Multifaceted effects of noisy galvanic vestibular stimulation on manual tracking behavior in Parkinson’s disease

Abstract

Parkinson's disease (PD) is a neurodegenerative movement disorder that is characterized clinically by slowness of movement, rigidity, tremor, postural instability, and often cognitive impairments. Recent studies have demonstrated altered cortico-basal ganglia rhythms in PD, which raises the possibility of a role for non-invasive stimulation therapies such as noisy galvanic vestibular stimulation (GVS). We applied noisy GVS to 12 mild-moderately affected PD subjects (Hoehn and Yahr 1.5-2.5) off medication while they performed a sinusoidal visuomotor joystick tracking task, which alternated between 2 task conditions depending on whether the displayed cursor position underestimated the actual error by 30% ('Better') or overestimated by 200% ('Worse'). Either sham or subthreshold, noisy GVS (0.1-10 Hz, 1/f-type power spectrum) was applied in pseudorandom order. We used exploratory (linear discriminant analysis with bootstrapping) and confirmatory (robust multivariate linear regression) methods to determine if the presence of GVS significantly affected our ability to predict cursor position based on target variables. Variables related to displayed error were robustly seen to discriminate GVS in all subjects particularly in the Worse condition. If we considered higher frequency components of the cursor trajectory as "noise," the signal-tonoise ratio of cursor trajectory was significantly increased during the GVS stimulation. The results suggest that noisy GVS influenced motor performance of the PD subjects, and we speculate that they were elicited through a combination of mechanisms: enhanced cingulate activity resulting in modulation of frontal midline theta rhythms, improved signal processing in neuromotor system via stochastic facilitation and/or enhanced "vigor" known to be deficient in PD subjects. Further work is required to determine if GVS has a selective effect on corrective submovements that could not be detected by the current analyses.

Vestibular neuromodulation: stimulating the neural crossroads of psychiatric illness

“…This is beginning to occur in neurological contexts, such as daily right‐ear CVS for four weeks improving aphasic syndrome in left‐hemisphere stroke and disturbed arm position sense in poststroke neglect improving with galvanic vestibular stimulation (GVS) relative to sham stimulation (note that GVS does not appear to activate ACC) . There are also reports of GVS relative to sham GVS improving autonomic, motor and other functions in Parkinson’s Disease and other central neurodegenerative disorders, and early evidence that repeated CVS for several weeks can induce behavioural improvement in the minimally conscious state . Moreover, following reports of persistent pain and allodynia modulation by CVS in case studies and small case series (discussed in Miller and Ngo 3 ; see also McGeoch et al), a recent study examined 34 subjects with persistent (mostly neuropathic) pain and found that (i) a single session of right‐ear CVS induced small but statistically significant short term modulations of pain relative to a forehead icepack cold‐arousal control condition, (ii) three of nine subjects with allodynia had large, clinically significant CVS modulations, and (iii) CVS was well tolerated, with only one subject experiencing vomiting.…”

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

“…A drug named levodopa is known as a standard traditional drug, accepted and proved to be ef icient in treating and managing PD. Unfortunately, this drug too has several side-effects like impairment in cognition and imbalance, leading to poor quality of life of patients with PD (Lee et al, 2015). It is the need of time that there should be some alternative therapy, either drug or technique to treat and manage PD, ensuring minimal to no side effects.…”

“…Neurodegenerative disease like PD is also associated with the damage in the connections of interhemisphere as observed in any other neurodegenerative disorder. Vestibular stimulation had proved to improve the interhemisphere connections; this is the positive and signi icant (Lee et al, 2015). Certain studies had even emphasized that there was enhanced in the motor system functioning by vestibular stimulation when applied in PD patients.…”

Effects of Galvanic Vestibular Stimulation on Upper and Lower Extremities Motor Symptoms in Parkinson’s Disease

“…Parkinson’s disease (PD) is the second most common neurodegenerative disease ( Hirtz et al, 2007 ) that is often accompanied by degradation of motor performance manifested by symptoms such as tremor, rigidity, bradykinesia, akinesia (especially of the face), postural instability, and freezing episodes ( Lee et al, 2015 ). The affected individuals also experience cognitive difficulties, sleep disorder, and sensory deficits ( Litvan et al, 2012 ).…”

“…The vestibular nerve projects from underneath the mastoid bone to the cerebellar vermis through which the basal ganglia and the limbic system are activated, and the dopamine and noradrenaline levels are altered ( Pan et al, 2008 ; Kataoka et al, 2015 ). Consequently, it has been shown that in neurodegenerative disorders such as PD, GVS can improve motor functions ( Yamamoto et al, 2005 ; Pan et al, 2008 ; Lee et al, 2015 ; Samoudi et al, 2015 ). The effect of GVS on postural stability and balance has also been reported ( Pal et al, 2009 ; Kataoka et al, 2015 ; Samoudi et al, 2015 ).…”