part by a grant from the National Institute of Mental 
Health. 
Dr. Scheller is also Associate Professor of Molec- 
ular and Cellular Physiology and Associate Pro- 
fessor of Biological Sciences (by courtesy) at 
Stanford University School of Medicine. 
Books and Chapters of Books 
Scheller, R.H., and Hall, Z.W. 1992. Chemical mes- 
sengers at synapses. In An Introduction to Molec- 
ular Neurobiology (Hall, Z.W., Ed.). Sunderland, 
MA: Sinauer, pp 119-147. 
Sweedler, J.V., Shear, J. B., Fishman, H.A., Zare, R.N., 
and Scheller, R.H. 1992. Analysis of neuropep- 
tides using capillary zone electrophoresis with 
multi-channel fluorescence detection. In Scien- 
tific Optical Imaging (Denton, M.B., Ed.). Proc. 
SPIE, pp 37-46. 
Articles 
Bennett, M.K., Calakos, N., Kreiner, T., and 
Scheller, R.H. 1992. Synaptic vesicle membrane 
proteins interact to form a multimeric complex./ 
Cell Biol 116:761-775. 
Bennett, M.K., Calakos, N., and Scheller, R.H. 
1992. Syntaxin: a synaptic protein implicated in 
docking of synaptic vesicles at presynaptic active 
zones. Science 257:255-259. 
Campanelli, J.T., Hoch, W., Rupp, F., Kreiner, T., 
and Scheller, R.H. 1991- Agrin mediates cell 
contact-induced acetylcholine receptor cluster- 
ing. Ce// 67:909-916. 
Elferink, L.A., Anzai, K , and Scheller, R.H. 1992. 
Rab 15: a novel low molecular weight GTP- 
binding protein specifically expressed in rat 
brain. /B/o/ Chem 267:5768-5775. 
Ferns, M., Hoch, W., Campanelli, J.T., Rupp, F., 
Hall, Z.W., and Scheller, R.H. 1992. RNA splic- 
ing regulates agrin-mediated acetylcholine- 
receptor clustering activity on cultured myo- 
tubes. Neuron 8:1079-1086. 
Rupp, F., Hoch, W., Campanelli, J.T., Kreiner, T., 
and Scheller, R.H. 1992. Agrin and the organiza- 
tion of the neuromuscular junction. Curr Opin 
Neurobiol 2:88-93. 
COMPUTATIONAL NEUROBIOLOGY OF THE VISUAL CORTEX 
TerrenceJ. Sejnowski, Ph.D., Investigator 
The visual system is the best-understood sensory 
system in the mammalian brain, and the visual cor- 
tex is the most intensively studied visual area. There 
is growing evidence that the development of the vi- 
sual cortex depends on electrical activity driven by 
the retina. The self-organization of neurons into cor- 
tical columns provides the brain with populations 
of neurons having a wide variety of response prefer- 
ences. Dr. Sejnowski's laboratory is using computer 
models constrained by the response properties of 
neurons from single-cell recordings and psychophys- 
ical measurements on performance to provide a 
conceptual framework for how visual information is 
distributed in neural populations. Such models are 
being used to explore how the visual cortex repre- 
sents the three-dimensional world, how this repre- 
sentation may arise during development, and how 
the information coded by these neurons might be 
used to coordinate actions such as eye movements. 
Disparity Selectivity in Visual Cortex 
When eyes are fixed on a location in space, the 
slight positional shift in the projection of an object 
between the two eyes, called the retinal disparity, 
provides information about the distance of the ob- 
ject from the point of fixation. Neurons in the first 
cortical stage of vision are sensitive to disparity, and 
the development of their disparity selectivity de- 
pends on binocular vision during a critical period in 
early life. In the adult visual cortex, neurons are 
observed to be either dominated by input from one 
eye (monocular cells) or relatively balanced with 
input from both eyes (binocular cells). Further- 
more, binocular cells tend to prefer zero disparity, 
whereas relatively monocular cells tend to prefer 
nonzero disparities. Computer models have been 
used to study how mechanisms that have been un- 
covered for plasticity in visual cortex during de- 
velopment could account for observed relation- 
ships such as that between ocular dominance and 
disparity. 
Drs. Michael Stryker and Kenneth Miller (Univer- 
sity of California, San Francisco), using a computer 
model, have shown how the activity-based segrega- 
tion of thalamic afferents in layer 4 of visual cortex 
could be driven by competition between inputs 
from the two eyes. Dr. Sejnowski's laboratory has 
extended this model to the development of disparity 
NEUROSCIENCE 435 
