HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Clements, J D Articles by Redman, S J Search for Related Content PubMed PubMed Citation Articles by Clements, J D Articles by Redman, S J

Single fibre group Ia excitatory post-synaptic potentials (e.p.s.p.s) were recorded in cat spinal motoneurones after the neurones were injected with tetraethylammonium (TEA) ions. TEA injection increased the peak amplitude of most e.p.s.p.s. The time course of e.p.s.p.s generated at the soma was unaffected, but the time course of e.p.s.p.s generated in the dendrites was prolonged. The membrane time constant did not change after TEA injection. Somatic e.p.s.p.s were voltage clamped after TEA was injected. The reversal potential for these e.p.s.p.s was more positive than for e.p.s.p.s unaffected by TEA. Composite e.p.s.p.s added linearly, or greater than linearly, whereas in motoneurones without TEA they added linearly or less than linearly. The enhanced amplitude and prolonged time course observed in dendritic e.p.s.p.s after TEA injection was reduced by small hyperpolarizing currents. Greater than linear summation of composite e.p.s.p.s was converted to linear summation by small hyperpolarizing currents. The increase in somatic e.p.s.p.s was attributed to a more positive reversal potential for the e.p.s.p.s. We suggest that TEA decreases the relative permeability of K+ in the subsynaptic channels. We propose that in the presence of TEA, dendritic depolarization activates an inward current which amplifies and prolongs synaptic potentials spreading towards the soma.

This article has been cited by other articles:

				C.J. Heckman, M. Johnson, C. Mottram, and J. Schuster Persistent Inward Currents in Spinal Motoneurons and Their Influence on Human Motoneuron Firing Patterns Neuroscientist, June 1, 2008; 14(3): 264 - 275. [Abstract] [PDF]

				S. Cushing, T. Bui, and P. K. Rose Effect of Nonlinear Summation of Synaptic Currents on the Input-Output Properties of Spinal Motoneurons J Neurophysiol, November 1, 2005; 94(5): 3465 - 3478. [Abstract] [Full Text] [PDF]

				M. G. Maltenfort and T. M. Hamm Estimation of the Electrical Parameters of Spinal Motoneurons Using Impedance Measurements J Neurophysiol, September 1, 2004; 92(3): 1433 - 1444. [Abstract] [Full Text] [PDF]

				R. H. Lee and C. J. Heckman Adjustable Amplification of Synaptic Input in the Dendrites of Spinal Motoneurons In Vivo J. Neurosci., September 1, 2000; 20(17): 6734 - 6740. [Abstract] [Full Text] [PDF]

				R. K. Powers and M. D. Binder Summation of Effective Synaptic Currents and Firing Rate Modulation in Cat Spinal Motoneurons J Neurophysiol, January 1, 2000; 83(1): 483 - 500. [Abstract] [Full Text] [PDF]

				D. M. Campbell and P. K. Rose Contribution of Voltage-Dependent Potassium Channels to the Somatic Shunt in Neck Motoneurons of the Cat J Neurophysiol, March 1, 1997; 77(3): 1470 - 1486. [Abstract] [Full Text] [PDF]