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Ibitoye RT, Mallas EJ, Bourke NJ, Kaski D, Bronstein AM, Sharp DJ. The human vestibular cortex: functional anatomy of OP2, its connectivity and the effect of vestibular disease. Cereb Cortex 2022; 33:567-582. [PMID: 35235642 PMCID: PMC9890474 DOI: 10.1093/cercor/bhac085] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 01/31/2022] [Accepted: 02/01/2022] [Indexed: 02/04/2023] Open
Abstract
Area OP2 in the posterior peri-sylvian cortex has been proposed to be the core human vestibular cortex. We investigated the functional anatomy of OP2 and adjacent areas (OP2+) using spatially constrained independent component analysis (ICA) of functional magnetic resonance imaging (fMRI) data from the Human Connectome Project. Ten ICA-derived subregions were identified. OP2+ responses to vestibular and visual motion were analyzed in 17 controls and 17 right-sided vestibular neuritis patients who had previously undergone caloric and optokinetic stimulation during fMRI. In controls, a posterior part of right OP2+ showed: (i) direction-selective responses to visual motion and (ii) activation during caloric stimulation that correlated positively with perceived self-motion, and negatively with visual dependence and peak slow-phase nystagmus velocity. Patients showed abnormal OP2+ activity, with an absence of visual or caloric activation of the healthy ear and no correlations with vertigo or visual dependence-despite normal slow-phase nystagmus responses to caloric stimulation. Activity in a lateral part of right OP2+ correlated with chronic visually induced dizziness in patients. In summary, distinct functional subregions of right OP2+ show strong connectivity to other vestibular areas and a profile of caloric and visual responses, suggesting a central role for vestibular function in health and disease.
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Affiliation(s)
- Richard T Ibitoye
- Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Brain Sciences, Imperial College London, London W12 0NN, United Kingdom,Neuro-otology Unit, Department of Brain Sciences, Imperial College London, London W6 8RP, United Kingdom
| | - Emma-Jane Mallas
- Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Brain Sciences, Imperial College London, London W12 0NN, United Kingdom,UK Dementia Research Institute, Care Research & Technology Centre, Imperial College London, London W12 0BZ, United Kingdom
| | - Niall J Bourke
- Computational, Cognitive and Clinical Neuroimaging Laboratory, Department of Brain Sciences, Imperial College London, London W12 0NN, United Kingdom
| | - Diego Kaski
- Department of Clinical and Motor Neurosciences, Centre for Vestibular and Behavioural Neurosciences, University College London, London WC1N 3BG, United Kingdom
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Nepveu JF, Mikhail Y, Pion CH, Gossard JP, Barthélemy D. Assessment of vestibulocortical interactions during standing in healthy subjects. PLoS One 2020; 15:e0233843. [PMID: 32497147 PMCID: PMC7272097 DOI: 10.1371/journal.pone.0233843] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 05/13/2020] [Indexed: 01/03/2023] Open
Abstract
The vestibular system is essential to produce adequate postural responses enabling voluntary movement. However, how the vestibular system influences corticospinal output during postural tasks is still unknown. Here, we examined the modulation exerted by the vestibular system on corticospinal output during standing. Healthy subjects (n = 25) maintained quiet standing, head facing forward with eyes closed. Galvanic vestibular stimulation (GVS) was applied bipolarly and binaurally at different delays prior to transcranial magnetic stimulation (TMS) which triggered motor evoked potentials (MEPs). With the cathode right/anode left configuration, MEPs in right Soleus (SOL) muscle were significantly suppressed when GVS was applied at ISI = 40 and 130ms before TMS. With the anode right/cathode left configuration, no significant changes were observed. Changes in the MEP amplitude were then compared to changes in the ongoing EMG when GVS was applied alone. Only the decrease in MEP amplitude at ISI = 40ms occurred without change in the ongoing EMG, suggesting that modulation occurred at a premotoneuronal level. We further investigated whether vestibular modulation could occur at the motor cortex level by assessing changes in the direct corticospinal pathways using the short-latency facilitation of the SOL Hoffmann reflex (H-reflex) by TMS. None of the observed modulation occurred at the level of motor cortex. Finally, using the long-latency facilitation of the SOL H-reflex, we were able to confirm that the suppression of MEP at ISI = 40ms occurred at a premotoneuronal level. The data indicate that vestibular signals modulate corticospinal output to SOL at both premotoneuronal and motoneuronal levels during standing.
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Affiliation(s)
- Jean-François Nepveu
- Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal, CRIR, Montreal, Canada
- Department of Neuroscience, Université de Montréal, Montreal, Canada
| | - Youstina Mikhail
- Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal, CRIR, Montreal, Canada
- School of Rehabilitation, Université de Montréal, Montreal, Canada
| | - Charlotte H. Pion
- Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal, CRIR, Montreal, Canada
- School of Rehabilitation, Université de Montréal, Montreal, Canada
| | | | - Dorothy Barthélemy
- Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal, CRIR, Montreal, Canada
- School of Rehabilitation, Université de Montréal, Montreal, Canada
- * E-mail:
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Glover IS, Baker SN. Multimodal stimuli modulate rapid visual responses during reaching. J Neurophysiol 2019; 122:1894-1908. [DOI: 10.1152/jn.00158.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The reticulospinal tract plays an important role in primate upper limb function, but methods for assessing its activity are limited. One promising approach is to measure rapid visual responses (RVRs) in arm muscle activity during a visually cued reaching task; these may arise from a tecto-reticulospinal pathway. We investigated whether changes in reticulospinal excitability can be assessed noninvasively using RVRs, by pairing the visual stimuli of the reaching task with electrical stimulation of the median nerve, galvanic vestibular stimulation, or loud sounds, all of which are known to activate the reticular formation. Surface electromyogram (EMG) recordings were made from the right deltoid of healthy human subjects as they performed fast reaching movements toward visual targets. Stimuli were delivered up to 200 ms before target appearance, and RVR was quantified as the EMG amplitude in a window 75–125 ms after visual target onset. Median nerve, vestibular, and auditory stimuli all consistently facilitated the RVRs, as well as reducing the latency of responses. We propose that this facilitation reflects modulation of tecto-reticulospinal excitability, which is consistent with the idea that the amplitude of RVRs can be used to assess changes in brain stem excitability noninvasively in humans. NEW & NOTEWORTHY Short-latency responses in arm muscles evoked during a visually driven reaching task have previously been proposed to be tecto-reticulospinal in origin. We demonstrate that these responses can be facilitated by pairing the appearance of a visual target with stimuli that activate the reticular formation: median nerve, vestibular, and auditory stimuli. We propose that this reflects noninvasive measurement and modulation of reticulospinal excitability.
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Affiliation(s)
- Isabel S. Glover
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Stuart N. Baker
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, United Kingdom
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Roberts RE, Ahmad H, Arshad Q, Patel M, Dima D, Leech R, Seemungal BM, Sharp DJ, Bronstein AM. Functional neuroimaging of visuo-vestibular interaction. Brain Struct Funct 2016; 222:2329-2343. [PMID: 27942855 PMCID: PMC5504268 DOI: 10.1007/s00429-016-1344-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 11/19/2016] [Indexed: 12/21/2022]
Abstract
The brain combines visual, vestibular and proprioceptive information to distinguish between self- and world motion. Often these signals are complementary and indicate that the individual is moving or stationary with respect to the surroundings. However, conflicting visual motion and vestibular cues can lead to ambiguous or false sensations of motion. In this study, we used functional magnetic resonance imaging to explore human brain activation when visual and vestibular cues were either complementary or in conflict. We combined a horizontally moving optokinetic stimulus with caloric irrigation of the right ear to produce conditions where the vestibular activation and visual motion indicated the same (congruent) or opposite directions of self-motion (incongruent). Visuo-vestibular conflict was associated with increased activation in a network of brain regions including posterior insular and transverse temporal areas, cerebellar tonsil, cingulate and medial frontal gyri. In the congruent condition, there was increased activation in primary and secondary visual cortex. These findings suggest that when sensory information regarding self-motion is contradictory, there is preferential activation of multisensory vestibular areas to resolve this ambiguity. When cues are congruent, there is a bias towards visual cortical activation. The data support the view that a network of brain areas including the posterior insular cortex may play an important role in integrating and disambiguating visual and vestibular cues.
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Affiliation(s)
- R E Roberts
- Neuro-otology Unit, Division of Brain Sciences, Charing Cross Hospital, Imperial College London, London, UK.
| | - H Ahmad
- Neuro-otology Unit, Division of Brain Sciences, Charing Cross Hospital, Imperial College London, London, UK
| | - Q Arshad
- Neuro-otology Unit, Division of Brain Sciences, Charing Cross Hospital, Imperial College London, London, UK
| | - M Patel
- Neuro-otology Unit, Division of Brain Sciences, Charing Cross Hospital, Imperial College London, London, UK
| | - D Dima
- Department of Psychology, City, University of London, London, UK.,Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - R Leech
- Computational, Cognitive and Clinical Neuroimaging Laboratory, Division of Brain Sciences, Imperial College London, Hammersmith Hospital, London, UK
| | - B M Seemungal
- Neuro-otology Unit, Division of Brain Sciences, Charing Cross Hospital, Imperial College London, London, UK
| | - D J Sharp
- Computational, Cognitive and Clinical Neuroimaging Laboratory, Division of Brain Sciences, Imperial College London, Hammersmith Hospital, London, UK
| | - A M Bronstein
- Neuro-otology Unit, Division of Brain Sciences, Charing Cross Hospital, Imperial College London, London, UK.
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Facilitation of descending excitatory and spinal inhibitory networks from training of endurance and precision walking in participants with incomplete spinal cord injury. PROGRESS IN BRAIN RESEARCH 2015; 218:127-55. [DOI: 10.1016/bs.pbr.2014.12.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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