EXTINCTION OF THE SOLEUS H REFLEX INDUCED BY CONDITIONING STIMULUS GIVEN AFTER TEST STIMULUS

2002 ◽  
Vol 112 (2) ◽  
pp. 143-154
Author(s):  
KOICHI HIRAOKA
Keyword(s):  
Test Stimulus ◽  
Conditioning Stimulus ◽  
H Reflex

Changes in central delay of soleus H reflex after facilitatory or inhibitory conditioning in humans

1991 ◽  
Vol 65 (6) ◽  
pp. 1598-1605 ◽  
Author(s):  
M. Abbruzzese ◽  
L. Reni ◽  
E. Favale
Keyword(s):  
Test Stimulus ◽  
Stimulus Intensity ◽  
Conditioning Stimulus ◽  
H Reflex ◽  
Reflex Response ◽  
Stimulus Strength ◽  
Inhibitory Conditioning ◽  
The Individual ◽  
Central Delay ◽  
Motoneuronal Pool

1. Central delay (CD) changes after facilitatory or inhibitory conditioning of the soleus H reflex have been investigated in a group of normal subjects as a function of the conditioning and test stimulus intensities and also as a function of the Hmax/Mmax ratio. Both facilitation and inhibition of the reflex response have been obtained by conditioning stimulation of the ipsilateral tibial nerve at suitable conditioning-test stimulus intervals. CD changes have been extrapolated from the variations of the time interval between afferent and efferent neural volleys underlying the H reflex, directly recorded from the sciatic nerve. 2. The CD was significantly decreased by facilitatory and increased by inhibitory conditioning. Facilitatory CD changes were positively related to test stimulus strength (at a given conditioning stimulus intensity) and negatively related to conditioning stimulus strength (at a given test stimulus intensity). Both trends were reversed after inhibitory conditioning. The effectiveness of facilitatory conditioning was positively related to the individual Hmax/Mmax ratio whereas a negative relationship could be observed after inhibitory conditioning. 3. Also, the "conditioning threshold" (the minimal conditioning stimulus strength affecting the reflex size) and the "maximal conditioning effect" (the conditioning stimulus intensities leading to either the saturation of the facilitatory effect or the suppression of the reflex response) were significantly related to the Hmax/Mmax ratio. 4. We suggest that temporal changes in the H reflex pathway after facilitatory or inhibitory conditioning stimuli depend both on the size of the motoneuronal pool underlying the reflex response, as determined by the test stimulus intensity, and on the individual excitability of the motoneuronal pool, as defined by the Hmax/Mmax ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Fade of cardiac responses during tonic vagal stimulation

1982 ◽  
Vol 243 (2) ◽  
pp. H219-H225 ◽  
Author(s):  
P. Martin ◽  
M. N. Levy ◽  
Y. Matsuda
Keyword(s):  
Test Stimulus ◽  
Vagal Stimulation ◽  
Conditioning Stimulus ◽  
Rest Period ◽  
Test Stimulation ◽  
Cardiac Responses ◽  
Conditioning Period ◽  
Stimulus Train ◽  
Time Courses ◽  
Inotropic Responses

We applied trains of stimuli to the vagosympathetic trunks of anesthetized dogs and studied the time courses of the resultant chronotropic and inotropic responses. These responses were maximum soon after the onset of the test stimulus train but then declined over the next 1-5 min despite continued stimulation. The fade ratio was defined as the magnitude of this decline divided by the magnitude of the maximum response. For both inotropic and chronotropic responses, maximum increased with stimulation frequency, but the fade ratio did not change. In some experiments, conditioning stimulus trains of variable duration were applied before a standard rest period, after which the test stimulus train was applied. The longer the conditioning period, the lower was the subsequent fade ratio of the inotropic responses to the test stimulation train. In other experiments, a conditioning train of 2 min was applied, and then variable rest periods were interposed before the test train was applied. The longer the rest period, the greater were the subsequent maximum and fade ratios of the inotropic responses to the test stimulus train. These results indicate that some factor persists well after the cardiac responses to a given stimulus, and this factor affects the next response to an identical vagal stimulation. The chronotropic responses faded about three times faster than the inotropic responses. Thus different mechanisms may account for the fade of the inotropic and chronotropic responses.

Functional specialization of central projections from identified primary afferent fibers

1988 ◽  
Vol 60 (5) ◽  
pp. 1597-1614 ◽  
Author(s):  
H. R. Koerber ◽  
L. M. Mendell
Keyword(s):  
Test Stimulus ◽  
Conditioning Stimulus ◽  
Hair Follicles ◽  
Single Fiber ◽  
High Frequency Stimulation ◽  
High Threshold ◽  
Primary Afferent ◽  
Afferent Fibers ◽  
Primary Afferent Fibers ◽  
Stimulation Of

1. Somata of primary afferent fibers were impaled in the L7 or S1 dorsal root ganglion in cats anesthetized with alpha-chloralose. Individual cells (n = 182) were characterized according to receptive field (RF) and by the peripheral mechanoreceptor they innervated. They were then stimulated intracellularly while recording the evoked cord dorsum potentials (CDPs) simultaneously at four sites. CDPs were recorded in response to single fiber stimulation while varying both the frequency and the numbers of action potentials (APs) evoked per trial. Stimulus parameters included: 1) single APs evoked at both high (18 Hz) and low (0.67 Hz) frequencies, 2) pairs of APs (50-ms ISI) delivered at 0.67 Hz, and 3) trains of four APs (20-ms ISI) also delivered at 0.67 Hz. The properties of the CDPs and their relationship to receptor type innervated by the fiber were determined. 2. CDPs evoked by 18-Hz stimulation consisted of an axon fiber spike followed at a short latency [600 +/- 9.9 (SEM) microseconds] by the onset of a monophasic negative wave. A-beta-afferent fibers innervating slowly adapting type 1 and 2 receptors (SA1 and SA2) evoked the largest amplitude CDPs followed by field and hair follicle afferents while A-delta-fibers rarely produced measurable CDPs at this frequency of stimulation. 3. The magnitude of the CDP varied at the four recording sites with clear evidence in individual experiments that the projections of individual fibers are somatotopically organized. 4. CDPs evoked by 0.67-Hz stimulation had the same onset latency but were larger in amplitude and had longer time-to-peak and durations than those elicited by high frequency stimulation. Under these conditions A-beta-fibers innervating hair follicles produced the largest CDPs followed by field receptors and SA1s and SA2s. A-beta- and A-delta-fibers innervating high threshold mechanoreceptors (HTMRs) and A-delta-fibers innervating down hair follicles (D-hairs) produced CDPs of amplitude and duration similar to those evoked by slower A-beta-fibers. 5. The response to a test stimulus delivered 50 ms after a conditioning stimulus to the same single fiber was always depressed in the case of A-beta-fibers supplying rapidly adapting receptors. The conditioning stimulus exerted relatively little effect on the response to the test stimulus for A-beta- fibers innervating slowly adapting receptors. The test response to stimulation of A-beta- and A-delta- fibers innervating HTMRs was consistently facilitated while stimulation of A-delta- D-hairs evoked either marked facilitation or slight depression.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibition of the Soleus H-Reflex during Dorsiflexion is Dependent on Individual Differences in Maximal Soleus H-Reflex as a Test Reflex

1996 ◽  
Vol 82 (2) ◽  
pp. 403-410 ◽  
Author(s):  
K. Funase ◽  
K. Imanaka ◽  
Y. Nishihira
Keyword(s):  
Individual Differences ◽  
Conditioning Stimulus ◽  
Reciprocal Inhibition ◽  
Inhibitory Effect ◽  
H Reflex

The quantitative differences among individuals in the natural reciprocal inhibition of the soleus H-reflex during dorsiflexion were examined, in conjunction with the maximal H-reflex as the test reflex size in each individual. Maximal H-reflex was expressed relative to the maximal M-response (Hmax) when compared among individuals. Analysis showed that with increases in Hmax at rest in each individual, the inhibitory effect was first enhanced, then reached a peak, and was finally alleviated. This pattern was similar to the intraindividual pattern of the inhibitory effect induced by specific conditioning stimulus as a function of the test reflex size.

Combined electric and pressure cuff pain stimuli for assessing conditioning pain modulation (CPM)

2017 ◽  
Vol 16 (1) ◽  
pp. 181-182
Author(s):  
M. Tsukamoto ◽  
K.K. Petersen ◽  
C.D. Mørch ◽  
L. Arendt-Nielsen
Keyword(s):  
Test Stimulus ◽  
Cuff Pressure ◽  
Detection Threshold ◽  
Conditioning Stimulus ◽  
Pain Modulation ◽  
Experimental Site ◽  
Pressure Cuff ◽  
Before And After ◽  
Median Split ◽  
Pain Stimuli

AbstractAimsTraditionally, conditioning pain modulation (CPM) can be assessed by applying a test stimulus (TS) before and after application of a conditioning stimulus (CS), which is normally applied extra-segmental. Currently, no studies have attempted to apply the TS and CS to the same site using different stimuli modalities. The aim of this study was to evaluate electrical TS and cuff pressure CS applied to the same experimental site for studying CPM.Methods20 male volunteers participated in this study, which consisted of stimulations applied by a cuff-algometer (NociTech and Aalborg University, Denmark) and current stimulator (Digitimer DS5, UK), through two Ag/AgCl electrodes (Ambu® Neuroline 700, Denmark). The cuff was wrapped around the lower leg and stimulation electrodes were placed under the cuff and to the same location on the contralateral leg. Electrical TS were applied to the non-dominant leg with or without cuff pressure CS on the dominant (CS1) or the same (non-dominant) leg (CS2, electrode under cuff). The subjects were instructed to rate the electrical evoked pain intensity on a 10-cm continuous visual analog scale (VAS, “0” represented “no pain”, and “10” represented “maximal pain”). The pain detection threshold (PDT) was defined as “1” on the VAS scale.ResultsThere was no significant deference in PDT for neither CS1 nor CS2. A median split subanalysis on CPM-responders versus CPM-nonresponders to the TS + CS1 combination. Using this grouping, there was significant increase in PDT when comparing TS to TS + CS1 or TS + CS2 (4.0 mA vs 5.6 mA; P < 0.05, 4.0 mA vs 5.1 mA; P < 0.05).ConclusionsThe study indicates that CPM can be evoked in a subgroup of subjects by applying the electrical test stimulus and cuff pressure conditioning stimuli to the same experimental site.

Cutaneous masking. I. Psychophysical observations on interactions of multipoint stimuli in man

1979 ◽  
Vol 42 (4) ◽  
pp. 1048-1060 ◽  
Author(s):  
S. E. Laskin ◽  
W. A. Spencer
Keyword(s):  
Test Stimulus ◽  
Time Course ◽  
Detection Threshold ◽  
Conditioning Stimulus ◽  
Stimulus Onset ◽  
Direct Function ◽  
Cutaneous Sensation ◽  
Test Stimulation ◽  
Temporal Features ◽  
The Central Nervous System

1. Psychophysical masking of cutaneous sensation at the locus of punctate test stimulation has been quantitatively examined with phasic mechanical and brief air-pulse stimuli using a conditioning-test stimulus paradigm. 2. Masking was maximal at the minimal interstimulus distance effective with this paradigm, varies inversely with interstimulus distance, and is demonstrable with the conditioning and test stimuli up to 10 cm apart on the forearm. 3. The degree of masking was found to be a direct function of the relative intensity of the conditioning stimulus with respect to the test stimulus. 4. Variations in the interstimulus interval permitted an investigation of the temporal features of cutaneous masking. It was detectable from 10 ms before to 70 ms after conditioning stimulation. Maximum masking occurred when the test stimulus was delivered about 10 ms following conditioning stimulus onset. 5. We also noted the much less marked, but still significant, enhancement phenomenon, in which weak conditioning stimuli, at just-threshold intensity levels, lowered the detection threshold for sensation at the test stimulus locus. We found this enhancement of sensation to have the same spatial distribution as did masking, but a much reduced time course. It began with the test stimulus presented simultaneously with the conditioning stimulus, peaked with 10--15 ms interstimulus intervals, but decayed in less than 40 ms. 6. Since psychophysical experiments often form the framework for the understanding of physiologic processes, it is suggested that these behavioral determinations of enhancement and masking may be correlated with the electrophysiologic properties of excitation and inhibition in neurons of the major primary somatic pathways of the central nervous system.

scholarly journals Development of a new bed-side-test assessing conditioned pain modulation: a test-retest reliability study

2019 ◽  
Vol 19 (3) ◽  
pp. 565-574 ◽  
Author(s):  
Jesper Bie Larsen ◽  
Pascal Madeleine ◽  
Lars Arendt-Nielsen
Keyword(s):  
Test Stimulus ◽  
Conditioning Stimulus ◽  
Pain Modulation ◽  
Clinical Settings ◽  
Conditioned Pain Modulation ◽  
Reliability Study ◽  
Test Protocol ◽  
Bedside Test ◽  
Pressure Algometer ◽  
Test Retest Reliability

Abstract Background and aims Conditioned pain modulation (CPM) is of considerable interest within pain research. Often CPM testing is conducted in experimental settings using complicated instrumentation, thus challenging the implementation in clinical settings. Being able to assess CPM in a fast and reliable way in clinical settings could lead to a new diagnostic tool allowing improved profiling of pain patients. Methods A test-retest reliability study and a methodological development study were conducted based on different populations. The reliability study included 22 healthy subjects, mean age 23.6 years (SD: 2.4) and the methodological study included 29 healthy subjects, mean age 21.5 years (SD: 1.6). As painful phasic test stimulus, a 6–10 kg handheld, spring-based pressure algometer was applied perpendicularly to the muscle belly of the tibialis anterior muscle for 10 s and as painful tonic conditioning stimulus, 1–2 standard clamps, inducing a force of 1.3 kg, were applied extra-segmentally at the ipsilateral earlobe for 60–120 s. Four different test protocols were evaluated, of which one protocol was investigated for reliability. Test protocol 1 used a 6 kg pressure algometer as painful phasic test stimulus and a single clamp applied for 60 s as painful tonic conditioning stimulus. Test protocol 2 used a 10 kg pressure algometer as painful phasic test stimulus, and two clamps applied for 60 s as painful tonic conditioning stimulus. Test protocol 3 used a 10 kg pressure algometer as painful phasic test stimulus and a single clamp applied for 120 s as painful tonic conditioning stimulus. Test protocol 4 used a 6 kg pressure algometer as painful phasic test stimulus and a single clamp applied for 120 s as painful tonic conditioning stimulus. Results None of the stimuli caused any adverse events, e.g. bruises. In the reliability study (test protocol (1), non-significant CPM effects of 0.3 (SD: 1.6) and 0.2 (SD: 1.0) were observed in session 1 and 2, respectively. The intra-class correlations were 0.67 and 0.72 (p = < 0.01) and limits of agreement (LoA) ranged from −2.76 to 3.31. Non-significant CPM effects of 0.2 (SD: 1.0), −0.1 (SD: 1.1), and 0.0 (SD: 1.2) were observed for test protocol 2, 3, and 4, respectively). Conclusions The bedside test developed for investigating CPM was feasible and easy to use in healthy volunteers. No significant CPM effects were measured and a large variation in CPM effect ranging from −0.14 to 0.32 was observed. Intra-class correlation (ICC) values for the pressure algometer were interpreted as “good relative reliability” (test protocol 1), and LoA revealed a somewhat low absolute reliability. Implications The pressure algometer provided reproducible measurements and was useful for inducing phasic test stimuli. Since no significant CPM effects were detected, no recommendations for the bedside test can yet be made. Further examinations will have to establish if the “one size fits all” application of both test and conditioning stimuli is useful. Future bedside studies involving patient populations are warranted to determine the usefulness of the method.

Effects of conditioning cutaneomuscular stimulation on the soleus H-reflex in normal and spastic paretic subjects during walking and standing

1994 ◽  
Vol 72 (5) ◽  
pp. 2090-2104 ◽  
Author(s):  
J. Fung ◽  
H. Barbeau
Keyword(s):  
Spinal Cord ◽  
Statistical Significance ◽  
Conditioning Stimulus ◽  
Normal Subjects ◽  
H Reflex ◽  
Quiet Standing ◽  
Inhibitory Influence ◽  
Sensory Threshold ◽  
Injured Patients ◽  
Spinal Cord Injured

1. The modulation of the soleus H-reflex by a conditioning cutaneomuscular stimulation was investigated in 10 normal and 10 spastic paretic subjects who suffered from incomplete spinal cord lesions. The different motor tasks examined were standing, locomotion, and the maintenance of static limb postures to mimic critical gait events. The test soleus H-reflex was obtained by stimulating the tibial nerve in the popliteal fossa with a single 1-ms pulse at an intensity that produced a barely detectable M wave. The conditioning stimulus, consisting of an 11-ms train of three 1-ms pulses at 200 Hz, was delivered to the ipsilateral medial plantar arch, stimulating predominantly the medial plantar nerve, at an innocuous intensity of 2.5–3.0 X sensory threshold and at a conditioning-test delay of 45 ms. 2. During quiet standing, the H-reflex amplitude was inhibited only marginally by the conditioning cutaneomuscular stimulation, not reaching statistical significance in either the normal or spastic group of subjects. Although there was a trend of reflex inhibition in the normal subjects as the conditioning intensity was increased, a reversed trend of reflex facilitation was observed in the spastic patients. 3. During treadmill walking, the conditioned H-reflex was inhibited significantly during all phases in all the normal subjects and in one mildly impaired patient. In the moderately and severely impaired patients, cutaneomuscular stimulation selectively inhibited the soleus H-reflex in the early stance and swing phases, thereby producing a near normal phasic modulation pattern. Such modulatory effects were not present under static gait-mimicking conditions. 4. The task-specific and phase-dependent effects of cutaneomuscular stimulation on the soleus H-reflex in the spinal cord-injured patients revealed strong inhibitory influence on Ia afferents from cutaneomuscular inputs. It is plausible that inhibition occurs at both pre- and postsynaptic levels. 5. It is concluded that normal Ia modulatory mechanisms during locomotion are deficient in spastic spinal cord-injured patients and can partially and artificially be restored by cutaneomuscular stimulation applied to the sole of the foot. This can be used as a functional electrical stimulation (FES) regime in gait rehabilitation.

On the Potential Role of the Corticospinal Tract in the Control and Progressive Adaptation of the Soleus H-Reflex During Backward Walking

2005 ◽  
Vol 94 (2) ◽  
pp. 1133-1142 ◽  
Author(s):  
Roth-Visal Ung ◽  
Marie-Andrée Imbeault ◽  
Christian Ethier ◽  
Laurent Brizzi ◽  
Charles Capaday
Keyword(s):  
Motor Cortex ◽  
Large Amplitude ◽  
Corticospinal Tract ◽  
Motor Evoked Potentials ◽  
Conditioning Stimulus ◽  
H Reflex ◽  
Emg Activity ◽  
Step Cycle ◽  
Voluntary Activity ◽  
Backward Walking

When untrained subjects walk backward on a treadmill, an unexpectedly large amplitude soleus H-reflex occurs in the midswing phase of backward walking. We hypothesized that activity in the corticospinal tract (CST) during midswing depolarizes the soleus α-motoneurons subliminally and thus brings them closer to threshold. To test this hypothesis, transcranial magnetic stimulation (TMS) was applied to the leg area of the motor cortex (MCx) during backward walking. Motor-evoked potentials (MEPs) were recorded from the soleus and tibialis anterior (TA) muscles in untrained subjects at different phases of the backward walking cycle. We reasoned that if soleus MEPs could be elicited in midswing, while the soleus is inactive, this would be strong evidence for increased postsynaptic excitability of the α-motoneurons. In the event, we found that in untrained subjects, despite the presence of an unexpectedly large H-reflex in midswing, no soleus MEPs were observed at that time. The soleus MEPs were in phase with the soleus electromyographic (EMG) activity during backward walking. Soleus MEPs increased more rapidly as a function of the EMG activity during voluntary activity than during backward walking. Furthermore, a conditioning stimulus to the motor cortex facilitated the soleus H-reflex at rest and during voluntary plantarflexion but not in the midswing phase of backward walking. With daily training at walking backward, the time at which the H-reflex began to increase was progressively delayed until it coincided with the onset of soleus EMG activity, and its amplitude was considerably reduced compared with its value on the first experimental day. By contrast, no changes were observed in the timing or amplitude of soleus MEPs with training. Taken together, these observations make it unlikely that the motor cortex via the CST is involved in control of the H-reflex during the backward step cycle of untrained subjects nor in its progressive adaptation with training. Our observations raise the possibility that the large amplitude of H-reflex in untrained subjects and its adaptation with training are mainly due to control of presynaptic inhibition of Ia-afferents by other descending tracts.

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