Biography
Biography: Woody R McGinnis
Abstract
Site-specific impairment of a small brainstem structure, nucleus tractus solitarius (NTS), is a potential break-through finding in the understanding of autistic spectrum disorder (ASD). NTS serves as initial central synapse for most sensory information from the viscera, and a broad set of unusual physical findings that associate with the diagnostic behaviors of ASD are explicable on the basis of reduced visceral afference. An exaggerated inflammatory response in ASD associates significantly with aberrant behaviors, and parallels the observation of increased inflammation after experimental splenic deafferentation. Likewise, deafferentation of the laryngeal viscera of animals results in reduced glottal closing force, proposed mechanism for our finding of whisper in association with autistic vocal regression. Experimental impairment of NTS results in depressed motor and secretory function of the gastrointestinal tract, prominent in ASD. Hypoperfusion of extensive brain regions with \\\\\\\"global dysregulation\\\\\\\" of cerebral blood-flow (CBF) is well-documented in ASD, and might be expected to alter development and integrated function of higher regions of brain. Animal experiments show that NTS is important in autoregulation of CBF, and that artificial stimulation of NTS increases CBF. An unusual vascular microanatomy is seen to confer a dual vulnerability of NTS to injury via hypoxia but also to toxins from the bloodstream that tend to concentrate preferentially in regions of brainstem such as NTS that are unprotected by BBB. Hence, we consider specific hypoxic events and common toxic exposures that could act together or separately in order to trigger ASD at varied points in the neurodevelopmental sequence.