Portrait of Professor David Wilkinson

Professor David Wilkinson

Professor of Psychology

About

Follow the links below for recent media coverage of Professor Wilkinson’s research:

For information on how to support Professor Wilkinson’s research please click here: https://giving.kent.ac.uk/discovery/neurostimulation

Research interests

David's main research seeks to understand how the human vestibular system shapes cognition and mental well-being.  His group is particularly interested in developing and trialling non-invasive methods of vestibular stimulation to help overcome neuro-disability associated with brain injury and neuro-degeneration. 

Most of this research is conducted with the close support of clinical and commercial collaborators. In allied work, David's group seeks to understand more about how vestibular injury and disease compromises cognitive and emotional function. In all cases, the work is motivated by the fundamental aim of translating theoretical knowledge of vestibular cognition into clinically-relevant applications. 

Supervision

Current PhD students

  • Saghi Arabi: The contribution of the vestibular system to temporal attention 
  • Mayur Bodani: Neuro-stimulation in fatigue/sleep disorder
  • Annita Gkioka: Vestibular stimulation in visual spatial memory
  • Kamlya Marques: Vestibular stimulation in Parkinson’s disease 

Past research students

  • Dr Emma Denby: Neuropsychological outcomes in military veterans with traumatic brain injury (KentHealth studentship)
  • Dr Laura Smith: Vestibular contributions to human memory
  • Dr Serena Vanzan: The effects of vestibular stimulation on awareness
  • Dr Olga Zubko: Sources of individual variability in face recognition
  • Rachael Morris: The effect of Galvanic Vestibular Stimulation on attention

Professional

Honorary positions

  • Expert Peer Reviewer, Parkinson’s UK College of Experts
  • Member of the Research Design Service South East External Advisory Board’    
  • Academic Research Fellow, East Kent Hospitals Trust, UK.
  • Investigator, Geriatric Neuropsychology Laboratory, VA Boston Healthcare System & Harvard Medical School, Boston, U.S.A. (http://www.heartbrain.com)

Professional membership

Grants and Awards

Can be disclosed on request.

Publications

Showing 50 of 85 total publications in the Kent Academic Repository. View all publications.

Article

  • Smith, L., Gkioka, A., & Wilkinson, D. (2020). Vestibular‐guided visual search. Experimental Brain Research. doi:10.1007/s00221-020-05741-x
    The amnesic symptoms that accompany vestibular dysfunction point to a functional relationship between the vestibular and visual memory systems. However, little is known about the underpinning cognitive processes. As a starting point, we sought evidence for a type of cross-modal interaction commonly observed between other sensory modalities in which the identification of a target (in this case, visual) is facilitated if earlier coupled to a unique, temporally coincident stimulus from another sensory domain (in this case, vestibular). Participants first performed a visual detection task in which stimuli appeared at random locations within a computerised grid. Unknown to participants, the onset of one particular stimulus was accompanied by a brief, sub-sensory pulse of galvanic vestibular stimulation (GVS). Across two visual search experiments, both old and new targets were identified faster when presented in the grid location at which the GVS-paired visual stimulus had appeared in the earlier detection task. This location advantage appeared to be based on relative rather than absolute spatial co-ordinates since the effect held when the search grid was rotated 90°. Together these findings indicate that when individuals return to a familiar visual scene (here, a 2D grid), visual judgements are facilitated when targets appear at a location previously associated with a unique, task-irrelevant vestibular cue. This novel case of multisensory interplay has broader implications for understanding how vestibular signals inform cognitive processes and helps constrain the growing therapeutic application of GVS.
  • Wilkinson, D., Podlewska, A., Banducci, S., Pellatt-Higgins, T., Slade, M., Bodani, M., Sakel, M., Smith, L., LeWitt, P., & Ade, K. (2019). Caloric Vestibular Stimulation for the Management of Motor and Non-MotorSymptoms in Parkinson’s Disease: Intention-to-Treat Data. Data in Brief, 1-9. doi:10.1016/j.dib.2019.104228
    This report provides data related to the safety and effectiveness of repeated time-varying caloric vestibular stimulation (CVS) as a treatment for motor and non-motor features of Parkinson’s disease (PD). Forty-six subjects receiving stable anti-Parkinsonian therapy were randomized to active (n=23) or placebo (n=23) treatment arms. Subjects self-administered CVS twice-daily over a period of 8 weeks at home via a portable, pre-programmed, solid-state ThermoNeuroModulation (TNM™) device delivering continually-varying thermal waveforms through aluminium ear-probes mounted on a wearable headset. Change scores from baseline to end of treatment and to a 1-month follow-up were determined using standardized clinical measures. The data presented here report sample demographics, detailed safety data and the statistical outcomes from the intention-to-treat and modified intention-to-treat analyses. These data supplement findings of the main per protocol analysis reported in the allied article entitled, ‘Caloric Vestibular Stimulation for the Management of Motor and Non-Motor Symptoms in Parkinson’s Disease’ .
  • Wilkinson, D., Podlewska, A., Banducci, S., Pellatt-Higgins, T., Slade, M., Bodani, M., Sakel, M., Smith, L., LeWitt, P., & Ade, K. (2019). Caloric vestibular stimulation for the management of motor and non-motor symptoms in Parkinson’s disease. Parkinsonism and Related Disorders. doi:10.1016/j.parkreldis.2019.05.031
    Introduction: A recent case study showed that repeated sessions of caloric vestibular stimulation (CVS) relieved motor and non-motor symptoms associated with Parkinson's disease (PD). Here we sought to confirm these results in a prospective, double-blind, randomized, placebo treatment-controlled study.

    Methods: 33 PD subjects receiving stable anti-Parkinsonian therapy completed an active (n = 16) or placebo (n = 17) treatment period. Subjects self-administered CVS at home twice-daily via a portable, pre-programmed, solid-state ThermoNeuroModulation (TNMTM) device, which delivered continually-varying thermal waveforms through aluminum ear-probes mounted on a wearable headset. Subjects were followed over a 4-week baseline period, 8 weeks of treatment and then at 5- and 24-weeks post-treatment. At each study visit, standardized clinical assessments were conducted during ON-medication states to evaluate changes in motor and non-motor symptoms, activities of daily living, and quality of life ratings.

    Results: Change scores between baseline and the end of treatment showed that active-arm subjects demonstrated clinically-relevant reductions in motor and non-motor symptoms that were significantly greater than placebo- arm subjects. Active treatment was also associated with improved scores on activities of daily living assessments. Therapeutic gains were still evident 5 weeks after the end of active treatment but had started to recede at 24 weeks follow-up. No serious adverse events were associated with device use, and there was high participant satisfaction and tolerability of treatment.

    Conclusion: The results provide evidence that repeated CVS can provide safe and enduring adjuvant relief for motor and non-motor symptoms associated with PD.
  • Denby, E., Murphy, D., Busuttil, W., Sakel, M., & Wilkinson, D. (2019). Neuropsychiatric Outcomes in UK Military Veterans with Mild Traumatic Brain Injury and Vestibular Dysfunction. Journal of Head Trauma Rehabilitation. doi:10.1097/HTR.0000000000000468
    Objective: To estimate the frequency of vestibular dysfunction following blunt, blast, and blunt & blast mild traumatic brain injury (mTBI) and thereon assess the long-term impact of vestibular dysfunction on neurobehavioral function and disability independently of co-morbid psychiatric symptoms. Setting: Combat Stress residential and Veterans’ Outreach drop-in centres for psychological support. Participants: 162 help-seeking UK military veterans. Main measures: Self-reported frequency and severity of mTBI (using the Ohio State Identification Method), Vertigo Symptom Scale, PTSD checklist for DSM5, Kessler Psychological Distress Scale, Neurobehavioral Symptom Inventory, HIT6, Memory Complaints Inventory, WHO Disability Assessment Scale 2.0. Results: 72% of the sample reported one or more mTBI over their lifetime. Chi-square analyses indicated that vestibular disturbance, which affected 69% of participants, was equally prevalent following blunt (59%) or blast (47%) injury and most prevalent following blunt and blast combined (83%). Mediation analysis indicated that when PTSD, depression and anxiety were taken into account, vestibular dysfunction in participants with mTBI was directly and independently associated with increased postconcussive symptoms and functional disability. Conclusion: Vestibular dysfunction is common after combined blunt and blast mTBI and singularly predictive of poor long-term mental health. From a treatment perspective, vestibular rehabilitation may provide relief from postconcussive symptoms other than dizziness and imbalance.
  • Beadle-Brown, J., Wilkinson, D., Richardson, L., Shaughnessy, N., Trimingham, M., Leigh, J., Whelton, B., & Himmerich, J. (2018). Imagining Autism: Feasibility of a Drama-Based Intervention on the Social, Communicative and Imaginative behaviour of Children with Autism. Autism: International Journal of Research and Practice, 22, 915-927. doi:10.1177/1362361317710797
    We report the feasibility of a novel, school-based intervention, coined ‘Imagining Autism’, in which children with autism engage with drama practitioners though participatory play and improvisation in a themed multi-sensory “pod” resembling a portable, tent-like structure. 22 children, aged 7–12 years, from three UK schools engaged in the 10week programme. Measures of social interaction, communication, emotion recognition, along with parent and teacher ratings, were collected before and up to 12 months after the intervention. Feasibility was evaluated through 4 domains: (1) process (recruitment, retention, blinding, inter-rater reliability, willingness of children to engage), (2) resources (space, logistics), (3) management (dealing with unexpected changes, ease of assessment), and (4) scientific (data outcomes, statistical analyses). Overall, the children, parents and teachers showed high satisfaction with the intervention, the amount of missing data was relatively low, key assessments were implemented as planned, and evidence of potential effect was demonstrated on several key outcome measures. Some difficulties were encountered with recruitment, test administration, parental response, and the logistics of setting up the pod. Following several protocol revisions and the inclusion of a control group, future investigation would be justified to more thoroughly examine treatment effects.
  • Smith, L., Wilkinson, D., Bodani, M., Bicknell, R., & Surenthiran, S. (2018). Short-term memory impairment in vestibular patients can arise independently of psychiatric impairment, fatigue and sleeplessness. Journal of Neuropsychology, 1-15. doi:10.1111/jnp.12157
    Vestibular dysfunction is associated with visual short-term memory impairment, however, it remains unclear if this impairment arises as a direct result of the vestibular dysfunction or is a consequence of comorbid changes in mood, affect, fatigue and/or sleep. To this end, we assessed the concurrence and inter-dependence of these comorbidities in 101 individuals recruited from a tertiary balance clinic with a neuro-otological diagnosis. Over fifty percent of the sample showed reduced visuospatial short-term memory, 60% and 37% exceeded cut-off on the Beck Anxiety and Depression Inventories respectively, 70% exceeded cut-off on the Fatigue Severity Scale, 44% reported daytime sleepiness on the Epworth Sleepiness Scale, and 78% scored above cut-off on the Pittsburg Sleep Quality Index. The high concurrence of these symptoms give reason to infer the existence of a vestibular cognitive affective syndrome. Structural equation modeling indicated that the significant statistical association between general unassisted posture (a marker of chronic vestibular dysfunction and strong predictor of falls risk) and short-term memory was not mediated by mood and wakefulness. Instead, the memory impairment related more directly to vestibular dysfunction. From a rehabilitation perspective, the implication is that if the vestibular disorder is treated successfully then the memory problem will likewise improve.
  • Khasru, M., Salek, A., Moniruzzaman, M., Marzen, T., Haseen, F., Saddiq, A., Rizvi, A., Islam, A., Hossain, Z., Hossain, S., Anowar, N., Hasan, M., Ahmed, B., Wilkinson, D., & Sakel, M. (2017). Early versus late rehabilitation for stroke survivors: A prospective study. Bangabandhu Sheikh Mujib Medical University Journal, 10, 204-209. doi:10.3329/bsmmuj.v10i4.34466
    The aim of this study was to examine the optimum time of rehabilitation initiation after stroke in terms of disabilities, mobility and fall risk assessment. Data were collected prospectively at seven tertiary level health care centers in Bangladesh during the 36 months period from 2013 to 2016. All respondents were divided into four groups based on the initiation of rehabilitation as: a) 0-24 hours, b) 25-72 hours, c) 4-7 days and d) 8-60 days. Results show that significant improvement on stroke recovery, disabilities reduction, improvement in mobility restriction and reduction of fall risks in all the four groups but more improvement was observed in 0-24 hour’s group during follow-up after 3 and 12 weeks. On multinomial logistic regression analysis, the independent factors shows the mobility restriction and fall risk were more in the younger patients, male gender, married, hemorrhagic lesion and bilateral stroke.
  • Wilkinson, D., Ade, K., Rogers, L., Attix, D., Kuchibhatla, M., Slade, M., Smith, L., Poynter, K., Laskowitz, D., Freeman, M., Hoffer, M., Saper, J., Scott, D., Sakel, M., Calhoun, A., & Black, R. (2017). Preventing episodic migraine with caloric vestibular stimulation: a randomized controlled trial. Headache: The Journal of Head and Face Pain, 57, 1065-1087. doi:10.1111/head.13120
    Objective: To evaluate the safety and efficacy of a novel solid-state, caloric vestibular stimulation (CVS) device to provide adjuvant therapy for the prevention of episodic migraine in adult migraineurs. Background: Migraine causes significant disability in ~12% of the world population. No current migraine preventive treatment provides full clinical relief, and many exhibit high rates of discontinuation due to adverse events. Thus, new therapeutic options are needed. CVS may be an effective and safe adjuvant-therapy for the prevention of episodic migraine.

    Methods: In a multicenter, parallel-arm, block-randomized, placebo-controlled clinical trial (clinicaltrials.gov: NCT01899040), subjects completed a 3-month treatment with the TNMTM device for CVS (refer to Figure 2 for patient enrollment and allocation). The primary endpoint was the change in monthly migraine days from baseline to the third treatment month. Secondary endpoints were 50% responder rates, change in prescription analgesic usage and difference in total subjective headache-related pain scores. Device safety assessments included evaluation of any impact on mood, cognition or balance.

    Results: Per-protocol, active-arm subjects showed immediate and steady declines in migraine frequency over the treatment period. After three months of treatment, active-arm subjects exhibited significantly fewer migraine days (-3.8 ± 0.5 from a baseline burden of 7.7 ± 0.5 migraine days). These improvements were significantly greater than those observed in control subjects (-1.1 ± 0.6 from a baseline burden = 6.9 ± 0.7 migraine days) and represented a therapeutic gain of -2.7 migraine days, CI = -0.9 to -4.7, p = 0.012. Active arm subjects also reported greater reductions in acute medication usage and monthly pain scores compared to controls. No adverse effects on mood, cognition or balance were reported. Subjects completed the trial with an average rate of 90% treatment adherence. No serious or unexpected adverse events were recorded. The rate of expected adverse events was similar across the active and the placebo groups, and evaluation confirmed that subject blinding remained intact.

    Conclusion: The TNM device for CVS appears to provide a clinically efficacious and highly tolerable adjuvant therapy for the prevention of episodic migraine.
  • Schmidt-Kassow, M., Wilkinson, D., Denby, E., & Ferguson, H. (2016). Synchronised vestibular signals increase the P300 event-related potential elicited by auditory oddballs. Brain Research, 1648, 224-231. doi:10.1016/j.brainres.2016.07.019
    The perception of beat within an auditory rhythm can be facilitated when accompanied by synchronised movements. Electrophysiological investigation shows that this facilitatory effect is associated with a larger P300 amplitude. It has remained unclear, however, which movement-related processes drive this P300 effect. To investigate whether vestibular signals play a role, we administered alternating, sub-sensory (mean =.3mA) galvanic current to the vestibular nerves of participants while they counted the number of oddballs presented in a stream of tones played at a rate of 1Hz. Consistent with a vestibular effect, the P300 elicited by the oddballs was increased during stimulation relative to a sham condition, but only when the frequency of the alternating current matched that at which the tones were played. This finding supports the general idea that the vestibular system is involved in audio-motor synchronisation and is the first to show by electrophysiological means that it influences cognitive processes involved in beat perception.
  • Vanzan, S., Wilkinson, D., Ferguson, H., Pullicino, P., & Sakel, M. (2016). Behavioural Improvement in Minimally Conscious State After Caloric Vestibular Stimulation: Evidence from two single case studies. Clinical Rehabilitation, 31, 1-8. doi:10.1177/0269215516646167
    Objective: To investigate whether caloric vestibular stimulation, a non-invasive form of neuro-modulation, alters level of awareness in people residing in minimally conscious state.
    Design: Single-case (n=2), prospective, controlled (ABAB) efficacy study.
    Setting: Tertiary, neuro-rehabilitation in-patient ward within a university hospital
    Participants: Two individuals in minimally conscious state
    Intervention: Left ear caloric vestibular stimulation was performed in two four/five-week blocks interleaved with two four/five-week blocks of sham stimulation. Session duration and frequency gradually increased within each block from once per day for 10 minutes (week 1) to once per day for 20 minutes (week 2) to 20 minutes twice per day in the remaining weeks.
    Measures: Wessex Head Injury Matrix, JFK Coma Recovery Scale – Revised.
    Results: Both participants’ Wessex Head Injury Matrix scores indicated a transition from involuntary (i.e. mechanical vocalization) to voluntary (i.e. gesture making, selective responses to family members) behaviour that was time-locked to the onset of active stimulation. In one participant, this improvement persisted for at least 4 weeks after active stimulation while in the other it diminished 2 weeks after stimulation. Allied, although less dramatic, changes were seen on the arousal and auditory subscales of the JFK Coma Recovery Scale – Revised.
    Conclusion: The data provide the first evidence that vestibular stimulation may help improve outcome in low awareness state although further studies are needed to replicate effect and determine longer-term benefit.
  • Ulrich, P., Wilkinson, D., Ferguson, H., Smith, L., Bindemann, M., Johnston, R., & Schmalzl, L. (2016). Perceptual and Memorial Contributions to Developmental Prosopagnosia. Quarterly Journal of Experimental Psychology. doi:10.1080/17470218.2016.1177101
    Developmental prosopagnosia (DP) is commonly associated with the failure to properly perceive individuating facial properties, notably those conveying configural or holistic
    content. While this may indicate that the primary impairment is perceptual, it is conceivable that some cases of DP are instead caused by a memory impairment, with any perceptual
    complaint merely allied rather than causal. To investigate this possibility, we administered a battery of face perception tasks to 11 individuals who reported that their face recognition difficulties disrupt daily activity and who also performed poorly on two formal tests of face recognition. Group statistics identified, relative to age- and gender-matched controls, difficulties in apprehending global-local relations and the holistic properties of faces, and in matching across viewpoints, but these were mild in nature and were not consistently evident at the level of individual participants. Six of the 11 individuals failed to show any evidence of perceptual impairment. In the remaining five individuals, no single perceptual deficit, or combination of deficits, was necessary or sufficient for poor recognition performance. These data suggest that some cases of DP are better explained by a memorial rather than perceptual deficit, and highlight the relevance of the apperceptive/associative distinction more commonly applied to the allied syndrome of acquired prosopagnosia.
  • Wilkinson, D., Podlewska, A., & Sakel, M. (2016). A durable gain in motor and non-motor symptoms of Parkinson’s Disease following repeated caloric vestibular stimulation: A single-case study. NeuroRehabilitation, 1-4. doi:10.3233/NRE-161308
    Objective: To gain ‘first-in-man’ evidence that repeated caloric vestibular stimulation (CVS), a non-invasive form of neuro-modulation, can induce a lasting and clinically-relevant reduction in Parkinson’s Disease (PD) symptoms.

    Methods: A 70yr old male, diagnosed with PD 7 years prior to study enrolment, self-administered CVS at home 2x20 minutes per day for three months using a solid-state portable device. Standardised neuropsychological assessments of motor, cognitive, affective and independent function were carried out prior to stimulation, at the start and end of the sham (month 1) and active (months 2-3) phases, and 5 months post-stimulation.

    Results: Relative to the pre-stimulation baseline, behavioural improvements that exceeded the minimal detectable change were observed on the EQ5D, Unified Parkinson’s Disease Rating Scale, Schwab and England scale, 2 minute walk, Timed up and go, Non-motor symptom assessment scale for PD, Montreal cognitive assessment, Hospital depression scale and Epworth sleepiness scale. The level of change exceeded the threshold for a minimal clinically important difference on all scales for which a threshold has been published. By contrast, little improvement was seen during the sham (i.e. placebo) phase.

    Conclusion: Caloric vestibular stimulation may offer a novel, home-based method of relieving everyday symptoms of PD, and merits further evaluative study.
  • Plant, G., James-Galton, M., & Wilkinson, D. (2015). Progressive cortical visual failure associated with occipital calcification and coeliac disease with relative preservation of the dorsal ‘action’ pathway. Cortex, 71, 160-170. doi:10.1016/j.cortex.2015.06.023
    We describe the first reported case of a patient with coeliac disease and cerebral occipital calcification who shows a progressive and seemingly selective failure to recognize visual stimuli. This decline was tracked over a study period of 22 years and occurred in the absence of primary sensory or widespread intellectual impairment. Subsequent tests revealed that although the patient was unable to use shape and contour information to visually identify objects, she was nevertheless able to use this information to reach, grasp and manipulate objects under central, immediate vision. This preservation of visuo-motor control was echoed in her day-to-day ability to navigate and live at home independently. We conclude that occipital calcification following coeliac disease can lead to prominent higher visual failure that, under prescribed viewing conditions, is consistent with separable mechanisms for visual perception and action control.
  • Wilkinson, D., Moreno, S., Ang, C., Deravi, F., Sharma, D., & Sakel, M. (2015). Emotional Correlates of Unirhinal Odor Identification. Laterality: Asymmetries of Body, Brain and Cognition, 21, 85-99. doi:10.1080/1357650X.2015.1075546
    It seems self-evident that smell profoundly shapes emotion, but less clear is the nature of this interaction. Here we sought to determine whether the ability to identify odors co-varies with self-reported feelings of empathy and emotional expression recognition, as predicted if the two capacities draw on common resource. Thirty six neurotypical volunteers were administered the Alberta Smell Test, The Interpersonal Reactivity Index and an emotional expression recognition task. Statistical analyses indicated that feelings of emotional empathy positively correlated with odor discrimination in right nostril, while the recognition of happy and fearful facial expressions positively correlated with odor discrimination in left nostril. These results uncover new links between olfactory discrimination and emotion which, given the ipsilateral configuration of the olfactory projections, point towards intra- rather than inter-hemispheric interaction. The results also provide novel support for the proposed lateralisation of emotional empathy and the recognition of facial expression, and give reason to further explore the diagnostic sensitivity of smell tests because reduced sensitivity to others’ emotions can mark the onset of certain neurological diseases.
  • Ulrich, P., Johnston, R., & Wilkinson, D. (2015). Caloric Vestibular Stimulation Modulates High Level Face Processing. Perception (ECVP Abstract Supplement).
    Understanding of the link between the vestibular organs and the visual system is becoming established (e.g. Della-Justina et al., 2015), yet few studies have explored the use of vestibular stimulation to modulate visual processing. Preliminary evidence that this can be achieved is seen in one clinical case study which reported improved face perception in an acquired prosopagnosic following vestibular stimulation (Wilkinson, Ko, Kilduff, McGlinchey, & Milberg, 2005), and in one study that demonstrated an enlarged N170 in healthy adults during vestibular stimulation (Wilkinson, Ferguson, & Worley, 2012). The present study tested the behavioural effects of caloric vestibular stimulation on a higher cognitive level of face recognition in sixty adults. Participants were required to identify the nationality of celebrities in four testing sessions following a counterbalanced ABAB design. Relative to no stimulation, caloric vestibular stimulation significantly increased accuracy scores which could not be accounted for by practise effects. This study constitutes the first attempt to improve healthy face recognition skills through vestibular stimulation and the findings have immediate real-world value in settings that require superior face recognition performance such as passport control and identity parades. The study also provides further evidence to the efficacy of vestibular stimulation in modulating cognitive processes.
  • Sakel, M., & Wilkinson, D. (2014). The management of spasticity in adults. British Medical Journal, 349, 4737-4737. doi:10.1136/bmj.g4737
  • Makin, S. (2014). Drama helps kids with autism communicate better. New Scientist, 2965, 17-17. Retrieved from http://www.newscientist.com/article/dn25419-drama-helps-kids-with-autism-communicate-better
    Could drama workshops help children with autism-spectrum disorders? Results from a pilot study called Imagining Autism suggests this might be the case.
  • Wilkinson, D., Zubko, O., Sakel, M., Coulton, S., Higgins, T., & Pullicino, P. (2014). Galvanic vestibular stimulation in hemi-spatial neglect. Frontiers in Integrative Neuroscience, 8, 1-13. doi:10.3389/fnint.2014.00004
    Hemi-spatial neglect is an attentional disorder in which the sufferer fails to acknowledge or respond to stimuli appearing in contralesional space. In recent years, it has become clear that a measurable reduction in contralesional neglect can occur during galvanic vestibular stimulation, a technique by which transmastoid, small amplitude current induces lateral, attentional shifts via asymmetric modulation of the left and right vestibular nerves. However, it remains unclear whether this reduction persists after stimulation is stopped. To estimate longevity of effect, we therefore conducted a double-blind, randomized, dose-response trial involving a group of stroke patients suffering from left-sided neglect (n = 52, mean age = 66 years). To determine whether repeated sessions of galvanic vestibular stimulation more effectively induce lasting relief than a single session, participants received 1, 5, or 10 sessions, each lasting 25 min, of sub-sensory, left-anodal right-cathodal noisy direct current (mean amplitude = 1 mA). Ninety five percent confidence intervals indicated that all three treatment arms showed a statistically significant improvement between the pre-stimulation baseline and the final day of stimulation on the primary outcome measure, the conventional tests of the Behavioral Inattention Test. More remarkably, this change (mean change = 28%, SD = 18) was still evident 1 month later. Secondary analyses indicated an allied increase of 20% in median Barthel Index (BI) score, a measure of functional capacity, in the absence of any adverse events or instances of participant non-compliance. Together these data suggest that galvanic vestibular stimulation, a simple, cheap technique suitable for home-based administration, may produce lasting reductions in neglect that are clinically important. Further protocol optimization is now needed ahead of a larger effectiveness study.
  • Gallagher, M., Wilkinson, D., & Sakel, M. (2013). Hemispatial Neglect: Clinical Features, Assessment and Treatment. British Journal of Neuroscience Nursing, 9, 273-277. doi:10.12968/bjnn.2013.9.6.273
    Hemispatial neglect is a disorder of attention which commonly follows from damage to the right side of the brain. Patients with neglect show symptoms of lateralised inattention, failing to acknowledge or report information on the left side. Neglect is a poor prognostic indicator for general functional recovery from stroke, and is associated with a range of co-morbid conditions including denial or indifference to the brain injury, hemiplegia and visual field loss. Mild to moderate cases can be over-shadowed by the more gross symptoms that accompany brain injury, however assessment and diagnosis is relatively quick and simple. Current treatment guidelines suggest that patients should be taught compensatory strategies, but these are largely ineffective. Although recent research has identified more promising treatment approaches, investigations are still preliminary. Given the prevalence and debilitating nature of neglect, there is a clear need to raise awareness and understanding of the condition amongst carers and healthcare professionals.
  • Wilkinson, D., Morris, R., Milberg, W., & Sakel, M. (2013). Caloric vestibular stimulation in aphasic syndrome. Frontiers in Integrative Neuroscience, 7, 1-9. doi:10.3389/fnint.2013.00099
    Caloric vestibular stimulation (CVS) is commonly used to diagnose brainstem disorder but its therapeutic application is much less established. Based on the finding that CVS increases blood flow to brain structures associated with language and communication, we assessed whether the procedure has potential to relieve symptoms of post-stroke aphasia. Three participants, each presenting with chronic, unilateral lesions to the left hemisphere, were administered daily CVS for 4 consecutive weeks. Relative to their pre-treatment baseline scores, two of the three participants showed significant improvement on both picture and responsive naming at immediate and one-week follow-up. One of these participants also showed improved sentence repetition, and another showed improved auditory word discrimination. No adverse reactions were reported. These data provide the first, albeit tentative, evidence that CVS may relieve expressive and receptive symptoms of aphasia. A larger, sham-controlled study is now needed to further assess efficacy.
  • Slabu, L., Guinote, A., & Wilkinson, D. (2013). Power Facilitates Attentional Orienting. Social Psychology, 44, 37-41.
    This study investigated how power impacts the ability to orient attention across space. Participants were assigned to a high power or control role and then performed a computerised spatial cueing task in which they were required to direct their attention to a target that had been preceded by either a valid or invalid location cue. Compared to participants in the control condition, power-holders were better able to override the misinformation provided by invalid cues. This advantage occurred only at 500 ms stimulus onset asynchrony (SOA), whereas at 1000 ms SOA, when there was more time to prepare a response, no differences were found. These findings are taken to support the growing idea that social power affects cognitive flexibility.
  • Zubko, O., Wilkinson, D., Langston, D., & Sakel, M. (2013). The effect of repeated sessions of galvanic vestibular stimulation on target cancellation in visuo-spatial neglect: Preliminary evidence from two cases. Brain Injury, 27, 613-619. doi:10.3109/02699052.2013.767938
    Objective: In recent years it has emerged that the attentional disorder of visuo-spatial neglect can be overcome via artificial stimulation of the balance system. One means of achieving this is via galvanic vestibular stimulation (GVS), a simple procedure in which tiny, electrical currents are discharged to the part of the scalp overlying the vestibular nerves. Attempts to remediate neglect with GVS have utilised only a single session of stimulation, and although this can induce spontaneous recovery, symptoms resurface soon after stimulation. Here we assessed whether repeated sessions induce longer carry-over.

    Methods: Two individuals diagnosed with neglect post-stroke received five days of sub-sensory, left anodal GVS. Performance was assessed via the letter and star cancellation tasks of the Behavioural Inattention Test on four occasions; three days before the start of stimulation, on the first and last day of stimulation, and three-days after stimulation.

    Results: Analyses of variance indicated that both participants missed significantly fewer targets in both tasks on the fifth day of stimulation compared to baseline. More so, this improvement was still evident at follow-up three days later.

    Conclusion: The results strengthen the need for a larger, sham-controlled trial to establish whether repeated GVS provides lasting relief from neglect.
  • Slabu, L., Guinote, A., & Wilkinson, D. (2013). How quickly can you detect it? Power facilitates attentional orienting. Social Psychology, 1, 37-41. doi:10.1027/1864-9335/a000096
    This study investigated how power impacts the ability to orient attention across space. Participants were assigned to a high-power or control role and then performed a computerized spatial cueing task that required them to direct their attention to a target preceded by either a valid or invalid location cue. Compared to participants in the control condition, power holders were better at overriding the misinformation provided by invalid cues. This advantage occurred only at 500 ms stimulus onset asynchrony (SOA), whereas at 1000 ms SOA, when there was more time to prepare a response, no differences were found. These findings are taken to support the growing idea that social power affects cognitive flexibility

Book section

  • Wilkinson, D., Zubko, O., Sakel, M., Coulton, S., Higgins, T., & Pullicino, P. (2015). Galvanic Vestibular Stimulation in Hemi-Spatial Neglect. In S. Besnard, C. Lopez, T. Brandt, P. Denise, & P. Smith (Eds.), The Vestibular System in Cognitive and Memory Processes in Mammals. Frontiers Research Topics. doi:10.3389/978-2-88919-744-6
    Since the beginning of life, all plant and animal kingdoms have been developed or modified based on gravity along with atmospheric composition and solar radiation existing on Earth. Gravity is mainly encoded by the otolithic sensors of the vestibular system but its role has been largely underestimated in favor of the vestibular semicircular canals and reduced to oculomotor and postural coordination. Over the last decade, it has been demonstrated that sensory information provided by the vestibular system is crucial in spatial-memory processes in rats and humans. More recently a role in attention processes has been raised. This topic aims to report and demonstrate the role and integration of vestibular information in cognitive processes in rodent models and human at the behavioral, imaging and electrophysiological levels.
  • Wilkinson, D., Morris, R., Milberg, W., & Sakel, M. (2015). Caloric vestibular stimulation in aphasic syndrome. In B. Stephane, L. Christophe, B. Thomas, D. Pierre, & S. Paul (Eds.), The Vestibular System in Cognitive and Memory Processes in Mammals. Frontiers Research Topics. doi:10.3389/978-2-88919-744-6
    Since the beginning of life, all plant and animal kingdoms have been developed or modified based on gravity along with atmospheric composition and solar radiation existing on Earth. Gravity is mainly encoded by the otolithic sensors of the vestibular system but its role has been largely underestimated in favor of the vestibular semicircular canals and reduced to oculomotor and postural coordination. Over the last decade, it has been demonstrated that sensory information provided by the vestibular system is crucial in spatial-memory processes in rats and humans. More recently a role in attention processes has been raised. This topic aims to report and demonstrate the role and integration of vestibular information in cognitive processes in rodent models and human at the behavioral, imaging and electrophysiological levels.

Conference or workshop item

  • Smith, L., Wilkinson, D., Bodani, M., Bicknell, R., & Surenthiran, S. (2016). The Neuropsychiatric Sequelae of Vestibular Disorders. In International Neuropsychology Society Mid-Year Meeting. London. Retrieved from http://www.the-ins.org/2016-Mid-Year-London
  • Smith, L., Wilkinson, D., Bodani, M., Bicknell, R., & Surenthiran, S. (2016). Cognitive and psychiatric co-morbidities in patients with vestibular disorder. In British Neuropsychiatry Association AGM. London.
  • Smith, L., Wilkinson, D., Bodani, M., Bicknell, R., & Surethiran, S. (2016). Cognitive and psychiatric co-morbidities in patients with vestibular disorder. In American Academy of Neurology Conference. Vancouver.
  • Smith, L., Wilkinson, D., Bodani, M., Bicknell, R., & Surenthiran, S. (2015). Cognitive and psychiatric comorbidities in patients with vestibular disorder. In British Neuropsychological Society Autumn meeting. London.
  • Ulrich, P., Wilkinson, D., & Johnston, R. (2015). Improving semantic recall from familiar faces with vestibular stimulation. In BPS Cognitive Psychology Section Conference. Kent, UK.
    The accuracy of semantic retrieval following face recognition is a fundamental social skill and can have profound consequences. There is building evidence for the link between both memory and visual processing with the vestibular organs, yet the effects of vestibular stimulation on the processing of these types of information is significantly under investigated. The present study tested the effects of caloric vestibular stimulation (CVS) on face familiarity decisions and semantic retrieval (nationality decisions) in sixty adults. Testing was in four sessions following a counterbalanced ABAB design. Relative to no stimulation, no benefits of CVS were observed for familiarity decisions but CVS significantly increased accuracy scores of nationality recall with no detriment to response times, suggesting vestibular contributions to high level cognitive processing. This study has immediate real-world value in settings such as teaching and criminal investigations.
  • Ulrich, P., Johnston, R., & Wilkinson, D. (2015). Caloric Vestibular Stimulation Modulates High Level Face Processing. In European Conference on Visual Perception (ECVP). Liverpool, UK. Retrieved from http://ecvp.org/2015/Booklet.pdf
    Understanding of the link between the vestibular organs and the visual system is becoming established (e.g. Della-Justina et al., 2015), yet few studies have explored the use of vestibular stimulation to modulate visual processing. Preliminary evidence that this can be achieved is seen in one clinical case study which reported improved face perception in an acquired prosopagnosic following vestibular stimulation (Wilkinson, Ko, Kilduff, McGlinchey, & Milberg, 2005), and in one study that demonstrated an enlarged N170 in healthy adults during vestibular stimulation (Wilkinson, Ferguson, & Worley, 2012). The present study tested the behavioural effects of caloric vestibular stimulation on a higher cognitive level of face recognition in sixty adults. Participants were required to identify the nationality of celebrities in four testing sessions following a counterbalanced ABAB design. Relative to no stimulation, caloric vestibular stimulation significantly increased accuracy scores which could not be accounted for by practise effects. This study constitutes the first attempt to improve healthy face recognition skills through vestibular stimulation and the findings have immediate real-world value in settings that require superior face recognition performance such as passport control and identity parades. The study also provides further evidence to the efficacy of vestibular stimulation in modulating cognitive processes.
  • Ulrich, P., Wilkinson, D., & Johnston, R. (2015). Superior face-recognition from vestibular stimulation. In Experimental Psychology Society Meeting. Leeds, UK. Retrieved from http://www.eps.ac.uk/images/epsfiles/2015/leeds_programme_apr15.pdf
    The vestibular organs, providing the sense of balance and acceleration, have dense neuroanatomical connections. Stimulation of these organs elicits widespread changes in cortical blood flow, including regions active during face perception and recognition. Previous studies report improved face recognition in acquired prosopagnosia following vestibular stimulation and an enlarged N170 in healthy adults. The present study explores the effect of pioneering caloric vestibular stimulation (CVS) in the behavioural performance of healthy adults during face recognition tasks. Sixty participants were asked to identify the nationality of celebrities in four testing sessions following an ABAB design. A significant main effect of stimulation demonstrated improved accuracy during those sessions with CVS. The findings have immediate real-world value in settings that require superior face recognition skills such as passport control and identity parades. The study also provides further evidence to the efficacy of vestibular stimulation in modulating cognitive processes.
  • Smith, L., & Wilkinson, D. (2015). Can visual memory recall be enhanced by galvanic vestibular stimulation?. In Experimental Psychology Society January Meeting. London.
  • Smith, L., Wilkinson, D., Bodani, M., Sakel, M., & Ferguson, H. (2014). Caloric vestibular Stimulation in traumatic brain injury: Study protocol. In British Psychological Society Division of Neuropsychology Annual Conference. London.
  • Ulrich, P., Wilkinson, D., Ferguson, H., Bindemann, M., & Johnston, R. (2014). Heterogeneity in Developmental Prosopagnosia. In 31st BPS Cognitive Psychology Section Conference. Nottingham, UK. Retrieved from http://www.ntu.ac.uk/webevents/soc/document_uploads/163523.pdf
    Developmental prosopagnosia, or face-blindness, is an isolable condition that impairs successful recognition of faces and is present from birth with no evidence of brain trauma. Despite the high suspected prevalence of developmental prosopagnosia, diagnostic criteria are informal, current treatment approaches lack trials validation, and, given the relatively small number of group studies, the relative integrity of underlying perceptual and memory processes remains unclear. To begin to address these shortcomings, we administered a large battery of behavioural tests to twenty one individuals with self-reported face recognition difficulties. Nine separate patterns of impairments emerged. Ten of these individuals were subsequently classified as developmentally prosopagnosic based on the most widely used assessment - the Cambridge Face Memory Test. Relative to a control sample (n=102), the majority of these individuals performed poorly on tests of memory but not perception. These results help clarify the nature of impairment in developmental prosopagnosia, and also guide the development of novel therapies such as caloric vestibular stimulation, a technique that we have begun to apply to this population and which, as will be described, may hold promise.
  • Ulrich, P., Wilkinson, D., Ferguson, H., Bindemann, M., & Johnston, R. (2014). Perceptual and memorial impairment in developmental prosopagnosia. In Experimental Psychology Society Meeting Symposium: Recent advances in developmental prosopagnosia research. Kent, UK. Retrieved from http://www.eps.ac.uk/images/epsfiles/kent%20programme%20apr%20-%202014%20-final.pdf
    Despite the high suspected prevalence of developmental prosopagnosia, diagnostic criteria are informal, current treatment approaches lack trials validation, and, given the relatively small number of group studies, the relative integrity of underlying perceptual and memory processes remains unclear. To begin to address these shortcomings, we administered a large battery of behavioural tests to twenty one individuals with self-reported face recognition difficulties. Ten of these individuals were subsequently classified as developmentally prosopagnosic based on the most widely used assessments - the Cambridge Face Memory Test and famous faces naming test. Relative to a control sample (n=103), the majority of these individuals performed poorly on tests of memory but not perception. These results help clarify the nature of impairment in developmental prosopagnosia, and also guide the development of novel therapies such as caloric vestibular stimulation, a technique that we have begun to apply to this population and which, as will be described, may hold promise.
  • Ulrich, P., Wilkinson, D., Ferguson, H., Bindemann, M., & Johnston, R. (2014). Vestibular Stimulation Therapy for Prosopagnosia. In Experimental Psychology Society Meeting. London, UK. Retrieved from http://www.eps.ac.uk/images/Jan%20-%202014%20-%20FINAL.pdf
    People with prosopagnosia may fail to recognise even the closest friends and relatives, and some even fail to recognise their own image in a mirror. Yet despite the negative impact this has for a reported 2.5 per cent of the population who have the condition, surprisingly few attempts have been made at developing a therapy, and even fewer have been successful. Caloric vestibular stimulation, or temperature changes surrounding the balance organs, affects blood flow to brain areas known to contribute towards memory and face processing. The effect this technique would have on memory and face recognition was therefore experimentally tested. Eight prosopagnosic patients and 11 age-matched controls were required to indicate the nationality of 60 celebrities while EEG was recorded, first with then without stimulation. Across all groups, stimulation significantly reduced reaction times with no loss in accuracy. Mapped to this behavioural change was a significantly reduced N400, an event related potential commonly associated with semantic activity. These findings lead the authors to describing the stimulation as acting synonymously with repetition priming effects. These experiments open a path to an empirically supported therapy to the hundreds of thousands of face-blindness sufferers.
  • Vanzan, S., Wilkinson, D., Ferguson, H., Dhamapurkar, s, Bodani, m, & Sakel, M. (2014). Caloric Vestibular Stimulation (CVS) in Low Awareness States. In 11th Conference of the Neuropsychological Rehabilitation Special Interest Group of the World Federation of NeuroRehabilitation (WFNR).
  • Beadle-Brown, J., Richardson, L., Wilkinson, D., Shaughnessy, N., Trimingham, M., Leigh, J., Whelton, B., & Himmerich, J. (2014). Imagining Autism: impact of a drama based intervention on the social communicative and imaginative behaviour of children with autism. In 4th IASSID-Europe congress (Vol. 27, pp. 343-343). Vienna: Wiley-Blackwell.
  • Richardson, L., Beadle-Brown, J., Wilkinson, D., Shaughnessy, N., Trimingham, M., Leigh, J., Whelton, B., & Himmerich, J. (2014). Imagining Autism: evaluation of a drama based intervention for children with autism-the views of teachers and parents. In 4th IASSID-Europe congress (Vol. 27, pp. 343-344). Vienna: Wiley-Blackwell.
  • Sakel, M., Wilkinson, D., & Morris, R. (2013). Caloric Vestibular Stimulation may improve aphasia and mobility. In 90th Annual Conference of the American Congress of Rehabilitation Medicine. Orlando, USA.
  • Sakel, M., & Wilkinson, D. (2013). Reducing length of stay within a provincial UK neurorehabilitation unit. In World Federation for NeuroRehabilitation. Maastrict, Netherlands.
  • Sakel, M., & Wilkinson, D. (2013). Can Galvanic Vestibular Stimulation promote recovery from cerebellar dysfunction?. In 11th Word Congress of the International Neuromodulation Society. Berlin.
  • Sakel, M., Wilkinson, D., Haque, I., Malovic, A., & Gallagher, M. (2013). Does upper limb spasticity treatment improve mobility?. In International Conference on Recent Advances in Neurorehabilitation. Valencia, Spain.
  • Sakel, M., & Wilkinson, D. (2012). Patients with hemi-spatial neglect are more prone to limb spasticity. In Second World Conference on Medical Rehabilitation in Rural and Developing Regions, International Rehabilitation Forum. Dhaka, Bangladesh.

Thesis

  • Smith, L. (2017). Vestibular Contributions to Human Memory.
    The vestibular system is an ancient structure which supports the detection and control of self-motion. The pervasiveness of this sensory system is evidenced by the diversity of its anatomical projections and the profound impact it has on a range of higher level functions, particularly spatial memory. The aim of this thesis was to better characterise the association between the vestibular system and human memory; while many studies have explored this association from a biological perspective few have done so from a psychological one. In Chapter 1, evidence was drawn from 101 neuro-otology patients to show that vestibular dysfunction can exert a direct negative effect on memory and allied cognitive processes, independently of age and comorbid psychiatric and fatigue symptoms. In Chapters 3 and 4, the separability of these cognitive, psychiatric and fatigue symptoms was further demonstrated in eight traumatic brain injury patients who, following a programme of daily vestibular stimulation, showed cognitive improvement and electrophysiological modulation in the absence of psychiatric or fatigue-related changes. Finally in Chapter 5, a set of normative experiments indicated that, beyond any generic arousal effect (unspecific to any particular cognitive process), visual memory can utilise temporally coincident vestibular activation to help individuate one memory from another. Together these findings help clarify the range of and manner in which vestibular signals interact with visual short-term memory and allied cognitive processes. The findings also have clinical implications for the diagnosis and management of vestibular, neuropsychiatric and amnesic conditions.
  • Marques, K. (2017). The Effects of Galvanic Vestibular Stimulation on Motor Cortical Excitability.
    Galvanic vestibular stimulation (GVS) can reduce the symptoms of numerous neurological conditions including episodic migraine, parkinsonism, acquired prosopagnosia and hemi-spatial neglect. Despite these preliminary findings, the mechanism underlying these therapeutic effects are still poorly understood. Functional imaging conducted during GVS indicates a potential change in cortical activation across widespread regions of the brain. However, these imaging studies are limited because they lack a functional correlate and rely on a relatively crude and poorly localised measure of excitability. The current study aimed to investigate the effects of GVS on cortical excitability via the more precise markers of TMS-induced motor-evoked potentials (MEPs) and movement-related cortical potentials (MRCPs), surrogate markers of long-term potentiation (LTP) and long-term depression (LTD) which are often compromised in neurological patients. Experiment 1 (N = 40) examined the effects of 25 minutes 1mA noisy, bipolar GVS on MEPs in the minutes and subsequent day after stimulation. Relative to sham, GVS reduced MEP amplitude 24 hours following stimulation for all participants who showed high cortical excitability at baseline. Experiment 2 (N = 24) followed a similar pre-post design to Experiment 1, however, the effects of GVS on the MRCP were measured via the Bereitschaftspotential (BP) while participants performed voluntary finger movements. Most likely owing to methodological shortcomings, Experiment 2 failed to obtain a BP response at baseline so did not enable the study hypothesis to be assessed. Experiment 3 was designed to both address these potential shortcomings and increase clinical relevance, recruiting a single individual with right hemisphere chronic stroke. A BP at baseline was observed but there was no evidence of GVS modulation. In sum, whilst Experiments 2 and 3 yielded few novel insights, the results of Experiment 1 indicate that GVS inhibits cortical excitability, potentially reflecting LTD-like effects. This observation may help explain its reported therapeutic benefits and also suggests that is should be applied to other disorders that involve cortical hyper-excitability.
  • Ulrich, P. (2017). Behavioural, Electrophysiological and Neurostimulatory Investigations into Developmental Prosopagnosia.
    Developmental prosopagnosia (DP) is the difficulty or inability to recognise a face and may affect up to 2.9 percent of the population. There is controversy over whether these impairments are perceptual or memorial in nature, and uncertainty about their stability over time and how to remediate symptoms. In the first stage, a battery of ten tests was assembled to assess a wide range of face recognition skills in DP (n = 11) and compared to a control group (Chapter Two). The majority of DPs showed no signs of impaired face perception but profound face memory deficits. To seek electrophysiological corroboration of these impairments, the DPs (n = 8) were given three behavioural tasks known to elicit specific event related potentials (Chapter Three), assessing face perception (N170), face familiarity (N250r) and semantic access (N400). During the experiment, caloric vestibular stimulation (CVS) was also administered to see if it could reduce symptoms. The tasks revealed intact face perception and impaired accuracy in both memory based tasks, corroborated by an atypical N400. Subtle effects of CVS were observed in all measures of the face familiarity task but not at a level that was clinically relevant. To establish, for the first time, whether the impairments in DP are consistent over time, the effects in Chapter Three were replicated (n = 7)(Chapter Four). A similar pattern emerged and test-retest correlations showed high reliability overtime in the familiarity task but not the semantic access task. This implies that reliable 'diagnosis' of developmental prosopagnosia should be based on judgements of face familiarity and not associated with semantic activity. The beneficial effects of CVS were again present in the N250r behavioural measures and were limited to familiar faces only. This implies that CVS is optimising memory recall for face representations. The source of impairments was consistently shown to be memorial in nature and future studies may wish to explore further divisions of memory in DP such as whether impairments are associated with encoding or recall. The thesis also demonstrates the potential for CVS as both a therapeutic tool and cognitive enhancer, and justify more robust trials investigation.
  • Vanzan, S. (2015). Effects of Caloric and Galvanic Vestibular Stimulation on Reduced Awareness.
    Approximately one fifth of those who emerge from coma following an acquired brain injury will be in a minimally conscious or vegetative state. Both conditions are associated with a range of physical co-morbidities, and currently no effective treatments are available. The main aim of this thesis is to seek preliminary evidence that vestibular stimulation can help remediate the reduced awareness that characterises these conditions. This objective was motivated by the fact that vestibular stimulation is already known to reduce lateralised (as opposed to global) disorders of awareness, and increases metabolic activity in the thalamo-cortical network, crucial to awareness. To seek proof-of-principle, five hospital in-patients (three MCS, two PVS) underwent a maximum of 40 minutes of daily left-ear caloric vestibular stimulation (CVS). Stimulation was delivered in four week blocks for a period of 16 weeks, alternating between CVS and sham. Behavioural changes in awareness and cognitive ability were measured weekly via the Wessex Head Injury Matrix (WHIM) and the JFK Coma Recovery Scale – Revised. Electrophysiological correlates of awareness (i.e., EEG power spectra and auditory P3 elicited by an oddball paradigm) were recorded monthly. The behavioural results showed that CVS triggered the emergence of awareness in both MCS patients, along with smaller signs of improvement in both PVS patients. The third MCS patient died three weeks after enrolment due to an unrelated respiratory infection. All participants’ electrophysiological responses were modulated by CVS but not in a manner that could be easily tied to their behavioural improvement. Taken together, these clinical studies establish proof-of-principle and justify a larger, more definitive study to reproduce the treatment effects and investigate the degree to which dose, disease chronicity and level of consciousness influence response. The results also suggest that EEG power spectra and auditory ERPs may not provide the best means of capturing allied neurophysiological change.
    A parallel stream of study was also conducted to seek analogous effects of vestibular stimulation on awareness and attention in healthy individuals. Two experiments tested whether galvanic vestibular stimulation (GVS) influences the behavioural and/or electrophysiological responses of participants while they performed a prolonged Go/NoGo task challenging their sustained attention. Four stimulation conditions were compared: supra-sensory GVS, sub-sensory GVS, Sham, and no stimulation. The results indicate that vestibular stimulation can modulate, partly in a dose-dependent way, higher-level processes linked to stimulus processing, motor inhibition and performance monitoring. In broader terms, the results give impetus to the idea that the vestibular sense is not only, as traditionally thought, central to autonomic motor control but also to the formation and maintenance of higher cognitive states. Previous studies indicate that the linear, angular and gravitational accelerations signaled by the vestibular system contribute to egocentric perception and body ownership. The current findings suggest that these signals also help initiate and influence processes involved in global self-awareness and purposeful behaviour, thereby pointing towards an altogether more profound role.

Forthcoming

  • Bodani, M., & Wilkinson, D. (2017). Neuro-stimulation in Neurological and Neuropsychiatric disorders. In M. Bodani (Ed.), Oxford Textbook of Neuropsychiatry. Oxford University Press.
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