Bursting Thresholds in CA3 at High and Low Network Excitability: Effects on Interburst Interval and Burst Duration
Abstract number :
1.020
Submission category :
Year :
2001
Submission ID :
2026
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
A.S. Yee, MD, Neurology, UCHSC, Denver, CO; K.J. Staley, MD, Neurology, UCHSC, Denver, CO
RATIONALE: Why is pentobarbital an ineffective anticonvulsant in a rapidly bursting CA3 and why do convulsant and anticonvulsant manipulations produce similar changes in interburst interval and burst duration in this preparation?
METHODS: To address these questions, we extended a model of CA3 bursting in which the [italic] burst duration [/italic]is limited by activity-dependent depression of the excitatory synapses that connect CA3 neurons, and the [italic]interburst interval [/italic]is determined by the time required to recover from this depression. We defined the as the level of synaptic strength at which synaptic depression had resolved enough for CA3 to initiate the next burst and the as the level of synaptic strength at which synaptic depression was sufficient to terminate bursting. The was defined by the difference between the bursting thresholds as well as the initial level of burst probability. The periodicity of CA3 bursting was interpreted in terms of these three parameters.
RESULTS: 1. A convulsant may [italic]decrease [/italic]the bursting thresholds whereas an anticonvulsant may [italic]increase [/italic]these thresholds. 2. The network excitability alters the changes in interburst interval and burst duration [Figure1).
CONCLUSIONS: 1. Initial network excitability influences the effect of convulsants and anticonvulsants on interburst interval and burst duration. 2. Analysis of the effects of compounds in terms of their changes on bursting thresholds may provide a basis for rational polypharmacy.[figure]
Support: NIH and EFA