JN Fuel your research with LabChart
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

J Neurophysiol 80: 3163-3172, 1998;
0022-3077/98 $5.00
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Rao-Mirotznik, R.
Right arrow Articles by Sterling, P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Rao-Mirotznik, R.
Right arrow Articles by Sterling, P.

The Journal of Neurophysiology Vol. 80 No. 6 December 1998, pp. 3163-3172
Copyright ©1998 The American Physiological Society

Transmitter Concentration at a Three-Dimensional Synapse

Rukmini Rao-Mirotznik2, Gershon Buchsbaum2, and Peter Sterling1

1 Department of Neuroscience and 2 Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104

Rao-Mirotznik, Rukmini, Gershon Buchsbaum, and Peter Sterling. Transmitter concentration at a three-dimensional synapse. J. Neurophysiol. 80: 3163-3172, 1998. At intensities from starlight to 1000-fold brighter, the mammalian rod synapse transmits a binary signal, the capture of 0 or 1 photon. Zero is signified by tonic exocytosis, and 1 is signified by a brief pause. The synapse is three dimensional: vesicles discharge at the apex of a deep cleft created by the invagination of four postsynaptic processes. Two horizontal cell spines bearing alpha -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors reach near to the release sites (16 nm), and two bipolar dendrites bearing mGluR6 receptors end far from the release sites (up to 640 nm). We considered two hypotheses for signal transfer: transmitter quanta might be integrated in the cleft and sensed as a steady concentration (high for 0 and low for 1); or quanta might be sensed at the postsynaptic membrane as discrete postsynaptic potentials (PSPs) and integrated within the dendrite. We calculate from a passive diffusion model that the invagination empties rapidly (tau  ~ 1.7 ms). Further calculations suggest that a glutamate concentration high enough to hold a bipolar cell in darkness at one end of its response range would require ~4,000 vesicles/s. On the other hand, the glutamate pulse from a single vesicle would reach both nearby AMPA receptors (low affinity) and distant mGluR6 receptors (high affinity) at spatiotemporal concentrations matched to their apparent binding affinities. Thus one vesicle could evoke a discrete PSP in all four postsynaptic processes. We calculate from a stochastic model that PSPs could transfer the binary signal at ~100 vesicles/s. Thus dendritic integration of unitary PSPs is both plausible and 40-fold more efficient than the alternative mechanism. The rod's deep invagination, rather than serving to pool transmitter, may serve to prevent "spillover" of transmitter to neighboring rods. Spillover, by pooling the noise from neighboring rods, would impair transmission of their binary signals.




This article has been cited by other articles:


Home page
 PhysiologyHome page
H. Okawa and A. P. Sampath
Optimization of Single-Photon Response Transmission at the Rod-to-Rod Bipolar Synapse
Physiology, August 1, 2007; 22(4): 279 - 286.
[Abstract] [Full Text] [PDF]

Home page
 Biophys. JHome page
S. Schein and K. M. Ahmad
Efficiency of Synaptic Transmission of Single-Photon Events from Rod Photoreceptor to Rod Bipolar Dendrite
Biophys. J., November 1, 2006; 91(9): 3257 - 3267.
[Abstract] [Full Text] [PDF]

Home page
 Biophys. JHome page
S. Schein and K. M. Ahmad
A Clockwork Hypothesis: Synaptic Release by Rod Photoreceptors Must Be Regular
Biophys. J., December 1, 2005; 89(6): 3931 - 3949.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurophysiol.Home page
J. A. Borycz, J. Borycz, A. Kubow, R. Kostyleva, and I. A. Meinertzhagen
Histamine Compartments of the Drosophila Brain With an Estimate of the Quantum Content at the Photoreceptor Synapse
J Neurophysiol, March 1, 2005; 93(3): 1611 - 1619.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
M. Roelandse and A. Matus
Hypothermia-Associated Loss of Dendritic Spines
J. Neurosci., September 8, 2004; 24(36): 7843 - 7847.
[Abstract] [Full Text] [PDF]

Home page
 International Journal of High Performance Computing ApplicationsHome page
H. Casanova, F. Berman, T. Bartol, E. Gokcay, T. Sejnowski, A. Birnbaum, J. Dongarra, M. Miller, M. Ellisman, M. Faerman, et al.
The Virtual Instrument: Support for Grid-Enabled Mcell Simulations
International Journal of High Performance Computing Applications, February 1, 2004; 18(1): 3 - 17.
[Abstract] [PDF]

Home page
 International Journal of High Performance Computing ApplicationsHome page
H. Casanova, T. M. Bartol Jr., J. Stiles, and F. Berman
Distributing MCell Simulations on the Grid
International Journal of High Performance Computing Applications, August 1, 2001; 15(3): 243 - 257.
[Abstract] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online