|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
Journal of Experimental Biology, Vol 199, Issue 10 2185-2198, Copyright © 1996 by Company of Biologists
JOURNAL ARTICLES |
U. Bassler and W. Stein
It is shown that the low-pass filter characteristics of the muscle-joint system of the femur-tibia joint of the stick insect Cuniculina impigra result from co-contraction of the extensor and flexor tibiae muscles. The most distal region of the extensor muscle, which contains a high percentage of slow muscle fibres, is involved in this co-contraction. This conclusion results from the following evidence. (1) Inertial and friction forces do not affect the characteristics of the low-pass filter of the muscle-joint system. (2) There is some co-contraction of the extensor and flexor muscles during sinusoidal stimulation of the femoral chordotonal organ at high stimulus frequencies. Both muscles generate tonic forces that increase with increasing stimulus frequency and also increase with time from the beginning of stimulation until a plateau is reached. (3) For the extensor muscle, this tonic force is produced by its most distal portion only. (4) Electrical stimulation of the common inhibitory motoneurone (CI1) reduces the tonic force generated in this most distal portion of the extensor muscle. Therefore, CI1 stimulation reduces the amplitude of tibial movement in response to sinusoidal stimulation of the femoral chordotonal organ at stimulus frequencies below 0.5 Hz (over this frequency range, the tibial movement amplitude is a function of the force amplitude produced by the whole extensor muscle and there is no co-contraction), but at chordotonal organ stimulus frequencies of 1 Hz and above, CI1 stimulation increases the tibial movement amplitude (in this case, movement amplitude is limited by the degree of co-contraction of the extensor and flexor muscles). With repeated chordotonal organ stimulation at higher stimulus frequencies, the tibial movement amplitude steadily decreases. This must be a consequence of increasing levels of co-contraction of the extensor and flexor muscles, since at low stimulus frequencies (no co-contraction) there is no reduction in movement amplitude during repeated stimulations. It is concluded that co-contraction of the extensor and flexor tibiae muscles prevents instability in the reflex loop in spite of the high gain necessary for the generation of catalepsy. Therefore, the mechanism described can be considered to be an adaptation to the ecological niche occupied by this animal. The contribution of the distal part of the extensor muscle to this system can be switched off by the CI1 during active movements.
This article has been cited by other articles:
|
|
 |
|
  K. L. Page, J. Zakotnik, V. Durr, and T. Matheson Motor Control of Aimed Limb Movements in an Insect J Neurophysiol, February 1, 2008; 99(2): 484 - 499. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. L. Hooper, C. Guschlbauer, G. von Uckermann, and A. Buschges Slow Temporal Filtering May Largely Explain the Transformation of Stick Insect (Carausius morosus) Extensor Motor Neuron Activity Into Muscle Movement J Neurophysiol, September 1, 2007; 98(3): 1718 - 1732. [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]
|
|
|
|
|
|
S. L. Hooper, C. Guschlbauer, G. von Uckermann, and A. Buschges Different Motor Neuron Spike Patterns Produce Contractions With Very Similar Rises in Graded Slow Muscles J Neurophysiol, February 1, 2007; 97(2): 1428 - 1444. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Zakotnik, T. Matheson, and V. Durr Co-contraction and passive forces facilitate load compensation of aimed limb movements. J. Neurosci., May 10, 2006; 26(19): 4995 - 5007. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Nishino Motor output characterizing thanatosis in the cricket Gryllus bimaculatus J. Exp. Biol., October 15, 2004; 207(22): 3899 - 3915. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Wolf, U. Bassler, R. Spie{beta}, and R. Kittmann The femur-tibia control system in a proscopiid (Caelifera, Orthoptera): a test for assumptions on the functional basis and evolution of twig mimesis in stick insects J. Exp. Biol., March 13, 2002; 204(22): 3815 - 3828. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. L. Newland and Y. Kondoh Dynamics of Neurons Controlling Movements of a Locust Hind Leg III. Extensor Tibiae Motor Neurons J Neurophysiol, June 1, 1997; 77(6): 3297 - 3310. [Abstract] [Full Text] [PDF]
|
|
