic child. The phenomenon has been classified into three basic categories according to the aspect of perception: (i) visual PMP; (ii) auditory PMP; and (iii) situational PMP. The proposal of this concept was made with the objective of capturing the onset of autism or the mechanism of appearance of the various symptoms from a more phenomenological viewpoint, to serve as a possible starting point for understanding the inner world of autistics. The proposal was made emphasizing the validity of this approach in mapping out new therapeutic approaches and for re-investigating the relationship between autism and schizophrenia.     

Physiognomic perception, vitality affect and delusional perception in autism

The relationship between autism and schizophrenia has been denied from the symptomatological and epidemiological standpoints. However, the mechanism whereby psychotic symptoms appear in association with autism has not been investigated at any length. Therefore, an investigation was conducted on how the unique modes of perception in autism are related to the psychotic symptoms observed. Through the therapy of one case of adolescent autism, the author points out the existence of physiognomic perception and vitality affect as characteristic modes of perception in autism. It was inferred that should autistics be placed under circumstances forcing them to withdraw from open communalism, their unique interpretation of the environmental world could give rise to psychopathological phenomena which would be considered delusional perception.     

Tracing the time course of emotion perception: the impact of stimulus physics and semantics on gesture processing

Numerous event-related brain potential (ERP) studies reveal the differential processing of emotional and neutral stimuli. Yet, it is an ongoing debate to what extent the ERP components found in previous research are sensitive to physical stimulus characteristics or emotional meaning. This study manipulated emotional meaning and stimulus orientation to disentangle the impact of stimulus physics and semantics on emotional stimulus processing. Negative communicative hand gestures of Insult were contrasted with neutral control gestures of Allusion to manipulate emotional meaning. An elementary physical manipulation of visual processing was implemented by presenting these stimuli vertically and horizontally. The results showed dissociable effects of stimulus meaning and orientation on the sequence of ERP components. Effects of orientation were pronounced in the P1 and N170 time frames and attenuated during later stages. Emotional meaning affected the P1, evincing a distinct topography to orientation effects. Although the N170 was not modulated by emotional meaning, the early posterior negativity and late positive potential components replicated previous findings with larger potentials elicited by the Insult gestures. These data suggest that the brain processes different attributes of an emotional picture in parallel and that a coarse semantic appreciation may already occur during relatively early stages of emotion perception.     

Can Spectro-Temporal Complexity Explain the Autistic Pattern of Performance on Auditory Tasks?

To test the hypothesis that level of neural complexity explain the relative level of performance and brain activity in autistic individuals, available behavioural, ERP and imaging findings related to the perception of increasingly complex auditory material under various processing tasks in autism were reviewed. Tasks involving simple material (pure tones) and/or low-level operations (detection, labelling, chord disembedding, detection of pitch changes) show a superior level of performance and shorter ERP latencies. In contrast, tasks involving spectrally- and temporally-dynamic material and/or complex operations (evaluation, attention) are poorly performed by autistics, or generate inferior ERP activity or brain activation. Neural complexity required to perform auditory tasks may therefore explain pattern of performance and activation of autistic individuals during auditory tasks.     

EEG power and coherence in autistic spectrum disorder.

OBJECTIVE: Autistic spectrum disorder (ASD) has been defined as a neurodevelopmental disorder with associated deficits in executive function, language, emotional, and social function. ASD has been associated with pathophysiology in cerebral organization. The current study investigated quantitative EEG findings in twenty children diagnosed with autistic disorders as compared to 20 controls matched for gender, age and IQ. METHODS: The EEG was recorded during an eyes-closed resting condition and topographical differences in cerebral functioning were examined using estimates of absolute, relative, and total power, as well as intrahemispheric and interhemispheric coherences. RESULTS: There were group differences in power, intrahemispheric and interhemispheric coherences. Findings included excessive theta, primarily in right posterior regions, in autistics. There was also a pattern of deficient delta over the frontal cortex and excessive midline beta. More significantly, there was a pattern of underconnectivity in autistics compared to controls. This included decreased intrahemispheric delta and theta coherences across short to medium and long inter-electrode distances. Interhemispherically, delta and theta coherences were low across the frontal region. Delta, theta and alpha hypocoherence was also evident over the temporal regions. Lastly, there were low delta, theta and beta coherence measurements across posterior regions. CONCLUSIONS: These results suggest dysfunctional integration of frontal and posterior brain regions in autistics along with a pattern of neural underconnectivity. This is consistent with other EEG, MRI and fMRI research suggesting that neural connectivity anomalies are a major deficit leading to autistic symptomatology. SIGNIFICANCE: This paper reports the largest integrated study of EEG power and coherence during a resting state in children suffering autism spectrum disorder.     

The framework for disturbed affective consciousness in autism

The current article explores the implication of the interaction of emotion and consciousness for autism. The framework that is proposed for the disorder explains that the compromised functional integrity of the amygdala is the root cause of disturbed affective consciousness. Amygdala, with its connections to various cortical and subcortical regions, helps detect a fearful facial expression at the attentional periphery and make it the focus of attention and awareness for enhanced processing. The conscious life of autistics with respect to affective objects can thus be very different from that of normal people, which leads them to perceive the world differently. They process fearful stimuli the way normal controls perceive common objects by activating areas responsible for feature based analysis rather than the amygdala and other connected areas. Conscious perception of such stimuli is important for appropriate development of emotion concepts, something that autistics lack, thus leading to impairment in the awareness of one's own emotions especially within the negative spectrum with a prominent position for fearful stimuli. Thus the interaction of emotion with consciousness is ripe for investigation and can help to throw light on the mental life of autistics.     

Brief Report: Recognition of Emotional and Non-emotional Biological Motion in Individuals with Autistic Spectrum Disorders

This study aimed to explore the perception of different components of biological movement in individuals with autism and Asperger syndrome. The ability to recognize a person's actions, subjective states, emotions, and objects conveyed by moving point-light displays was assessed in 19 participants with autism and 19 comparable typical control participants. Results showed that the participants with autism were as able as controls to name point-light displays of non-human objects and human actions. In contrast, they were significantly poorer at labeling emotional displays, suggesting that they are specifically impaired in attending to emotional states. Most studies have highlighted an emotional deficit in facial expression perception; our results extend this hypothesized deficit to the perception and interpretation of whole-body biological movements.     

Emotional contagion for pain is intact in autism spectrum disorders

Perceiving others in pain generally leads to empathic concern, consisting of both emotional and cognitive processes. Empathy deficits have been considered as an element contributing to social difficulties in individuals with autism spectrum disorders (ASD). Here, we used functional magnetic resonance imaging and short video clips of facial expressions of people experiencing pain to examine the neural substrates underlying the spontaneous empathic response to pain in autism. Thirty-eight adolescents and adults of normal intelligence diagnosed with ASD and 35 matched controls participated in the study. In contrast to general assumptions, we found no significant differences in brain activation between ASD individuals and controls during the perception of pain experienced by others. Both groups showed similar levels of activation in areas associated with pain sharing, evidencing the presence of emotional empathy and emotional contagion in participants with autism as well as in controls. Differences between groups could be observed at a more liberal statistical threshold, and revealed increased activations in areas involved in cognitive reappraisal in ASD participants compared with controls. Scores of emotional empathy were positively correlated with brain activation in areas involved in embodiment of pain in ASD group only. Our findings show that simulation mechanisms involved in emotional empathy are preserved in high-functioning individuals with autism, and suggest that increased reappraisal may have a role in their apparent lack of caring behavior.     

Differential cerebral activation during observation of expressive gestures and motor acts

We compared brain activation involved in the observation of isolated right hand movements (e.g. twisting a lid), body-referred movements (e.g. brushing teeth) and expressive gestures (e.g. threatening) in 20 healthy subjects by using functional magnetic resonance imaging (fMRI). Perception-related areas in the occipital and inferior temporal lobe but also the mirror neuron system in the lateral frontal (ventral premotor cortex and BA 44) and superior parietal lobe were active during all three conditions. Observation of body-referred compared to common hand actions induced increased activity in the bilateral posterior superior temporal sulcus (STS), the left temporo-parietal lobe and left BA 45. Expressive gestures involved additional areas related to social perception (bilateral STS, temporal poles, medial prefrontal lobe), emotional processing (bilateral amygdala, bilateral ventrolateral prefrontal cortex (VLPFC), speech and language processing (Broca's and Wernicke's areas) and the pre-supplementary motor area (pre-SMA). In comparison to body-referred actions, expressive gestures evoked additional activity only in the left VLPFC (BA 47). The valence-ratings for expressive gestures correlated significantly with activation intensity in the VLPFC during expressive gesture observation. Valence-ratings for negative expressive gestures correlated with right STS-activity. Our data suggest that both, the VLPFC and the STS are coding for differential emotional valence during the observation of expressive gestures.     

The Autism-Spectrum Quotient and Visual Search: Shallow and Deep Autistic Endophenotypes

A high Autism-Spectrum Quotient (AQ) score (Baron-Cohen et al. in J Autism Dev Disord 31(1):5–17, 2001) is increasingly used as a proxy in empirical studies of perceptual mechanisms in autism. Several investigations have assessed perception in non-autistic people measured for AQ, claiming the same relationship exists between performance on perceptual tasks in high-AQ individuals as observed in autism. We question whether the similarity in performance by high-AQ individuals and autistics reflects the same underlying perceptual cause in the context of two visual search tasks administered to a large sample of typical individuals assessed for AQ. Our results indicate otherwise and that deploying the AQ as a proxy for autism introduces unsubstantiated assumptions about high-AQ individuals, the endophenotypes they express, and their relationship to Autistic Spectrum Conditions (ASC) individuals.     

Infantile autism: adult outcome

Although the core features of autism do not change qualitatively, a gradual overall symptomatic improvement including an increase in adaptive skills is observed in most cases with age. Follow-up studies show that the diagnostic features, the differential diagnosis, and clinical problems of adult autistics differ substantially from that of autistic children. The differential diagnosis of older autistics include personality disorders, learning disabilities, and mood disorder. Depression, epilepsy, and behavioral problems such as aggression and agitation may be major clinical problems during adolescence. The early indicators of a better outcome include a higher level of IQ and language. Among the neuropsychological variables, measures of flexibility and cognitive shift are important as prognostic factors. Early behavioral and educational intervention may especially increase the adaptive skills of the patients and promote the in-family communication. The outcome studies of autism are particularly helpful in addressing the appropriate and most effective programs of remediation for adult autistics.     

Platelet imipramine binding in autistic subjects

Previous reports of elevated platelet serotonin (5-HT) concentrations in autistic subjects suggest that platelet 5-HT uptake might be altered in autism. Parameters of 3H-imipramine (IMI) binding were measured in 11 drug-free autistic subjects and 10 normal volunteers. Similar means (+/- SD) for Bmax (autistics, 1350 +/- fmole/mg protein; normals, 1590 +/- 206 fmole/mg protein) and Kd (autistics, 0.98 +/- 0.10 nM; normals, 0.94 +/- 0.13 nM) were found in the two groups. The normal number (Bmax) and affinity (Kd) of the IMI binding site in autistic subjects suggest that the regulation of 5-HT uptake is not different in autism.     

Differential activation of the amygdala and the 'social brain' during fearful face-processing in Asperger Syndrome

Impaired social cognition is a core feature of autism. There is much evidence showing people with autism use a different cognitive style than controls for face-processing. We tested if people with autism would show differential activation of social brain areas during a face-processing task. Thirteen adults with high-functioning autism or Asperger Syndrome (HFA/AS) and 13 matched controls. We used fMRI to investigate 'social brain' activity during perception of fearful faces. We employed stimuli known to reliably activate the amygdala and other social brain areas, and ROI analyses to investigate brain areas responding to facial threat as well as those showing a linear response to varying threat intensities. We predicted: (1) the HFA/AS group would show differential activation (as opposed to merely deficits) of the social brain compared to controls and (2) that social brain areas would respond to varied intensity of fear in the control group, but not the HFA/AS group. Both predictions were confirmed. The controls showed greater activation in the left amygdala and left orbito-frontal cortex, while the HFA/AS group showed greater activation in the anterior cingulate gyrus and superior temporal cortex. The control group also showed varying responses in social brain areas to varying intensities of fearful expression, including differential activations in the left and right amygdala. This response in the social brain was absent in the HFA/AS group. HFA/AS are associated with different patterns of activation of social brain areas during fearful emotion processing, and the absence in the HFA/AS brain of a response to varying emotional intensity.     

Traitement de l’information faciale dans l’autisme

One of the core deficits of autistic pathology is disturbances in reciprocal social interactions. As faces are essential components of social interactions, many studies have explored face processing in autism. The present paper reviews behavioural and neuroimaging studies on neutral and emotional face processing. After hypothesis of deficit of face processing in autism, recent data suggest atypical perceptual processing of faces. Indeed, individuals with autism pay less attention to eyes’ region than typically developing persons and present a local bias, contrasting with configural processing of faces in non-autistic individuals. Furthermore, people with autism do not display automatic process typically induced in persons without autism by perception of emotional faces. Peculiarities of processing are also observed at the neurobiological level. Persons with autism do not activate the same brain regions than typically developing participants during facial information processing and do not exhibit the same pattern of evoked cerebral responses. However, to date, there is no data converging to the dysfunction of a specific cerebral area in autistic pathology. Recent hypothesis suggest alteration of cerebral connectivity instead of one neural structure. These peculiarities of processing are discussed in terms of social experience and expertise in face processing.     

Disrupted action perception in autism: behavioral evidence, neuroendophenotypes, and diagnostic utility

Disruptions in the visual perception of biological motion are emerging as a hallmark of autism spectrum disorder (ASD), consistent with the pathognomonic social deficits of this neurodevelopmental disorder. Accumulating evidence suggests an early and marked divergence in ASD from the typical developmental tuning of brain regions to process social information. In this review, we discuss a relatively recent yet substantial literature of behavioral and neuroimaging studies that consistently indicates impairments in biological motion perception in ASD. We then illustrate the fundamental disruption in this form of social perception in autism, drawing connections between a genetic liability to develop autism and disrupted associated brain mechanisms, as we describe neuroendophenotypes of autism derived from an fMRI study of biological motion perception in children with autism and their unaffected siblings. Finally, we demonstrate the diagnostic utility of brain responses to biological motion. With the ability to measure brain function in the first year of life comes the potential to chart the development of disrupted biological motion processing in ASD and to specify the gene-brain-behavior interactions shaping this atypical trajectory. We propose that a comprehensive understanding of the development of impaired responses to biological motion in ASD can inform future diagnosis and treatment approaches.     

Etiological implication of maternal age and birth order in infantile autism

Birth orders and maternal ages of the 113 autistic patients were compared with those of the general population. An excess of mothers aged 35 or older was observed in the autistic group, though the mean maternal age for the whole group was very similar to those of the general population. A deviation from average in birth order was observed in autistics. Significantly more autistics were products of at-risk pregnancies (defined as either first, fourth, or later born, or born to mothers aged 30 or older) than the base population. The results suggest that at least some environmental factors are involved in the causation of autism. The findings support the idea that a multifactorial mechanism is responsible for some or all of the cases.     

Perception of emotions from facial expressions in high-functioning adults with autism

Impairment in social communication is one of the diagnostic hallmarks of autism spectrum disorders, and a large body of research has documented aspects of impaired social cognition in autism, both at the level of the processes and the neural structures involved. Yet one of the most common social communicative abilities in everyday life, the ability to judge somebody's emotion from their facial expression, has yielded conflicting findings. To investigate this issue, we used a sensitive task that has been used to assess facial emotion perception in a number of neurological and psychiatric populations. Fifteen high-functioning adults with autism and 19 control participants rated the emotional intensity of 36 faces displaying basic emotions. Every face was rated 6 times—once for each emotion category. The autism group gave ratings that were significantly less sensitive to a given emotion, and less reliable across repeated testing, resulting in overall decreased specificity in emotion perception. We thus demonstrate a subtle but specific pattern of impairments in facial emotion perception in people with autism.     

Language patterns of adolescent autistics

The language samples of seven verbal autistic adolescents were analyzed. Linguistic deficits were compared to characteristics reported for preteen autistics and described structurally. Only four subjects demonstrated linguistic impairments. These clustered primarily in the area of prosodic features, semantic cooccurrence constraints and general disfluency. No such clustering had been reported for the preteen population. No correlation between linguistic deficits, IQ, and age was found. However, performance on the Seashore Test for Musical Ability correlated highly with linguistic performance. Results suggest that (a) autism includes linguistically, and possibly etiologically, distinct subgroups; (b) the basic linguistic deficits in autism may be more specific than thought previously; and (c) perception of prosodie features may be crucial for decoding and encoding linguistic signals. Autistic children may be lacking in this ability.     

Dissociable neural pathways for the perception and recognition of expressive and instrumental gestures

Previous functional imaging studies have sought to characterize the neural correlates of gesture representation. However, little is yet known about the representation of different categories of gesture. Here we contrasted the perception of hand gestures that express inner feeling states, e.g. I am angry, I do not care, with the perception of instrumental gestures intended to change the behavior of others by communicating commands, e.g. come here, look over there. We hypothesised that recognition of expressive gestures would activate a network of brain regions associated with mentalising ('theory of mind') whereas instrumental gestures would activate different neural pathways. Twelve normal volunteers underwent fMRI while they watched a series of short videos (3 s duration) of actors performing expressive and instrumental gestures. The volunteers had either to recognise the gesture or to monitor the positions of the hands. As predicted, different neural networks were activated by the observation of instrumental or expressive gestures. The perception of expressive gestures elicited activity in the anterior paracingulate cortex, the amygdala and the temporal poles bilaterally and the right superior temporal sulcus. These regions have all previously been activated during the performance of mentalising tasks. In contrast, instrumental gestures elicited activity in a left-lateralised system previously associated with language and motor imitation.