SPD-SWG Participants

Schneider, Mary L., PhD, OTR/L

Title: Professor
Department: Department of Kinesiology and Psychology, Harlow Primate Lab
Institution: University of Wisconsin – Madison
Mailing Address: 1500 Highland Avenue, Madison, WI 53705
Phone: (608) 265-5118
Website: www.wisc.edu

Research Interests

Dr. Schneider's research program focuses on behavioral and neurobiological effects from fetal alcohol exposure alone or in combination with prenatal stress. We study rhesus monkeys, examining growth and development, learning and memory, and stress reactivity across the life span. We also use state-of-the-art neuroimaging techniques to elucidate possible abnormalities in neural processing. We assess dopamine system function, using positron emission tomography, to determine whether altered DA function might underlie some of the motor, learning, and neuroendocrine outcomes associated with these prenatal treatments. We have recently expanded our nonhuman primate model to examine the neurochemical and developmental basis for sensory regulation disorders. Our fetal alcohol work is funded by the National Institute on Alcohol Abuse and Alcoholism and our sensory regulation work is funded by the Wallace Foundation.

SPD Research Summary

Dr. Schneider is researching Sensory Processing Disorder in a Primate Model. Recently her studies have examined whether disrupted sensory processing occurs in monkeys and if so, whether it is associated with dopamine functioning in the striatum assessed with positron emission tomography (PET) neuroimaging. Little is known about the neurobiological substrates of Sensory Processing Disorders or the developmental precursors. Casey (2001) proposed that disruptions in the basal ganglia thalamocortical circuits underlie poor inhibitory control and viewed disruptions of one or more of these circuits as potential contributors to developmental disorders characterized by poor inhibitory control or difficulty filtering information appropriately.

The primates were tested at age 5-7 with the Sensory Processing Scale for Monkeys (SPS-M); a scale was developed by adapting procedures from sensory processing assessments for children. Prenatal-stressed and/or prenatal alcohol- exposed adult rhesus monkeys and their controls were examined. Positron emission tomography (PET) imaging was used in order to examine post-synaptic receptor binding (D2R) and DA synthesis (DAsyn) in the striatum. The striatum is rich in DAergic innervation and is part of the basal ganglia thalamocortical loop involved in behavioral inhibition. Fallypride (FAL), an F-18 labeled raclopride analog, was chosen to assess D2 receptor binding as an index of D2 receptor functioning because it has a high affinity for D2 receptors and high brain uptake. Findings were: first, reduced habituation to repeated tactile stimulation and higher average withdrawal response was associated with increased striatal D2R binding and increased ratio of D2R binding to DA synthesis. Second, the pattern of habituation/sensitization to repeated tactile stimuli differed as a function of prenatal treatment. Monkeys not exposed to prenatal stress showed the expected behavioral pattern of habituation across trials while exposure to prenatal stress induced slight behavioral sensitization. Moreover, compared to no exposure to prenatal alcohol, prenatal alcohol exposure induced a higher overall magnitude of withdrawal response (average across trials).

Why would up-regulation of D2R binding in the striatum as indexed by FAL and the D2R/DA ratio be related to increased magnitude of withdrawal (aversion) responses and failure to habituate to tactile stimulation? DA is an important neurotransmitter that modulates the activity of many brain regions, signaling both excitatory and inhibitory messages. Most neural processes in the brain involve delicately tuned feedback mechanisms in that initial responses are either increased or dampened as they are transmitted through the brain. Such feedback systems may be dependent upon developmental processes involving reorganization of interactions between various cortical and sub-cortical regions.

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