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Bipysical Joumal Voume 67 August 1994 515-520 Modeling State-Dependent Inactivation of Membrane Currents

Summary: Bipysical Joumal Voume 67 August 1994 515-520
Modeling State-Dependent Inactivation of Membrane Currents
Shimon Marom and L F. Abbott
Departnt of Bichemisty and Physics, Center for Cmnplex Systm, Brandeis Univerity, Waltam, Massachusset 02254 USA
ABSTRACT Inactivation of many ion channels occurs through largely voltage-independent traitions to an inactivated state
fron the open state or from oher states in the pathway leaing to openirg of the chanel. Beause this form Of inactvati
is rathe than voltage-den it canot be desctxed by the standard Huxley formalism used in
virtually all stdi of neuronal behavior. Using two exanmpes, cumulative inactivaton of the Kv3 channel
and inctvaton of the fast sodium chanel, we extend the standad formalimn for modeling currents
to acut for state-dependet inacvati. Our results provide an accurate de tOn f cumurlativ inatIvaton of the Kv3
channel, new insight into intivation of the sodium chiarnn, and a general framework for modeling macrc currents when
state-dependent processes are involved. In a model neuron, the m c Kv3 current produces a novel short-term memory
effect and firing delays similar to those seen in hipocampal neurons.
The general approach developed by Hodgkin and Huxley
(1952) over 40 years ago to descnbe sodium and potas-
sium currents in the squid giant axon has been success-
fully applied to many other membrane currents and now
forms the basis for virtually all modeling studies of neu-
ronal behavior. However, further research has clearly


Source: Abbott, Laurence - Center for Neurobiology and Behavior & Department of Physiology and Cellular Biophysics, Columbia University


Collections: Biology and Medicine