Dexter Speck, PhD

As Director of Teaching for the Department of Physiology, I act as Course director for several different courses: PGY 206 Elementary Physiology, PGY 207 Case studies in physiology, OBI 814 Dental Physiology and a new Medical School course for M2's on Gastrointestinal Physiology. In addition, I direct a Graduate Program leading to a Certificate in Teaching of Physiology which includes both didactic courses and formalized teaching experiences. Many of our graduate students participate in this program to enhance their teaching skills and knowledge. My previous research investigated the mechanisms responsible for the neural generation of respiratory patterns. The respiratory control system serves as a useful model for discovering basic principles of rhythmic motor systems including the normal homeostatic responses to behavioral perturbations. Sleep, wakefulness, sneezing, coughing, vomiting, postural changes, etc. are all important behaviors that involve respiratory adaptations. Most of these perturbations involve afferent inputs that either initiate or modify the resultant motor program. Results from these experiments contributed to our understanding of these connections and the basic mechanisms involved in modulation of the central respiratory pattern generator. This aids in understanding central respiratory disorders such as sudden infant death or the sleep apnea syndromes. Past experiments examined the nuclei and neurotransmitter receptor subtypes that are important in the processing of inspiratory-inhibitory reflexes elicited by stimulation of the superior laryngeal, intercostal, phrenic and vagus nerves and brainstem nuclei such as the dorsal, ventral and pontine respiratory groups. Stimulation of these inputs elicits an inspiratory termination and/or a transient attenuation of the motor output. These inhibitory reflexes are believed to represent distinct effects on the timing generation and pattern generation mechanisms. These experiments involved techniques such as stimulation and/or recording of whole nerves, brainstem nuclei and individual neurons. Chemical, pharmacologic and electrolytic lesions were used to interrupt specific pathways. Extracellular recording of in vivo neurons permitted close examination of the components of many reflexes. In addition, neuropharmacologic techniques (including systemic application and local microinjections of neurotransmitter receptor agonists and antagonists) were used to elucidate the specific synaptic connections between interneurons.