| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
The Journal of Neurophysiology Vol. 87 No. 3 March 2002, pp. 1603-1615
Copyright ©2002 by the American Physiological Society
Biology Department, Emory University, Atlanta, Georgia 30322
Masino, Mark A. and
Ronald L. Calabrese.
Period Differences Between Segmental Oscillators Produce
Intersegmental Phase Differences in the Leech Heartbeat Timing
Network. J. Neurophysiol. 87: 1603-1615, 2002. Considerable experimental and theoretical effort has been
exerted to understand how constant intersegmental phase relationships are produced between oscillators in segmentally organized pattern generating networks. The phase relationship between the segmental oscillators in the isolated timing network of the leech heartbeat central pattern generator is quite regular within individual
preparations. However, it varies considerably among different
preparations. Our goal is to determine how the phase relationships in
this network are established. Here we assess whether inherent period
differences, as suggested by the excitability-gradient hypothesis, play
a role in establishing the phase relationships between the two coupled segmental oscillators of the leech heartbeat timing network. To do this
we developed methods for reversibly uncoupling the segmental oscillators (sucrose knife) and pharmacological manipulation of the
individual oscillators (split bath). Differences in inherent cycle
periods between the third and fourth segmental oscillators (G3 and G4)
were present in most (20 of 26) preparations. These period differences
correlated with the phase differences observed between the segmental
oscillators in the recoupled timing network, such that the oscillator
with the faster cycle period, regardless of the segment in which it was
located, led in phase in proportion to its period difference with the
other oscillator. The phase differences between the original (coupled)
and recoupled states of individual preparations were similar. Thus
application and removal of the sucrose knife did not alter the period
difference between the segmental oscillators in the timing network.
Pharmacological manipulation of the uncoupled oscillators to alter the
period difference between the oscillators led to similar correlated
phase differences in the recoupled timing network. Across all
experiments the uncoupled segmental oscillator with the faster cycle
period established the cycle period of the timing network when
recoupled. In conclusion, our findings indicate that an
excitability-gradient plays a role in establishing the phase
relationship between the segmental oscillators of the leech heartbeat
central pattern generator since inherent period differences present
between the oscillators are correlated to the phase relationships of
the coupled/recoupled timing network.
This article has been cited by other articles:
|
|
 |
|
  B. J. Norris, A. L. Weaver, A. Wenning, P. S. Garcia, and R. L. Calabrese A Central Pattern Generator Producing Alternative Outputs: Phase Relations of Leech Heart Motor Neurons With Respect to Premotor Synaptic Input J Neurophysiol, November 1, 2007; 98(5): 2983 - 2991. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Wenning and E. P. Meyer Hemodynamics in the leech: blood flow in two hearts switching between two constriction patterns J. Exp. Biol., August 1, 2007; 210(15): 2627 - 2636. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Mulloney and W. M. Hall Not by Spikes Alone: Responses of Coordinating Neurons and the Swimmeret System to Local Differences in Excitation J Neurophysiol, January 1, 2007; 97(1): 436 - 450. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A.-E. Tobin and R. L. Calabrese Endogenous and Half-Center Bursting in Morphologically Inspired Models of Leech Heart Interneurons J Neurophysiol, October 1, 2006; 96(4): 2089 - 2106. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. J. Norris, A. L. Weaver, L. G. Morris, A. Wenning, P. A. Garcia, and R. L. Calabrese A Central Pattern Generator Producing Alternative Outputs: Temporal Pattern of Premotor Activity J Neurophysiol, July 1, 2006; 96(1): 309 - 326. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A.-E. Tobin and R. L. Calabrese Myomodulin Increases Ih and Inhibits the Na/K Pump to Modulate Bursting in Leech Heart Interneurons J Neurophysiol, December 1, 2005; 94(6): 3938 - 3950. [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. Wenning, A. A. V. Hill, and R. L. Calabrese Heartbeat Control in Leeches. II. Fictive Motor Pattern J Neurophysiol, January 1, 2004; 91(1): 397 - 409. [Abstract] [Full Text]
|
|
|
|
|
|
A. A.V. Hill, M. A. Masino, and R. L. Calabrese Intersegmental Coordination of Rhythmic Motor Patterns J Neurophysiol, August 1, 2003; 90(2): 531 - 538. [Full Text] [PDF]
|
|
|
|
 |
|
 M. A. Masino and R. L. Calabrese A Functional Asymmetry in the Leech Heartbeat Timing Network Is Revealed by Driving the Network across Various Cycle Periods J. Neurosci., June 1, 2002; 22(11): 4418 - 4427. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. A. Masino and R. L. Calabrese Phase Relationships Between Segmentally Organized Oscillators in the Leech Heartbeat Pattern Generating Network J Neurophysiol, March 1, 2002; 87(3): 1572 - 1585. [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]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
