At Qsac Day Habilitation and Residential Programs, I emphasize to our clinicians and staff members the importance of the neurobehavioral model for understanding autism. This model combines our understanding of the neurological dysfunction of autistic individuals with applied behavioral analysis. It frames a more complete picture of the autistic condition beyond behavior, thus allowing us to view autism not only as a set of core symptom domains, such as impairment in socialization, language and speech deficits and restricted repetitive patterns of behaviors, but also as a condition resulting in part from a dysfunction in brain development and genetic heredity. The neurobehavioral model provides tools to define the etiology and design treatment of autism.
One proposed neurological hypothesis on the etiology of autism is that abnormalities in the Limbic System and Cerebellum are responsible for some characteristic behaviors that we observe in autistic individuals.
Based on neuro-imaging, several neuroanatomic defects and subsequently dysfunctions in these areas have been found in the brains of autistic individuals. Important findings suggest that damage in the Limbic System, in particular to the amygdala and hippocampus, and also damage to the Cerebellum may explain some autistic behaviors and sensory processing problems.
The amygdala seems to play an important role in emotional arousal, assigning significance to environmental stimuli, and supporting social and emotional functioning. The amygdala appears to be related to our aggression and emotions and the hippocampus with memory and learning. Damages in the amygdala have been associated with self-injurious behaviors and aggressive behaviors towards others; damages in the hippocampus are associated with an inability to store new information. The amygadala and hippocampus hypothesis may explain some of the characteristics that we observe in autistic individuals, such as declarative memory impairments, autistic anxiety, impaired social interaction, language and speech impairment, seizure activity, sensory deficits and stereotypical/compulsive behaviors. The argument that limbic system structures and functions and some cortical regions are more consistently impaired in autism spectrum disorder has stressed the complexity of the etiology of Autism Spectrum Disorder (ASD).
Although research suggests that the Limbic System and Cerebellum are dysfunctional in autistic individuals, the brain nevertheless has the ability to adapt to changes and circumstances and develop new ways of learning. Dr. Merzenich, a professor emeritus of neuroscience from University of California San Francisco, has studied for two decades brain plasticity, that is, the ability of the brain to learn and form new networks of nerve connections. His studies suggest that brain stimulation could quickly maximize the full potential for recovery of function in a damaged brain. Dr. Merzenich and his team created the “Brain Fitness” program based on the notion of the brain’s natural plasticity. New areas of studies based on neuroplasticity are; 1) “Neural retraining”, a computer program develop by Dr. Merzenich to teach language skills to autistic children; 2) the “video modeling,” and “joint attention”, used by educators at the New England Center for Children (NECC) in Southborough, Massachusetts. Children learn new behaviors and skills, and change disruptive or harmful ones, by constant positive reinforcement.
Based on brain plasticity, we embraced a neurobehavioral model that tells us that human function, which is controlled by the central nervous system and more specifically the brain, can be changed through cerebral stimulation and improving health conditions. All autistic individuals vary widely in their neurobehavioral developmental strengths and weaknesses, and this variation has powerful implications for their unique learning processes, and how as clinicians we develop individualized treatment plans.
1) Bauman, M.L, & Kemper, T.L. (Ed.). (1997). The Neurobiology of Autism. Baltimore, Maryland: The Johns Hopkins University Press.
2) Bauman, M.L, & Kemper, T.L. (1985). “Histoanatomic Observations of the Brain in Early Infantile Autism.” Neurology 35, 866-874.
3) Bear, M.F., Connors, B.W. and Paradiso, M.A. (2007). Neuroscience. Exploring the Brain. Philadelphia, PA: Lippincott Williams & Wilkins.
4) Kemper, T.L, and Bauman, M.L. (1993). “The Contribution of Neuropathologic Studies to the Understanding of Autism.” Neurology Clinic 11, 175-187.
5) McAlone, G.M. et al. (2005). “Mapping the Brain in Autism. A Voxel-Based MRI study of Volumetric Differences and Intercorrelations in Autism.” Brain 128, 268-276.