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.

Recurrent inhibition to and from motoneurons innervating the flexor digitorum and flexor hallucis longus muscles of the cat

1990 ◽  
Vol 63 (3) ◽  
pp. 395-403 ◽  
Author(s):  
T. M. Hamm
Keyword(s):  
Tibialis Anterior ◽  
Recurrent Inhibition ◽  
Medial Gastrocnemius ◽  
Flexor Hallucis Longus ◽  
Flexor Digitorum Longus ◽  
Lateral Gastrocnemius ◽  
Hindlimb Muscles ◽  
Inhibitory Postsynaptic Potentials ◽  
Flexor Digitorum ◽  
Stimulation Of

1. Recurrent inhibitory postsynaptic potentials (IPSPs) to and from motoneurons innervating the flexor digitorum longus (FDL) and flexor hallucis longus (FHL) muscles of the cat were investigated to determine whether recurrent inhibitory projections involving these motoneurons are similar--as would be consistent with the Ia and anatomic synergism of FDL and FHL--or are dissimilar, as are the activities of these muscles during locomotion (O'Donovan et al. 1982). 2. Composite recurrent IPSPs were recorded in several species of motoneurons innervating hindlimb muscles in response to stimulation of a number of muscle nerves in cats allowed to become unanesthetized after ischemic decapitation. 3. No recurrent IPSPs from stimulation of the FDL nerve were observed in motoneurons innervating FDL, FHL, lateral gastrocnemius-soleus (LG-S), medial gastrocnemius (MG), plantaris (Pl), tibialis anterior (TA), or extensor digitorum longus (EDL). 4. The recurrent IPSPs produced by stimulation of FHL were larger and found more frequently in LG-S than in FDL motoneurons. Recurrent inhibition from FHL was also greater in Pl than in FDL motoneurons. 5. The recurrent IPSPs produced by stimulation of LG-S, PL, and MG were larger in FHL than in FDL motoneurons, and those from LG-S and MG were found more frequently in FHL than in FDL motoneurons. 6. Stimulation of the TA nerve produces recurrent IPSPs in FDL but not in FHL motoneurons. A few FDL and FHL cells (6 of 23 and 9 of 34, respectively) received small (less than 0.5 mV) recurrent IPSPs from stimulation of the EDL nerve.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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.

scholarly journals The Effectiveness Of Quadriceps Strengthening Exercises Combined With Neuromuscular Electrical Stimulation on Patellofemoral Pain Syndrome

2017 ◽  
Vol 5 (2_suppl2) ◽  
pp. 2325967117S0010
Author(s):  
Sezen Karabörklü Argut ◽  
Nilgün Türker ◽  
Derya Çelik ◽  
Önder İsmet Kılıçoğlu
Keyword(s):  
Electrical Stimulation ◽  
Muscle Strength ◽  
Neuromuscular Electrical Stimulation ◽  
Pain Syndrome ◽  
Quadriceps Strength ◽  
Patellofemoral Pain ◽  
Group I ◽  
Strengthening Exercises ◽  
Group Ii ◽  
And Function

Objective: The weakness of the quadriceps strength in patellofemoral pain syndrome (PFPS) is very evident. Therefore, quadriceps strengthening exercises are very important part of the rehabilitation program. Neuromuscular Electrical Stimulation (NMES) is considered one of the methods for increasing quadriceps muscle strength. To evaluate the effectiveness of combined NMES and strengthening exercises to improve the recovery of quadriceps strength and function in patients with PFPS. Methods: This study was planned as a randomized controlled pilot study. A total of 27 patients (mean age=38.9±10.8 years, range=20-60 years; 16 females) with PFPS were assessed and randomly assigned into 2 groups. Group I received a standard program (quadriceps strengthening, hip strengthening and hamstring stretching) and NMES combined with quadriceps strengthening exercises simultaneously. Group II received the same standard program without NMES. Both groups were enrolled 3 times per week for 40 minutes per day in 6 weeks. Patients were assessed at the baseline, 3 rd, 6th, and 12th weeks of treatment. Quadriceps strength was evaluated by isokinetic dynamometer. The range of motion at testing was set between 0 for extension to 90 for flexion. The test was performed at 60 degrees/sn and concentric maximum peak torque value was recorded. Kujala and Lysholm scores were used for functional assessments. The data were analyzed using the SPSS 20.0. Shapiro-Wilk test was used to assess the distribution of data. The changes in dependent variables before treatment, 3 rd, 6th, and 12th weeks were analyzed using a 2 by 4 mixed-model analysis of variance (ANOVA). Pairwise comparisons with paired t test were used to determine whether the Group I or Group II, has changed over time. An intention- to- treat analysis was performed to impute values for missing data. An alpha level of 0.05 was established. Results: The study was completed with 20 patients. Group I (n=10; mean age=39.4±8.5 years; 7 females) and group II (n=10; mean age=43.2±11.7 years; 5 females) had no differences in pre-operative measures (p>.05). There was significant improvements in within groups statistics of all parameters for both groups (p<.05). No differences in quadriceps strength, Kujala and Lysholm scores between groups were found at the different time points (F= 0.86; p = 0.12, F=0,001; p =0.97, F=0.12; p=0.73, respectively) Conclusion: NMES combined with quadriceps strengthening exercises has no additional effect on PFPS patients’ on muscle strength and function. When considering these results, we believe that there is no need to continue the study in progress. [Table: see text]

Brain stem responses to electrical stimulation of ventral vagal gastric fibers

1989 ◽  
Vol 257 (1) ◽  
pp. G24-G29
Author(s):  
W. D. Barber ◽  
C. S. Yuan
Keyword(s):  
Electrical Stimulation ◽  
Brain Stem ◽  
Time Of Arrival ◽  
Neuronal Responses ◽  
Proximal Stomach ◽  
Afferent Fibers ◽  
Sensory Modalities ◽  
The Mean ◽  
The Brain ◽  
Stimulation Of

The brain stem neuronal responses to electrical stimulation of gastric branches of the ventral vagal trunk serving the proximal stomach were localized and evaluated in anesthetized cats. The responses were equally distributed bilaterally in the region of nucleus solitarius in the caudal brain stem. The mean latency of the response was 289 +/- 46 (SD) ms, which translated into a conduction velocity of less than 1 m/s based on the distance between the stimulating and recording electrodes. The responses consisted of single and multiple spikes that showed slight variability in the latency, indicating orthodromic activation via a synapse in approximately 98% of the responses recorded. Forty two percent of the units tested showed evidence of convergence of input from vagal afferent fibers in different branches of the ventral vagal trunk that served the proximal stomach. The resultant activity pattern of the unitary response appeared to be the product of 1) the gastric sensory input or modality conveyed by the afferent source and 2) the time of arrival and diversity of modalities served by other gastric afferents impinging on the unit. This provides a mechanism capable of responding on the basis of specific sensory modalities that dynamically reflect ongoing events monitored and conveyed by other gastric afferents in the region.

Declining inhibition elicited in cat lumbar motoneurons by repetitive stimulation of group II muscle afferents

1993 ◽  
Vol 70 (5) ◽  
pp. 1805-1810 ◽  
Author(s):  
J. Lafleur ◽  
D. Zytnicki ◽  
G. Horcholle-Bossavit ◽  
L. Jami
Keyword(s):  
Muscle Afferents ◽  
Repetitive Stimulation ◽  
Excitatory Postsynaptic Potential ◽  
Constant Input ◽  
Rapid Reduction ◽  
Group I ◽  
Constant Strength ◽  
Group I Afferents ◽  
Group Ii ◽  
Stimulation Of

1. The aim of the present experiments was to verify whether group II inputs from gastrocnemius medialis (GM) muscle could elicit declining inhibitions similar to those observed during GM contractions in a variety of lumbar motoneurons of the cat spinal cord. Motoneurons were recorded intracellularly in chloralose- or pentobarbitone-anesthetized preparations during electrical stimulation of GM nerve with repetitive trains. 2. With strengths in the group I range, repetitive stimulation evoked the usual Ia excitation in homonymous motoneurons and excitatory postsynaptic potential (EPSP) amplitudes remained constant throughout the stimulation sequence. In synergic plantaris motoneurons lacking an excitatory connection with Ia afferents from GM, the same stimulation, kept at a constant strength throughout the stimulation sequence, elicited rapidly decreasing inhibitory potentials reminiscent of those evoked by GM contractions. 3. In motoneurons of pretibial flexors, quadriceps, and posterior biceps-semitendinosus, the stimulation strength required to observe declining inhibitions resembling those produced by GM contractions was 4-8 times group I threshold, engaging group II in addition to group I fibers. 4. These results show that input from GM group II plus group I afferents can elicit inhibitory effects in a variety of motoneurons. Such observations support the hypothesis that messages from spindle secondary endings and/or nonspecific muscle receptors activated during contraction might contribute to the widespread inhibition caused by GM contractions. 5. Inasmuch as constant input in group II and group I afferents evoked declining inhibitory potentials, the origin of the decline must be central, which suggests that the rapid reduction of contraction-induced inhibitions also depended on a central mechanism.

Rescue of motoneurons from the axotomized state by regeneration into a sensory nerve in cats

1991 ◽  
Vol 66 (5) ◽  
pp. 1462-1470 ◽  
Author(s):  
H. Nishimura ◽  
R. D. Johnson ◽  
J. B. Munson
Keyword(s):  
Electrical Stimulation ◽  
Electrical Properties ◽  
Sensory Nerve ◽  
Input Resistance ◽  
Cutaneous Nerve ◽  
Medial Gastrocnemius ◽  
Mechanical Activity ◽  
Muscle Nerve ◽  
Muscle Innervation ◽  
Stimulation Of

1. We studied the electrical properties of spinal motoneurons, the axons of which had regenerated into a cutaneous nerve. 2. In cats, all or part of the medial gastrocnemius (MG) muscle nerve was cut and directed distally into the caudal cutaneous sural (CCS) nerve, a sensory (primarily cutaneous) nerve. One or 2 yr later, electrical properties [conduction velocity (CV), rheobase (Irh), input resistance (RN), afterhyperpolarization (AHP), and excitatory postsynaptic potentials (EPSPs)] of MG motoneurons that had cross-regenerated into the CCS nerve were determined. These were compared with properties of normal and of axotomized MG motoneurons and with data from previous studies in which MG motoneurons had reinnervated their own or a foreign muscle. 3. Electrical stimulation of the MG-innervated CCS nerve produced no detected mechanical activity, indicating an absence of muscle innervation. Tactile stimulation of skin did not activate these motoneurons; i.e., they did not acquire properties of cutaneous afferents. 4. The CV and Irh of MG motoneurons axotomized 11 mo declined by 48 and 60%, respectively. 5. The CV of MG motoneurons that had regenerated through CCS was only slightly slower than normal, similar to that of MG motoneurons that reinnervated the “slow” muscle soleus (Foehring and Munson 1990). 6. The Irh and RN were also similar to those of MG motoneurons that had regenerated into the soleus muscle. 7. Electrical stimulation of the lateral gastrocnemius-soleus nerve generated EPSPs of normal or almost normal amplitude in MG motoneurons axotomized for 11 mo or cross-regenerated into CCS up to 2 yr.(ABSTRACT TRUNCATED AT 250 WORDS)

Reflex vasodilatation in the cat lip elicited by stimulation of nasal mucosa by chemical irritants

1993 ◽  
Vol 265 (4) ◽  
pp. R733-R738 ◽  
Author(s):  
H. Izumi ◽  
K. Karita
Keyword(s):  
Blood Flow ◽  
Electrical Stimulation ◽  
Nasal Mucosa ◽  
Threshold Dose ◽  
Ammonia Vapor ◽  
Autonomic Ganglion ◽  
Afferent Fibers ◽  
Autonomic Reflex ◽  
Chemical Irritants ◽  
Stimulation Of

Local application of capsaicin (threshold dose 150 microM) or nicotine (threshold dose 15 mM) to the nasal mucosa as well as electrical stimulation (threshold intensity 10 V) of the nasal mucosa elicited dose- or intensity-dependent blood flow increases in the ipsilateral lower lips of the anesthetized cats. Pretreatment with 3 mM capsaicin applied locally to the nasal mucosa abolished or reduced the vasodilation in response to capsaicin, nicotine, and ammonia vapor but not to light mechanical or electrical stimulation of the nasal mucosa. The blood flow increases elicited by all above stimuli were greatly reduced by pretreatment with hexamethonium, an autonomic ganglion blocker. These results suggest that stimulation of the nasal mucosa by chemical (capsaicin, nicotine, ammonia), mechanical, or electrical methods elicits the autonomic reflex vasodilatation in the cat lower lips. Furthermore, there seem to be at least two types of afferent fibers in the nasal mucosa of the cats: one type is capsaicin-sensitive fibers, while another type is capsaicin-resistant fibers involved in reflex vasodilatation.

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