The Journal of Neuroscience, November 1, 1998, 18(21):8580-8589
Computational Properties of Peri-Dendritic Calcium
Fluctuations
David M.
Egelman and
P. Read
Montague
Division of Neuroscience, Center for Theoretical Neuroscience,
Baylor College of Medicine, Houston, Texas 77030
Using a model of the extracellular space, we show how external
calcium fluctuations, engendered during normal neural activity, can act
as a rapid information-bearing signal in nervous systems. We
demonstrate that action potentials propagating along a dendrite can
induce large peri-dendritic calcium fluctuations, lowering significantly the external calcium available to overlying presynaptic terminals. The geometrical distribution of active calcium sinks critically influences the time and spatial extent of fluctuations in
external calcium. In particular, clusters of coactive dendrites can
prolong and amplify an external calcium fluctuation. This latter effect
provides a natural substrate for a computational mechanism that locates
specific volumes of neural tissue on rapid time scales. Such an
interpretation suggests that the detailed structure of the
extracellular space, in combination with the three-dimensional
distribution of active calcium sinks, may play a role in neural
information processing.
Key words:
resource consumption principle; back-propagating action
potential; self-organized computing; dendrites; content-addressable
memory; external calcium
Copyright © 1998 Society for Neuroscience 0270-6474/98/18218580-10$05.00/0