scholarly journals Actions on gamma-motoneurones elicited by electrical stimulation of group II muscle afferent fibres in the hind limb of the cat.

1983 ◽  
Vol 335 (1) ◽  
pp. 255-273 ◽  
Author(s):  
B Appelberg ◽  
M Hulliger ◽  
H Johansson ◽  
P Sojka
Keyword(s):  
Electrical Stimulation ◽  
Hind Limb ◽  
Gamma Motoneurones ◽  
Muscle Afferent ◽  
Group Ii ◽  
Muscle Afferent Fibres ◽  
Stimulation Of

Contribution of hind limb flexor muscle afferents to the timing of phase transitions in the cat step cycle

1996 ◽  
Vol 75 (3) ◽  
pp. 1126-1137 ◽  
Author(s):  
G. W. Hiebert ◽  
P. J. Whelan ◽  
A. Prochazka ◽  
K. G. Pearson
Keyword(s):  
Electrical Stimulation ◽  
Stance Phase ◽  
Flexor Muscle ◽  
Step Cycle ◽  
Locomotor Rhythm ◽  
Ia Afferents ◽  
Group I ◽  
Flexor Muscles ◽  
Group Ii ◽  
Stimulation Of

1. In this investigation, we tested the hypothesis that muscle spindle afferents signaling the length of hind-leg flexor muscles are involved in terminating extensor activity and initiating flexion during walking. The hip flexor muscle iliopsoas (IP) and the ankle flexors tibialis anterior (TA) and extensor digitorum longus (EDL) were stretched or vibrated at various phases of the step cycle in spontaneously walking decerebrate cats. Changes in electromyogram amplitude, duration, and timing were then examined. The effects of electrically stimulating group I and II afferents in the nerves to TA and EDL also were examined. 2. Stretch of the individual flexor muscles (IP, TA, or EDL) during the stance phase reduced the duration of extensor activity and promoted the onset of flexor burst activity. The contralateral step cycle also was affected by the stretch, the duration of flexor activity being shortened and extensor activity occurring earlier. Therefore, stretch of the flexor muscles during the stance phase reset the locomotor rhythm to flexion ipsilaterally and extension contralaterally. 3. Results of electrically stimulating the afferents from the TA and EDL muscles suggested that different groups of afferents were responsible for the resetting of the step cycle. Stimulation of the TA nerve reset the locomotor step cycle when the stimulus intensity was in the group II range (2-5 xT). By contrast, stimulation of the EDL nerve generated strong resetting of the step cycle in the range of 1.2-1.4 xT, where primarily the group Ia afferents from the muscle spindles would be activated. 4. Vibration of IP or EDL during stance reduced the duration of the extensor activity by similar amounts to that produced by muscle stretch or by electrical stimulation of EDL at group Ia strengths. This suggests that the group Ia afferents from IP and EDL are capable of resetting the locomotor pattern generator. Vibration of TA did not affect the locomotor rhythm. 5. Stretch of IP or electrical stimulation of TA afferents (5 xT) during the flexion phase did not change the duration of the flexor activity. Stimulation of the EDL nerve at 1.8-5 xT during flexion increased the duration of the flexor activity. In none of our preparations did we observe resetting to extension when the flexor afferents were activated during flexion. 6. We conclude that as the flexor muscles lengthen during the stance phase of gait, their spindle afferents (group Ia afferents for EDL and IP, group II afferents for TA) act to inhibit the spinal center generating extensor activity thus facilitating the initiation of swing.

Spinoreticular neurons that receive group III input are inhibited by MLR stimulation

2002 ◽  
Vol 93 (1) ◽  
pp. 92-98 ◽  
Author(s):  
Alexandr M. Degtyarenko ◽  
Marc P. Kaufman
Keyword(s):  
Electrical Stimulation ◽  
Tibial Nerve ◽  
Afferent Input ◽  
Ventrolateral Medulla ◽  
Central Command ◽  
Mesencephalic Locomotor Region ◽  
Group Iii ◽  
Tibial Nerve Stimulation ◽  
Muscle Afferent ◽  
Stimulation Of

In decerebrate paralyzed cats, we examined the responses of 18 spinoreticular neurons to electrical stimulation of the mesencephalic locomotor region. The activity of each of the spinoreticular neurons was recorded extracellularly from laminae IV through VI of the L7 and S1 spinal cord. In addition, each of the 18 spinoreticular neurons received group III afferent input from the tibial nerve. Spinoreticular projections were established for each of 18 neurons by antidromic invasion of the ventro lateral medulla at the P11 though P14 levels. The onset latencies and current thresholds for antidromic invasion from the ventro lateral medulla averaged 15.0 ± 3.8 ms and 117 ± 11 μA, respectively. Electrical stimulation of the mesencephalic locomotor region attenuated the spontaneous activity or the responses of each of the spinoreticular neurons to tibial nerve stimulation at currents that recruited group III afferents. Our data support the notion that thin-fiber muscle afferent input to the ventrolateral medulla is gated by a central command to exercise.

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.

Responses of neurons in feline trigeminal subnucleus caudalis (medullary dorsal horn) to cutaneous, intraoral, and muscle afferent stimuli

1986 ◽  
Vol 55 (2) ◽  
pp. 227-243 ◽  
Author(s):  
N. Amano ◽  
J. W. Hu ◽  
B. J. Sessle
Keyword(s):  
Electrical Stimulation ◽  
Receptive Field ◽  
Neuronal Population ◽  
Afferent Stimulation ◽  
Nociceptive Neurons ◽  
Medullary Dorsal Horn ◽  
Tongue Muscles ◽  
Muscle Afferent ◽  
Afferent Inputs ◽  
Stimulation Of

The extracellular activity of single neurons was recorded in subnucleus caudalis (medullary dorsal horn) of chloralose-anesthetized cats to test the effects of electrical and natural stimuli that activated afferents supplying the jaw and tongue muscles as well as the face, teeth, and intraoral mucosa. Many caudalis neurons that could be functionally classified on the basis of their cutaneous receptive-field properties as low-threshold mechanoreceptive (LTM), wide-dynamic-range (WDR), or nociceptive-specific (NS) neurons could be excited by muscle afferent stimuli. Only five neurons were encountered that received muscle afferent inputs and had no demonstrable cutaneous, dental, or mucosal input. The muscle afferent inputs were a particular feature of the cutaneous nociceptive (i.e., WDR and NS) neurons. Approximately two-thirds of this nociceptive neuronal population (n = 109) could be excited by jaw and/or tongue muscle stimulation, whereas only a small proportion of the LTM neuronal population (n = 247) was activated by muscle afferent stimulation. Neurons with a demonstrated direct axonal projection to the contralateral thalamus as well as nonprojection neurons received muscle afferent inputs. The caudalis nociceptive neurons receiving muscle as well as cutaneous afferent inputs had receptive-field properties comparable to those previously described for caudalis cutaneous nociceptive neurons; they were predominantly located in laminae I/II and V/VI, and many also received convergence of tooth pulp afferent inputs. These neurons generally had larger cutaneous receptive fields than neurons unresponsive to muscle afferent stimulation. The muscle afferent inputs were considered to be predominantly of a nociceptive character for several reasons. These included the long latency and high threshold of most neuronal responses evoked by electrical stimulation of the muscle afferents, the predominance of afferents of small diameter in some of the muscle nerves stimulated, the preferential responsiveness to the muscle afferent stimulation of neurons that were functionally identified as cutaneous nociceptive neurons, and the responsiveness of most of the neurons excited by electrical stimulation of the muscle nerves also to noxious mechanical or thermal stimulation of muscle and the injection of two or more algesic chemicals into small arteries supplying the jaw and tongue muscles. Of the algesic chemicals used in this study (7% NaCl, KCl, bradykinin, histamine, 5-HT), the first two were found to be the most effective and to cause the most rapidly induced excitation.(ABSTRACT TRUNCATED AT 400 WORDS)

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