Sensory Experience, Behavioral Therapy, and Neural Plasticity: Implications for Autism Remediation
Autism is characterized by impairments in social interaction, disordered communication, repetitive behavior, and stereotyped interests. We propose that these symptoms lead to a form of isolation that disrupts the development of normal brain responses and in turn hinders the acquisition of critical language skills. Anatomical studies have established that even mild isolation during development can lead to significant weakening of cortical circuits. Although behavioral therapy and auditory training appear to improve language skills in autistic children, the neural basis of these improvements is not known. We have recently demonstrated that early sensory enrichment in rats leads to a profound increase in the sensitivity, frequency selectivity, response strength, and processing speed of neurons in primary auditory cortex. Similar brain plasticity may explain training-induced improvements of language function in autistic children. To better understand how plasticity can be used to treat autism we will 1) more completely characterize what specific aspects of an enriched environment strengthen cortical circuits, 2) document how daily behavioral training improves cortical processing, 3) establish the time course of developmental plasticity, and 4) determine how dysfunction in the central cholinergic system affects auditory cortex maturation. Our preliminary findings indicate that during development cortical circuits are highly susceptible to degradation, and that targeted sensory enrichment can be extremely effective at restoring these circuits to normal performance. Results from the these experiments will significantly influence the development of behavioral and pharmacological treatments for autism.