Vestibular-dependent spinal reflexes evoked by brief lateral accelerations of the heads of standing subjects

2012 ◽  
Vol 112 (11) ◽  
pp. 1906-1914 ◽  
Author(s):  
Robyn Laube ◽  
Sendhil Govender ◽  
James G. Colebatch
Keyword(s):  
Head Rotation ◽  
Vestibular Dysfunction ◽  
Spinal Reflexes ◽  
Lateral Acceleration ◽  
Initial Interval ◽  
Eyes Closed ◽  
Long Latency ◽  
Long Duration ◽  
Closed Head ◽  
Biphasic Responses

An impulsive acceleration stimulus, previously shown to activate vestibular afferents, was applied to the mastoid. Evoked EMG responses from the soleus muscles in healthy subjects ( n = 10) and patients with bilateral vestibular dysfunction ( n = 3) were recorded and compared with the effects of galvanic stimulation (GVS). Subjects were stimulated while having their eyes closed, head rotated, and while tonically activating their soleus muscles. Rectified EMG responses were recorded from the leg contralateral to the direction of head rotation. Responses were characterized by triphasic potentials that consisted of short-latency (SL), medium-latency (ML), and long-latency (LL) components beginning at (mean ± SD) 54.2 ± 4.8, 88.4 ± 4.7, and 121 ± 7.1 ms, respectively. Mean amplitudes for the optimum stimulus rise times were 9.05 ± 3.44% for the SL interval, 16.70 ± 4.41% for the ML interval, and 9.75 ± 4.89% for the LL interval compared with prestimulus values. Stimulus rise times of 14 and 20 ms evoked the largest ML amplitudes. GVS evoked biphasic responses (SL and ML) with similar latencies. Like GVS, the polarity of the initial interval was determined by the polarity of the stimulus and the evoked EMG response was attenuated when subjects were seated. There was no significant EMG response evoked when subjects were stimulated using 500-Hz vibration or in patients with bilateral vestibular dysfunction. Our study demonstrates that a brief lateral acceleration, likely to activate the utricle, can evoke spinal responses with properties similar to those previously shown for vestibular activation by GVS. The triphasic nature of the responses may allow the nervous system to respond differently to short compared with long-duration linear accelerations, consistent with their differing significance.

scholarly journals Stabilizing stretch reflexes are modulated independently from the rapid release of perturbation-triggered motor plans

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hyunglae Lee ◽  
Eric J. Perreault
Keyword(s):  
Motor Response ◽  
Spinal Reflexes ◽  
Reflex Response ◽  
Voluntary Activity ◽  
Motor Responses ◽  
Triggered Reaction ◽  
Triggered Reactions ◽  
Long Latency ◽  
Target Effect ◽  
Long Latency Reflex

Abstract Responses elicited after the shortest latency spinal reflexes but prior to the onset of voluntary activity can display sophistication beyond a stereotypical reflex. Two distinct behaviors have been identified for these rapid motor responses, often called long-latency reflexes. The first is to maintain limb stability by opposing external perturbations. The second is to quickly release motor actions planned prior to the disturbance, often called a triggered reaction. This study investigated their interaction when motor tasks involve both limb stabilization and motor planning. We used a robotic manipulator to change the stability of the haptic environment during 2D arm reaching tasks, and to apply perturbations that could elicit rapid motor responses. Stabilizing reflexes were modulated by the orientation of the haptic environment (field effect) whereas triggered reactions were modulated by the target to which subjects were instructed to reach (target effect). We observed that there were no significant interactions between the target and field effects in the early (50–75 ms) portion of the long-latency reflex, indicating that these components of the rapid motor response are initially controlled independently. There were small but significant interactions for two of the six relevant muscles in the later portion (75–100 ms) of the reflex response. In addition, the target effect was influenced by the direction of the perturbation used to elicit the motor response, indicating a later feedback correction in addition to the early component of the triggered reaction. Together, these results demonstrate how distinct components of the long-latency reflex can work independently and together to generate sophisticated rapid motor responses that integrate planning with reaction to uncertain conditions.

Original study. The clinical value of foam posturography in assessing patients with peripheral vestibular dysfunction – our experience

2017 ◽  
Vol 7 (26) ◽  
pp. 93-101
Author(s):  
Raluca Enache ◽  
Dorin Sarafoleanu ◽  
Codrut Sarafoleanu
Keyword(s):  
Center Of Pressure ◽  
Balance Control ◽  
Vestibular Dysfunction ◽  
Control Group ◽  
Vestibular Disorders ◽  
Clinical Value ◽  
Dynamic Posturography ◽  
Eyes Closed ◽  
Peripheral Vestibulopathy ◽  
Romberg Test

Abstract BACKGROUND. Computerized dynamic posturography is the most important battery test designed to assess the ability to use visual, vestibular and proprioceptive cues in the maintenance of posture. Foam posturography reduces the availability of proprioceptive inputs, which makes more difficult the balance control. OBJECTIVE. The objective of the study was to assess the clinical use of foam posturography in evaluating peripheral vestibular dysfunction. MATERIAL AND METHODS. We evaluated 41 patients with vestibular disorders and 41 normal patients by using the sensory organization test in eyes opened, eyes closed and mislead vision conditions with and without the foam. We measured several parameters: the position of the center of pressure, the displacement in the center of pressure in anteroposterior and mediolateral planes and Romberg’s ratio on static and foam rubber. RESULTS. The values of all parameters were significantly higher in patients with peripheral vestibular disorders than in the control group (p<0.05). Also. comparing the Romberg test results, the foam surface used by the patient was larger than the static one. CONCLUSION. Foam posturography can be a reliable test in assessing patients with peripheral vestibulopathy, being also able to identify the visual and proprioceptive dependence levels.

scholarly journals Greater exposure to repetitive subconcussive head impacts is associated with vestibular dysfunction and balance impairments during walking

Neurology ◽  
2018 ◽  
Vol 91 (23 Supplement 1) ◽  
pp. S27.2-S27
Author(s):  
Fernando Santos ◽  
Jaclyn B Caccese ◽  
Mariana Gongora ◽  
Ian Sotnek ◽  
Elizabeth Kaye ◽  
...  
Keyword(s):  
Center Of Pressure ◽  
Balance Control ◽  
Center Of Mass ◽  
Vestibular Stimulation ◽  
Vestibular Dysfunction ◽  
Foot Placement ◽  
Head Impacts ◽  
Eyes Closed ◽  
Balance Deficits ◽  
Soccer Heading

Exposure to repetitive subconcussive head impacts (RSHI), specifically soccer heading, is associated with white matter microstructural changes and cognitive performance impairments. However, the effect of soccer heading exposure on vestibular processing and balance control during walking has not been studied. Galvanic vestibular stimulation (GVS) is a tool that can be used to probe the vestibular system during standing and walking. The purpose of this study was to investigate the association of soccer heading with subclinical balance deficits during walking. Twenty adult amateur soccer players (10 males and 10 females, 22.3 ± 4.5 years, 170.5 ± 9.8 cm, 70.0 ± 10.5 kg) walked along a foam walkway with the eyes closed under 2 conditions: with GVS (∼40 trials) and without GVS (∼40 trials). Outcome measures included mediolateral center-of-mass (COM), center-of-pressure (COP) separation, foot placement, mediolateral ankle modulation, hip adduction, and ankle push off. For each balance mechanism, a GVS response was calculated (GVS, mean [without GVS]). In addition, participants completed a questionnaire, reporting soccer heading exposure over the past year. A linear regression model was used to determine if vestibular processing and balance during walking were related to RSHI exposure. Both foot placement (R2 = 0.324, p = 0.009) and hip adduction (R2 = 0.183, p = 0.50) were predicted by RSHI; whereby, greater exposure to RSHI was associated with greater foot placement and hip adduction responses. However, COM-COP separation (R2 < 0.001, p = 0.927), ankle modulation (R2 = 0.037, p = 0.417), and push off (R2 < 0.001, p = 0.968) were not related to RSHI exposure. Individuals who were exposed to greater RSHI were more perturbed by vestibular stimulation during walking, suggesting that there may be vestibular dysfunction and balance impairments with frequent heading; specifically, individuals with greater exposure to RSHI responded with larger foot placement and hip adduction responses to GVS.

Rhythmical eye-head-torso rotation alters fore-aft head stabilization during treadmill locomotion in humans*

2000 ◽  
Vol 10 (1) ◽  
pp. 41-49
Author(s):  
Nicole Paquet ◽  
Douglas G.D. Watt ◽  
Luc Lefebvre
Keyword(s):  
Drift Velocity ◽  
Time Course ◽  
Linear Acceleration ◽  
Head Rotation ◽  
Upper Body ◽  
Control Series ◽  
Eyes Closed ◽  
Start Up ◽  
Vestibulo Ocular Reflex ◽  
The Moment

A repetitive manoeuvre called torso rotation (TR) is known to temporarily reduce the gain of the horizontal vestibulo-ocular reflex by 10–15% consists of a series of rhythmical rotations of the eyes, head and upper body executed continuously for 30 minutes while standing. Our aim was to investigate whether TR affects the ability to hold the head in a fixed fore-aft position relative to space while walking on a treadmill with eyes closed. Ten healthy subjects stood in a carefully standardized position on a stationary treadmill. The treadmill started unexpectedly and ran for 4 s at 29 cm/s. The test stimulus was a linear acceleration in the fore-aft direction at the moment of treadmill start-up. Linear head position (i.e., ability to stabilize the head) was measured during and following the stimulus. A mechanical system prevented head rotation. Two series of 60 trials were performed before TR (control 1 and control 2 series) and one after TR. Before TR, subjects drifted rearward at an average drift velocity ± S.D. = 3.1 ± 0.9 cm / s. This drift was reasonably stable over time within and between the two control series. After TR, head holding ability was further impaired, with subjects having more difficulty to stabilize their head after treadmill start-up. In the first 10 trials after the arrest of TR, the average drift velocity was significantly larger than before TR ( 6.1 ± 1.5 cm / sec, p < 0.01). Recovery to control values followed a roughly exponential time course, with 67% impairs the ability to sense and/or respond to fore-aft linear accelerations of the head following treadmill start-up in the absence of vision.

Long-latency spinal reflexes in humans

1985 ◽  
Vol 53 (6) ◽  
pp. 1604-1618 ◽  
Author(s):  
K. Darton ◽  
O. C. Lippold ◽  
M. Shahani ◽  
U. Shahani
Keyword(s):  
Spinal Cord ◽  
Spinal Reflexes ◽  
Mechanical Device ◽  
Central Processing ◽  
Long Latency ◽  
Reflex Arc ◽  
M2 Response ◽  
Subcutaneous Tissues ◽  
Human Muscles ◽  
Afferent Terminals

Stretching human muscles with a mechanical device gave rise to multiple peaks in the rectified and averaged electromyogram. In the first dorsal interosseous the latency of the first peak (M1) was 32.4 +/- 2.4 ms (SD) and the latency of the second peak (M2) was 55.1 +/- 11.3 ms, in both cases measured from the time of the stimulus to the take-off point of the peak. Often a third peak (M3) was seen, having a considerably longer latency. The origin of peak M1 was considered to be in the stretch reflex arc because of its latency and its invariable association with muscle movement. Peak M2 was due to stimulation of afferent terminals in the skin and/or subcutaneous tissues by the mechanical device producing the muscle stretch. The conduction velocity of the pathway involved in the generation of the M1 component is the same as that for M2. This implies that central processing in the spinal cord delays the M2 response. The M2 mechanism does not involve a transcortical (long-loop) pathway because in foot muscles the M1-M2 delay remains the same as is found for hand muscles, although M1 latency is prolonged (to 39.4 +/- 6.2 ms for extensor digitorum longus). This indicates that there is not time for M2 impulses to traverse a pathway any longer than that passing to and from the spinal cord.

Ocular vestibular evoked myogenic potentials produced by impulsive lateral acceleration in unilateral vestibular dysfunction

2011 ◽  
Vol 122 (12) ◽  
pp. 2498-2504 ◽  
Author(s):  
Sendhil Govender ◽  
Sally M. Rosengren ◽  
Neil P. McAngus Todd ◽  
James G. Colebatch
Keyword(s):  
Vestibular Dysfunction ◽  
Lateral Acceleration ◽  
Vestibular Evoked Myogenic Potentials

scholarly journals Vestibulo-perceptual influences upon the vestibulo-spinal reflex

2021 ◽  
Author(s):  
Angela N. Bonsu ◽  
Sofia Nousi ◽  
Rhannon Lobo ◽  
Paul H. Strutton ◽  
Qadeer Arshad ◽  
...  
Keyword(s):  
High Order ◽  
Short Latency ◽  
Head Movements ◽  
Spinal Reflexes ◽  
Spinal Reflex ◽  
Roll Motion ◽  
Activity Levels ◽  
Amplitude Control ◽  
Long Duration ◽  
Reduce Activity

AbstractThe vestibular system facilitates gaze and postural stability via the vestibulo-ocular (VOR) and vestibulo-spinal reflexes, respectively. Cortical and perceptual mechanisms can modulate long-duration VOR responses, but little is known about whether high-order neural phenomena can modulate short-latency vestibulo-spinal responses. Here, we investigate this by assessing click-evoked cervical vestibular myogenic-evoked potentials (VEMPS) during visual roll motion that elicited an illusionary sensation of self-motion (i.e. vection). We observed that during vection, the amplitude of the VEMPs was enhanced when compared to baseline measures. This modulation in VEMP amplitude was positively correlated with the subjective reports of vection strength. That is, those subjects reporting greater subjective vection scores exhibited a greater increase in VEMP amplitude. Control experiments showed that simple arousal (cold-induced discomfort) also increased VEMP amplitude but that, unlike vection, it did not modulate VEMP amplitude linearly. In agreement, small-field visual roll motion that did not induce vection failed to increase VEMP amplitude. Taken together, our results demonstrate that vection can modify the response of vestibulo-collic reflexes. Even short-latency brainstem vestibulo-spinal reflexes are influenced by high-order mechanisms, illustrating the functional importance of perceptual mechanisms in human postural control. As VEMPs are inhibitory responses, we argue that the findings may represent a mechanism whereby high-order CNS mechanisms reduce activity levels in vestibulo-collic reflexes, necessary for instance when voluntary head movements need to be performed.

scholarly journals THE RELATIONS BETWEEN PREPOTENTIAL, RESTING POTENTIAL, AND LATENT PERIOD IN FROG MUSCLE FIBERS

1956 ◽  
Vol 39 (5) ◽  
pp. 773-787 ◽  
Author(s):  
Howard Peter Jenerick
Keyword(s):  
Latent Period ◽  
Action Potentials ◽  
Transmembrane Potential ◽  
Striated Muscle ◽  
Muscle Fibers ◽  
Resting Potential ◽  
Spike Potential ◽  
Long Latency ◽  
Long Duration ◽  
Striated Muscle Fibers

1. Prepotentials and action potentials were recorded from amphibian striated muscle fibers. Intracellular electrodes were used for stimulating and recording. The resting potential was varied from 55 to 120 mv. by alterations of the KCl concentration of the Ringer's fluid. The magnitude of the prepotential at the initiation of the spike potential was measured and compared to the resting potential and the latent period (time between stimulus "make" and excitation). The magnitude of this prepotential varied with the resting potential. 2. A large prepotential or cathodal depolarization was required to excite a fiber with a high resting potential. If a fiber with a high resting potential fired late (long latency), the adequate prepotential was larger than if the fiber fired early. Fibers with low resting potentials had smaller adequate prepotentials. Also, the adequate prepotential was independent of the latent period, in these depolarized fibers. 3. If the concentration of Ca++ was increased tenfold, the adequate prepotential of depolarized fibers became strongly dependent upon the latency. 4. Fibers with large or normal resting potentials were prone to respond repetitively during the passage of long duration shock, whereas depolarized and Ca++-treated fibers were not. 5. The so-called critical membrane potential (which is defined as the transmembrane potential at the point of excitation) was not independent of the resting potential.

Changes in Posture Following a Single Session of Long-Duration Water Immersion

2018 ◽  
Vol 34 (6) ◽  
pp. 435-441
Author(s):  
Stephen M. Glass ◽  
Christopher K. Rhea ◽  
Matthew W. Wittstein ◽  
Scott E. Ross ◽  
John P. Florian ◽  
...  
Keyword(s):  
Postural Control ◽  
Postural Sway ◽  
Center Of Pressure ◽  
Water Immersion ◽  
Specific Pattern ◽  
Eyes Closed ◽  
Stable Surface ◽  
Visual Inputs ◽  
Long Duration ◽  
Eyes Open

Transitioning between different sensory environments is known to affect sensorimotor function and postural control. Water immersion presents a novel environmental stimulus common to many professional and recreational pursuits, but is not well-studied with regard to its sensorimotor effects upon transitioning back to land. The authors investigated the effects of long-duration water immersion on terrestrial postural control outcomes in veteran divers. Eleven healthy men completed a 6-hour thermoneutral pool dive (4.57 m) breathing diver air. Center of pressure was observed before and 15 minutes after the dive under 4 conditions: (1) eyes open/stable surface (Open-Stable); (2) eyes open/foam surface (Open-Foam); (3) eyes closed/stable surface (Closed-Stable); and (4) eyes closed/foam surface (Closed-Foam). Postdive decreases in postural sway were observed in all testing conditions except for Open-Stable. The specific pattern of center of pressure changes in the postdive window is consistent with (1) a stiffening/overregulation of the ankle strategy during Open-Foam, Closed-Stable, and Closed-Foam or (2) acute upweighting of vestibular input along with downweighting of somatosensory, proprioceptive, and visual inputs. Thus, our findings suggest that postimmersion decreases in postural sway may have been driven by changes in weighting of sensory inputs and associated changes in balance strategy following adaptation to the aquatic environment.

Excitation of area postrema neurons by transmitters, peptides, and cyclic nucleotides

1988 ◽  
Vol 59 (2) ◽  
pp. 358-369 ◽  
Author(s):  
D. O. Carpenter ◽  
D. B. Briggs ◽  
A. P. Knox ◽  
N. Strominger
Keyword(s):  
Area Postrema ◽  
Phosphodiesterase Inhibitors ◽  
Second Messenger ◽  
Threshold Concentration ◽  
Cyclic Monophosphate ◽  
Behavioral Studies ◽  
Long Latency ◽  
Long Duration ◽  
Other Substances ◽  
Anesthetized Dogs

1. Multiple-barreled microelectrodes were used to record from neurons in the area postrema of anesthetized dogs and to test the responses of the neurons to a variety of substances in this structure, which is known to function as the chemoceptive trigger zone for emesis. 2. The neurons in area postrema were silent at rest but could be "found" by virtue of their response to ionophoretic glutamate. The glutamic response was brief and of short latency with high frequency of discharge. 3. Dog area postrema neurons were also excited by over 20 other substances, including acetylcholine, the biogenic amines, several peptides, and at least two hormones. Not all agents were excitatory, however. 4. The responses to all excitatory agents except glutamate were similar and unusual. All responses showed a relatively long latency (3-20 s), a long duration of excitation (30 s to many minutes), and a low discharge frequency (1-3 Hz). 5. There was a good correlation between substances that were excitatory on area postrema neurons and substances known to cause emesis. Because emesis due to intravenous application of these substances is known to be abolished in animals with ablation of the area postrema, it is very likely that recordings were from the neurons which trigger the response. 6. Because so many substances elicit the same type of response there is a possibility that all utilize a common second messenger. Neurons were not excited by ionophoresis of guanosine 3',5'-cyclic monophosphate (cGMP) but were excited by 8-bromo-adenosine 3',5'-cyclic monophosphate (cAMP) and by forskolin, an activator of adenylate cyclase. 7. Behavioral studies were performed looking for emetic responses in awake dogs following intravenous injection of apomorphine, insulin, angiotensin II, and leucine enkephalin. For each a threshold concentration could be determined, which would consistently evoke emesis. 8. Dogs pretreated with phosphodiesterase inhibitors (theophylline, 3-isobutyl-1-methylxanthine, or RO 1724) showed a shift in the threshold concentration of the above substances that triggered emesis, such that emesis was evoked by lower concentrations than in the control. 9. These results suggest that neurons of the dog area postrema trigger the emetic reflex in response to specific receptors for a great variety of transmitters, peptides, and hormones, and that these receptors act through a common second messenger, cAMP.

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