| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Biological Sciences, Ohio University, Athens, Ohio, United States; Zoologisches Institut, Universität zu Köln, Köln, Germany
2 Zoologisches Institut, Universität zu Köln, Koeln, Germany
3 Dept. of Animal Physiology, Zoological Institute, Cologne, Germany
* To whom correspondence should be addressed. E-mail: hooper{at}ohio.edu.
Graded muscles produce small twitches in response to individual motor neuron spikes. During the early part of their contractions, contraction amplitude in many such muscles depends primarily on the number of spikes the muscle has received, not the frequency or pattern with which they were delivered. Stick insect (Carausius morosus) extensor muscles are graded, and thus would likely show spike number dependency early in their contractions. Tonic stimulations of the extensor motor nerve showed that the response of the muscles differed from the simplest form of spike number dependency. However, these differences actually increased the spike number range over which spike number dependency was present. When the motor nerve was stimulated with patterns mimicking the motor neuron activity present during walking, amplitude during contraction rises also depended much more on spike number than on spike frequency. A consequence of spike number dependence is that brief changes in spike frequency do not alter contraction slope, and we show here that extensor motor neuron bursts with different spike patterns give rise to contractions with very similar contraction rises. We also examined in detail the early portions of a large number of extensor motor neuron bursts recorded during single leg walking, and show that these portions of the bursts do not appear to have any common spike pattern. Although alternative explanations are possible, the simplest interpretation of these data is that extensor motor neuron firing during leg swing is not tightly controlled.
This article has been cited by other articles:
|
|
 |
|
  M. Meseke, J. F. Evers, and C. Duch Developmental Changes in Dendritic Shape and Synapse Location Tune Single-Neuron Computations to Changing Behavioral Functions J Neurophysiol, July 1, 2009; 102(1): 41 - 58. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. L. Hooper, C. Guschlbauer, M. Blumel, P. Rosenbaum, M. Gruhn, T. Akay, and A. Buschges Neural Control of Unloaded Leg Posture and of Leg Swing in Stick Insect, Cockroach, and Mouse Differs from That in Larger Animals J. Neurosci., April 1, 2009; 29(13): 4109 - 4119. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. L. Hooper, E. Buchman, A. L. Weaver, J. B. Thuma, and K. H. Hobbs Slow Conductances Could Underlie Intrinsic Phase-Maintaining Properties of Isolated Lobster (Panulirus interruptus) Pyloric Neurons J. Neurosci., February 11, 2009; 29(6): 1834 - 1845. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Guschlbauer, H. Scharstein, and A. Buschges The extensor tibiae muscle of the stick insect: biomechanical properties of an insect walking leg muscle J. Exp. Biol., March 15, 2007; 210(6): 1092 - 1108. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
