Extensor- and flexor-like modulation within motor pools of the rat hindlimb during treadmill locomotion and swimming

EMG activity was recorded from the vastus lateralis (VL, knee extensor), rectus femoris (RF, hip flexor and knee extensor), tibialis anterior (TA, ankle flexor and digit extensor) and either the lateral or medial gastrocnemius (LG, MG, knee flexors and ankle extensors) muscles of 7 adult rats during treadmill locomotion and swimming. Most flexors and extensors are activated as a single burst but each is known to be modulated differently during locomotion. For example, the extensor EMG bursts are shortened and amplitude elevated as speed increases, whereas little change occurs in the EMG duration and amplitude in flexors. The RF and VL displayed a double burst of EMG activity per cycle during treadmill locomotion and a single burst during swimming. Kinematic and EMG analyses showed that during running, one of these EMG bursts occurred primarily during swing while the other burst occurred primarily during stance. Modulation of the burst occurring during swing approximated a flexor pattern, while the second burst was modulated like a typical extensor when running over a range of speeds and grades on a treadmill. These data suggest that motoneurons within a motor pool of a uniarticular (VL) as well as a biarticular (RF) muscle can be modulated by more than one cyclical input, probably of central origin, and that under some conditions several motor pools may share the same central commands.

[1]  C. Perret,et al.  Analysis of the Pattern of Activity in “Knee Flexor” Motoneurons During Locomotion in the Cat , 1988 .

[2]  Michael J. O'Donovan,et al.  Cat hindlimb motoneurons during locomotion. II. Normal activity patterns. , 1987, Journal of neurophysiology.

[3]  W. Jungers,et al.  Telemetered electromyography of the fast and slow extensors of the leg of the brown lemur (Lemur fulvus). , 1987, The Journal of experimental biology.

[4]  V R Edgerton,et al.  EMG patterns of rat ankle extensors and flexors during treadmill locomotion and swimming. , 1991, Journal of applied physiology.

[5]  V. Reggie Edgerton,et al.  Electromyographic activity of cat hindlimb flexors and extensors during locomotion at varying speeds and inclines , 1989, Brain Research.

[6]  M Tokuriki,et al.  四足獣の歩行運動の筋電図学的関節機構学的研究 : III. 駈歩 , 1974 .

[7]  G. E. Goslow,et al.  The cat step cycle: Hind limb joint angles and muscle lengths during unrestrained locomotion , 1973, Journal of morphology.

[8]  V. Reggie Edgerton,et al.  Coordination of motor pools controlling the ankle musculature in adult spinal cats during treadmill walking , 1991, Brain Research.

[9]  V. Edgerton,et al.  Electromyographic (EMG) amplitude patterns in the proximal and distal compartments of the cat semitendinosus during various motor tasks , 1989, Brain Research.

[10]  R. Roy,et al.  Recruitment patterns in the rat hindlimb muscle during swimming , 1985, Brain Research.

[11]  S. Grillner.  Control of Locomotion in Bipeds, Tetrapods, and Fish , 1981 .

[12]  G. H. Wentink.  The action of the hind limb musculature of the dog in walking. , 1976, Acta anatomica.

[13]  S. Rossignol,et al.  A kinematic and electromyographic study of cutaneous reflexes evoked from the forelimb of unrestrained walking cats. , 1987, Journal of neurophysiology.

[14]  J. Cabelguen,et al.  Main characteristics of the hindlimb locomotor cycle in the decorticate cat with special reference to bifunctional muscles , 1980, Brain Research.

[15]  Michael J. O'Donovan,et al.  Cat hindlimb motoneurons during locomotion. III. Functional segregation in sartorius. , 1987, Journal of neurophysiology.

[16]  G E Goslow,et al.  The cat step cycle: Electromyographic patterns for hindlimb muscles during posture and unrestrained locomotion , 1978, Journal of morphology.

[17]  幹彦 徳力,et al.  四足獣の歩行運動の筋電図学的・関節機構学的研究 : II. 速歩 , 1973 .

[18]  V. Edgerton,et al.  EMG amplitude relationships between the rat soleus and medial gastrocnemius during various motor tasks , 1989, Brain Research.

[19]  M. Tokuriki.  四走獣の歩行運動の筋電図学的・関節機構学的研究 : I. 常歩 , 1973 .

[20]  J. Cabelguen,et al.  Central and reflex participation in the timing of locomotor activations of a bifunctional muscle, the semi-tendinosus, in the cat , 1976, Brain Research.

[21]  I. Engberg,et al.  An electromyographic analysis of muscular activity in the hindlimb of the cat during unrestrained locomotion. , 1969, Acta physiologica Scandinavica.