Delayed Development of the Claustrum in Autism

The clinical phenotype of autism, with deficits in social interactions; verbal and nonverbal communication; and restricted repetitive and stereotyped patterns of behavior, interests and activities, suggests that numerous high-order functions are not processed properly. Extensive reciprocal connections between the claustrum and almost all brain regions suggest that developmental alterations of the claustrum may contribute to autism’s clinical profile, as it integrates a number of physiological processes that collectively maintain contact between the individual and the environment. Stereological studies revealed a significant delay of neuronal growth in the claustrum. Examination of older children and adults with autism shows that during the teenage years acceleration of neuronal growth results in a partial correction of neuronal size in the claustrum. Desynchronization of neuronal growth in the claustrum and interacting brain modalities, including the social brain, the sensorimotor system and the memory system, appears to be a significant contributor to the clinical symptoms of autism. A smaller claustrum and undersized neurons could be indicative of underconnectivity in the brains of autistic subjects. Underconnectivity of the claustrum may result in defects/deficits of the integration of cortical and subcortical modalities and may contribute to the cognitive impairment, repetitive behaviors, deficits of social interactions, altered processing of sensory signals and other components of the autistic phenotype.