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Richard O. Davies, D.V.M., Ph.D.

Professor, Dept of Animal Biology
School of Veterinary Medicine
211E VET/6046
(215) 898-8853 Lab: (215) 898-6489
FAX: (215) 573-5186
email:   rodavies@vet.upenn.edu
Click here for selected publications since Dr. Davies's arrival at Penn

RESEARCH INTERESTS

RESEARCH TECHNIQUES

RESEARCH SUMMARY

Current investigations center on the neural mechanisms underlying sleep disordered breathing, especially during rapid eye movement sleep (REMS). For this, a decerebrate cat model of REMS is used to study the changes in motoneuronal activity to various respiratory muscles that accompany the postural muscle atonia characteristic of REMS. A REMS-like state, with full postural muscle atonia and rapid eye movements is induced by the microinjection of a cholinergic agonist, carbachol, into the dorsal pontine tegmentum. Such injections induce a profound hypotonia in all respiratory and postural motoneurons studied. There was a differential suppression of respiratory motor nerve activities, with a pattern similar to natural REMS in that phrenic motoneurons were least affected and hypoglossal pharyngeal strongly depressed. The depression of hypoglossal motoneurons, unlike the situation with lumbar motoneurons, was not due to fast synaptic inhibition. Rather, it is likely that the depression is caused by a disfacilitation from serotonergic neurons of the raphe and catecholaminergic neurons of the pons. The role of the aminergic systems of the brainstem in the motor control of upper airway motoneurons (hypoglossal, pharyngeal, laryngeal) and its relation to REMS atonia is currently under investigation using a variety of complementary neurophysiological and neuropharmacological techniques.

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