Neural Circuits Unit - Division of Intramural Research

 Ralph   Nelson  Ph.D., Senior Investigator

Dr. Nelson received his B.A. in Biophysics from Amherst College and his Ph. D. in Biophysics from Johns Hopkins University. At Johns Hopkins, under the preceptorship of John Dowling, he studied conductance mechanisms responsible for light responses of retinal bipolar cells. In his postdoctoral studies at the National Institutes of Health he formed a close collaboration with Helga Kolb in pioneering a type of study in which the light responses of retinal neurons were tightly interpreted in terms of synaptic connectivity. Dr. Nelson's laboratory is currently investigating the relationship of retinal neuron receptors to processing of visual information in retinal neural circuits.

Laboratory Staff

Victoria Connaughton, Ph.D.,  , 202-885- 2188
Marc Walton, M.D., Ph.D.,  , 301-827- 5096

Research Interests

The retina is composed of a network of nerve cells which receive, process and transform visual information. Visual information is transduced by photoreceptors and processed by numerous retinal interneurons before transmis The light sensitive tissue at the back of the eye is the retina. sion through optic nerve fibers to brain visual centers. During periods of dim illumination specialized bipolar and amacrine cells selectively process signals from rod photoreceptors. There are other bipolar and amacrine cells which process signals from cone photoreceptors when the visual scene is brightly illuminated. Some neurons are excited by bright contours (ON-center bipolar and ganglion cells). Others are excited by dark contours (OFF-center bipolar and ganglion cells). The goal of studies in the Neural Circuitry Unit is to define systems of neurons devoted to selective visual tasks, and to identify the synaptic mechanisms they employ. A web tutorial on retinal circuitry and function can be found in WEBVISION (below).

Selected Recent Publications

Connaughton, V.P. and Nelson, R.
Axonal stratification patterns and glutamate-gated conductance mechanisms in zebrafish retinal bipolar cells. - Journal of Physiology (London)    2000

Connaughton, V. P., Graham D., and Nelson R.
Identification and morphological classification of horizontal, bipolar, and amacrine cells within the zebrafish retina.  - J. Comp. Neurol  477 371-385 2004

Nelson, R. Bender, A. M. and Connaughton, V. P.
Stimulation of sodium pump restores membrane potential to neurons excited by glutamate in zebrafish distal retina -  J. Physiol  549 787-800 2003

Nelson, R., Janis A. T., Behar T. N. and Connaughton V. P.
Physiological Responses Associated with Kainate Receptor Immunoreactivity in Dissociated Zebrafish Retinal Neurons: a Voltage Probe Study. In H. Kolb and S. Wu editors: "Concepts and Challenges in Retinal Biology: A Tribute to John E. Dowling" - Progress in Brain Research   131 255-265 2001

Kolb, H., Nelson, R., Ahnelt, P. and Cuenca, N.
Cellular organization of the vertebrate retina. In H. Kolb and S. Wu editors: "Concepts and Challenges in Retinal Biology: A Tribute to John E. Dowling" - Progress in Brain Research   131 3-26 2001

Kolb, H., Fernandez, E., Nelson, R.
WEBVISION The organization of the vertebrate retina. - N/A    2000

Selected Earlier Publications

Contact Information

Neural Circuits Unit Basic Neurosciences Program, NINDS  5625 Fishers Lane   Bethesda MD  20892-

Telephone: 301-496- 8133 (office), 301- 496-8133 (laboratory), 301-496- 1565 (fax), Email: rnelson@codon.nih.gov