Current Clamp and Modeling Studies of Low-Threshold Calcium Spikes in Cells of the Cat's Lateral Geniculate Nucleus

  1 Department of Neurobiology, State University of New York, Stony Brook, 11794-5230; and   2 Center for Neural Science and Courant Institute of Mathematical Sciences, New York University, New York, New York 10003 Zhan, X. J., C. L. Cox, J. Rinzel, and S. Murray Sherman. Current Clamp and Modeling...

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Bibliographic Details
Published in:Journal of neurophysiology 1999-05, Vol.81 (5), p.2360-2373
Main Authors: Zhan, X. J, Cox, C. L, Rinzel, J, Sherman, S. Murray
Format: Article
Language:English
Subjects:
Action Potentials - physiology
Animals
Calcium - physiology
Cats
Computer Simulation
Differential Threshold - physiology
Female
Geniculate Bodies - cytology
Geniculate Bodies - physiology
Male
Models, Neurological
Neurons - physiology
Patch-Clamp Techniques
Reaction Time - physiology
Thalamus - cytology
Thalamus - physiology
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Summary:  1 Department of Neurobiology, State University of New York, Stony Brook, 11794-5230; and   2 Center for Neural Science and Courant Institute of Mathematical Sciences, New York University, New York, New York 10003 Zhan, X. J., C. L. Cox, J. Rinzel, and S. Murray Sherman. Current Clamp and Modeling Studies of Low-Threshold Calcium Spikes in Cells of the Cat's Lateral Geniculate Nucleus. J. Neurophysiol. 81: 2360-2373, 1999. Current clamp and modeling studies of low-threshold calcium spikes in cells of the cat's lateral geniculate nucleus. All thalamic relay cells display a voltage-dependent low-threshold Ca 2+ spike that plays an important role in relay of information to cortex. We investigated activation properties of this spike in relay cells of the cat's lateral geniculate nucleus using the combined approach of current-clamp intracellular recording from thalamic slices and simulations with a reduced model based on voltage-clamp data. Our experimental data from 42 relay cells showed that the actual Ca 2+ spike activates in a nearly all-or-none manner and in this regard is similar to the conventional Na + /K + action potential except that its voltage dependency is more hyperpolarized and its kinetics are slower. When the cell's membrane potential was hyperpolarized sufficiently to deinactivate much of the low-threshold Ca 2+ current ( I T ) underlying the Ca 2+ spike, depolarizing current injections typically produced a purely ohmic response when subthreshold and a full-blown Ca 2+ spike of nearly invariant amplitude when suprathreshold. The transition between the ohmic response and activated Ca 2+ spikes was abrupt and reflected a difference in depolarizing inputs of
ISSN:0022-3077
1522-1598
DOI:10.1152/jn.1999.81.5.2360