Transient visual perturbations boost short-term balance learning in virtual reality by modulating electrocortical activity

Peterson, Steven M.; Rios, Estefania; Ferris, Daniel P.

doi:10.1152/jn.00292.2018

Cited by 41 publications

(55 citation statements)

References 103 publications

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“…VR-based perturbations are typically provided by altering the virtual environment (VE). This is commonly done by unexpectedly rotating the visual field presented to the participant across the pitch, yaw, and roll principle axes [12,13,14]. Similar to the moving wall, this particular paradigm provides inaccurate visual sensory information and thus forces an increased reliance on the vestibular and somatosensory systems to maintain balance.…”

Section: Introductionmentioning

confidence: 99%

Virtual-Reality-Induced Visual Perturbations Impact Postural Control System Behavior

Chander

Arachchige

Hill

et al. 2019

Behavioral Sciences

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Background: Virtual reality (VR) is becoming a widespread tool in rehabilitation, especially for postural stability. However, the impact of using VR in a “moving wall paradigm” (visual perturbation), specifically without and with anticipation of the perturbation, is unknown. Methods: Nineteen healthy subjects performed three trials of static balance testing on a force plate under three different conditions: baseline (no perturbation), unexpected VR perturbation, and expected VR perturbation. The statistical analysis consisted of a 1 × 3 repeated-measures ANOVA to test for differences in the center of pressure (COP) displacement, 95% ellipsoid area, and COP sway velocity. Results: The expected perturbation rendered significantly lower (p < 0.05) COP displacements and 95% ellipsoid area compared to the unexpected condition. A significantly higher (p < 0.05) sway velocity was also observed in the expected condition compared to the unexpected condition. Conclusions: Postural stability was lowered during unexpected visual perturbations compared to both during baseline and during expected visual perturbations, suggesting that conflicting visual feedback induced postural instability due to compensatory postural responses. However, during expected visual perturbations, significantly lowered postural sway displacement and area were achieved by increasing the sway velocity, suggesting the occurrence of postural behavior due to anticipatory postural responses. Finally, the study also concluded that VR could be used to induce different postural responses by providing visual perturbations to the postural control system, which can subsequently be used as an effective and low-cost tool for postural stability training and rehabilitation.

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Section: Introductionmentioning

confidence: 99%

Virtual-Reality-Induced Visual Perturbations Impact Postural Control System Behavior

Chander

Arachchige

Hill

et al. 2019

Behavioral Sciences

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“…Our analysis also may have been limited by projecting only onto 144 sensorimotor brain regions, which we chose based on the decoding task. For real-world decoders, the most informative regions may not be clear, requiring data-driven region-selection approaches to avoid high memory usage and slow computation times [37, 38]. Finally, we could have constrained HTNet’s temporal convolution layer to learn more meaningful narrow-band filters [93].…”

Section: Discussionmentioning

confidence: 99%

Generalized neural decoders for transfer learning across participants and recording modalities

Peterson

Steine-Hanson

Davis

et al. 2020

Preprint

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Advances in neural decoding have enabled brain-computer interfaces to perform increasingly complex and clinically-relevant tasks. However, such decoders are often tailored to specific participants, days, and recording sites, limiting their practical long-term usage. Therefore, a fundamental challenge is to develop neural decoders that can robustly train on pooled, multi-participant data and generalize to new participants. We introduce a new decoder, HTNet, which uses a convolutional neural network with two innovations: (1) a Hilbert transform that computes spectral power at data-driven frequencies and (2) a layer that projects electrode-level data onto predefined brain regions. The projection layer critically enables applications with intracranial electrocorticography (ECoG), where electrode locations are not standardized and vary widely across participants. We trained HTNet to decode arm movements using pooled ECoG data from 11 of 12 participants and tested performance on unseen ECoG or electroencephalography (EEG) participants; these pretrained models were also subsequently fine-tuned to each test participant. HTNet outperformed state-of-the-art decoders when tested on unseen participants, even when a different recording modality was used. By fine-tuning these generalized HTNet decoders, we achieved performance approaching the best tailored decoders with as few as 50 ECoG or 20 EEG events. We were also able to interpret HTNet's trained weights and demonstrate its ability to extract physiologically-relevant features. By generalizing to new participants and recording modalities, robustly handling variations in electrode placement, and allowing participant-specific fine-tuning with minimal data, HTNet is applicable across a broader range of neural decoding applications compared to current state-of-the-art decoders.

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“…In either event, we would interpret these time-dependent effects as favorable outcomes during perturbation training. In addition, based on recently published EEG data [40], the time-dependent changes we report here may be simultaneously accompanied by altered cortical activation; Peterson et al (2018) found that intermittent optical flow perturbations in young participants walking on a balance beam increased electrocortical activity in the parietal, occipital, and cingulate areas [40]. Those authors interpreted their findings to suggest that such perturbations promoted motor learning of a balance task in brain areas associated with integrating visual information with motor coordination.…”

Section: Discussionmentioning

confidence: 99%

Time-dependent tuning of balance control and aftereffects following optical flow perturbation training in older adults

Richards

Selgrade

Qiao

et al. 2019

J NeuroEngineering Rehabil

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Background Walking balance in older adults is disproportionately susceptible to lateral instability provoked by optical flow perturbations. The prolonged exposure to these perturbations could promote reactive balance control and increased balance confidence in older adults, but this scientific premise has yet to be investigated. This proof of concept study was designed to investigate the propensity for time-dependent tuning of walking balance control and the presence of aftereffects in older adults following a single session of optical flow perturbation training. Methods Thirteen older adults participated in a randomized, crossover design performed on different days that included 10 min of treadmill walking with (experimental session) and without (control session) optical flow perturbations. We used electromyographic recordings of leg muscle activity and 3D motion capture to quantify foot placement kinematics, lateral margin of stability, and antagonist coactivation during normal walking (baseline), early (min 1) and late (min 10) responses to perturbations, and aftereffects immediately following perturbation cessation (post). Results At their onset, perturbations elicited 17% wider and 7% shorter steps, higher step width and length variability (+171% and +132%, respectively), larger and more variable margins of stability (MoS), and roughly twice the antagonist leg muscle coactivation ( p -values<0.05). Despite continued perturbations, most outcomes returned to values observed during normal, unperturbed walking by the end of prolonged exposure. After 10 min of perturbation training and their subsequent cessation, older adults walked with longer and more narrow steps, modest increases in foot placement variability, and roughly half the MoS variability and antagonist lower leg muscle coactivation as they did before training. Conclusions Findings suggest that older adults: ( i ) respond to the onset of perturbations using generalized anticipatory balance control, ( ii ) deprioritize that strategy following prolonged exposure to perturbations, and ( iii ) upon removal of perturbations, exhibit short-term aftereffects that indicate a lessening of anticipatory control, an increase in reactive control, and/or increased balance confidence. We consider this an early, proof-of-concept study into the clinical utility of prolonged exposure to optical flow perturbations as a training tool for corrective motor adjustments relevant to walking balance integrity toward reinforcing task-specific, reactive control and/or improving balance confidence in older adults. Trial registration clinicaltrials.gov ( NCT03341728 ). Registered 14 November 2017. Electronic supplementary material The online version of this article (10.1186/s...

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Transient visual perturbations boost short-term balance learning in virtual reality by modulating electrocortical activity

Cited by 41 publications

References 103 publications

Virtual-Reality-Induced Visual Perturbations Impact Postural Control System Behavior

Virtual-Reality-Induced Visual Perturbations Impact Postural Control System Behavior

Generalized neural decoders for transfer learning across participants and recording modalities

Time-dependent tuning of balance control and aftereffects following optical flow perturbation training in older adults

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