| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Physiology, Northwestern University, Chicago, IL, USA
2 Biomedical Engineering, Emory University, Atlanta, GA, USA
3 Physiology, Northwestern University, Chicago, IL, USA; Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL, USA
* To whom correspondence should be addressed. E-mail: c-heckman{at}northwestern.edu.
Synaptic integration in vivo often involves activation of many afferent inputs whose firing patterns modulate over time. In spinal motoneurons, sustained excitatory inputs undergo enormous enhancement due to persistent inward currents (PICs) that are generated primarily in the dendrites and are dependent on monoaminergic neuromodulatory input from the brainstem to the spinal cord. We measured the interaction between dendritic PICs and inhibition generated by tonic electrical stimulation of nerves to antagonist muscles during voltage clamp in motoneurons in the lumbar spinal cord of the cat. Separate samples of cells were obtained for two different states of monoaminergic input: standard (provided by the decerebrate preparation, which has tonic activity in monoaminergic axons) and minimal (the chloralose anesthetized preparation, which lacks tonic monoaminergic input). In the standard state, steady inhibition that increased the input conductance of the motoneurons by an average of 38% reduced the PIC by 69%. The range of this reduction, from <10% to >100%, was proportional to the magnitude of the applied inhibition. Thus, nearly linear integration of synaptic inhibition may occur in these highly active dendrites. In the minimal state, PICs were much smaller, being approximately equal to inhibition-suppressed PICs in the standard state. Inhibition did not further reduce these already small PICs. Overall, these results demonstrate that inhibition from local spinal circuits can oppose the facilitation of dendritic PICs by descending monoaminergic inputs. As a result, local inhibition may also suppress active dendritic integration of excitatory inputs.
This article has been cited by other articles:
|
|
 |
|
  E. R. Williams and S. N. Baker Renshaw Cell Recurrent Inhibition Improves Physiological Tremor by Reducing Corticomuscular Coupling at 10 Hz J. Neurosci., May 20, 2009; 29(20): 6616 - 6624. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. P. Carlin, T. V. Bui, Y. Dai, and R. M. Brownstone Staircase Currents in Motoneurons: Insight into the Spatial Arrangement of Calcium Channels in the Dendritic Tree J. Neurosci., April 22, 2009; 29(16): 5343 - 5353. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 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]
|
|
|
|
 |
|
 A. S. Hyngstrom, M. D. Johnson, and C. J. Heckman Summation of Excitatory and Inhibitory Synaptic Inputs by Motoneurons With Highly Active Dendrites J Neurophysiol, April 1, 2008; 99(4): 1643 - 1652. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Hyngstrom, M. Johnson, J. Schuster, and C. J. Heckman Movement-related receptive fields of spinal motoneurones with active dendrites J. Physiol., March 15, 2008; 586(6): 1581 - 1593. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. J. Heckman, A. S. Hyngstrom, and M. D. Johnson Active properties of motoneurone dendrites: diffuse descending neuromodulation, focused local inhibition J. Physiol., March 1, 2008; 586(5): 1225 - 1231. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. V. Bui, G. Grande, and P. K. Rose Multiple Modes of Amplification of Synaptic Inhibition to Motoneurons by Persistent Inward Currents J Neurophysiol, February 1, 2008; 99(2): 571 - 582. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. V. Bui, G. Grande, and P. K. Rose Relative Location of Inhibitory Synapses and Persistent Inward Currents Determines the Magnitude and Mode of Synaptic Amplification in Motoneurons J Neurophysiol, February 1, 2008; 99(2): 583 - 594. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Manuel, C. Meunier, M. Donnet, and D. Zytnicki Resonant or Not, Two Amplification Modes of Proprioceptive Inputs by Persistent Inward Currents in Spinal Motoneurons J. Neurosci., November 21, 2007; 27(47): 12977 - 12988. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. M. ElBasiouny and V. K. Mushahwar Modulation of motoneuronal firing behavior after spinal cord injury using intraspinal microstimulation current pulses: a modeling study J Appl Physiol, July 1, 2007; 103(1): 276 - 286. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. J. Fuglevand, A. P. Dutoit, R. K. Johns, and D. A. Keen Evaluation of plateau-potential-mediated 'warm up' in human motor units J. Physiol., March 15, 2006; 571(3): 683 - 693. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. V. Bui, M. Ter-Mikaelian, D. Bedrossian, and P. K. Rose Computational Estimation of the Distribution of L-type Ca2+ Channels in Motoneurons Based on Variable Threshold of Activation of Persistent Inward Currents J Neurophysiol, January 1, 2006; 95(1): 225 - 241. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. M. ElBasiouny, D. J. Bennett, and V. K. Mushahwar Simulation of Dendritic CaV1.3 Channels in Cat Lumbar Motoneurons: Spatial Distribution J Neurophysiol, December 1, 2005; 94(6): 3961 - 3974. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. G. Maltenfort, M. L. McCurdy, C. A. Phillips, V. V. Turkin, and T. M. Hamm Location and Magnitude of Conductance Changes Produced by Renshaw Recurrent Inhibition in Spinal Motoneurons J Neurophysiol, September 1, 2004; 92(3): 1417 - 1432. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Brizzi, C. Meunier, D. Zytnicki, M. Donnet, D. Hansel, B. L. d'Incamps, and C. van Vreeswijk How shunting inhibition affects the discharge of lumbar motoneurones: a dynamic clamp study in anaesthetized cats J. Physiol., July 15, 2004; 558(2): 671 - 683. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
