Effects Of Caloric Vestibular Stimulation Research Articles

IMPACT OF CALORIC VESTIBULAR STIMULATION ON CO-ORDINATION IN PARKINSON DISEASE INDUCED MICE

Objective: This study was undertaken to evaluate the effect of vestibular stimulation on motor coordination in Parkinson’s disease (PD) induced mice. Methods: 18 healthy adult male Swiss albino mice were used in this study. Vestibule was stimulated by caloric vestibular stimulation (CVS). Pesticide Rotenone was used to induce Parkinson’s disease (PD). Motor coordination was assessed by the fall-off time and the activity score using the rotarod and actophotometer, respectively. Results: In the rotarod test, there was a significant increase in the fall-off time (p<0.01) in the CVS PD group (131.63±18.34) on the 30th day when compared to the PD group (95.33±15.17). In the actophotometer, the activity score improved in the PD CVS group on the 15 (235±47.09) and 30th days (251.38±25.76), while there was no improvement in the PD group. This shows the significant effect of caloric vestibular stimulation on motor coordination in Parkinson’s disease. Conclusion: This study confirms that caloric vestibular stimulation with hot water resulted in the improvement of motor coordination in PD. Hence this study certainly merits further studies with a higher sample size to confirm the effect of caloric vestibular stimulation on the enhancement of motor coordination in individuals with Parkinson’s disease.

Effect of caloric vestibular stimulation on brain neurochemicals in rotenone induced mouse model of Parkinson’s disease

It is learnt that Parkinson’s disease has no specific standard treatment, without side effects. Hence, it is very essential to discover a natural therapy which promises less or minimum side effects in delaying or preventing Parkinson’s disease (PD). This study was taken-up to demonstrate the effectiveness of caloric vestibular stimulation on the brain neurochemicals in rotenone induced mouse model of Parkinson's disease. T he study included 24 healthy and adult male Swiss albino mice . Their body weight was between 25 - 40g . Mice were randomly divided into four groups, wherein each group was containing 6 rats. Cold water treatment was used in the study as specified in literature as hot water (40 C) causes irritation in the middle ear cavity of the mice. The following neurotransmitters like Acetylcholine, serotonin, dopamine and GABA were estimated by using kit method procured from Sigma Chemical Co. The results of the study suggest a positive impact of vestibular stimulation in Parkinson’s disease management. The study results are in accordance to the earlier studies showing a positive impact of vestibular stimulation on the brain neuro -transmitters in rotenone induced mouse model of Parkinson's disease. Therefore, the study demands further research to learn the mechanism of action of vestibular stimulation in the management of Parkinson’s disease.

Vestibular Stimulation Modulates Neural Correlates of Own-body Mental Imagery.

There is growing evidence that vestibular information is not only involved in reflexive eye movements and the control of posture but it also plays an important role in higher order cognitive processes. Previous behavioral research has shown that concomitant vestibular stimuli influence performance in tasks that involve imagined self-rotations. These results suggest that imagined and perceived body rotations share common mechanisms. However, the nature and specificity of these effects remain largely unknown. Here, we investigated the neural mechanisms underlying this vestibulocognitive interaction. Participants (n = 20) solved an imagined self-rotation task during caloric vestibular stimulation. We found robust main effects of caloric vestibular stimulation in the core region of the vestibular network, including the rolandic operculum and insula bilaterally, and of the cognitive task in parietal and frontal regions. Interestingly, we found an interaction of stimulation and task in the left inferior parietal lobe, suggesting that this region represents the modulation of imagined body rotations by vestibular input. This result provides evidence that the inferior parietal lobe plays a crucial role in the neural integration of mental and physical body rotation.

Effect of caloric vestibular stimulation in a paraquat-induced parkinsonian mouse model

The present study was taken up to observe the effect of caloric vestibular stimulation on brain neurochemicals in a paraquat-induced Parkinso-nian mouse model. 24 healthy, adult male Swiss albino mice with body weight ranging between 25 - 40g were used in the study. The middle ear cavity of the mice was irrigated with hot (40oC) water. 0.5 ml of water was taken in 5 ml syringe with the needle removed. The ear was irrigated with water drop by drop, using the syringe. Gently the earlobe of mice was shaken. The procedure was continued with the other ear. Acetylcholine, dopamine, serotonin and GABA were estimated. The results of the present study show a positive impact of vestibular stimulation in the management of the Parkinson’s disease. Further detailed research is required to understand the mechanism of action behind the performance of vestibular stimulation and could be adopted in the management of Parkinson’s disease.

The Effects of Caloric Vestibular Stimulation (CVS) on Low Awareness States

Existing treatments for individuals in Low Awareness State (LAS) are often ineffective. We assessed whether Caloric Vestibular Stimulation (CVS) might promote recovery from LAS. CVS involves thermal activation of the vestibular organs which, in turn, increases activity within the reticular activating system which is the target of other therapeutic interventions.

Caloric Vestibular Stimulation Modulates Affective Control and Mood

BackgroundClinical evidence suggests a link between vestibular dysfunctions and mood disorders. No study has yet investigated mood and affective control during vestibular stimulation in healthy participants. ObjectiveWe predicted a modulating effect of caloric vestibular stimulation (CVS) on affective control measured in an affective Go/NoGo task (AGN). MethodsThirty-two participants performed an AGN task while they were exposed to cold left or right ear CVS (20 °C) and sham stimulation (37 °C). In each block, either positive or negative pictures (taken from the International Affective Picture System) were defined as targets. Participants had to respond to targets (Go), and withhold responses to distractors (NoGo). ResultsThe sensitivity index d′ (hits – false alarms) was used to measure affective control. Affective control improved during right ear CVS when viewing positive stimuli (P = .005), but decreased during left ear CVS when compared to sham stimulation (P = .009). CVS had a similar effect on positive mood ratings (Positive and Negative Affect Schedule). Positive mood ratings decreased during left ear CVS when compared to sham stimulation, but there was no effect after right ear CVS. DiscussionThe results suggest that CVS, depending on side of stimulation, has a modulating effect on mood and affective control. The results complement previous findings in manic patients and provide new evidence for the clinical potential of CVS.

Beneficial effects of caloric vestibular stimulation on denial of illness and manic delusions in schizoaffective disorder: A case report

Preliminary data suggests that caloric vestibular nerve stimulation (CVS) single session application of cold water to the left ear induces a clinically significant, short-lived beneficial effect on specific types of illness denial (i.e., anosognosia) and delusions (i.e., somatic type). We recently studied the effect of left versus right ear ice water (4°C) CVS on delusions and insight of illness in a patient with manic episode due to schizoaffective disorder. The patient was evaluated at baseline, immediately after the CVS, and then at 20 minutes, 60 minutes, and 24 hours. The method was first applied to one ear and 4 days later to the other. To assess whether the effect is specific to mania we employed the same procedure in two other patients with schizophrenia who also demonstrated delusions and impaired insight. All three patients showed a difference favoring left versus right ear CVS that was maintained for 20 minutes, and diminished over a 60 minute period. EEG analyses showed a numerically non-significant increase in bilateral frontal and central alpha EEG band activation (more pronounced in the right hemisphere) with left but not right ear CVS 5 minutes after the CVS, and that diminished after 20 minutes. The results suggest that left versus right CVS may have a short lived beneficial effect on manic delusions and insight of illness that seem to appear in other types of psychoses (i.e., schizophrenia). These preliminary results suggest that single session CVS may have short lived beneficial effects in mania and perhaps in other types of psychoses. Further research is mandatory.

Effects of caloric vestibular stimulation on serotoninergic system in the media vestibular nuclei of guinea pigs

Anatomic and electrophysiological studies have revealed that the neurons located in the media vestibular nuclei (MVN) receive most of the sensory vestibular input coming from the ipsilateral labyrinth and the responses of MVN neurons to caloric stimulation directly reflect changes in primary vestibular afferent activity. The aim of this study was to clarify the intrinsic characteristics of serotonin (5-hydroxytryptamine, 5-HT) release in the MVN during the period of vertigo induced by caloric stimulation. We used an in vivo microdialysis technique to examine the effects of caloric stimulation on the serotoninergic system in MVN. Twenty four guinea pigs were randomly divided into the groups of irrigation of the ear canal with hot water (n = 6), ice water (n = 6) and 37 degrees C water (n = 4), and the groups of irrigation of the auricle with hot water (n = 4) and ice water (n = 4), according to different caloric vestibular stimulation. We examined the animal's caloric nystagmus with a two-channel electronystagmographic recorder (ENG), and meanwhile examine serotonin (5-hydroxytryptamine, 5-HT) level in the MVN with microdialysis technique after caloric stimulation. In the caloric test the hot water (44 degrees C) irrigation of the right external auditory canal induced horizontal nystagmus towards the right side lasting about 60 seconds and the ice water irrigation of the right external auditory canal induced it towards the left side lasting for about 90 seconds. No nystagmus was induced by 37 degrees C water irrigation of the external ear canal. Therefore, it was used as a negative control stimulation to the middle ear. The MVN 5-HT levels significantly increased in the first 5-minute collecting interval and increased to 254% and 189% of the control group in the second collecting interval in response to caloric vestibular stimulation with ice water and hot water respectively. The serotonin release was not distinctly changed by the irrigation of the auricle with ice water or hot water. Neither somato-sensory stimulation of the middle ear nor nonspecific cold or hot stress affects the serotonin release. The rise of 5-HT in MVN may be involved in the mechanism of vertigo induced by caloric stimulation.

Dominance for vestibular cortical function in the non-dominant hemisphere.

The aim of this (15)O-labelled H(2)O bolus positron emission tomography (PET) study was to analyse the hemispheric dominance of the vestibular cortical system. Therefore, the differential effects of caloric vestibular stimulation (right or left ear irrigation with warm water at 44 degrees C) on cortical and subcortical activation were studied in 12 right-handed and 12 left-handed healthy volunteers. Caloric irrigation induces a direction-specific sensation of rotation and nystagmus. Significant regional cerebral blood flow increases were found in a network within both hemispheres, including the superior frontal gyrus/sulcus, the precentral gyrus and the inferior parietal lobule with the supramarginal gyrus. These areas correspond best to the cortical ocular motor centres, namely the prefrontal cortex, the frontal eye field and the parietal eye field, known to be involved in the processing of caloric nystagmus. Furthermore, distinct temporo-parietal activations could be separated in the posterior part of the insula with the adjacent superior temporal gyrus, the inferior parietal lobule and precuneus. These areas fit best to the human homologues of multisensory vestibular cortex areas identified in the monkey and correspond to the parieto-insular vestibular cortex (PIVC), the visual temporal sylvian area (VTS) and areas 7 and 6. Further cortical activations were seen in the anterior insula, the inferior frontal gyrus and anterior cingulum. The subcortical activation pattern in the putamen, thalamus and midbrain is consistent with the organization of efferent ocular motor pathways. Cortical and subcortical activation of the described areas was bilateral during monaural stimulation, but predominant in the hemisphere ipsilateral to the stimulated ear and exhibited a significant right hemispheric dominance for vestibular and ocular motor structures in right-handed volunteers. Similarly, a significant left hemispheric dominance was found in the 12 left-handed volunteers. Thus, this PET study showed for the first time that cortical and subcortical activation by vestibular caloric stimulation depends (i) on the handedness of the subjects and (ii) on the side of the stimulated ear. Maximum activation was therefore found when the non-dominant hemisphere was ipsilateral to the stimulated ear, i.e. in the right hemisphere of right-handed subjects during caloric irrigation of the right ear and in the left hemisphere of left-handed subjects during caloric irrigation of the left ear. The localization of handedness and vestibular dominance in opposite hemispheres might conceivably indicate that the vestibular system and its hemispheric dominance, which matures earlier during ontogenesis, determine right- or left-handedness.

Vestibular input to brain monoamine neurons--a review.

Yates et al. reported that serotonergic RN neurons are associated with vestibulo-sympathetic responses and may control BP changes during body repositioning (Yates et al., 1992; 1993). Pompeiano et al. demonstrated that LC-NA neurons participate in the postural control and modify the vestibulo-spinal reflex (Pompeiano et al., 1990; 1991a; 2001). Nishiike et al. (1996a) examined the effects of caloric vestibular stimulation on the neuronal activity of LC-NA neurons in rats. The predominant effect of CA with both hot- and cold-water on the electrical activity of LC neurons is inhibitory and persists for several minutes. GABAA receptors located on the postsynaptic membrane of LC neurons are responsible for these inhibitory responses. The VLM may inhibit LC neuronal activity in response to the CA via GABAA receptors (Nishiike et al., 1997). It is suggested that LC-NA inhibition is involved in the development of motion sickness (Nishiike et al., 2001).

The effects of caloric vestibular stimulation on EEGs in patients with central vertigo.

The EEGs of 30 patients with central vertigo were examined by caloric vestibular stimulation (CVS). The control group consisted of 30 persons without vertigo disturbances. In the standard procedure (and after hyperventilation), there was no statistically significant difference between the two groups of patients. In comparison to the EEGs of healthy persons, CVS produced statistically significant differences ( P<0.001) in the EEGs of patients with vertigo.

Effects of caloric vestibular stimulation on head and trunk movements during walking

The effects of vestibular stimulation on head and trunk movements were investigated during human walking (4.0 km/h). Vestibular stimulation was produced by irrigating an external auditory meatus with 4 degrees C ice water for 10 s. Using a 3-D motion analysis system, the linear (medial/lateral and vertical) translations and angular (yaw, pitch and roll) rotations were determined at the head, thorax, pelvis, knee, and foot. After caloric stimulation, waking trajectory deviated toward the stimulated side during dizziness. In addition, the amplitude of medial/lateral (M/L) linear translation and yaw rotation were significantly increased by caloric stimulation, especially at the head and thorax, whereas changes in vertical translation and pitch and roll rotations were not significant. The compensatory coordination (i.e., the yaw rotation to oppose the M/L linear translation) of the head was precisely maintained both before and after caloric stimulations, but it was decreased at the thorax and pelvis after stimulation. Our results suggested that vestibular sensory information, probably via the horizontal semicircular canals, contributes predominantly to the regulation of dynamic head and trunk movements in the M/L direction.

Vestibular stimulation affects dichotic lexical decision performance

We report an experimental attempt to shift, by vestibular stimulation, healthy subjects right ear advantage (REA) in a dichotic listening (DL) task with words and nonwords as stimuli. Forty right-handed men performed the task under two different conditions, once while sitting in a stationary turning chair (baseline) and once during sinusoidal rotation. In this latter condition, every other stimulation was received during maximal left-to-right (i.e., clockwise), every other during maximal right-to-left (i.e., counterclockwise) acceleration. There was a reliable REA for lexical decision accuracy in the baseline and right-to-left trials but not during left-to-right rotation. While right ear performance was unaffected by rotation, there were more correct lexical decisions to left ear targets exclusively during left-to-right turns (one-tailed P = 0.05). Since there were no parallel shifts in auditory thresholds under the different conditions, this effect is not due to any hypothetical auditory-vestibular interactions on a primary sensory level. The improvement in left ear DL performance, although small in our study, is comparable to the symptom-alleviating effect of caloric vestibular stimulation in patients with left-sided hemispatial neglect and interpreted as a consequence of a rotation-induced attentional shift towards the left hemispace.

A 'sticky' interhemispheric switch in bipolar disorder?

Despite years of research into bipolar disorder (manic depression), its underlying pathophysiology remains elusive. It is widely acknowledged that the disorder is strongly heritable, but the genetics are complex with less than full concordance in monozygotic twins and at least four susceptibility loci identified. We propose that bipolar disorder is the result of a genetic propensity for slow interhemispheric switching mechanisms that become 'stuck' in one or the other state. Because slow switches are also 'sticky' when compared with fast switches, the clinical manifestations of bipolar disorder may be explained by hemispheric activation being 'stuck' on the left (mania) or on the right (depression). Support for this 'sticky' interhemispheric switching hypothesis stems from our recent observation that the rate of perceptual alternation in binocular rivalry is slow in euthymic subjects with bipolar disorder (n = 18, median = 0.27 Hz) compared with normal controls (n = 49, median = 0.60 Hz, p < 0.0005). We have presented evidence elsewhere that binocular rivalry is itself an interhemispheric switching phenomenon. The rivalry alternation rate (putative interhemispheric switch rate) is robust in a given individual, with a test-retest correlation of more than 0.8, making it suitable for genetic studies. The interhemispheric switch rate may provide a trait-dependent biological marker for bipolar disorder.

Neurons in rostral ventrolateral medulla mediate vestibular inhibition of locus coeruleus in rats

The effects of caloric vestibular stimulation on the central noradrenergic neuron system were examined in the rat. In urethane-anesthetized rats, caloric stimulation inhibited the spontaneous activity of noradrenergic locus coeruleus neurons and increased systemic blood pressure. Electrical and chemical lesions in the ventrolateral medulla attenuated both the locus coeruleus inhibition and the blood pressure increase in response to caloric stimulation. Neither the neuronal inhibition nor the pressor effect was attenuated by any deafferentation of the forebrain or baroreceptors, or lesioning of the nucleus tractus solitarius. These findings indicate that the caloric stimulation-induced locus coeruleus inhibition is mediated by neurons in the ventrolateral medulla, and that these neurons also mediate the vestibulo-pressor responses. The locus coeruleus inhibition via the ventrolateral medulla is, however, considered to be independent of ventrolateral medulla-mediated systemic pressor effect. Collectively these findings suggest that the ventrolateral medulla is the major origin of inhibitory vestibular input to the noradrenergic neurons of the locus coeruleus, and that the ventrolateral medulla plays an important role in the vestibulo-autonomic response.

Reduction in posterior cerebral artery blood flow velocity during caloric vestibular stimulation.

Transcranial Doppler (TCD) sonography was performed to assess the differential effects of caloric vestibular stimulation on cerebral blood flow (CBF) to the vestibular [middle cerebral artery (MCA)] and the visual [posterior cerebral artery (PCA)] cortices in 15 healthy volunteers with eyes closed. Caloric irrigation caused a sensation of rotation and nystagmus and not only increased velocity in the MCA (2.7 +/- 3.3%) but also, simultaneously, decreased velocity in the PCA (4.2 +/- 6.2%, p < 0.001 vs. MCA). CBF changes indicated by changes in velocity through the MCA and PCA may reflect functional deactivation of the visual cortex together with activation of the vestibular cortex: this beneficial multisensory interaction suppresses distressing oscillopsia.

Effects Of Caloric Vestibular Stimulation on Parietal and Temporal Blood Flow in Human Brain: A Consecutive Technetium-99m-HMPAO SPECT Study

The effects of caloric vestibular stimulation on regional cerebral blood flow (rCBF) of the parietal and temporal cortex were examined in 10 healthy volunteers. The consecutive 99mTe-hexamethyl-propyleneamine oxime (99mTc-HMPAO) single-photon emission computed tomography (SPECT) method with region of interest analysis was used. Changes in rCBF induced by caloric stimulation with cold air (25 degrees C) were evaluated in comparison with those induced by control stimulation with air at body temperature (37 degrees C). Caloric stimulation with cold air induced vertigo in 4 subjects, dizziness in 2, and no sensation of self-motion in the remaining 4 subjects, whereas, control stimulation did not induce the sensation of self-motion in any subject. Although both parietal and temporal rCBF were slightly decreased during caloric stimulation, a correlation could be established between the magnitude of left-right differences in change of parietal rCBF and the degree of self-motion perception induced by cold-air caloric stimulation, as compared to control stimulation. Left-right differences in change of parietal rCBF in subjects with vertigo during caloric stimulation were significantly higher than those in subjects without any sensation of self-motion. In contrast, there was no correlation between the magnitude of left-right difference in change of parietal rCBF and maximum slow phase eye velocity induced by caloric stimulation. These findings suggest that the parietal lobe is involved in the perception of vertigo due to vestibular stimulation, but not in the vestibulo-ocular reflex.

GABAergic inhibitory response of locus coeruleus neurons to caloric vestibular stimulation in rats

We examined the effects of caloric vestibular stimulation on the neuronal activity of the locus coeruleus (LC) in urethane-anesthetized rats. The middle ear cavity was irrigated with hot (44°C) or cold (30°C) water through a polyethylene tube. Most neurons (hot water: 76%, 55 72 ; cold water: 90%, 19 21 ) exhibited suppression of neuronal discharge in response to caloric stimulation. The suppression of LC neuronal discharge following caloric stimulation occurred with a long latency (approximately 80 s), and lasted a long period of time (approximately 3 min). Neither caloric stimulation of the auricle, nor irrigation of the middle ear with water at 37°C, nor caloric stimulation of the middle ear after labyrinthectomy inhibited LC neuronal discharge. The caloric stimulation-induced LC neuronal inhibition was significantly attenuated by the intravenous injection of picrotoxin and by the iontophoretic application of bicuculline methiodide. These findings indicate that the predominant effect of caloric vestibular stimulation on LC neuronal discharge is inhibitory, and that the caloric stimulation-induced LC neuronal inhibition is mediated by GABAA receptors located on the membrane of LC neurons. It is suggested that the suppressed activity of noradrenergic LC neurons is involved in the vestibulo-autonomic reflex.

Contralateral glare effect on the fusion frequency of flicker.

The fusion frequency of flicker (FFF) depends upon the condition of all visual pathways, and decrease of the FFF by lesion in various parts of the visual pathways has been demonstrated. Yet, there is strong evidence that in the case of intact ocular structures the FFF is determined in the occipital cortical centers. The evidence includes photodriving, decrease of the FFF in brain pathology, binocular summation effect, and reflex changes, and it was reviewed by Simonson and Brozek. 1 The reflex changes of the FFF are of particular interest for experimental differentiation between peripheral and central components of the visual pathways, because diagnostic tests could readily be developed on this basis. In an earlier study on the effect of caloric vestibular stimulation, a statistically highly significant differentiation between 16 normal subjects and 16 patients with postconcussion syndrome was obtained. 2 The FFF decreased in all normal subjects and increased in