Rat Brain

This photomicrograph shows a section through layer IV of the barrel field in primary somatosensory cortex in rat brain. A morphological map of the body surface exists whereby individual clusters of cells, called barrels, represent specific regions of the body surface. Five rows of large barrels correspond to the representation of the large mystacial vibrissae on face; smaller anteriorly-located barrels represent sinus hairs on the face,and regions of the upper lip. The lower lip is represented by an isolated cluster of barrels as are the forepaw, and hindlimb. The trunk is represented posteriorly by a nebulous field that takes up the cytochrome oxidase stain used to visualize the barrel field in this example. Here the shoulder, abdomen, body sides, and back are represented. You will find references to these body representations in barrel field cortex in subsequent paragraphs.

Dr. Robert Waters

Research carried out in our laboratory focuses on understanding the mechanisms underlying cortical plasticity in neonatal and adult animals. Our previous work focused on understanding the development, organization, and reorganization of the forepaw barrel subfield (FBS) in layer IV of rat somatosensory cortex and we continue to use the FBS as our model system. Currently, our ongoing studies include: in-vitro whole cell patch recordings in rat to examine the role of GABAergic inhibition on corticocortical connections between neurons in neighboring FBS barrels, 2) in-vivo intracellular recording and immunohistochemistry to examine the role of GABAerigic inhibition on rapid and delayed cortical reorganization, 3) in-vivo intracellular recording to examine the role of thalamocortical neurons in delayed cortical reorganization, 4) in-vivo and in-vitro recordings and immunohistochemistry to examine the consequences of fetal alcohol exposure in FBS neurons in juvenile and adult rats.

More recently, we have begun to use quantitative techniques to characterize genes that underlie cortical organization and neuron number in the somatosensory cortex of inbred mice. Quantitative trait loci (QTL) will be mapped using BXD inbred strains.

We continue to study the effects of chronic endurance exercise on aging using the rodent animal model.

Dr. Cheng Li

My research interest centers on understanding the mechanisms that underline rapid and delayed somatosensory reorganization. I also study the effects of fetal alcohol exposure on the development and organization of barrel cortex in rodents. Other areas of research investigation include the study of gustatory processing. Techniques used in my research include in-vivo extracellular recording and mapping, in-vivo intracellular recording and labeling on cortex, thalamus, and brain stem, and immunocytochemistry.

Dr. Eldrige Johnson

Research interests include the morphological and physiological characteristics of motor output cells in the neocortex and striatum. The axonal interconnections of these areas are also of concern. In addition to the primary motor cortex, several areas of the somatosensory cortex are responsible for separate and autonomous motor control of facial muscles. Intracortical micro-stimulation of secondary (SII), third (SIII), and/or fourth (SIV) somatosensory cortex indicates that these areas contain low threshold regions in which stimulating currents less than 5UA were effective in producing contraction of facial musculature. Utilizing the anterograde tracer and plant lectin phaseolus vulgaris leucoagglutin (PHAL) and the extracellular recording of motor output neurons in SII, SIII, and SIV cortices, attempts are being made to elucidate the pathway(s) between these somatosensory cortical regions, basal ganglia, other brain stem nuclei, and facial muscles.

The Waters Lab
University of Tennessee
Health Science Center
855 Monroe Avenue, Suite 515
Memphis, TN 38163
Lab Tel: 901-448-7193
Office Tel: 901-448-5796
Lab: 224 Wittenborg Anatomy Building


Robert S. Waters, Ph.D.
Cheng X. Li, M.D.
Eldridge F. Johnson, Ph.D.
Taha A. Jan
David J. Reiner