Developmental change in predictive motor abilities.

Prediction is critical for successful interactions with a dynamic environment. To test the development of predictive processes over the life span, we designed a suite of interceptive tasks implemented as interactive video games. Four tasks involving interactions with a flying ball with titrated challenge quantified spatiotemporal aspects of prediction. For comparison, reaction time was assessed in a matching task. The experiments were conducted in a museum, where over 400 visitors across all ages participated, and in a laboratory with a focused age group. Results consistently showed that predictive ability improved with age to reach adult level by age 12. In contrast, reaction time continued to decrease into late adolescence. Inter-task correlations revealed that the tasks tested different aspects of predictive processes. This developmental progression complements recent findings on cerebellar and cortical maturation. Additionally, these results can serve as normative data to study predictive processes in individuals with neurodevelopmental conditions.

Altered engagement of the speech motor network is associated with reduced phonological working memory in autism.

Nonword repetition, a common clinical measure of phonological working memory, involves component processes of speech perception, working memory, and speech production. Autistic children often show behavioral challenges in nonword repetition, as do many individuals with communication disorders. It is unknown which subprocesses of phonological working memory are vulnerable in autistic individuals, and whether the same brain processes underlie the transdiagnostic difficulty with nonword repetition. We used functional magnetic resonance imaging (fMRI) to investigate the brain bases for nonword repetition challenges in autism. We compared activation during nonword repetition in functional brain networks subserving speech perception, working memory, and speech production between neurotypical and autistic children. Autistic children performed worse than neurotypical children on nonword repetition and had reduced activation in response to increasing phonological working memory load in the supplementary motor area. Multivoxel pattern analysis within the speech production network classified shorter vs longer nonword-repetition trials less accurately for autistic than neurotypical children. These speech production motor-specific differences were not observed in a group of children with reading disability who had similarly reduced nonword repetition behavior. These findings suggest that atypical function in speech production brain regions may contribute to nonword repetition difficulties in autism.

Autonomic and Electrophysiological Evidence for Reduced Auditory Habituation in Autism.

It is estimated that nearly 90% of children on the autism spectrum exhibit sensory atypicalities. What aspects of sensory processing are affected in autism? Although sensory processing can be studied along multiple dimensions, two of the most basic ones involve examining instantaneous sensory responses and how the responses change over time. These correspond to the dimensions of 'sensitivity' and 'habituation'. Results thus far have indicated that autistic individuals do not differ systematically from controls in sensory acuity/sensitivity. However, data from studies of habituation have been equivocal. We have studied habituation in autism using two measures: galvanic skin response (GSR) and magneto-encephalography (MEG). We report data from two independent studies. The first study, was conducted with 13 autistic and 13 age-matched neurotypical young adults and used GSR to assess response to an extended metronomic sequence. The second study involved 24 participants (12 with an ASD diagnosis), different from those in study 1, spanning the pre-adolescent to young adult age range, and used MEG. Both studies reveal consistent patterns of reduced habituation in autistic participants. These results suggest that autism, through mechanisms that are yet to be elucidated, compromises a fundamental aspect of sensory processing, at least in the auditory domain. We discuss the implications for understanding sensory hypersensitivities, a hallmark phenotypic feature of autism, recently proposed theoretical accounts, and potential relevance for early detection of risk for autism.

Reduced Sensory Habituation in Autism and Its Correlation with Behavioral Measures.

Autism is strongly associated with sensory processing difficulties. We investigate sensory habituation, given its relevance for understanding important phenotypic traits like hyper- and hypo-sensitivities. We collected electroencephalography data from 22 neuro-typical(NT) and 13 autistic(ASD) children during the presentation of visual and auditory sequences of repeated stimuli. Our data show that the ASD children have significantly reduced habituation relative to the NT children for both auditory and visual stimuli. These results point to impaired habituation as a modality-general phenomenon in ASD. Additionally, the rates of habituation are correlated with several clinical scores associated with competence along diverse phenotypic dimensions. These data suggest that the sensory difficulties in autism are likely to be associated with reduced habituation and are related to clinical symptomology.

Shared neuroanatomical substrates of impaired phonological working memory across reading disability and autism.

BACKGROUND: Individuals with reading disability or individuals with autism spectrum disorder (ASD) are characterized, respectively, by their difficulties in reading or social communication, but both groups often have impaired phonological working memory (PWM). It is not known whether the impaired PWM reflects distinct or shared neuroanatomical abnormalities in these two diagnostic groups. METHODS: White-matter structural connectivity via diffusion weighted imaging was examined in sixty-four children, ages 5-17 years, with reading disability, ASD, or typical development (TD), who were matched in age, gender, intelligence, and diffusion data quality. RESULTS: Children with reading disability and children with ASD exhibited reduced PWM compared to children with TD. The two diagnostic groups showed altered white-matter microstructure in the temporo-parietal portion of the left arcuate fasciculus (AF) and in the temporo-occipital portion of the right inferior longitudinal fasciculus (ILF), as indexed by reduced fractional anisotropy and increased radial diffusivity. Moreover, the structural integrity of the right ILF was positively correlated with PWM ability in the two diagnostic groups, but not in the TD group. CONCLUSIONS: These findings suggest that impaired PWM is transdiagnostically associated with shared neuroanatomical abnormalities in ASD and reading disability. Microstructural characteristics in left AF and right ILF may play important roles in the development of PWM. The right ILF may support a compensatory mechanism for children with impaired PWM.

Autism as a disorder of prediction.

A rich collection of empirical findings accumulated over the past three decades attests to the diversity of traits that constitute the autism phenotypes. It is unclear whether subsets of these traits share any underlying causality. This lack of a cohesive conceptualization of the disorder has complicated the search for broadly effective therapies, diagnostic markers, and neural/genetic correlates. In this paper, we describe how theoretical considerations and a review of empirical data lead to the hypothesis that some salient aspects of the autism phenotype may be manifestations of an underlying impairment in predictive abilities. With compromised prediction skills, an individual with autism inhabits a seemingly "magical" world wherein events occur unexpectedly and without cause. Immersion in such a capricious environment can prove overwhelming and compromise one's ability to effectively interact with it. If validated, this hypothesis has the potential of providing unifying insights into multiple aspects of autism, with attendant benefits for improving diagnosis and therapy.

Auditory temporal structure processing in dyslexia: processing of prosodic phrase boundaries is not impaired in children with dyslexia.

Reading disability in children with dyslexia has been proposed to reflect impairment in auditory timing perception. We investigated one aspect of timing perception--temporal grouping--as present in prosodic phrase boundaries of natural speech, in age-matched groups of children, ages 6-8 years, with and without dyslexia. Prosodic phrase boundaries are characterized by temporal grouping of functionally related speech elements and can facilitate syntactic processing of speech. For example, temporary syntactic ambiguities, such as early-closure structures, are processed faster when prosodic phrase boundaries are present. We examined children's prosodic facilitation by measuring their efficiency of sentence processing for temporary syntactic ambiguities spoken with (facilitating) versus without (neutral) prosodic phrase boundaries. Both groups of children benefited similarly from prosodic facilitation, displaying faster reaction times in facilitating compared to neutral prosody. These findings indicate that the use of prosodic phrase boundaries for speech processing is not impaired in children with dyslexia.

Assessing the predictive validity of the admission process in a master's level speech language pathology program.

Astin's Input-Environment-Outcome (I-E-O) model served as the theoretical foundation to assess (a) undergraduate GPA, (b) undergraduate Speech Language Pathology majors, and (c, d) GRE-Q and GRE-V scores (Input) as predictors of students' graduate GPA (Environment), and graduate GPA as a predictor of PRAXIS scores (Outcome). The sample for this study was 122 students who completed the Speech-Language Pathology Program in recent academic cycles at a graduate school in the northeastern United States. The sample was representative of other programs in the country in terms of gender, undergraduate GPA, and GRE scores. Results appear to support the predictive validity of the linear combination of the input predictors of the environment variable (GPA) and of the environment variable on the outcome, i.e., PRAXIS scores.

Age-related impairments in the revision of syntactic misanalyses: effects of prosody.

Two experiments examined whether young and older adults differ in comprehending sentences that contain temporary syntactic closure ambiguities. Experiment 1 examined age-related differences using the Auditory Moving Window (AMW) task, in which sentences were presented in a segment-by-segment self-paced fashion. Experiment 2 examined age-related differences using a sentence recall task, in which sentences were presented in their entirety. Sentences were constructed to have cooperating prosody (i.e., where prosody is consistent with the syntactic boundaries), baseline prosody (i.e., where prosody is ambiguous in the syntactically ambiguous region), and conflicting prosody (i.e., where cross-splicing relocates the prosodic phrase break at a misleading point in syntactic structure). The results showed that both young and older adults make comparable use of prosodic information to interpret temporary syntactic ambiguities, although younger adults may make use of this information more quickly than older adults. In addition, older adults appeared to be less able than young adults to revise initial syntactic misinterpretations caused by conflicting prosodic information. These results are interpreted with respect to age-related impairments in the allocation of working memory resources and inefficient inhibitory function during spoken language processing.

An Investigation of Language Impairment in Autism: Implications for Genetic Subgroups.

Autism involves primary impairments in both language and communication, yet in recent years the main focus of research has been on the communicative deficits that define the population. The study reported in this paper investigated language functioning in a group of 89 children diagnosed with autism using the ADI-R, and meeting DSM-IV criteria. The children, who were between 4- and 14- years-old were administered a battery of standardized language tests tapping phonological, lexical, and higher-order language abilities. The main findings were that among the children with autism there was significant heterogeneity in their language skills, although across all the children, articulation skills were spared. Different subgroups of children with autism were identified on the basis on their performance on the language measures. Some children with autism have normal language skills; for other children, their language skills are significantly below age expectations. The profile of performance across the standardized measures for the language-impaired children with autism was similar to the profile that defines the disorder specific language impairment (or SLI). The implications of this language impaired subgroup in autism for understanding the genetics and definition of both autism and SLI are discussed.