Effects of ankle extensor muscle afferent inputs on hip abductor and adductor activity in the decerebrate walking cat

2012 ◽  
Vol 108 (11) ◽  
pp. 3034-3042 ◽  
Author(s):  
D. A. E. Bolton ◽  
J. E. Misiaszek
Keyword(s):  
Gluteus Medius ◽  
Extensor Muscle ◽  
The Body ◽  
Burst Duration ◽  
Medial Gastrocnemius ◽  
Decerebrate Cat ◽  
Group I ◽  
Adductor Muscles ◽  
Hip Abductor ◽  
Stimulation Of

Electrical stimulation of the lateral gastrocnemius-soleus (LGS) nerve at group I afferent strength leads to adaptations in the amplitude and timing of extensor muscle activity during walking in the decerebrate cat. Such afferent feedback in the stance leg might result from a delay in stance onset of the opposite leg. Concomitant adaptations in hip abductor and adductor activity would then be expected to maintain lateral stability and balance until the opposite leg is able to support the body. As many hip abductors and adductors are also hip extensors, we hypothesized that stimulation of the LGS nerve at group I afferent strength would produce increased activation and prolonged burst duration in hip abductor and adductor muscles in the premammillary decerebrate walking cat. LGS nerve stimulation during the extensor phase of the locomotor cycle consistently increased burst amplitude of the gluteus medius and adductor femoris muscles, but not pectineus or gracilis. In addition, LGS stimulation prolonged the burst duration of both gluteus medius and adductor femoris. Unexpectedly, long-duration LGS stimulus trains resulted in two distinct outcomes on the hip abductor and adductor bursting pattern: 1) a change of burst duration and timing similar to medial gastrocnemius; or 2) to continue rhythmically bursting uninterrupted. These results indicate that activation of muscle afferents from ankle extensors contributes to the regulation of activity of some hip abductor and adductor muscles, but not all. These results have implications for understanding the neural control of stability during locomotion, as well as the organization of spinal locomotor networks.

Distribution of oligosynaptic group I input to the cat medial gastrocnemius motoneuron pool

1985 ◽  
Vol 53 (2) ◽  
pp. 497-517 ◽  
Author(s):  
R. K. Powers ◽  
M. D. Binder
Keyword(s):  
Sural Nerve ◽  
Afferent Input ◽  
Medial Gastrocnemius ◽  
Resting Potential ◽  
Tibialis Posterior ◽  
Medial Branch ◽  
Motoneuron Pool ◽  
Group I ◽  
Flexor Digitorum ◽  
Stimulation Of

To characterize the oligosynaptic group I afferent input to the cat medial gastrocneumius (MG) motoneuron pool, the medial branch of the tibial nerve (MTIB: flexor digitorum and hallucis longus, popliteus, tibialis posterior and interosseous nerves), the nerves to flexor digitorum and hallucis longus (FDHL), or the nerves to the quadriceps muscles (QUAD) were stimulated at submaximal group I strength while recording intracellularly from MG motoneurons. Since previous work indicates that stimulation of these nerves at group I strength produces no significant monosynaptic Ia excitation or Renshaw inhibition of MG motoneurons, group I effects were assumed to be predominantly, though not exclusively, due to the action of Ib-fibers. Evidence supporting this assumption is presented in the following paper. MTIB, FDHL, and QUAD postsynaptic potentials (PSPs) were most commonly inhibitory. Since the MTIB, FDHL, and QUAD nerves are composed predominantly of fibers innervating muscles with extensor action, their inhibitory effect on MG motoneurons is consistent with previous findings that stimulation of Ib-afferents in nerves to extensor muscles produces di- and trisynaptic inhibition of extensor motoneurons. However, excitatory effects were observed in about one third of the motoneurons, indicating that oligosynaptic group I input is not homogeneously distributed within the MG motoneuron pool. Variations in QUAD, FDHL, and MTIB PSP pattern and amplitude were correlated with variations in the PSP pattern evoked by stimulation of the sural nerve: excitatory oligosynaptic group I PSPs generally appeared in motoneurons receiving excitatory cutaneous (sural nerve) input, whereas inhibitory PSPs generally appeared in motoneurons receiving some inhibitory cutaneous input and were largest in motoneurons receiving predominantly inhibition from the sural nerve. These variations in QUAD, FDHL, and MTIB PSP pattern and amplitude were not due to variations in resting potential and were only partly due to variations in intrinsic motoneuron properties or motoneuron "type." Our results indicate that activation of these cutaneous and group I muscle afferents can exert similar effects on the MG motoneuron pool. Moreover, the presence of a strong correlation between the distributions of cutaneous and oligosynaptic group I PSPs within a single motoneuron pool is consistent with the results of previous studies that have shown that some of the input to motoneurons from these peripheral afferents is mediated through common interneurons.

Motor-unit recruitment in the decerebrate cat: several unit properties are equally good predictors of order

1991 ◽  
Vol 66 (4) ◽  
pp. 1127-1138 ◽  
Author(s):  
T. C. Cope ◽  
B. D. Clark
Keyword(s):  
Motor Unit ◽  
Rank Order ◽  
Motor Units ◽  
Afferent Input ◽  
Medial Gastrocnemius ◽  
Size Principle ◽  
Recruitment Pattern ◽  
Decerebrate Cat ◽  
Recruitment Order ◽  
Stimulation Of

1. Recruitment order was studied in pairs of motor units of the medial gastrocnemius (MG) muscle of decerebrate cats with the use of dual microelectrode recording from intact ventral root filaments. Excitation was provided by stretch of MG, stretch of synergists [lateral gastrocnemius (LG), plantaris (PL), and soleus (SOL) muscles] or electrical stimulation of the caudal cutaneous sural (CCS) nerve. Motor units were characterized by axonal conduction velocity (CV), tetanic tension (Pmax), twitch contraction time (CT), and fatigue index (FI). 2. Consistent with the recruitment pattern described by others, most often in relation to either CV or Pmax, the first unit of a pair to be recruited by MG stretch was typically the one with the lower CV and Pmax, and the higher FI and CT. The proportion of pairs that agreed in rank order of each property and recruitment order was as follows: for CT, 94%; for CV, 87%; for Pmax, 84%; and for FI, 75%. With a single marginal exception (CT vs. FI), no motor-unit property proved to be significantly better than the others at predicting recruitment (G test; P greater than 0.05). 3. In all 11 tested pairs containing one slow (type S) and one fast (type F) unit, the S was more easily recruited by stretch. Type F units divided into groups with high (type FR), low (type FF), and intermediate (type FInt) values for FI were recruited in order from FR to FInt to FF in 8/11 pairs. Thus our findings were similar to earlier demonstrations that recruitment proceeds in order by type. 4. Stretch of MG synergists usually recruited units in the same order as MG stretch. In two S-S pairs, recruitment order was switched with synergist stretch. 5. Stimulation of the CCS nerve was generally excitatory to the MG units sampled. Most unit pairs were recruited by CCS stimulation in the same order as by MG stretch, but, for 6 of 39 pairs, CCS stimulation switched the order produced by stretch. Thus, whereas sural afferent input can preferentially excite some units over others as suggested by Kanda et al., that effect is not widespread or selective for unit type under these conditions. 6. Assuming that all MG motor units cooperate as a single functional pool in homonymous stretch reflexes, we support others in concluding that a motoneuron's recruitment threshold is not strictly determined by its size. However, our data do not distinguish other schemes that predict recruitment order more accurately than the size principle.(ABSTRACT TRUNCATED AT 400 WORDS)

Synaptic organization of defined motor-unit types in cat tibialis anterior

1980 ◽  
Vol 43 (6) ◽  
pp. 1631-1644 ◽  
Author(s):  
R. P. Dum ◽  
T. T. Kennedy
Keyword(s):  
Motor Unit ◽  
Tibialis Anterior ◽  
Muscle Afferents ◽  
Medial Gastrocnemius ◽  
Synaptic Organization ◽  
Ia Afferents ◽  
Group I ◽  
Ia Epsp ◽  
Group I Afferents ◽  
Stimulation Of

1. Synaptic potentials were recorded intracellularly in tibialis anterior (TA) motoneurons following stimulation of a descending brain stem pathway, the medial longitudinal fasciculus (MLF), and three segmental inputs, the homonymous and heteronymous group Ia afferents, the group I afferents from the antagonist, and the cutaneous and muscle afferents. Intracellular stimulation of the motoneurons was used to classify them, based on the properties of the innervated muscle units, into types FF, F(int), FR, and S (6, 16). 2. The sum of the monosynaptic EPSP amplitudes resulting from stimulation of homonymous and heteronymous group Ia afferents (summed group Ia EPSP) was inversely related to motoneuron size, as assessed by motoneuron input resistance, and was inversely related to motor-unit tetanic tension. Type-FF, -FR, and -S motoneurons showed significant differences in the mean amplitude of their summed group Ia EPSPs. 3. The amplitudes of disynaptic IPSPs resulting from stimulation of group I afferents in the antagonist muscle also showed an inverse relationship to motoneuron size. The observed relationships between motoneuron size and the monosynaptic group Ia EPSP amplitude or the disynaptic group I IPSP amplitude are compatible with the “size principle” of motor-unit recruitment (26). 4. The amplitudes of the monosynaptic EPSPs evoked in TA motoneurons by stimulation of the MLF were distributed rather randomly among all types of TA motoneurons. A slight tendency of larger monosynaptic EPSPs to occur in motoneurons with larger tetanic tensions was observed. 5. The polysynaptic effects from cutaneous and muscle afferents in sural and gastrocnemius-soleus nerves were frequently excitatory on type-FF motoneurons, but were primarily inhibitory on type-FR and -S motoneurons. Clearly, the polysynaptic cutaneous and muscle inputs and the monosynaptic MLF input onto TA motoneurons show a different pattern of synaptic organization than the group I inputs. 6. In general, the synaptic organization of the TA motor nucleus is similar to that of its extensor antagonist, medial gastrocnemius (MG) (2--5, 7, 8), when analogous neural circuits are compared. This parallel organization suggests a commonality of motor-control systems for both flexor and extensor muscles.

Hip Adduction and Abduction Torque-angle Curve Characterization of Speed Skating Athletes

2020 ◽  
Vol 41 (04) ◽  
pp. 248-254
Author(s):  
Luciano Luporini Menegaldo ◽  
Lyon Aragão ◽  
Thiago Matta ◽  
Liliam Fernandes de Oliveira
Keyword(s):  
Gluteus Medius ◽  
Recovery Phase ◽  
Control Group ◽  
Tensor Fascia Lata ◽  
Speed Skating ◽  
Adductor Muscles ◽  
Hip Abductor ◽  
Torque Angle ◽  
Similar Peak

Abstract Speed skating is a cyclic sport which involves the hip abductor muscles, impelling the participant forwards, and adductor muscles, in the recovery phase and decelerating the abduction movement eccentrically. This paper has the objective of describing and comparing the abduction/adduction torque-angle curves of speed skating athletes (N=10) with a group of non-practitioners young participants (N=10). Both groups presented similar peak torques and electromyography patterns for tensor fascia lata, gluteus medius, long adductor and adductor magnus. However, athletes showed higher torque-angle curve integral and abduction and adduction peak torques at different hip angles than the control group. These findings suggest an adaptation of their musculotendon actuators and a better capacity to generate mechanical work and power during a propulsion-recovery cycle.

Parallel suppression of extensor muscle tone and respiration by stimulation of pontine dorsal tegmentum in decerebrate cat

1988 ◽  
Vol 473 (1) ◽  
pp. 81-90 ◽  
Author(s):  
Koichi Kawahara ◽  
Yoshimi Nakazono ◽  
Shigeru Kumagai ◽  
Yoshiko Yamauchi ◽  
Yoshimi Miyamoto
Keyword(s):  
Muscle Tone ◽  
Extensor Muscle ◽  
Decerebrate Cat ◽  
Stimulation Of

Plasticity of the extensor group I pathway controlling the stance to swing transition in the cat

1995 ◽  
Vol 74 (6) ◽  
pp. 2782-2787 ◽  
Author(s):  
P. J. Whelan ◽  
G. W. Hiebert ◽  
K. G. Pearson
Keyword(s):  
Medial Gastrocnemius ◽  
Lateral Gastrocnemius ◽  
Group I ◽  
Excitatory Pathways ◽  
Extensor Muscles ◽  
Stimulus Train ◽  
Control Response ◽  
Control Limb ◽  
Adult Cats ◽  
Stimulation Of

1. This study examines whether the efficacy of polysynaptic group I excitatory pathways to extensor motoneurons are modified after axotomy of a synergistic nerve. Previously, it has been shown that stimulation of extensor nerves at group I strength can extend the stance phase and delay swing. Stimulation of the lateral gastrocnemius and soleus (LG/S) nerve prolongs stance for the duration of the stimulus train, whereas stimulation of the medial gastrocnemius (MG) nerve moderately increases stance. Our hypothesis was that after axotomy of the LG/S nerve the efficacy of the MG group I input would increase. 2. This idea was tested in 10 adult cats that had their left LG/S nerves axotomized for 3-28 days. On the experimental day the cats were decerebrated and the left (experimental) and right (control) LG/S and MG nerves were stimulated during late stance as the animals were walking on a motorized treadmill. A significant increase in the efficacy of the left MG nerve occurred 5 days after axotomy of the LG/S nerve when compared with the control response. By contrast, the previously cut LG/S nerve showed a reduction in efficacy after 3 days compared with the control limb. 3. Functionally, this plasticity may be an important mechanism by which the strength of the group I pathway is calibrated to different loads on the extensor muscles.

Determination of afferent fibers mediating oligosynaptic group I input to cat medial gastrocnemius motoneurons

1985 ◽  
Vol 53 (2) ◽  
pp. 518-529 ◽  
Author(s):  
R. K. Powers ◽  
M. D. Binder
Keyword(s):  
Electrical Stimulation ◽  
Medial Gastrocnemius ◽  
Flexor Hallucis Longus ◽  
Selective Activation ◽  
Group I ◽  
Afferent Fibers ◽  
Series Of Experiments ◽  
Group Ii ◽  
Flexor Digitorum ◽  
Stimulation Of

In the experiments described in the preceding paper electrical stimulation of the quadriceps (QUAD), medial tibial (MTIB), and flexor digitorum and hallucis longus (FDHL) muscle nerves was used to evoke oligosynaptic group I postsynaptic potentials (PSPs) in medial gastrocnemius (MG) motoneurons. In the present study, we attempted to specify the types of afferent fibers which mediate that oligosynaptic activity (FDHL to MG only). In one series of experiments, isolated single flexor digitorum longus (FDL) and flexor hallucis longus (FHL) afferents were identified as Ia, Ib, or group II fibers according to their conduction velocities, responses to muscle contraction, and mechanical thresholds to small amplitude triangular stretches applied to the parent muscles. We also determined the electrical thresholds of the identified afferent fibers by applying graded electrical stimulation to their muscle nerve. These results were used as criteria to define the types of afferents that mediated the electrically and stretch-evoked FDHL oligosynaptic PSPs recorded in MG motoneurons during a second series of experiments. The amplitudes of the oligosynaptic PSPs evoked in MG motoneurons increased as the strength of the electrical stimuli applied to the FDHL muscle nerves was raised to activate greater numbers of Ia- and Ib-fibers, but showed little or no additional increase when the stimulus intensity was raised further to include the majority of group II fibers. On this basis, a significant contribution by group II fibers to these oligosynaptic PSPs was considered unlikely. Simultaneous electrical activation of both Ia- and Ib-fibers produced distinct oligosynaptic PSPs in MG motoneurons, but these were likely due primarily to Ib-afferent activity, since selective activation of Ia-afferents (by stretch) rarely produced oligosynaptic PSPs in the same motoneurons. There was, however, evidence for some Ia contribution to these oligosynaptic PSPs. This is consistent with the demonstration that Ia- and Ib-afferent fibers converge onto common interneurons and that selective activation of Ia-fibers can produce PSPs similar to those evoked by concurrent stimulation of Ia- and Ib-fibers. On the basis of the present results and those of several related studies it is argued that the oligosynaptic PSPs evoked in MG motoneurons by submaximal group I stimulation of the FDHL, MTIB, or QUAD muscle nerves can be ascribed predominantly to the activation of Ib-afferent fibers, with only minimal Ia and probably no group II contribution.

Phasic and tonic modulation of impulse rates in gamma-motoneurons during locomotion in premammillary cats

1984 ◽  
Vol 52 (2) ◽  
pp. 228-243 ◽  
Author(s):  
P. R. Murphy ◽  
R. B. Stein ◽  
J. Taylor
Keyword(s):  
Ventral Root ◽  
The Body ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Nerve Branch ◽  
Significant Difference ◽  
Natural Stimulation ◽  
Triceps Surae Muscles ◽  
Stimulation Of

To determine the role of gamma-motoneurons in the control of locomotion, we isolated single units from nerves to triceps surae muscles in the premammillary cat. The limb used for recording was largely denervated, except for the muscles of interest, and fixed in place, while the other three limbs walked on a treadmill. One type of gamma-motoneuron (13 units) had a high impulse rate at rest, which changed little on average during walking, but was deeply modulated with each step (phasically modulated gamma-motoneuron or gamma p). Another type (19 units) had a low impulse rate at rest, which increased greatly on average during walking, but was not highly modulated with each step (tonically modulated gamma-motoneuron or gamma t). Peak gamma p rates generally occurred after peak EMG, often near the peak of tension. In contrast, peak gamma t activity generally preceded peak electromyograms (EMG). No significant difference was observed in conduction velocities for the two types of units. At rest all gamma t units were excited by natural stimulation of the fur over a large part of the body surface, whereas 3 of 11 gamma p units were inhibited. During locomotion the same natural stimuli had no observable effect on either type of unit. By recording in continuity from fine branches of the lateral and medial gastrocnemius nerves and stimulating ventral root filaments in continuity, we identified dynamic and static gamma-motoneurons in terms of their effects on muscle spindle afferents. After cutting the nerve branch distally and other ventral root filaments supplying the muscle, the resting discharge of dynamic and static gamma-motoneurons was recorded and found to correspond to that of the gamma p and gamma t units, respectively. Other evidence is presented for a correspondence between phasically and tonically modulated units and dynamic and static gamma-motoneurons, contrary to some suggestions in the literature.

Sustained Firing of Alpha and Gamma Hind Limb Motoneurons Induced by Stimulation of the Pudendal Nerve

2002 ◽  
Vol 88 (6) ◽  
pp. 3232-3242 ◽  
Author(s):  
Rafael Cueva-Rolón ◽  
Rodolfo Delgado-Lezama ◽  
J. G. Raya ◽  
M. Raya ◽  
R. Tecuanhuey ◽  
...  
Keyword(s):  
Hind Limb ◽  
Pudendal Nerve ◽  
Muscle Spindles ◽  
Vaginal Wall ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Emg Activity ◽  
Decerebrate Cat ◽  
Integrated Emg ◽  
Stimulation Of

Axons from receptors in the cat vaginal wall run in the sensory pudendal nerve (SPN), and brief (<10 s) vaginal probing (VP) in the decerebrate cat produces a long-lasting (>1 min) contraction of the triceps surae (TS) muscles. The aim of the present project was to find out whether brief SPN stimulation also produces sustained TS response and, eventually, to study the mechanisms involved in it. Decerebrate female cats were used. In some cats, TS electromyography (EMG) and tension response were recorded; stimulation of left SPN with single or repetitive trains of shocks produced a bilateral TS response that outlasted the stimulus >1 min as VP did. In paralyzed cats (pancuronium; Panc), intracellular recordings were made from hind limb motoneurons (MNs). SPN stimulation produced a depolarization ≤5 s long and occasional cell firing only lasting <2.5 s; this is in contrast with the prolonged TS postdischarge seen in nonparalyzed cats. If MNs were depolarized below the firing threshold by current injection, about half of them showed bistable firing that could last several minutes in response to SPN train. It is suggested that MNs might hyperpolarize after Panc injection. Before Panc injection, SPN train produced long-lasting (>1 min) electroneurographic (ENG) postdischarge in a small filament of the medial gastrocnemius (MG) nerve; the MG EMG postdischarge was also recorded. Large spikes (LS) and small spikes (SS) were distinguished in the ENG. During the postdischarge, LS frequency and the integrated EMG activity correlated well ( r > 0.9); no correlation was found between SS and EMG. After Panc injection, LS postdischarge was absent but the SS postdischarge remained. LS followed by EMG potential were also evoked by brief TS stretch (reflex LS); single shocks to SPN only elicited SS that were not followed by EMG potential. It is concluded that alpha axons and gamma axons produced LS and SS, respectively, and that SPN activates gamma axons. It is proposed that, in the nonparalyzed cats, the stimulation of SPN with trains of shocks might cause an increase in the afferent inflow from muscle spindles to alpha MNs through the sustained firing of gamma MNs. The increased excitatory inflow would depolarize alpha MNs and allow bistable MN firing; Panc would decrease this inflow by blocking transmission to the spindle fibers.

Control of Frontal Plane Motion of the Hindlimbs in the Unrestrained Walking Cat

2006 ◽  
Vol 96 (4) ◽  
pp. 1816-1828 ◽  
Author(s):  
John E. Misiaszek
Keyword(s):  
Stance Phase ◽  
Frontal Plane ◽  
Plane Motion ◽  
The Body ◽  
Three Dimensions ◽  
Support Surface ◽  
Electromyographic Activity ◽  
Lateral Stability ◽  
Adductor Muscles ◽  
Hip Abductor

This study describes the patterns of activity of hip abductor and adductor muscles and relates their activity to the frontal plane motions of the hindlimbs during unrestrained walking in the cat to provide insight into the function of these muscles in maintaining stability during walking. Electromyographic activity was recorded from hindlimb muscles while cats walked across a walkway. Four video cameras were used to record the movement of the animal in three dimensions. To further delineate the role of the hip abductors and adductors in regulating frontal plane movements of the legs, medial-lateral translations of the walking surface were periodically introduced. During walking, the hip abducts throughout much of the stance phase and adducts during swing. Normally, the abductors and adductors are co-active during much of the stance phase and are quiescent during swing. Consequently, the adduction observed during swing is likely the result of passive events. It is argued that the activity of the hip abductors during stance phase plays a prominent role in regulating frontal plane motion of the legs during walking. However, when medial-lateral stability is disturbed, both the hip abductors and adductors respond to stabilize the frontal plane motion of the body mass while also adjusting the frontal plane swing trajectory and subsequent paw placement. The balance corrective reactions observed in the cat after medial-lateral perturbations of the support surface reasonably approximate the reactions observed previously in humans, indicating that the cat is a reasonable model to explore the neural mechanisms of lateral stability during walking.

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