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Chen PH, Rau PLP. Using EEG to investigate the influence of boredom on prospective memory in top-down and bottom-up processing mechanisms for intelligent interaction. ERGONOMICS 2023; 66:690-703. [PMID: 35959646 DOI: 10.1080/00140139.2022.2113151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
We aimed to investigate the alpha (α) activity in operators experiencing boredom while performing prolonged monitoring and prospective memory tasks using different processing mechanisms. Fifty-four participants underwent electroencephalography (EEG) and were found to have poorer prospective memory performance under top-down conditions. Further, α power and synchronisation were higher during bottom-up than in top-down processes, revealing an inhibition effect of the former. Significant differences in brain regions and hemispheres were identified to distinguish different cognitive processes in both information-processing mechanisms. Thus, people are likely to cope with boredom differently in terms of top-down and bottom-up processes. Specifically, a higher attention level was reported during top-down processing, to mitigate the negative influences of boredom. Overall, this study provides EEG evidence which suggests that prospective memory can be enhanced in top-down processing during prolonged monitoring tasks by increasing the salience of cues.
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Affiliation(s)
- Pin-Hsuan Chen
- Department of Industrial Engineering, Tsinghua University, Beijing, China
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2
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Factors influencing clinical outcome in vestibular neuritis - A focussed review and reanalysis of prospective data. J Neurol Sci 2023; 446:120579. [PMID: 36807973 DOI: 10.1016/j.jns.2023.120579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 12/22/2022] [Accepted: 01/31/2023] [Indexed: 02/05/2023]
Abstract
Following vestibular neuritis (VN), long term prognosis is not dependent on the magnitude of the residual peripheral function as measured with either caloric or the video head-impulse test. Rather, recovery is determined by a combination of visuo-vestibular (visual dependence), psychological (anxiety) and vestibular perceptual factors. Our recent research in healthy individuals has also revealed a strong association between the degree of lateralisation of vestibulo-cortical processing and gating of vestibular signals, anxiety and visual dependence. In the context of several functional brain changes occurring in the interaction between visual, vestibular and emotional cortices, which underpin the aforementioned psycho-physiological features in patients with VN, we re-examined our previously published findings focusing on additional factors impacting long term clinical outcome and function. These included: (i) the role of concomitant neuro-otological dysfunction (i.e. migraine and benign paroxysmal positional vertigo (BPPV)) and (ii) the degree to which brain lateralisation of vestibulo-cortical processing influences gating of vestibular function in the acute stage. We found that migraine and BPPV interfere with symptomatic recovery following VN. That is, dizziness handicap at short-term recovery stage was significantly predicted by migraine (r = 0.523, n = 28, p = .002), BPPV (r = 0.658, n = 31, p < .001) and acute visual dependency (r = 0.504, n = 28, p = .003). Moreover, dizziness handicap in the long-term recovery stage continued to be predicted by migraine (r = 0.640, n = 22, p = .001), BPPV (r = 0.626, n = 24, p = .001) and acute visual dependency (r = 0.667, n = 22, p < .001). Furthermore, surrogate measures of vestibulo-cortical lateralisation were predictive of the amount of cortical suppression exerted over vestibular thresholds. That is, in right-sided VN patients, we observed a positive correlation between visual dependence and acute ipsilesional oculomotor thresholds (R2 0.497; p < .001), but not contralateral thresholds (R2 0.017: p > .05). In left-sided VN patients, we observed a negative correlation between visual dependence and ipsilesional oculomotor thresholds (R2 0.459; p < .001), but not for contralateral thresholds (R2 0.013; p > .05). To surmise, our findings illustrate that in VN, neuro-otological co-morbidities retard recovery, and that measures of the peripheral vestibular system are an aggregate of residual function and cortically mediated gating of vestibular input.
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Crampton A, Schneider KJ, Grilli L, Chevignard M, Katz-Leurer M, Beauchamp MH, Debert C, Gagnon IJ. Characterizing the evolution of oculomotor and vestibulo-ocular function over time in children and adolescents after a mild traumatic brain injury. Front Neurol 2022; 13:904593. [PMID: 35928133 PMCID: PMC9344998 DOI: 10.3389/fneur.2022.904593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 06/28/2022] [Indexed: 11/30/2022] Open
Abstract
Background Impairments to oculomotor (OM) and vestibulo-ocular reflex (VOR) function following pediatric mTBI have been demonstrated but are poorly understood. Such impairments can be associated with more negative prognosis, affecting physical and mental wellbeing, emphasizing the need to more fully understand how these evolve. Objectives to determine i) the extent to which performance on clinical and computerized tests of OM and VOR function varies over time in children and adolescents at 21 days, 3-, and 6-months post-mTBI; ii) the proportion of children and adolescents with mTBI presenting with abnormal scores on these tests at each timepoint. Design Prospective longitudinal design. Setting Tertiary care pediatric hospital. Participants 36 participants with mTBI aged 6 to18. Procedures Participants were assessed on a battery of OM and VOR tests within 21 days, at 3- and 6-months post injury. Outcome measures Clinical measures: Vestibular/ocular motor screening tool (VOMS) (symptom provocation and performance); Computerized measures: reflexive saccade test (response latency), video head impulse test (VOR gain), and dynamic visual acuity test (LogMAR change). Analysis Generalized estimating equations (parameter estimates and odd ratios) estimated the effect of time. Proportions above and below normal cut-off values were determined. Results Our sample consisted of 52.8% females [mean age 13.98 (2.4) years, assessed on average 19.07 (8–33) days post-injury]. Older children performed better on visual motion sensitivity (OR 1.43, p = 0.03) and female participants worse on near point of convergence (OR 0.19, p = 0.03). Change over time (toward recovery) was demonstrated by VOMS overall symptom provocation (OR 9.90, p = 0.012), vertical smooth pursuit (OR 4.04, p = 0.03), voluntary saccade performance (OR 6.06, p = 0.005) and right VOR gain (0.068, p = 0.013). Version performance and VOR symptom provocation showed high abnormal proportions at initial assessment. Discussion Results indicate impairments to the VOR pathway may be present and driving symptom provocation. Vertical smooth pursuit and saccade findings underline the need to include these tasks in test batteries to comprehensively assess the integrity of OM and vestibular systems post-mTBI. Implications Findings demonstrate 1) added value in including symptom and performance-based measures in when OM and VOR assessments; 2) the relative stability of constructs measured beyond 3 months post mTBI.
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Affiliation(s)
- Adrienne Crampton
- School of Physical and Occupational Therapy, McGill University, Montreal, QC, Canada
- *Correspondence: Adrienne Crampton
| | - Kathryn J. Schneider
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Lisa Grilli
- Montreal Children's Hospital-McGill University Health Centre, Montreal, QC, Canada
| | - Mathilde Chevignard
- Laboratoire d'Imagerie Biomédicale, LIB, CNRS, INSERM, Sorbonne Université, Paris, France
- GRC 24 Handicap Moteur et Cognitif et Réadaptation, Sorbonne Université, Paris, France
- Rehabilitation Department for Children With Acquired Neurological Injury and Outreach Team for Children and Adolescents With Acquired Brain Injury, Saint Maurice Hospitals, Saint Maurice, France
| | | | - Miriam H. Beauchamp
- Ste-Justine Hospital Research Centre, Montreal, QC, Canada
- Department of Psychology, University of Montreal, Montreal, QC, Canada
| | - Chantel Debert
- Department of Clinical Neuroscience, University of Calgary, Calgary, AB, Canada
| | - Isabelle J. Gagnon
- School of Physical and Occupational Therapy, McGill University, Montreal, QC, Canada
- Montreal Children's Hospital-McGill University Health Centre, Montreal, QC, Canada
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4
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Cooke JI, Guven O, Abarca PC, Ibitoye RT, Pettorossi VE, Bronstein AM. Electroencephalographic response to transient adaptation of vestibular perception. J Physiol 2022; 600:3517-3535. [PMID: 35713975 PMCID: PMC9544486 DOI: 10.1113/jp282470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 06/06/2022] [Indexed: 12/04/2022] Open
Abstract
Abstract When given a series of sinusoidal oscillations in which the two hemicycles have equal amplitude but asymmetric velocity, healthy subjects lose perception of the slower hemicycle (SHC), reporting a drift towards the faster hemicycle (FHC). This response is not reflected in the vestibular–ocular reflex, suggesting that the adaptation is of higher order. This study aimed to define EEG correlates of this adaptive response. Twenty‐five subjects underwent a series of symmetric or asymmetric oscillations and reported their perceived head orientation at the end using landmarks in the testing room; this was converted into total position error (TPE). Thirty‐two channel EEG was recorded before, during and after adaptation. Spectral power and coherence were calculated for the alpha, beta, delta and theta frequency bands. Linear mixed models were used to determine a region‐by‐condition effect of the adaptation. TPE was significantly greater in the asymmetric condition and reported error was always in the direction of the FHC. Regardless of condition, alpha desynchronised in response to stimulation, then rebounded back toward baseline values. This pattern was accelerated and attenuated in the prefrontal and occipital regions, respectively, in the asymmetric condition. Functional connectivity networks were identified in the beta and delta frequency bands; these networks, primarily comprising frontoparietal connections, were more coherent during asymmetric stimulation. These findings suggest that the temporary vestibulo‐perceptual ‘neglect’ induced by asymmetric vestibular stimulation may be mediated by alpha rhythms and frontoparietal attentional networks. The results presented further our understanding of brain rhythms and cortical networks involved in vestibular perception and adaptation.
![]() Key points Whole‐body asymmetric sinusoidal oscillations, which consist of hemicycles with equal amplitude but differing velocities, can induce transient ‘neglect’ of the slower hemicycle in the vestibular perception of healthy subjects. In this study, we aimed to elucidate EEG correlates of this ‘neglect’, thereby identifying a cortical role in vestibular perception and adaptation. We identified a desynchronisation–resynchronisation response in the alpha frequency band (8–14 Hz) that was accelerated in the prefrontal region and attenuated in the occipital region when exposed to asymmetric, as compared to symmetric, rotations. We additionally identified functional connectivity networks in the beta (14–30 Hz) and delta (1–4 Hz) frequency bands consisting primarily of frontoparietal connections. These results suggest a prominent role of alpha rhythms and frontoparietal attentional networks in vestibular perception and adaptation.
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Affiliation(s)
- Josephine I Cooke
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, Charing Cross Hospital, London, UK
| | - Onur Guven
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, Charing Cross Hospital, London, UK
| | - Patricia Castro Abarca
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, Charing Cross Hospital, London, UK.,Escuela de Fonoaudiología, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Richard T Ibitoye
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, Charing Cross Hospital, London, UK
| | - Vito E Pettorossi
- Dipartimento di Medicina e Chirurgia, Sezione di Fisiologia Umana e Biochemica, Università Degli Studi di Perugia, Perugia, Italy
| | - Adolfo M Bronstein
- Neuro-otology Unit, Department of Brain Sciences, Imperial College London, Charing Cross Hospital, London, UK
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5
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Arshad Q, Saman Y, Sharif M, Kaski D, Staab JP. Magnitude Estimates Orchestrate Hierarchal Construction of Context-Dependent Representational Maps for Vestibular Space and Time: Theoretical Implications for Functional Dizziness. Front Integr Neurosci 2022; 15:806940. [PMID: 35185485 PMCID: PMC8855482 DOI: 10.3389/fnint.2021.806940] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/20/2021] [Indexed: 12/24/2022] Open
Abstract
Maintaining balance necessitates an accurate perceptual map of the external world. Neuro-physiological mechanisms of locomotor control, sensory perception, and anxiety systems have been viewed as separate entities that can on occasion affect each other (i.e., walking on ice). Emerging models are more integrated, that envision sensory perception and threat assessment as a fundamental component of balance. Here we present an empirically based theoretical argument that vestibular cortical areas construct magnitude estimates of our environment via neural integration of incoming sensory signals. In turn, these cortically derived magnitude estimates, construct context-dependent vestibulo-spatial and vestibulo-temporal, representational maps of the external world, and ensure an appropriate online scaling factor for associated action-perceptual risk. Thus, threat signals are able to exert continuous influence on planning movements, predicting outcomes of motion of self and surrounding objects, and adjusting tolerances for discrepancies between predicted and actual estimates. Such a process affects the degree of conscious attention directed to spatial and temporal aspects of motion stimuli, implying that maintaining balance may follow a Bayesian approach in which the relative weighting of vestibulo-spatial and vestibulo-temporal signals and tolerance for discrepancies are adjusted in accordance with the level of threat assessment. Here, we seek to mechanistically explain this process with our novel empirical concept of a Brainstem Cortical Scaling Metric (BCSM), which we developed from a series of neurophysiological studies illustrating the central role of interhemispheric vestibulo-cortical asymmetries for balance control. We conclude by using the BCSM to derive theoretical predictions of how a dysfunctional BCSM can mechanistically account for functional dizziness.
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Affiliation(s)
- Qadeer Arshad
- Neuro-Otology Unit, Department of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, London, United Kingdom
- inAmind Laboratory, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
- Department of Clinical and Motor Neurosciences, Institute of Neurology, University College London, London, United Kingdom
| | - Yougan Saman
- inAmind Laboratory, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Mishaal Sharif
- inAmind Laboratory, Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, United Kingdom
| | - Diego Kaski
- Department of Clinical and Motor Neurosciences, Institute of Neurology, University College London, London, United Kingdom
| | - Jeffrey P. Staab
- Departments of Psychiatry and Psychology and Otorhinolaryngology – Head and Neck Surgery, Mayo Clinic, Rochester, MN, United States
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6
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Interhemispheric co-alteration of brain homotopic regions. Brain Struct Funct 2021; 226:2181-2204. [PMID: 34170391 PMCID: PMC8354999 DOI: 10.1007/s00429-021-02318-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 06/07/2021] [Indexed: 11/11/2022]
Abstract
Asymmetries in gray matter alterations raise important issues regarding the pathological co-alteration between hemispheres. Since homotopic areas are the most functionally connected sites between hemispheres and gray matter co-alterations depend on connectivity patterns, it is likely that this relationship might be mirrored in homologous interhemispheric co-altered areas. To explore this issue, we analyzed data of patients with Alzheimer’s disease, schizophrenia, bipolar disorder and depressive disorder from the BrainMap voxel-based morphometry database. We calculated a map showing the pathological homotopic anatomical co-alteration between homologous brain areas. This map was compared with the meta-analytic homotopic connectivity map obtained from the BrainMap functional database, so as to have a meta-analytic connectivity modeling map between homologous areas. We applied an empirical Bayesian technique so as to determine a directional pathological co-alteration on the basis of the possible tendencies in the conditional probability of being co-altered of homologous brain areas. Our analysis provides evidence that: the hemispheric homologous areas appear to be anatomically co-altered; this pathological co-alteration is similar to the pattern of connectivity exhibited by the couples of homologues; the probability to find alterations in the areas of the left hemisphere seems to be greater when their right homologues are also altered than vice versa, an intriguing asymmetry that deserves to be further investigated and explained.
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7
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Winnick A, Sadeghpour S, Sova M, Otero-Millan J, Kheradmand A. No handedness effect on spatial orientation or ocular counter-roll during lateral head tilts. Physiol Rep 2020; 7:e14160. [PMID: 31278854 PMCID: PMC6612230 DOI: 10.14814/phy2.14160] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 06/12/2019] [Accepted: 06/12/2019] [Indexed: 11/30/2022] Open
Abstract
Although vestibular inputs are bilaterally represented within the cerebral hemispheres, the higher level vestibular functions exhibit hemispheric asymmetries. Previous studies have suggested that such asymmetries are associated with handedness. Here, we studied the impact of handedness (i.e., hemispheric lateralization) on spatial orientation using a subjective visual vertical (SVV) task. We tested 22 right‐handed and 22 left‐handed subjects in upright position, during prolonged lateral head tilts of 20° (~15 min), and after the head returned to upright position. The corresponding changes in torsional eye position were measured simultaneously using video‐oculography. During lateral head tilts, both right‐ and left‐handers had initial SVV biases in the opposite direction of the head tilt (right‐handers: left tilt 3.0 ± 1.3°, right tilt −4.7 ± 1.5°; left‐handers: left tilt 3.4 ± 1.1°, right tilt −4.1 ± 1.0°). The SVV subsequently drifted in the direction of the head tilt, and there was an aftereffect in the same direction when the head was brought back upright. The ocular torsion initially changed in the opposite direction of the head tilt (right‐handers: left tilt 3.8 ± 0.4°, right tilt −3.8 ± 0.4°; left‐handers: left tilt 4.2 ± 0.5°, right tilt −4.5 ± 0.5°), and there were also drift and aftereffect in the same direction as the head tilt. The changes in upright perception and ocular torsion did not differ between right‐ and left‐handers. These findings show no functional laterality, neither in the higher level neural mechanisms that maintain spatial orientation, nor in the lower level mechanisms that generate the ocular torsion response during lateral head tilt.
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Affiliation(s)
- Ariel Winnick
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Shirin Sadeghpour
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Michael Sova
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jorge Otero-Millan
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Amir Kheradmand
- Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, Maryland.,Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland
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8
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Bednarczuk NF, Bonsu A, Ortega MC, Fluri AS, Chan J, Rust H, de Melo F, Sharif M, Seemungal BM, Golding JF, Kaski D, Bronstein AM, Arshad Q. Abnormal visuo-vestibular interactions in vestibular migraine: a cross sectional study. Brain 2020; 142:606-616. [PMID: 30759189 PMCID: PMC6391603 DOI: 10.1093/brain/awy355] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 10/11/2018] [Accepted: 11/26/2018] [Indexed: 11/30/2022] Open
Abstract
Vestibular migraine is among the commonest causes of episodic vertigo. Chronically, patients with vestibular migraine develop abnormal responsiveness to both vestibular and visual stimuli characterized by heightened self-motion sensitivity and visually-induced dizziness. Yet, the neural mechanisms mediating such symptoms remain unknown. We postulate that such symptoms are attributable to impaired visuo-vestibular cortical interactions, which in turn disrupts normal vestibular function. To assess this, we investigated whether prolonged, full-field visual motion exposure, which has been previously shown to modulate visual cortical excitability in both healthy individuals and avestibular patients, could disrupt vestibular ocular reflex and vestibular-perceptual thresholds of self-motion during rotations. Our findings reveal that vestibular migraine patients exhibited abnormally elevated reflexive and perceptual vestibular thresholds at baseline. Following visual motion exposure, both reflex and perceptual thresholds were significantly further increased in vestibular migraine patients relative to healthy controls, migraineurs without vestibular symptoms and patients with episodic vertigo due to a peripheral inner-ear disorder. Our results provide support for the notion of altered visuo-vestibular cortical interactions in vestibular migraine, as evidenced by vestibular threshold elevation following visual motion exposure.
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Affiliation(s)
- Nadja F Bednarczuk
- Academic Department of Neuro-Otology, Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, UK
| | - Angela Bonsu
- Academic Department of Neuro-Otology, Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, UK
| | - Marta Casanovas Ortega
- Academic Department of Neuro-Otology, Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, UK
| | - Anne-Sophie Fluri
- Academic Department of Neuro-Otology, Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, UK
| | - John Chan
- Academic Department of Neuro-Otology, Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, UK
| | - Heiko Rust
- Department of Neurology, University Hospital Basel, Petersgraben 4, Basel, Switzerland
| | - Fabiano de Melo
- Department of Neurology, Hospital das Clinicas da Faculdade de Medicina de Rebeirao Preto-USP, Campus Universitario s/n Riberao Preto, Sao Paulo, Brazil
| | - Mishaal Sharif
- Academic Department of Neuro-Otology, Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, UK
| | - Barry M Seemungal
- Academic Department of Neuro-Otology, Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, UK
| | - John F Golding
- Academic Department of Neuro-Otology, Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, UK.,Department of Psychology, School of Social Sciences, University of Westminster, 115 New Cavendish Street, London, UK
| | - Diego Kaski
- Academic Department of Neuro-Otology, Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, UK.,Department of Neuro-otology, Royal National Throat Nose and Ear Hospital, University College London, London, UK
| | - Adolfo M Bronstein
- Academic Department of Neuro-Otology, Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, UK
| | - Qadeer Arshad
- Academic Department of Neuro-Otology, Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, UK
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Abstract
BACKGROUND Through transcranial magnetic stimulation (TMS) it is possible to change cortical excitability of the visual cortex, and to influence binocular balance. The main goal of our study is to assess the effect of transcranial magnetic stimulation, specifically theta burst stimulation (TBS), in a group of amblyopic volunteers measuring several visual parameters: visual acuity, suppressive imbalance, and stereoacuity. METHODS Thirteen volunteers aged 19 to 24 years, randomly split in 2 groups, underwent 1 session of continuous TBS, stimulating the right occipital lobe. The first group with 8 volunteers was exposed to active stimulation with cTBS, and the other group with 5 volunteers was exposed to placebo stimulation. RESULTS Significant improvements in visual acuity, suppressive imbalance, and stereoacuity were found in the amblyopic eye after cTBS. The average value of amblyopia in visual acuity before stimulation was 0.32 ± 0.20 logMar and after cTBS was 0.19 ± 0.17 logMar. The mean value for the control group before placebo stimulation was 0.28 ± 0.17 and after placebo stimulation was 0.28 ± 0.16. The suppressive imbalance in the group of amblyope subjects stimulated before cTBS was 0.26 ± 0.18 and after was 0.12 ± 0.12; the suppressive imbalance of the control group before the placebo stimulation was 0.34 ± 0.37 and after was 0.32 ± 0.40. CONCLUSIONS Visual acuity, suppressive imbalance, and stereoacuity had significant enhancements compared with baseline after cTBS over the right occipital lobe in an ambliopic population.
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Castro P, Kaski D, Al-Fazly H, Ak D, Oktay L, Bronstein A, Arshad Q. Body sway during postural perturbations is mediated by the degree of vestibulo-cortical dominance. Brain Stimul 2019; 12:1098-1100. [PMID: 31105028 DOI: 10.1016/j.brs.2019.05.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 05/07/2019] [Indexed: 11/29/2022] Open
Affiliation(s)
- Patricia Castro
- Academic Department of Neuro-Otology, Division of Brain Sciences, Department of Medicine, Charing Cross Hospital Campus, Imperial College London, London, W6 8RF, UK; Escuela de Fonoaudiología, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Diego Kaski
- Academic Department of Neuro-Otology, Division of Brain Sciences, Department of Medicine, Charing Cross Hospital Campus, Imperial College London, London, W6 8RF, UK
| | - Hussein Al-Fazly
- Academic Department of Neuro-Otology, Division of Brain Sciences, Department of Medicine, Charing Cross Hospital Campus, Imperial College London, London, W6 8RF, UK
| | - Deniz Ak
- Academic Department of Neuro-Otology, Division of Brain Sciences, Department of Medicine, Charing Cross Hospital Campus, Imperial College London, London, W6 8RF, UK
| | - Liam Oktay
- Academic Department of Neuro-Otology, Division of Brain Sciences, Department of Medicine, Charing Cross Hospital Campus, Imperial College London, London, W6 8RF, UK
| | - Adolfo Bronstein
- Academic Department of Neuro-Otology, Division of Brain Sciences, Department of Medicine, Charing Cross Hospital Campus, Imperial College London, London, W6 8RF, UK
| | - Qadeer Arshad
- Academic Department of Neuro-Otology, Division of Brain Sciences, Department of Medicine, Charing Cross Hospital Campus, Imperial College London, London, W6 8RF, UK; Department of Neuroscience, Psychology and Behaviour, University of Leicester, University Road, Leicester, LE1 7RH, UK.
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11
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Arshad Q, Ortega MC, Goga U, Lobo R, Siddiqui S, Mediratta S, Bednarczuk NF, Kaski D, Bronstein AM. Interhemispheric control of sensory cue integration and self-motion perception. Neuroscience 2019; 408:378-387. [PMID: 31026563 DOI: 10.1016/j.neuroscience.2019.04.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 04/10/2019] [Accepted: 04/11/2019] [Indexed: 10/27/2022]
Abstract
Spatial orientation necessitates the integration of visual and vestibular sensory cues, in-turn facilitating self-motion perception. However, the neural mechanisms underpinning sensory integration remain unknown. Recently we have illustrated that spatial orientation and vestibular thresholds are influenced by interhemispheric asymmetries associated with the posterior parietal cortices (PPC) that predominantly house the vestibulo-cortical network. Given that sensory integration is a prerequisite to both spatial orientation and motion perception, we hypothesized that sensory integration is similarly subject to interhemispheric influences. Accordingly, we explored the relationship between vestibulo-cortical dominance - assessed using a biomarker, the degree of vestibular-nystagmus suppression following transcranial direct current stimulation over the PPC - with visual dependence measures obtained during performance of a sensory integration task (the rod-and-disk task). We observed that the degree of visual dependence was correlated with vestibulo-cortical dominance. Specifically, individuals with greater right hemispheric vestibulo-cortical dominance had reduced visual dependence. We proceeded to assess the significance of such dominance on behavior by correlating measures of visual dependence with self-motion perception in healthy subjects. We observed that right-handed individuals experienced illusionary self-motion (vection) quicker than left-handers and that the degree of vestibular cortical dominance was correlated with the time taken to experience vection, only during conditions that induced interhemispheric conflict. To conclude, we demonstrate that interhemispheric asymmetries associated with vestibulo-cortical processing in the PPC functionally and mechanistically link sensory integration and self-motion perception, facilitating spatial orientation. Our findings highlight the importance of dynamic interhemispheric competition upon control of vestibular behavior in humans.
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Affiliation(s)
- Qadeer Arshad
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, W6 8RF, UK; Department of Neuroscience, Psychology and Behaviour, University of Leicester, University Road, Leicester, LE1 7RH, UK.
| | - Marta Casanovas Ortega
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, W6 8RF, UK
| | - Usman Goga
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, W6 8RF, UK
| | - Rhannon Lobo
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, W6 8RF, UK
| | - Shuaib Siddiqui
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, W6 8RF, UK
| | - Saniya Mediratta
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, W6 8RF, UK
| | - Nadja F Bednarczuk
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, W6 8RF, UK
| | - Diego Kaski
- Department of Neuro-otology, Royal National Throat Nose and Ear Hospital, University College London, London, WC1X 8DA, UK
| | - Adolfo M Bronstein
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham Palace Road, London, W6 8RF, UK
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12
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Edwards AE, Guven O, Furman MD, Arshad Q, Bronstein AM. Electroencephalographic Correlates of Continuous Postural Tasks of Increasing Difficulty. Neuroscience 2018; 395:35-48. [DOI: 10.1016/j.neuroscience.2018.10.040] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 10/13/2018] [Accepted: 10/23/2018] [Indexed: 12/27/2022]
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13
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An fMRI study of visuo-vestibular interactions following vestibular neuritis. NEUROIMAGE-CLINICAL 2018; 20:1010-1017. [PMID: 30336357 PMCID: PMC6197146 DOI: 10.1016/j.nicl.2018.10.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 10/01/2018] [Accepted: 10/08/2018] [Indexed: 11/22/2022]
Abstract
Vestibular neuritis (VN) is characterised by acute vertigo due to a sudden loss of unilateral vestibular function. A considerable proportion of VN patients proceed to develop chronic symptoms of dizziness, including visually induced dizziness, specifically during head turns. Here we investigated whether the development of such poor clinical outcomes following VN, is associated with abnormal visuo-vestibular cortical processing. Accordingly, we applied functional magnetic resonance imaging to assess brain responses of chronic VN patients and compared these to controls during both congruent (co-directional) and incongruent (opposite directions) visuo-vestibular stimulation (i.e. emulating situations that provoke symptoms in patients). We observed a focal significant difference in BOLD signal in the primary visual cortex V1 between patients and controls in the congruent condition (small volume corrected level of p < .05 FWE). Importantly, this reduced BOLD signal in V1 was negatively correlated with functional status measured with validated clinical questionnaires. Our findings suggest that central compensation and in turn clinical outcomes in VN are partly mediated by adaptive mechanisms associated with the early visual cortex. VN clinical status related to V1 response to congruent visuo-vestibular stimuli Reduced V1 BOLD signal during congruent stimulation correlates with subjective dizziness scores No association between V1 BOLD signal and incongruent visuo-vestibular stimulation Changes in V1 activity may reflect cortical adaptive mechanisms following VN
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14
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Bednarczuk NF, Casanovas Ortega M, Fluri AS, Arshad Q. Vestibulo-cortical hemispheric dominance: The link between anxiety and the vestibular system? Eur J Neurosci 2018; 47:1517-1524. [PMID: 29768682 PMCID: PMC6099323 DOI: 10.1111/ejn.13948] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 03/09/2018] [Accepted: 04/04/2018] [Indexed: 11/29/2022]
Abstract
Vestibular processing and anxiety networks are functionally intertwined, as demonstrated by reports of reciprocal influences upon each other. Yet whether there is an underlying link between these two systems remains unknown. Previous findings have highlighted the involvement of hemispheric lateralisation in processing of both anxiety and vestibular signals. Accordingly, we explored the interaction between vestibular cortical processing and anxiety by assessing the relationship between anxiety levels and the degree of hemispheric lateralisation of vestibulo-cortical processing in 64 right-handed, healthy individuals. Vestibulo-cortical hemispheric lateralisation was determined by gaging the degree of caloric-induced nystagmus suppression following modulation of cortical excitability using trans-cranial direct current stimulation targeted over the posterior parietal cortex, an area implicated in the processing of vestibular signals. The degree of nystagmus suppression yields an objective biomarker, allowing the quantification of the degree of right vestibulo-cortical hemisphere dominance. Anxiety levels were quantified using the Trait component of the Spielberger State-Trait Anxiety Questionnaire. Our findings demonstrate that the degree of an individual's vestibulo-cortical hemispheric dominance correlates with their anxiety levels. That is, those individuals with greater right hemispheric vestibulo-cortical dominance exhibited lower levels of anxiety. By extension, our results support the notion that hemispheric lateralisation determines an individual's emotional processing, thereby linking cortical circuits involved in processing anxiety and vestibular signals, respectively.
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Affiliation(s)
- Nadja F Bednarczuk
- Division of Brain Sciences, Academic Department of Neuro-Otology, Department of Medicine, Imperial College London, London, UK
| | - Marta Casanovas Ortega
- Division of Brain Sciences, Academic Department of Neuro-Otology, Department of Medicine, Imperial College London, London, UK
| | - Anne-Sophie Fluri
- Division of Brain Sciences, Academic Department of Neuro-Otology, Department of Medicine, Imperial College London, London, UK
| | - Qadeer Arshad
- Division of Brain Sciences, Academic Department of Neuro-Otology, Department of Medicine, Imperial College London, London, UK
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15
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Pasinska P, Kowalska K, Klimiec E, Szyper-Maciejowska A, Wilk A, Klimkowicz-Mrowiec A. Frequency and predictors of post-stroke delirium in PRospective Observational POLIsh Study (PROPOLIS). J Neurol 2018; 265:863-870. [DOI: 10.1007/s00415-018-8782-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/30/2018] [Accepted: 02/01/2018] [Indexed: 02/06/2023]
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16
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Abstract
The vestibular cortex differs in various ways from other sensory cortices. It consists of a network of several distinct and separate temporoparietal areas. Its core region, the parietoinsular vestibular cortex (PIVC), is located in the posterior insula and retroinsular region and includes the parietal operculum. The entire network is multisensory (in particular, vestibular, visual, and somatosensory). The peripheral and central vestibular systems are bilaterally organized; there are various pontomesencephalic brainstem crossings and at least two transcallosal connections of both hemispheres, between the PIVC and the motion-sensitive visual cortex areas, which also mediate vestibular input. Structural and functional vestibular dominance characterizes the right hemisphere in right-handers and the left hemisphere in left-handers. This explains why right-hemispheric lesions in right-handers more often generally cause hemispatial neglect and the pusher syndrome, both of which involve vestibular function. Vestibular input also contributes to cognition and may determine individual lateralization of brain functions such as handedness. Bilateral organization is a major key to understanding cortical functions and disorders, for example, the visual-vestibular interaction that occurs in spatial orientation. Although the vestibular cortex is represented in both hemispheres, there is only one global percept of body position and motion. The chiefly vestibular aspects of the multiple functions and disorders of the parietal lobe dealt with in this chapter cannot be strictly separated from various multisensory vestibular functions within the entire brain.
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Affiliation(s)
- Marianne Dieterich
- Department of Neurology, Ludwig-Maximilians-University, Munich, Germany; German Center for Vertigo and Balance Disorders-IFB, Ludwig-Maximilians-University, Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.
| | - Thomas Brandt
- German Center for Vertigo and Balance Disorders-IFB, Ludwig-Maximilians-University, Munich, Germany; Clinical Neuroscience, Ludwig-Maximilians-University, Munich, Germany
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17
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Arshad Q, Nigmatullina Y, Siddiqui S, Franka M, Mediratta S, Ramachandaran S, Lobo R, Malhotra PA, Roberts RE, Bronstein AM. Influence of biases in numerical magnitude allocation on human prosocial decision making. J Neurophysiol 2017; 118:3007-3013. [PMID: 28904100 DOI: 10.1152/jn.00372.2017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 08/28/2017] [Accepted: 08/28/2017] [Indexed: 11/22/2022] Open
Abstract
Over the past decade neuroscientific research has attempted to probe the neurobiological underpinnings of human prosocial decision making. Such research has almost ubiquitously employed tasks such as the dictator game or similar variations (i.e., ultimatum game). Considering the explicit numerical nature of such tasks, it is surprising that the influence of numerical cognition on decision making during task performance remains unknown. While performing these tasks, participants typically tend to anchor on a 50:50 split that necessitates an explicit numerical judgement (i.e., number-pair bisection). Accordingly, we hypothesize that the decision-making process during the dictator game recruits overlapping cognitive processes to those known to be engaged during number-pair bisection. We observed that biases in numerical magnitude allocation correlated with the formulation of decisions during the dictator game. That is, intrinsic biases toward smaller numerical magnitudes were associated with the formulation of less favorable decisions, whereas biases toward larger magnitudes were associated with more favorable choices. We proceeded to corroborate this relationship by subliminally and systematically inducing biases in numerical magnitude toward either higher or lower numbers using a visuo-vestibular stimulation paradigm. Such subliminal alterations in numerical magnitude allocation led to proportional and corresponding changes to an individual's decision making during the dictator game. Critically, no relationship was observed between neither intrinsic nor induced biases in numerical magnitude on decision making when assessed using a nonnumerical-based prosocial questionnaire. Our findings demonstrate numerical influences on decisions formulated during the dictator game and highlight the necessity to control for confounds associated with numerical cognition in human decision-making paradigms.NEW & NOTEWORTHY We demonstrate that intrinsic biases in numerical magnitude can directly predict the amount of money donated by an individual to an anonymous stranger during the dictator game. Furthermore, subliminally inducing perceptual biases in numerical-magnitude allocation can actively drive prosocial choices in the corresponding direction. Our findings provide evidence for numerical influences on decision making during performance of the dictator game. Accordingly, without the implementation of an adequate control for numerical influences, the dictator game and other tasks with an inherent numerical component (i.e., ultimatum game) should be employed with caution in the assessment of human behavior.
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Affiliation(s)
- Qadeer Arshad
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom
| | - Yuliya Nigmatullina
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom
| | - Shuaib Siddiqui
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom
| | - Mustafa Franka
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom
| | - Saniya Mediratta
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom
| | - Sanjeev Ramachandaran
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom
| | - Rhannon Lobo
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom
| | - Paresh A Malhotra
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom
| | - R E Roberts
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom
| | - Adolfo M Bronstein
- Division of Brain Sciences, Charing Cross Hospital Campus, Imperial College London, Fulham, London, United Kingdom
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18
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Bednarczuk NF, Casanovas Ortega M, Fluri AS, Bronstein AM, Arshad Q. Inter-hemispheric control of vestibular thresholds. Brain Stimul 2017; 10:988-991. [DOI: 10.1016/j.brs.2017.06.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 06/19/2017] [Accepted: 06/21/2017] [Indexed: 11/24/2022] Open
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19
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Arshad Q. Dynamic interhemispheric competition and vestibulo-cortical control in humans; A theoretical proposition. Neuroscience 2017; 353:26-41. [DOI: 10.1016/j.neuroscience.2017.04.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 04/05/2017] [Accepted: 04/10/2017] [Indexed: 11/26/2022]
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20
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Dieterich M, Kirsch V, Brandt T. Right-sided dominance of the bilateral vestibular system in the upper brainstem and thalamus. J Neurol 2017; 264:55-62. [DOI: 10.1007/s00415-017-8453-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 03/06/2017] [Accepted: 03/10/2017] [Indexed: 10/19/2022]
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21
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Lateralisation of the Vestibular Cortex Is More Pronounced in Left-Handers. Brain Stimul 2016; 9:942-944. [DOI: 10.1016/j.brs.2016.08.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 08/01/2016] [Indexed: 11/23/2022] Open
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22
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Arshad Q, Nigmatullina Y, Roberts RE, Goga U, Pikovsky M, Khan S, Lobo R, Flury AS, Pettorossi VE, Cohen-Kadosh R, Malhotra PA, Bronstein AM. Perceived state of self during motion can differentially modulate numerical magnitude allocation. Eur J Neurosci 2016; 44:2369-74. [DOI: 10.1111/ejn.13335] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Revised: 06/08/2016] [Accepted: 07/11/2016] [Indexed: 11/27/2022]
Affiliation(s)
- Q. Arshad
- Division of Brain Sciences; Imperial College; Charing Cross Hospital; Fulham Palace Road London W6 8RF UK
| | - Y. Nigmatullina
- Division of Brain Sciences; Imperial College; Charing Cross Hospital; Fulham Palace Road London W6 8RF UK
| | - R. E. Roberts
- Division of Brain Sciences; Imperial College; Charing Cross Hospital; Fulham Palace Road London W6 8RF UK
| | - U. Goga
- Division of Brain Sciences; Imperial College; Charing Cross Hospital; Fulham Palace Road London W6 8RF UK
| | - M. Pikovsky
- Division of Brain Sciences; Imperial College; Charing Cross Hospital; Fulham Palace Road London W6 8RF UK
| | - S. Khan
- Division of Brain Sciences; Imperial College; Charing Cross Hospital; Fulham Palace Road London W6 8RF UK
| | - R. Lobo
- Division of Brain Sciences; Imperial College; Charing Cross Hospital; Fulham Palace Road London W6 8RF UK
| | - A.-S. Flury
- Division of Brain Sciences; Imperial College; Charing Cross Hospital; Fulham Palace Road London W6 8RF UK
| | - V. E. Pettorossi
- Department of Medicina Interna; Sezione di Fisiologia Umana; Universita di Perugia; Perugia Italy
| | - R. Cohen-Kadosh
- Department of Experimental Psychology; Oxford University; Oxford UK
| | - P. A. Malhotra
- Division of Brain Sciences; Imperial College; Charing Cross Hospital; Fulham Palace Road London W6 8RF UK
| | - A. M. Bronstein
- Division of Brain Sciences; Imperial College; Charing Cross Hospital; Fulham Palace Road London W6 8RF UK
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23
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Arshad Q, Nigmatullina Y, Nigmatullin R, Asavarut P, Goga U, Khan S, Sander K, Siddiqui S, Roberts RE, Cohen Kadosh R, Bronstein AM, Malhotra PA. Bidirectional Modulation of Numerical Magnitude. Cereb Cortex 2016; 26:2311-2324. [PMID: 26879093 PMCID: PMC4830300 DOI: 10.1093/cercor/bhv344] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Numerical cognition is critical for modern life; however, the precise neural mechanisms underpinning numerical magnitude allocation in humans remain obscure. Based upon previous reports demonstrating the close behavioral and neuro-anatomical relationship between number allocation and spatial attention, we hypothesized that these systems would be subject to similar control mechanisms, namely dynamic interhemispheric competition. We employed a physiological paradigm, combining visual and vestibular stimulation, to induce interhemispheric conflict and subsequent unihemispheric inhibition, as confirmed by transcranial direct current stimulation (tDCS). This allowed us to demonstrate the first systematic bidirectional modulation of numerical magnitude toward either higher or lower numbers, independently of either eye movements or spatial attention mediated biases. We incorporated both our findings and those from the most widely accepted theoretical framework for numerical cognition to present a novel unifying computational model that describes how numerical magnitude allocation is subject to dynamic interhemispheric competition. That is, numerical allocation is continually updated in a contextual manner based upon relative magnitude, with the right hemisphere responsible for smaller magnitudes and the left hemisphere for larger magnitudes.
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Affiliation(s)
- Qadeer Arshad
- Division of Brain Sciences, Imperial College London, London W6 8RF, UK
| | | | - Ramil Nigmatullin
- Institut für Quantenphysik and Centre for Integrated Quantum Science and Technology (IQST), Albert Einstein Allell, Universität Ulm, Ulm D-89069, Germany
| | - Paladd Asavarut
- Division of Brain Sciences, Imperial College London, London W6 8RF, UK
| | - Usman Goga
- Division of Brain Sciences, Imperial College London, London W6 8RF, UK
| | - Sarah Khan
- Division of Brain Sciences, Imperial College London, London W6 8RF, UK
| | - Kaija Sander
- Division of Brain Sciences, Imperial College London, London W6 8RF, UK
| | - Shuaib Siddiqui
- Division of Brain Sciences, Imperial College London, London W6 8RF, UK
| | - R E Roberts
- Division of Brain Sciences, Imperial College London, London W6 8RF, UK
| | - Roi Cohen Kadosh
- Department of Experimental Psychology, Oxford University, Oxford 0X1 3UD, UK
| | | | - Paresh A Malhotra
- Division of Brain Sciences, Imperial College London, London W6 8RF, UK
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