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)

scholarly journals No relevant differences in conditioned pain modulation effects between parallel and sequential test design. A cross-sectional observational study

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12330
Author(s):  
Roland R. Reezigt ◽  
Sjoerd C. Kielstra ◽  
Michel W. Coppieters ◽  
Gwendolyne G.M. Scholten-Peeters
Keyword(s):  
Test Stimulus ◽  
Stimulus Intensity ◽  
Mechanical Test ◽  
Conditioning Stimulus ◽  
Lower Leg ◽  
Pain Modulation ◽  
Sequential Design ◽  
Stimulus Selection ◽  
Conditioned Pain Modulation ◽  
Parallel Design

Background Conditioned pain modulation (CPM) is measured by comparing pain induced by a test stimulus with pain induced by the same test stimulus, either during (parallel design) or after (sequential design) the conditioning stimulus. Whether design, conditioning stimulus intensity and test stimulus selection affect CPM remains unclear. Methods CPM effects were evaluated in healthy participants (N = 89) at the neck, forearm and lower leg using the cold pressor test as the conditioning stimulus. In three separate experiments, we compared the impact of (1) design (sequential versus parallel), (2) conditioning stimulus intensity (VAS 40/100 versus VAS 60/100), and (3) test stimulus selection (single versus dual, i.e., mechanical and thermal). Statistical analyses of the main effect of design (adjusted for order) and experiment were conducted using linear mixed models with random intercepts. Results No significant differences were identified in absolute CPM data. In relative CPM data, a sequential design resulted in a slightly lower CPM effect compared to a parallel design, and only with a mechanical test stimulus at the neck (−6.1%; 95% CI [−10.1 to −2.1]) and lower leg (−5.9%; 95% CI [−11.7 to −0.1]) but not forearm (−4.5%; 95% CI [−9.0 to 0.1]). Conditioning stimulus intensity and test stimulus selection did not influence the CPM effect nor the difference in CPM effects derived from parallel versus sequential designs. Conclusions Differences in CPM effects between protocols were minimal or absent. A parallel design may lead to a minimally higher relative CPM effect when using a mechanical test stimulus. The conditioning stimulus intensities assessed in this study and performing two test stimuli did not substantially influence the differences between designs nor the magnitude of the CPM effect.

scholarly journals Separation of the ‘blue’ and ‘green’ mechanisms of foveal vision by measurements of increment thresholds

1946 ◽  
Vol 133 (873) ◽  
pp. 418-434 ◽  
Keyword(s):  
Test Stimulus ◽  
High Intensity ◽  
Light Adaptation ◽  
Foveal Vision ◽  
Low Intensity ◽  
Individual Variations ◽  
Low Threshold ◽  
Intense Light ◽  
The Individual ◽  
Very High

The curve relating the smallest perceptible intensity of a blue test stimulus with the intensity of an orange conditioning field against which it is viewed shows a characteristic division into low- and high-intensity components, indicating the operation of two mechanisms of cone vision at the fovea. The justification for calling these ‘blue’ and ‘green’ mechanisms is taken from an earlier investigation (Stiles 1939). While most subjects show this division clearly, for some the low-intensity component is masked by the intrusion of rod vision. The correctness of this view is established by measurements made while the eye is recovering from an intense light adaptation. The individual variations of the sensitivities of the ‘green’ and ‘blue’ mechanisms in twenty subjects are assessed. Further evidence is obtained of an anomalously low threshold for the ‘blue’ mechanisms at very high conditioning fields of orange light.

scholarly journals Effect of aging on H-reflex response to fatigue

2019 ◽  
Vol 238 (2) ◽  
pp. 273-282
Author(s):  
Andrew Philip Lavender ◽  
Sadik Balkozak ◽  
Mustafa Görkem Özyurt ◽  
Betilay Topkara ◽  
İlhan Karacan ◽  
...  
Keyword(s):  
H Reflex ◽  
Reflex Response

scholarly journals Effect of conditioning and test stimulus intensity on cortical excitability using triad-conditioning transcranial magnetic stimulation

2020 ◽  
Vol 238 (5) ◽  
pp. 1305-1309 ◽  
Author(s):  
Shady Safwat Hassan ◽  
Carlos Trenado ◽  
Tarek Ali Rageh ◽  
Alfons Schnitzler ◽  
Stefan Jun Groiss
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Test Stimulus ◽  
Stimulus Intensity ◽  
Magnetic Stimulation ◽  
Cortical Excitability

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.

Conditioned pain modulation in rodents can feature hyperalgesia or hypoalgesia depending on test stimulus intensity

Pain ◽  
2019 ◽  
Vol 160 (4) ◽  
pp. 784-792 ◽  
Author(s):  
Shannon N. Tansley ◽  
Leigh C. Macintyre ◽  
Laura Diamond ◽  
Susana G. Sotocinal ◽  
Nicole George ◽  
...  
Keyword(s):  
Test Stimulus ◽  
Stimulus Intensity ◽  
Pain Modulation ◽  
Conditioned Pain Modulation

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.

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