PrEP Stigma as a Minority Stressor among Black Sexual Minority Men: A Mixed-Methods Study.

Black sexual minority men (BSMM) remain disproportionately affected by HIV, yet Pre-exposure prophylaxis (PrEP) uptake in this population remains relatively low. Informed by minority stress theory, PrEP stigma may manifest in and exacerbate societal marginalization based on sexuality and race. We used an exploratory sequential mixed-methods approach to determine if PrEP-specific stigma was associated with reduced PrEP uptake among BSMM, and qualitatively explored how PrEP use is stigmatized among BSMM. We analyzed cross-sectional data from a pilot sample of BSMM (n = 151) collected in late 2020 in the United States, testing for associations between PrEP stigma and PrEP use using modified Poisson regression. Subsequently, we selected participants (n = 23) from this sample for qualitative interviews starting in 2022. Responses to questions related to PrEP stigma were analyzed using thematic analysis. PrEP stigma was associated less than half the PrEP use (aPR = 0.43, 95% CI = 0.24, 0.75) among BSMM after adjustment. Qualitatively, we identified three major themes in how PrEP use is stigmatized among BSMM: PrEP-specific sexual stigma, intersections between PrEP and HIV stigma, and PrEP misinformation and disinformation. Aligned with minority stress theory, each theme was based in part in stigma related to sexuality or race. We found strong relationships between PrEP stigma and PrEP use independent of several sociobehavioral factors. Each of our themes were based in part in minority stressors, and underscore the importance of culturally competent PrEP promotion efforts towards BSMM. Addressing stigma is a core component of health equity efforts towards ending the HIV epidemic.

Black Sexual Minority Men's Experiences in MPowerment Interventions: Implications for HIV Prevention.

BACKGROUND: Black sexual minority men (BSMM) are disproportionately vulnerable to HIV acquisition; the MPowerment model is one community-based framework for preventing HIV in this population. It focuses on developing a supportive network of peers to promote health messaging, reduce stigma, and improve resilience. While these interventions have demonstrated general success, there are important challenges related to race, sexuality, and internalized stigma. Our study aimed to explore these experiences among BSMM in MPowerment models focused on HIV prevention. METHOD: We conducted 24 qualitative interviews of BSMM attending HIV prevention-related MPowerment events in the greater D.C. Metropolitan area. In-depth interviews were conducted via phone, and interviews were analyzed using thematic analysis. RESULTS: We identified four themes from the transcript analysis process: Black queer intersectional social support and community, HIV-related information and destigmatization, social status, and sexuality. Within each of these themes, we identified relationships with overall HIV prevention messaging, including barriers to PrEP use. Barriers related to social status were especially prevalent and described as unique to the D.C. metropolitan area. CONCLUSION: Overall, MPowerment event spaces provide a forum for BSMM to feel safe and supported while gaining important HIV-related knowledge and prevention access. Challenges related to social status and destigmatization of sexuality are important considerations in designing and implementing this model, especially related to PrEP promotion.

COVID-19, Vaccine Hesitancy, and HIV Pre-exposure Prophylaxis Among Black Sexual Minority Men.

BACKGROUND: The COVID-19 pandemic has created substantial and profound barriers to several forms of health care engagement. For Black sexual minority men, this may include engagement with pre-exposure prophylaxis (PrEP) to prevent HIV infection, with significant implications for HIV disparities. Our study explored how the COVID-19 pandemic affected Black sexual minority men, with a focus on relationships between COVID-19 and PrEP engagement. SETTING: We sampled 24 Black sexual minority men attending HIV prevention-related events in the greater D.C. Metropolitan area (D.C., Maryland, Virginia). METHODS: We conducted qualitative phone interviews among our sample. Questions were primarily focused on the COVID-19 pandemic and how it affected engagement and considerations of PrEP use. Interviews were transcribed and qualitatively analyzed using the 6 stages of thematic analysis. RESULTS: We identified 3 major themes from our thematic analysis: Changes in the health care system, changes in sexual and relationship contexts, and COVID-19 vaccine hesitancy and misinformation. Relationships between COVID-19 vaccine hesitancy and PrEP hesitancy were especially prevalent, with participants describing that COVID-19 hesitancy can directly deter PrEP use through eroding medical trust further. CONCLUSIONS: We identified changes in the health care system, sexual and relationship contexts, and COVID-19 vaccine hesitancy as important issues driven by COVID-19 with significant implications for PrEP use. The COVID-19 pandemic has changed the health care and social landscape in profound ways that affect PrEP access, sexual networks, and associated HIV vulnerability. Future research further exploring relationships between specific pandemic stressors and HIV prevention among Black sexual minority men is recommended .

Monkeypox-Related Stigma and Vaccine Challenges as a Barrier to HIV Pre-Exposure Prophylaxis among Black Sexual Minority Men.

BACKGROUND: The U.S. monkeypox (mpox) outbreak of 2022 was a unique emergent public health crisis disproportionately affecting Black sexual minority men (BSMM). Similar to other stigmas, mpox-related stigma may have adverse effects on BSMM, including deterring HIV prevention such as PrEP. METHODS: Our study investigated the experiences and perceptions of BSMM related to mpox, including mpox-associated stigma, and PrEP engagement among BSMM. We conducted qualitative interviews of 24 BSMM attending HIV prevention-related events in the greater D.C. Metropolitan area. In-depth interviews were conducted via phone, and responses to questions specific to the mpox outbreak were analyzed using thematic analysis. RESULTS: We identified three key themes from the analysis: Mpox-related stigma, Mpox vaccine availability concerns, and Mpox vaccine hesitancy. Participants also described relationships between each of these three themes and PrEP use. Mpox stigma was particularly relevant as it is related to sexual stigma and is a deterrent to PrEP use. A sense of health system neglect of BSMM, especially related to low mpox vaccine availability, was also described. CONCLUSIONS: We identified mpox stigma and challenges related to mpox vaccination as key themes among BSMM, with implications for PrEP use. Future research exploring medical mistrust among BSMM, particularly related to HIV prevention, is recommended.

Response characteristics of vestibular evoked myogenic potentials recorded over splenius capitis in young adults and adolescents.

BACKGROUND AND OBJECTIVES: Examine vestibular evoked myogenic potential (VEMP) responses recorded from surface electrodes over Splenius Capitis (SPC) in a seated position. SPECIFIC AIMS: (1) validate response characteristics of VEMP recordings from surface electrodes over Sternocleidomastoid (SCM) and over SCP and (2) assess age effects on responses in adolescents and young adults. MATERIALS AND METHODS: Simultaneous surface VEMP was recorded bilaterally from electrodes placed over the dorsal neck musculature at a location known from previous work to record from SPC in 15 healthy participants during trials with head rotation toward and away from the stimulated ear. VEMP was also recorded from electrodes over SCM, ipsilateral to the stimulus ear, in the same participants in a supine, head lift/turn position. RESULTS: Response amplitudes significantly increased with contraction strength and decreased with age. Participants were able to maintain sufficient contraction strength (amplitude) with head rotation to reliably measure over SPC. Normalized response amplitudes measured from electrodes over contralateral SPC were largest with head rotation contralateral to the stimulus ear. Normalized amplitudes and peak latencies were comparable to the same measures from SCM obtained in supine, head lift/turn position. CONCLUSIONS: Otolith generated myogenic responses can be recorded seated from electrodes over the dorsal neck with head rotation contralateral to the stimulus ear. In this position, contralateral recordings are consistent with responses known from previous work to arise from SPC; ipsilateral recordings may include crosstalk from activated muscles nearby, including ipsilateral SCM. Overall, techniques targeting contralateral SPC during contralateral head turn may provide additional methods of recording VEMPs.

Response characteristics of vestibular evoked myogenic potentials recorded over splenius capitis in young adults and adolescents

Background and objectives: Examine vestibular evoked myogenic potential (VEMP) responses recorded from surface electrodes over Splenius Capitis (SPC) in a seated position. Specific aims: (1) validate response characteristics of VEMP recordings from surface electrodes over Sternocleidomastoid (SCM) and over SCP and (2) assess age effects on responses in adolescents and young adults. Materials and methods: Simultaneous surface VEMP was recorded bilaterally from electrodes placed over the dorsal neck musculature at a location known from previous work to record from SPC in 15 healthy participants during trials with head rotation toward and away from the stimulated ear. VEMP was also recorded from electrodes over SCM, ipsilateral to the stimulus ear, in the same participants in a supine, head lift/turn position. Results: Response amplitudes significantly increased with contraction strength and decreased with age. Participants were able to maintain sufficient contraction strength (amplitude) with head rotation to reliably measure over SPC. Normalized response amplitudes measured from electrodes over contralateral SPC were largest with head rotation contralateral to the stimulus ear. Normalized amplitudes and peak latencies were comparable to the same measures from SCM obtained in supine, head lift/turn position. Conclusions: Otolith generated myogenic responses can be recorded seated from electrodes over the dorsal neck with head rotation contralateral to the stimulus ear. In this position, contralateral recordings are consistent with responses known from previous work to arise from SPC; ipsilateral recordings may include crosstalk from activated muscles nearby, including ipsilateral SCM. Overall, techniques targeting contralateral SPC during contralateral head turn may provide additional methods of recording VEMPs.(AU)

Antecedentes y objetivos: Examinamos las respuestas de los potenciales evocados miogénicos vestibulares (PEMV) recogidas de los electrodos de superficie sobre el músculo esplenio (ME) en posición sentada. Objetivos específicos: 1) validar las características de los registros de la respuesta de los PEMV recogidos de los electrodos de superficie sobre el músculo esternocleidomastoideo (SCM) y el ME, y 2) evaluar los efectos de la edad en adolescentes y adultos jóvenes. Materiales y métodos: Se registraron simultáneamente los PEMV bilaterales de los electrodos situados en la musculatura dorsal del cuello, en un sitio conocido de un estudio anterior para obtener registros del ME en 15 participantes sanos durante los ensayos, con rotación de cabeza hacia y fuera del oído estimulado. También se registraron los PEMV de los electrodos situados sobre el SCM, en posición ipsilateral al oído estimulado, en los mismos participantes, en posición supina y con elevación/giro de cabeza. Resultados: Las amplitudes de la respuesta se incrementaron significativamente con la fuerza de la contracción y disminuyeron con la edad. Los participantes fueron capaces de mantener suficiente fuerza de contracción (amplitud) con la rotación de cabeza, para realizar mediciones fiables sobre el ME. Las amplitudes de la respuesta normalizada medidas en los electrodos sobre el ME contralateral fueron mayores con la rotación de cabeza contralateral al oído estimulado. Las amplitudes normalizadas y las latencias máximas fueron comparables a las mismas medidas del SCM obtenidas en posición supina, y elevación/giro de cabeza. Conclusiones: Las respuestas miogénicas generadas por otolitos pueden registrarse en posición sentada a partir de los electrodos situados en la parte dorsal del cuello, contralateral al oído estimulado. En esta posición, los registros contralaterales son coherentes con las respuestas conocidas de un estudio previo, derivadas del ME; los registros ipsilaterales pueden incluir interferencias de los músculos activados cercanos, incluyendo el SCM ipsilateral. En general, las técnicas centradas en el ME contralateral durante el giro de cabeza contralateral pueden aportar métodos adicionales de registro de los PEMV.(AU)

Stochastic and sinusoidal electrical stimuli increase the irregularity and gain of Type A and B medial vestibular nucleus neurons, in vitro.

Galvanic vestibular stimulation (GVS) has been shown to improve vestibular function potentially via stochastic resonance, however, it remains unknown how central vestibular nuclei process these signals. In vivo work applying electrical stimuli to the vestibular apparatus of animals has shown changes in neuronal discharge at the level of the primary vestibular afferents and hair cells. This study aimed to determine the cellular impacts of stochastic, sinusoidal, and stochastic + sinusoidal stimuli on individual medial vestibular nucleus (MVN) neurons of male and female C57BL/6 mice. All stimuli increased the irregularity of MVN neuronal discharge, while differentially affecting neuronal gain. This suggests that the heterogeneous MVN neuronal population (marked by differential expression of ion channels), may influence the impact of electrical stimuli on neuronal discharge. Neuronal subtypes showed increased variability of neuronal firing, where Type A and B neurons experienced the largest gain changes in response to stochastic and sinusoidal stimuli. Type C neurons were the least affected regarding neuronal firing variability and gain changes. The membrane potential (MP) of neurons was altered by sinusoidal and stochastic + sinusoidal stimuli, with Type B and C neuronal MP significantly affected. These results indicate that GVS-like electrical stimuli impact MVN neuronal discharge differentially, likely as a result of heterogeneous ion channel expression.

Response characteristics of vestibular evoked myogenic potentials recorded over splenius capitis in young adults and adolescents.

BACKGROUND AND OBJECTIVES: Examine vestibular evoked myogenic potential (VEMP) responses recorded from surface electrodes over Splenius Capitis (SPC) in a seated position. SPECIFIC AIMS: (1) validate response characteristics of VEMP recordings from surface electrodes over Sternocleidomastoid (SCM) and over SCP and (2) assess age effects on responses in adolescents and young adults. MATERIALS AND METHODS: Simultaneous surface VEMP was recorded bilaterally from electrodes placed over the dorsal neck musculature at a location known from previous work to record from SPC in 15 healthy participants during trials with head rotation toward and away from the stimulated ear. VEMP was also recorded from electrodes over SCM, ipsilateral to the stimulus ear, in the same participants in a supine, head lift/turn position. RESULTS: Response amplitudes significantly increased with contraction strength and decreased with age. Participants were able to maintain sufficient contraction strength (amplitude) with head rotation to reliably measure over SPC. Normalized response amplitudes measured from electrodes over contralateral SPC were largest with head rotation contralateral to the stimulus ear. Normalized amplitudes and peak latencies were comparable to the same measures from SCM obtained in supine, head lift/turn position. CONCLUSIONS: Otolith generated myogenic responses can be recorded seated from electrodes over the dorsal neck with head rotation contralateral to the stimulus ear. In this position, contralateral recordings are consistent with responses known from previous work to arise from SPC; ipsilateral recordings may include crosstalk from activated muscles nearby, including ipsilateral SCM. Overall, techniques targeting contralateral SPC during contralateral head turn may provide additional methods of recording VEMPs.

Summating potentials from the utricular macula of anaesthetized guinea pigs.

The Summating Potential (SP) was first recorded in the cochlea in the 1950s and represents an objective measure of cochlear hair cell function, in vivo. Despite being a regular tool in hearing research, a similar response has not yet been recorded from the vestibular system. This is mainly due to the lack of experimental techniques available to record electrical vestibular hair cell responses in isolation from the much larger cochlear potentials. Here we demonstrate the first recordings of the vestibular SP, evoked by Bone-Conducted Vibration (BCV) and Air-Conducted Sound (ACS) stimuli, in anaesthetized guinea pigs. Field potential measurements were taken from the basal surface of the utricular macula, and from the facial nerve canal following surgical or chemical ablation of the cochlea. SPs were evoked by stimuli with frequencies above ~200 Hz, and only with moderate to high intensity (~0.005-0.05 g) BCV and ACS (~120-140 dB SPL). Neural blockade abolished the Vestibular short-latency Evoked Potential (VsEP) and Vestibular Nerve Neurophonic (VNN) from the facial nerve canal recordings but did not abolish the vestibular SP nor the vestibular microphonic. Importantly, the vestibular SP was irreversibly abolished from the utricle and facial nerve canal recordings following local gentamicin application, highlighting its hair cell origin. This is the first study to record the Summating Potential from the mammalian vestibular system, in vivo, providing a novel research tool to assess vestibular hair cell function during experimental manipulations and animal models of disease.

K369I Tau Mice Demonstrate a Shift Towards Striatal Neuron Burst Firing and Goal-directed Behaviour.

Pathological forms of the microtubule-associated protein tau are involved in a large group of neurodegenerative diseases named tauopathies, including frontotemporal lobar degeneration (FTLD-tau). K369I mutant tau transgenic mice (K3 mice) recapitulate neural and behavioural symptoms of FTLD, including tau aggregates in the cortex, alterations to nigrostriatum, memory deficits and parkinsonism. The aim of this study was to further characterise the K3 mouse model by examining functional alterations to the striatum. Whole-cell patch-clamp electrophysiology was used to investigate the properties of striatal neurons in K3 mice and wildtype controls. Additionally, striatal-based instrumental learning tasks were conducted to assess goal-directed versus habitual behaviours (i.e., by examining sensitivity to outcome devaluation and progressive ratios). The K3 model demonstrated significant alterations in the discharge properties of striatal neurons relative to wildtype mice, which manifested as a shift in neuronal output towards a burst firing state. K3 mice acquired goal-directed responding faster than control mice and were goal-directed at test unlike wildtype mice, which is likely to indicate reduced capacity to develop habitual behaviour. The observed pattern of behaviour in K3 mice is suggestive of deficits in dorsal lateral striatal function and this was supported by our electrophysiological findings. Thus, both the electrophysiological and behavioural alterations indicate that K3 mice have early deficits in striatal function. This finding adds to the growing literature which indicate that the striatum is impacted in tau-related neuropathies such as FTLD, and further suggests that the K3 model is a unique mouse model for investigating FTLD especially with striatal involvement.

Utricular Sensitivity during Hydrodynamic Displacements of the Macula.

To explore the effects of cochlear hair cell displacement, researchers have previously monitored functional and mechanical responses during low-frequency (LF) acoustic stimulation of the cochlea. The induced changes are believed to result from modulation of the conductance of mechano-electrical transduction (MET) channels on cochlear hair cells, along with receptor potential modulation. It is less clear how, or if, vestibular hair cell displacement affects vestibular function. Here, we have used LF (<20 Hz) hydrodynamic modulation of the utricular macula position, whilst recording functional and mechanical responses, to investigate the effects of utricular macula displacement. Measured responses included the Utricular Microphonic (UM), the vestibular short-latency evoked potential (VsEP), and laser Doppler vibrometry recordings of macular position. Over 1 cycle of the LF bias, the UM amplitude and waveform were cyclically modulated, with Boltzmann analysis suggesting a cyclic modulation of the vestibular MET gating. The VsEP amplitude was cyclically modulated throughout the LF bias, demonstrating a relative increase (~20-50 %; re baseline) and decrease (~10-20 %; re baseline), which is believed to be related to the MET conductance and vestibular hair cell sensitivity. The relationship between macular displacement and changes in UM and VsEP responses was consistent within and across animals. These results suggest that the sensory structures underlying the VsEP, often thought to be a cranial jerk-sensitive response, are at least partially sensitive to LF (and possibly static) pressures or motion. Furthermore, these results highlight the possibility that some of the vestibular dysfunction related to endolymphatic hydrops may be due to altered vestibular transduction following mechanical (or morphological) changes in the labyrinth.

The intrinsic plasticity of medial vestibular nucleus neurons during vestibular compensation-a systematic review and meta-analysis.

BACKGROUND: Vestibular compensation is a homeostatic process that occurs in the central nervous system in response to peripheral vestibular dysfunction. Experimental studies in rodent models have suggested that unilateral peripheral vestibular lesions are correlated with an increase in the intrinsic excitability of central vestibular neurons. This process may be dependent on the intrinsic properties of the neurons themselves. We aimed to conduct a systematic review of the literature to survey the evidence for changes in intrinsic plasticity observed during the acute phase of vestibular compensation. METHODS: We systematically reviewed the literature regarding the electrophysiological effect of experimentally induced unilateral vestibular deafferentation (UVD) on the intrinsic membrane properties of medial vestibular nucleus neurons in animal models. We developed tools to assess the methodological quality (precision, validity and bias) of studies that met pre-determined inclusion and exclusion criteria. We extracted numerical data and performed a meta-analysis of specific quantitative data pooled from these studies. RESULTS: We identified 17 studies that satisfied the inclusion criteria. There is moderate quality evidence to suggest a statistically significant increase in the intrinsic excitability of medial vestibular nucleus neurons following unilateral vestibular deafferentation. Specifically, the spontaneous discharge rate increases by 4 spikes/s on average and the sensitivity to current stimuli increases. CONCLUSION: Using this novel approach, we demonstrate that the methodology of systematic review and meta-analysis is a useful tool in the summation of data across experimental animal studies with similar aims.

Elucidating the time course of the transcriptomic response to photobiomodulation through gene co-expression analysis.

Photobiomodulation (PBM) with low-intensity red to near infrared light elicits neuroprotection in various pre-clinical models and in some clinical contexts, yet the intracellular mechanisms triggered by PBM, and their temporal sequence of modulation, remain unclear. We aimed to address this uncertainty by mapping the temporal transcriptomic response to PBM. Human SH-SY5Y neuroblastoma cells were treated with 670 nm PBM and RNA collected a various time points over 24 h. The transcriptome was screened by RNA microarray, and gene co-expression analysis by hierarchical clustering was coupled with bioinformatics analysis to reveal the molecular systems modulated by PBM and their expression patterns over the time course. The findings suggest that PBM induces distinct early phase (up to 8 h post-PBM) and late phase (24 h post-PBM) intracellular responses. The early intracellular response features enrichment of pathways relating to transcriptional regulation and cellular stress responses, while the late intracellular response demonstrates a physiological shift to enrichment of downstream pathways such as cell death and DNA damage. These findings provide support for the hypothesis that PBM acts as a transient stressful stimulus, activating endogenous stress response pathways that in turn enhance cellular resilience. Further, the study introduces a novel method for retaining the richness of the temporal component when analysing transcriptomic time course data sets.

Correction: Are viral-infections associated with Ménière's Disease? A systematic review and meta-analysis of molecular-markers of viral-infection in case-controlled observational studies of MD.

[This corrects the article DOI: 10.1371/journal.pone.0225650.].

Are viral-infections associated with Ménière's Disease? A systematic review and meta-analysis of molecular-markers of viral-infection in case-controlled observational studies of MD.

Despite considerable research, it remains controversial as to whether viral-infections are associated with Meniere's Disease (MD), a clinically heterogeneous set of chronic inner-ear disorders strongly associated with endolymphatic hydrops. Here, we investigated whether viral-infections are associated with MD through a systematic review and meta-analysis of observational clinical studies using molecular-diagnostics. Eligible for inclusion were case-controlled studies which ascertained molecular-determinants of past or present viral-infection through either viral nucleic acids or host serological marker in MD cases and non-MD controls. Across online databases and grey literature, we identified 210 potentially relevant articles in the English language, from which a total of 14 articles fully satisfied our eligibility criteria such that meta-groups of 611 MD-cases and 373 controls resulted. The aggregate quality of the modest-sized (14 studies) body of evidence was limited and varied considerably with regards to participant selection, matching, and ascertainment(s) and determinant(s) of viral-infection. Most data identified concerned the human cytomegalovirus (CMV), and meta-analysis of eligible studies revealed that evidence of CMV-infection was associated approximately three-fold with MD compared to controls, however the timing of the infections was indeterminate as the pooled analyses combined antiviral serological markers with viral nucleic acid markers. No association was found for any of HSV-1, -2, VZV, or EBV. Associative analyses of any viral species not aforementioned were precluded by limited data, and thus potential associations between other viral species and MD, especially other than Herpesviridae, are yet to be characterised. Overall, we have found a small association between CMV-infection and MD, however it is to be determined for what sub-groups of MD this finding may be relevant, and ideally the reported association remains would be reproduced by a greater volume of higher quality evidence.

Stochastic Noise Application for the Assessment of Medial Vestibular Nucleus Neuron Sensitivity In Vitro.

Galvanic vestibular stimulation (GVS) has been shown to improve balance measures in individuals with balance or vestibular impairments. This is proposed to be due to the stochastic resonance (SR) phenomenon, which is defined as application of a low-level/subthreshold stimulus to a non-linear system to increase detection of weaker signals. However, it is still unknown how SR exhibits its positive effects on human balance. This is one of the first demonstrations of the effects of sinusoidal and stochastic noise on individual neurons. Using whole-cell patch clamp electrophysiology, sinusoidal and stochastic noise can be applied directly to individual neurons in the medial vestibular nucleus (MVN) of C57BL/6 mice. Here we demonstrate how to determine the threshold of MVN neurons in order to ensure the sinusoidal and stochastic stimuli are subthreshold and from this, determine the effects that each type of noise has on MVN neuronal gain. We show that subthreshold sinusoidal and stochastic noise can modulate the sensitivity of individual neurons in the MVN without affecting basal firing rates.

Splenius capitis: sensitive target for the cVEMP in older and neurodegenerative patients.

BACKGROUND: The vestibular evoked myogenic potential (VEMP) is a technique used to assess vestibular function. Cervical VEMPs (cVEMPs) are obtained conventionally from the sternocleidomastoid (SCM) muscle; however, the dorsal neck muscle splenius capitis (SPL) has also been shown to be a reliable target alongside the SCM in young subjects. OBJECTIVE: This study aimed to compare cVEMPs from the SCM and SPL in two positions across young, older, and Parkinson's disease (PD) patients. METHOD: Experiments were carried out using surface EMG electrodes placed over the SCM and SPL. cVEMPs were measured using a 30 s, 126 dB sound stimulus with 222 individual tone bursts, while subjects were in a supine and head-turned posture (also known as the head elevation method), and in a seated head-turned posture. RESULTS: When comparing cVEMPs across positions, the incidence of supine and seated SCM-cVEMPs diminished significantly in older and PD patients in comparison with young subjects. However, no statistically significant differences in incidences were found in seated SPL-cVEMPs when comparing young, older and PD patients. SPL-cVEMPs were present significantly more often than seated SCM-cVEMPs in PD patients. CONCLUSIONS: SPL-cVEMPs are not altered to the same extent that SCM-cVEMPs are by aging and disease and its addition to cVEMP testing may reduce false-positive tests for vestibulopathy.

Animal Models of Vestibular Evoked Myogenic Potentials: The Past, Present, and Future.

Vestibular-evoked myogenic potentials (VEMPs) provide a simple and cost-effective means to assess the patency of vestibular reflexes. VEMP testing constitutes a core screening method in a clinical battery that probes vestibular function. The confidence one has in interpreting the results arising from VEMP testing is linked to a fundamental understanding of the underlying functional anatomy and physiology. In this review, we will summarize the key role that studies across a range of animal models have fulfilled in contributing to this understanding, covering key findings regarding the mechanisms of excitation in the sensory periphery, the processing of sensory information in central networks, and the distribution of reflexive output to the motor periphery. Although VEMPs are often touted for their simplicity, work in animals models have emphasized how vestibular reflexes operate within a broader behavioral and functional context, and as such vestibular reflexes are influenced by multisensory integration, governed by task demands, and follow principles of muscle recruitment. We will conclude with considerations of future questions, and the ways in which studies in current and emerging animal models can contribute to further use and refinement of this test for both basic and clinical research purposes.

Corrigendum: Reviewing the Role of the Efferent Vestibular System in Motor and Vestibular Circuits.

[This corrects the article on p. 552 in vol. 8, PMID: 28824449.].