 |
||||
|
||||
|
||||
|
||||
Previous Article | Next Article
Volume 16, Number 16, Issue of August 15, 1996 pp. 4958-4970
Copyright ©1996 Society for NeuroscienceActivation of Intrinsic and Synaptic Currents in Leech Heart Interneurons by Realistic Waveforms
Received Feb. 6, 1996; revised May 22, 1996; accepted May 28, 1996.
Øystein H. Olsen and Ronald L. Calabrese Department of Biology, Emory University, Atlanta, Georgia 30322
Leech heart interneurons were voltage-clamped with realistic waveforms to investigate the currents underlying the oscillation in the cells. By estimating the leak current parameters in regions in which there was little contamination by voltage-gated currents, it was possible to measure the Ca2+ current, the persistent Na+ current, IP, and the hyperpolarization-activated inward current, Ih.
The experiments verified a prediction of a computer model of HN cells that the shape of the typical waveform was such that the low-threshold Ca2+ currents were partially inactivated during a slow up-ramp to a plateau potential. A step within the same range of the membrane potential as the realistic waveform produced >4 times as much Ca2+ current. In two-cell voltage-clamp experiments, the step produced 20 times more graded inhibition than the normal presynaptic waveform. When the presynaptic heart interneuron oscillated with spikes, the graded inhibition was larger. The difference may arise from integration of a slowly decaying component of the spike-mediated inhibition.
The persistent Na+ current had a very low threshold. During the most hyperpolarized phase of the waveform, IP deactivated to 50% of its maximum conductance. A substantial part of IP, therefore, was effectively contributing to the leak current in the HN cells.
The h-current increased for waveforms that had longer periods, whereas increasing the h-current in the model reduced the period. The h-current thus provides negative feedback to perturbations that alter the period of the oscillation.
Key words: central pattern generator (CPG); neural oscillator; voltage-clamp; model; graded synapse; h-current
This article has been cited by other articles:
A. V. Olypher and R. L. Calabrese
Using Constraints on Neuronal Activity to Reveal Compensatory Changes in Neuronal Parameters
J Neurophysiol, December 1, 2007; 98(6): 3749 - 3758.
[Abstract] [Full Text] [PDF]
B. J. Norris, A. L. Weaver, A. Wenning, P. S. Garcia, and R. L. Calabrese
A Central Pattern Generator Producing Alternative Outputs: Pattern, Strength, and Dynamics of Premotor Synaptic Input to Leech Heart Motor Neurons
J Neurophysiol, November 1, 2007; 98(5): 2992 - 3005.
[Abstract] [Full Text] [PDF]
P. Rabbah and F. Nadim
Distinct Synaptic Dynamics of Heterogeneous Pacemaker Neurons in an Oscillatory Network
J Neurophysiol, March 1, 2007; 97(3): 2239 - 2253.
[Abstract] [Full Text] [PDF]
J. H. Peck, E. Gaier, E. Stevens, S. Repicky, and R. M. Harris-Warrick
Amine Modulation of Ih in a Small Neural Network
J Neurophysiol, December 1, 2006; 96(6): 2931 - 2940.
[Abstract] [Full Text] [PDF]
A. Olypher, G. Cymbalyuk, and R. L. Calabrese
Hybrid Systems Analysis of the Control of Burst Duration by Low-Voltage-Activated Calcium Current in Leech Heart Interneurons
J Neurophysiol, December 1, 2006; 96(6): 2857 - 2867.
[Abstract] [Full Text] [PDF]
A.-E. Tobin, S. D. Van Hooser, and R. L. Calabrese
Creation and Reduction of a Morphologically Detailed Model of a Leech Heart Interneuron
J Neurophysiol, October 1, 2006; 96(4): 2107 - 2120.
[Abstract] [Full Text] [PDF]
A. I. Ivanov and R. L. Calabrese
Graded Inhibitory Synaptic Transmission Between Leech Interneurons: Assessing the Roles of Two Kinetically Distinct Low-Threshold Ca Currents
J Neurophysiol, July 1, 2006; 96(1): 218 - 234.
[Abstract] [Full Text] [PDF]
A. I. Ivanov and R. L. Calabrese
Spike-Mediated and Graded Inhibitory Synaptic Transmission Between Leech Interneurons: Evidence for Shared Release Sites
J Neurophysiol, July 1, 2006; 96(1): 235 - 251.
[Abstract] [Full Text] [PDF]
P. Rabbah and F. Nadim
Synaptic Dynamics Do Not Determine Proper Phase of Activity in a Central Pattern Generator
J. Neurosci., December 7, 2005; 25(49): 11269 - 11278.
[Abstract] [Full Text] [PDF]
B. R. Johnson, L. R. Schneider, F. Nadim, and R. M. Harris-Warrick
Dopamine Modulation of Phasing of Activity in a Rhythmic Motor Network: Contribution of Synaptic and Intrinsic Modulatory Actions
J Neurophysiol, November 1, 2005; 94(5): 3101 - 3111.
[Abstract] [Full Text] [PDF]
M. Sorensen, S. DeWeerth, G. Cymbalyuk, and R. L. Calabrese
Using a Hybrid Neural System to Reveal Regulation of Neuronal Network Activity by an Intrinsic Current
J. Neurosci., June 9, 2004; 24(23): 5427 - 5438.
[Abstract] [Full Text] [PDF]
A. Mamiya and F. Nadim
Dynamic Interaction of Oscillatory Neurons Coupled with Reciprocally Inhibitory Synapses Acts to Stabilize the Rhythm Period
J. Neurosci., June 2, 2004; 24(22): 5140 - 5150.
[Abstract] [Full Text] [PDF]
S. H. Jezzini, A. A. V. Hill, P. Kuzyk, and R. L. Calabrese
Detailed Model of Intersegmental Coordination in the Timing Network of the Leech Heartbeat Central Pattern Generator
J Neurophysiol, February 1, 2004; 91(2): 958 - 977.
[Abstract] [Full Text] [PDF]
A. Mamiya, Y. Manor, and F. Nadim
Short-Term Dynamics of a Mixed Chemical and Electrical Synapse in a Rhythmic Network
J. Neurosci., October 22, 2003; 23(29): 9557 - 9564.
[Abstract] [Full Text] [PDF]
A. I. Ivanov and R. L. Calabrese
Modulation of Spike-Mediated Synaptic Transmission by Presynaptic Background Ca2+ in Leech Heart Interneurons
J. Neurosci., February 15, 2003; 23(4): 1206 - 1218.
[Abstract] [Full Text] [PDF]
G. S. Cymbalyuk, Q. Gaudry, M. A. Masino, and R. L. Calabrese
Bursting in Leech Heart Interneurons: Cell-Autonomous and Network-Based Mechanisms
J. Neurosci., December 15, 2002; 22(24): 10580 - 10592.
[Abstract] [Full Text] [PDF]
A. A. V. Hill, M. A. Masino, and R. L. Calabrese
Model of Intersegmental Coordination in the Leech Heartbeat Neuronal Network
J Neurophysiol, March 1, 2002; 87(3): 1586 - 1602.
[Abstract] [Full Text] [PDF]
V. A. Straub and P. R. Benjamin
Extrinsic Modulation and Motor Pattern Generation in a Feeding Network: a Cellular Study
J. Neurosci., March 1, 2001; 21(5): 1767 - 1778.
[Abstract] [Full Text] [PDF]
A. I. Ivanov and R. L. Calabrese
Intracellular Ca2+ Dynamics During Spontaneous and Evoked Activity of Leech Heart Interneurons: Low-Threshold Ca Currents and Graded Synaptic Transmission
J. Neurosci., July 1, 2000; 20(13): 4930 - 4943.
[Abstract] [Full Text] [PDF]
P. Kloppenburg, D. Ferns, and A. R. Mercer
Serotonin Enhances Central Olfactory Neuron Responses to Female Sex Pheromone in the Male Sphinx Moth Manduca sexta
J. Neurosci., October 1, 1999; 19(19): 8172 - 8181.
[Abstract] [Full Text] [PDF]
J. Tegner and S. Grillner
Interactive Effects of the GABABergic Modulation of Calcium Channels and Calcium-Dependent Potassium Channels in Lamprey
J Neurophysiol, March 1, 1999; 81(3): 1318 - 1329.
[Abstract] [Full Text] [PDF]
Y. Manor, F. Nadim, L. F. Abbott, and E. Marder
Temporal Dynamics of Graded Synaptic Transmission in the Lobster Stomatogastric Ganglion
J. Neurosci., July 15, 1997; 17(14): 5610 - 5621.
[Abstract] [Full Text] [PDF]
J. Lu, J. F. Dalton IV, D. R. Stokes, and R. L. Calabrese
Functional Role of Ca2+ Currents in Graded and Spike-Mediated Synaptic Transmission Between Leech Heart Interneurons
J Neurophysiol, April 1, 1997; 77(4): 1779 - 1794.
[Abstract] [Full Text] [PDF]
|
|
|
|
 |
|