T. Nieminen-von Wendt

Auditory perception and attention as reflected by the brain event-related potentials in children with Asperger syndrome

OBJECTIVE Language development is delayed and deviant in individuals with autism, but proceeds quite normally in those with Asperger syndrome (AS). We investigated auditory-discrimination and orienting in children with AS using an event-related potential (ERP) paradigm that was previously applied to children with autism. METHODS ERPs were measured to pitch, duration, and phonetic changes in vowels and to corresponding changes in non-speech sounds. Active sound discrimination was evaluated with a sound-identification task. RESULTS The mismatch negativity (MMN), indexing sound-discrimination accuracy, showed right-hemisphere dominance in the AS group, but not in the controls. Furthermore, the children with AS had diminished MMN-amplitudes and decreased hit rates for duration changes. In contrast, their MMN to speech pitch changes was parietally enhanced. The P3a, reflecting involuntary orienting to changes, was diminished in the children with AS for speech pitch and phoneme changes, but not for the corresponding non-speech changes. CONCLUSIONS The children with AS differ from controls with respect to their sound-discrimination and orienting abilities. SIGNIFICANCE The results of the children with AS are relatively similar to those earlier obtained from children with autism using the same paradigm, although these clinical groups differ markedly in their language development.

Neurophysiological evidence for cortical discrimination impairment of prosody in Asperger syndrome.

Asperger syndrome (AS), belonging to the autism spectrum of disorders, is one of the pervasive developmental disorders. Individuals with AS usually have normal development of formal speech but pronounced problems in perceiving and producing speech prosody. The present study addressed the discrimination of speech prosody in AS by recording the mismatch negativity (MMN) and behavioural responses to natural utterances with different emotional connotations. MMN responses were abnormal in the adults with AS in several ways. In these subjects, fewer significantly elicited MMNs, diminished MMN amplitudes, as well as prolonged latencies were found. In addition, the MMN generator loci differed between the subjects with AS and control subjects. These findings were predominant over the right cerebral hemisphere. These results show impaired neurobiological basis for speech-prosody processing at an early, pre-attentive auditory discrimination stage in AS.

Genome-wide scan for loci of Asperger syndrome

Asperger syndrome (AS), characterised by inadequate social interaction, lack of empathy and a dependence of routines and rituals, is classified as belonging to the autism spectrum disorders (DSM-IV and ICD-10). Although the prevalence of AS has been estimated to range from 0.3 up to 48.4 per 10 000, the phenotype still remains relatively unrecognised by clinicians. Several reports, including the original description by Hans Asperger (1944), have suggested that AS has a strong genetic component. Here, we have performed a genome-wide scan on Finnish families ascertained for AS with a strictly defined phenotype. In the initial scan, Zmax>1.5 was observed on nine chromosomal regions, 1q21–22, 3p14–24, 3q25–27, 4p14, 4q32, 6p25, 6q16, 13q31–33 and 18p11. In the fine mapping stage, the highest two-point LOD scores were observed on chromosomes 1q21–22 (D1S484, Zmax dom=3.58), 3p14–24 (D3S2432, Zmax dom=2.50) and 13q31–33 (D13S793, Zmax dom=1.59). The loci on 1q21–22 and 3p14–24 overlap with previously published autism susceptibility loci, and the loci on 1q21–22 and 13q31–33 overlap with the reported schizophrenia susceptibility loci. The present study is the first genome-wide screen in AS and therefore replication data sets are needed to evaluate further the significance of the AS-loci identified here.

Changes in cerebral blood flow in Asperger syndrome during theory of mind tasks presented by the auditory route.

Abstract. Lack of theory of mind (ToM) has been considered to be a key feature in Asperger syndrome (AS). The main aim of the present study was to determine whether an exclusively auditory input of ToM stories activated the same brain areas as demonstrated previously using visual stimuli. Eight righthanded otherwise healthy men with AS and eight healthy righthanded male controls participated in a PET activation study using auditory given ToM stories and stories about physical events for induction. Both subjects with AS and controls showed increased activation in the occipitotemporal area bilaterally and in thalamus during ToM tasks. Both groups also showed activation in the medial frontal area during ToM tests. However, this activation was more intensive and extensive in the control group, especially when a more sensitive analysis method was used. As a group, unrelated to the tasks, the AS subjects showed increased activation of the cerebellum. It was concluded that the activation pattern was mainly in agreement with earlier studies using comparable stimuli administered differently. There was no support for a right hemisphere specific dysfunction.

Atypical pattern of discriminating sound features in adults with Asperger syndrome as reflected by the mismatch negativity.

Asperger syndrome, which belongs to the autistic spectrum of disorders, is characterized by deficits of social interaction and abnormal perception, like hypo- or hypersensitivity in reacting to sounds and discriminating certain sound features. We determined auditory feature discrimination in adults with Asperger syndrome with the mismatch negativity (MMN), a neural response which is an index of cortical change detection. We recorded MMN for five different sound features (duration, frequency, intensity, location, and gap). Our results suggest hypersensitive auditory change detection in Asperger syndrome, as reflected in the enhanced MMN for deviant sounds with a gap or shorter duration, and speeded MMN elicitation for frequency changes.

Auditory stream segregation in children with Asperger syndrome

Individuals with Asperger syndrome (AS) often have difficulties in perceiving speech in noisy environments. The present study investigated whether this might be explained by deficient auditory stream segregation ability, that is, by a more basic difficulty in separating simultaneous sound sources from each other. To this end, auditory event-related brain potentials were recorded from a group of school-aged children with AS and a group of age-matched controls using a paradigm specifically developed for studying stream segregation. Differences in the amplitudes of ERP components were found between groups only in the stream segregation conditions and not for simple feature discrimination. The results indicated that children with AS have difficulties in segregating concurrent sound streams, which ultimately may contribute to the difficulties in speech-in-noise perception.

A quantitative controlled MRI study of the brain in 28 persons with Asperger syndrome

Background: As structural brain abnormalities have been reported in infantile autism, the aim of this study was to determine whether such findings also exist in Asperger Syndrome (AS). Methods: The diagnosis of Asperger Syndrome was based on the criteria in ICD-10 and DSM-IV. Brain magnetic resonance imaging (MRI) was performed with a 1.5 T imager. T2-weighted axial and coronal slices and T1- weighted three dimensional sagittal slices were obtained and visual and quantitative analysis were performed. Subjects: There were 28 Asperger individuals, 17 children and adolescents (age 6–19 years, mean 12.4 years), 11 adults (age 20–60 years, mean 37. 9 years) and 28 healthy age and gender matched controls. Results: Mild inconsistent alterations were detected in 13/28 of the individuals with Asperger Syndrome compared to 6/23 in the comparable controls. There were no differences between the right and left hemispheres, nor was there any abnormality in terms of myelination or migration. The anterior-posterior diameters of the mesencephalon were statistically significantly shorter in the Asperger syndrome individuals than in the controls. Conclusions: No consistent focal brain abnormalities for Asperger Syndrome were detected. The reduced diameters of the mesencephalon in the Asperger group support the hypothesis that the mesencephalon may be involved in the pathogenesis of Asperger Syndrome.

Atypical perceptual and neural processing of emotional prosodic changes in children with autism spectrum disorders

OBJECTIVE The present study explored the processing of emotional speech prosody in school-aged children with autism spectrum disorders (ASD) but without marked language impairments (children with ASD [no LI]). METHODS The mismatch negativity (MMN)/the late discriminative negativity (LDN), reflecting pre-attentive auditory discrimination processes, and the P3a, indexing involuntary orienting to attention-catching changes, were recorded to natural word stimuli uttered with different emotional connotations (neutral, sad, scornful and commanding). Perceptual prosody discrimination was addressed with a behavioral sound-discrimination test. RESULTS Overall, children with ASD (no LI) were slower in behaviorally discriminating prosodic features of speech stimuli than typically developed control children. Further, smaller standard-stimulus event related potentials (ERPs) and MMN/LDNs were found in children with ASD (no LI) than in controls. In addition, the amplitude of the P3a was diminished and differentially distributed on the scalp in children with ASD (no LI) than in control children. CONCLUSIONS Processing of words and changes in emotional speech prosody is impaired at various levels of information processing in school-aged children with ASD (no LI). SIGNIFICANCE The results suggest that low-level speech sound discrimination and orienting deficits might contribute to emotional speech prosody processing impairments observed in ASD.

Corrigendum to "Auditory stream segregation in children with Asperger syndrome" [Biol. Psychol. 82 (2009) 301-307]

Cognitive Brain Research Unit, Department of Psychology, University of Helsinki, P.O. Box 9, Helsinki FIN-00014, Finland Department of Child Neurology, Helsinki University Central Hospital, Finland Department of Neuroscience, Albert Einstein College of Medicine, USA Faculty of Humanities, Logopedics, University of Oulu, Finland Department of Clinical Neurophysiology, Oulu University Hospital, Finland Neuropsychiatric Rehabilitation and Medical Centre NeuroMental, Helsinki, Finland