Welcome to Matthew Ennis Lab
Research in Olfaction and Pain
Dept. Anatomy & Neurobiology,
Univ. of Tennessee

Health Science Center,
855 Monroe Ave., Suite 515

Memphis, TN 38163, U.S.A. 
Tel.  901-448-1225
Fax: 901-448-7193



My primary interests are centered on the functional organization and physiological properties of neural networks involved in nociception/analgesia processing and the chemical senses (i.e., olfaction and gustation). My research utilizes an integrative, multidisciplinary approach combining tract tracing, immunocytochemistry, immediate early gene expression and electrophysiology to delineate cellular and circuit properties of functionally defined networks. The major current projects in my laboratory are:

lation of Brainstem Opioid Analgesic Circuits. A well defined brainstem-spinal cord circuit is known to play a key role in opioid-mediated analgesia. We are investigating how higher levels of the CNS (cortical and subcortical sites) involved in emotions, motivational state and cognitive processing can regulate this brainstem analgesic circuit to allow for state-dependent modulation of pain thresholds. We are also investigating how sweet and fatty components of mothers milk produces profound opiate receptor-dependent analgesic and calming effects in newborn rats and humans.

•Synaptic Integration and Information Processing in the Olfactory Bulb.
We are investigating how neuronal membrane properties and extrinsic/intrinsic neurotransmitter systems modulate information processing and output from the olfactory bulb circuit using functional imaging and neurophysiology approaches in vivo and in vitro.

Integration in the Olfactory Bulb (OB)-Piriform Cortex (PC) Circuit. Olfactory receptor neurons that express a single common odorant receptor project to one glomerulus in the OB. The glomeruli thus form a map that mirrors receptor activity. Different odors stimulate different patterns of glomerular activity.  The OB and PC comprise the major components of the neural network that decipher such patterns to arrive at the recognition of an odor. The goal of this research is to understand how glomerular activity is relayed to, and processed within PC using neuroanatomical and neurophysiological approaches.

Laboratory Techniques

•Neurophysiology: (1) Intracellular and extracellular recordings in vivo and in vitro preparations; (2) Functional imaging using voltage-sensitive dyes; (3) Electrical and chemical brain microstimulation.

(1) Microiontophoretic and micropressure drug application with multibarrel pipettes; (2) Intravenous and intracerebroventricular drug injection; (3) High pressure liquid chromatography (HPLC) combined with in vivo microdialysis to determine the steady state and evoked synaptic release of neurotransmitters.

•Neuroanatomy: (1) Anterograde and retrograde axonal tract tracing; (2) Immunocytochemistry  and histochemistry; (3) Computer-based image analysis.

Personal History

Ph.D. in  Neuroscience from New York University in 1988 and postdoctoral training in the Departments of Physiology & Biophysics and Anatomy & Cell Biology at The University of Cincinnati College of Medicine.


Representative publications

Olfactory Bulb

All Medline publications

Current & Previous Lab Members

Click to visit website of Abdallah Hayar
Abdallah Hayar, Ph.D., (website)
Currently at the Univ. of Arkansas for Medical Sciences

HongWei Dong, Ph.D., (CV)
Neurophysiology of the olfactory bulb.

Yi-Hong Zhang, Ph.D., (CV)
Neurophysiology of pain

Dongxia-Jiang, M.D.

Baltimore lab group party
Souvenir photo
Dr. Ennis with his graduating (Ph.D.) Ph.D. student, Kelly Ciombor

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Last modified July 15, 2006
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