Faculty are listed by Department within their Research Areas,
with descriptions of their active projects.

ANATOMY AND NEUROBIOLOGY

JULIE SANDELL
Associate Professor of Anatomy and Neurobiology;
PhD, Massachusetts Institute of Technology

My lab has two major areas of interest: 1) we are part of a group that is building a retinal prosthesis to treat retinal degeneration and 2) we are interested in discovering the biological basis for cognitive impairment during normal aging. For the first project, we use anatomical techniques to investigate the remodeling that occurs in the retina in retinitis pigmentosa. We also study retinas from animals that have retinal degeneration as a result of a mutation, or as a result of a photoreceptor toxin. For the second project, we study the changes in neurons and neuroglial cells in the brain in monkeys as they age, and try to correlate the structural changes with the monkey's cognitive performance, which is determined in another laboratory. We are particularly interested in teasing apart the changes that are related to age alone from those that are related to cognitive status. Ultimately we would like to know what allows some individuals to age "successfully," while others are severely impaired. I also have long standing interests in visual system plasticity, and the role of GABA in neuronal development.
> Top of Page


DEPARTMENT OF BIOLOGY

WILLIAM D. ELDRED
Professor of Biology; Director of the Program in Neuroscience;
Professor in the Molecular Biology, Cell Biology and Biochemistry
Program; Department of Cognitive and Neural Systems Research
Fellow; PhD, University of Colorado Health Sciences Center

We are doing multidisciplinary studies of the role of cGMP in synaptic mechanisms in retinal neurons. These studies employ immunocytochemistry, retrograde tracers, intracellular injections, pharmacology, electrophysiology, biochemistry and image analysis at the light and electron microscopic levels. Particular emphasis is placed on regional differences in the retina and the biochemical and pharmacological mechanisms for modulating cGMP in identifies neurons.

SUSAN TSUNODA
Assistant Professor of Biology; PhD, Washington University
School of Medicine

Every cell is faced with the task of sorting through a vast array of extracellular signals and transducing them into the appropriate intracellular responses. How do signaling molecules within one pathway activate downstream components with the necessary speed and specificity, while avoiding cross-talk with other pathways in the same cell? There is increasing recognition that this is accomplished by organizing signaling components into physically and functionally distinct signaling complexes. Our long-term interest is to understand how this organization is achieved and maintained, and how it produces effective signaling. We use Drosophila phototransduction as a model system for studying the organization of signaling cascades. Phototransduction in Drosophila is a G-protein-coupled signaling pathway similar to many other signaling cascades. Drosophila is an ideal model organism for studying intracellular signaling because it is amenable to combining a wide variety of experimental approaches to address biological questions. Classical genetic schemes can be used to isolate mutants, defects can be characterized using biochemical, cell-biological, and electrophysiological approaches, while powerful molecular-genetic techniques can be used to identify the affected molecules and examine the function of the proteins they encode in vivo.

How are signaling complexes assembled, targeted, and anchored in photoreceptor cells? How does a photoreceptor ensure that transduction complexes have the appropriate composition of components and that they are situated in the proper location? Drosophila offers the opportunity to take a genetic approach to identifying the molecules involved in the assembly and localization of complexes, and to study the molecular mechanisms underlying these processes in vivo.

> Top of Page


DEPARMENT OF BIOMEDICAL ENGINEERING

CHRISTOPHER PASSAGLIA
Assistant Professor, Biomedical Engineering; PhD, Syracuse University

Dr. Passaglia studies how the eye transforms visual images into the neural signals it transmits to the brain and how target neurons in the brain process these signals. His laboratory is presently focused on quantitatively describing the receptive field properties of mammalian retinal ganglion cells in normal and diseased states and on building computer models that accurately simulate the retinal output under natural viewing conditions. Another interest of the lab is to characterize the response properties of invertebrate visual neurons, particularly those of horseshoe crabs, which mediate comparatively simple visually-guided behaviors. His research uses electrophysiological, anatomical, computational, and behavioral methods.

LUCIA M. VAINA
Professor, Biomedical Engineering; Research Professor of Neurology,
School of Medicine; PhD, Sorbonne (France) and Doctorat D'Etat es
Sciences, National Politechnique Institute-Toulouse (France)

Professor Vaina's main areas of current interest involve: (a) Visual motion analysis in the human brain based on computational, psychophysical and neuroimaging methods; (b) Perceptual learning and plasticity in the human visual cortex: psychophysics and neuronal network models; (c) structural and functional neuroimaging applied to diagnosis, evaluation of the effect of treatment, surgical planing and anatomical localization of vision mechanisms involved in perception and learning.

> Top of Page

DEPARMENT OF PSYCHOLOGY

GREGOR J. JONES
Assistant Professor; PhD

Photoreceptor mechanisms, especially the mechanisms of light and dark adaptation as measured electrically in isolated single photoreceptors.

SIMON LEVY
Associate Professor; PhD, Boston University

In many nerve cells, transient increases in intracellular free calcium concentrations (Cai) are caused primarily by influx through voltage-dependent calcium channels. Second messengers like inositol trisphosphate (InsP3) also have the ability to increase Cai through release from intracellular stores, or gating of calcium channels. The long-term goal of the Levy laboratory is to investigate mechanisms by which second messengers modulate the excitability of nerve cells by controlling their membrane permeability. The lab has developed suitable technologies to: i) measure single-channel activities; ii) simultaneously measure changes in intracellular calcium and membrane currents; iii) pressure-inject pharmacological agents to investigate putative pathways involved in neuronal excitability. The combination of these electrophysiological and pharmacological techniques has proven useful in gathering new and important information about nerve cell function.

There are four main projects: 1. Intracellular calcium regulation and detection in nerve cells. Effects of second messengers on internal calcium and membrane currents in nerve cells. 2. Role of calcium-induced calcium release in the excitability of the peptidergic neurons of Aplysia californica. 3. Role of calcium and inositol trisphosphate in phototransduction in Limulus photoreceptors. 4. Genetic Dissociation of phototransduction in Drosophila photoreceptors.

ENRICO NASI
Associate Professor; PhD, Bryn Mawr College

Research in our laboratory focuses primarily on the mechanisms of G protein-mediated signaling, using isolated photoreceptor cells as a particularly convenient experimental model system. Light transduction in the double retina of certain invertebrates exemplifies two of the more ubiquitous pathways in nature, which entail the activation of phospholipase C and the mobilization of cyclic nucleotides, respectively. The focus is on the amplification of the incoming signal and the modulation of the receptor operating characteristics to optimize responsiveness in the face of varying conditions of ambient stimulation. Current lines of research include 1) The role of phospoinositude lipids and their metabolites as internal messengers 2) Novel G protein-controlled enzymes 3) Gating mechanisms of ion channels controlled by cGMP and their relation to the ancestral superfamily of voltage-dependent K-selective channels. The approaches employed included a variety of electrophysiological recording techniques, optical measurements of intracellular ions, immunodetection, and molecular biology. Our interests in transduction have recently expanded to encompass thermo-reception by TRP-class channels, a different scheme in which a single membrane protein consolidates all key functions, bypassing all G protein-dependent enzymatic cascades.

> Top of Page