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Cellular
Neurobiology Laboratory
Richard H. Masland, Ph.D.
Dr. Masland is the
Charles A. Pappas Professor of Neuroscience at Harvard Medical School
and Neurophysiologist in Neurosurgery at Massachusetts General Hospital,
Boston. He received his A.B. degree from Harvard College and his
Ph.D. degree from McGill University. His postdoctoral work was done
at Stanford and Harvard Medical Schools. Among his awards is Harvard
Universitys Hoopes Prize, for excellence in teaching.
Research in this laboratory
concerns local cellular interactions within the retina. Mammalian
retinas contain a surprising diversity of cell types. Amacrine cells,
upon which we have especially concentrated, exist in atleast 20
different morphological subclasses. By fluorescent staining many
of these classes can be visualized by distinct, reproducible populations
in histological material or intact retinas in vitro during electrophysiological
recording. The broad questions under investigation are: (1) why
this diversity exists, i.e., what functions the many cells carry
out; (2) how orderly structural relations among the cells are created
and maintained; and (3) how inner retinal cell's local dendritic
networks function.
At present, we have two
main lines of work. The first is a systematic, quantitative study
of the mosaics and arrays of retinal neurons. The goal is to account
for all of players in the retina's microcircuitry. Toward this end,
we have invented a new method for revealing the shapes of dendrites,
which uses a photochemical reaction initiated by irradiation of
a single cell's nucleus with a microbeam of light. The method is
in effect a quantitative Golgi, in the sense that almost every cell
targeted is successfully filled. We have used it to characterize
the population of amacrine cells and are now extending it to other
retinal neurons.
A second focus is the mechanism
of direction selectivity by retinal ganglion cells. We have identified
the probable bipolar cell that drives the directionally selective
ganglion cell. We are now searching among the populations of amacrine
cells for the detailed microcircuitry that computes the directional
discrimination.
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Neurosurgery
Clinical Units
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