Influence of voltage-sensitive dendritic conductances on bistable firing and effective synaptic current in cat spinal motoneurons in vivo. Lee, R.H. and C.J. Heckman. Department of Physiology, Northwestern University Medical School.
APStracts 3:0129N, 1996.
SUMMARY AND CONCLUSIONS
1. Following application of noradrenergic [alpha] 1 agonist methoxamine, muscle spindle Ia input evoked bistable firing patterns (i.e. persistent discharges after Ia input ceased) in adult spinal motoneurons in the decerebrate cat preparation. These bistable discharge patterns were compared to the Ia currents generated in voltage clamp conditions. 2. During voltage clamp at depolarized holding potentials, the Ia effective synaptic current underwent strong amplification. In those cells with strong bistable firing, a prolonged tail current followed the Ia input. Because the voltage clamp held the behavior of somatic conductances constant, these data indicate that voltage-sensitive conductances in the motoneuron dendrites made an important contribution to bistable firing.

Received 8 April 1996; accepted in final form 30 May 1996.
APS Manuscript Number J287-6.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 June 96