Biology subjects

Vette, A. H.

Publications and source records attributed to Vette, A. H..

3 recordsLinked to original sources

bioRxiv2023

Combining transcutaneous spinal stimulation and functional electrical stimulation increases force generated by lower limbs: When more is more

BackgroundTranscutaneous Spinal Stimulation (TSS) has been shown to promote activation of the lower limb and trunk muscles and is being actively explored for improving the motor outcomes of people with neurological conditions. However, individual responses to TSS vary, and often the muscle responses are insufficient to produce enough force for self-supported standing. Functional electrical stimulation (FES) can activate individual muscles and assist in closing this functional gap, but it introduces questions regarding timing between modalities. MethodsTo assess the effects of TSS and FES on force generation, ten neurologically intact participants underwent (1) TSS only, (2) FES only, and (3) TSS + FES. TSS was delivered using four electrodes placed at T10-T11 through the L1-L2 intervertebral spaces simultaneously, while FES was delivered to the skin over the right knee extensors and plantarflexors. For all conditions, TSS and FES were delivered using three 0.5 ms biphasic square-wave pulses at 15 Hz. During the TSS + FES condition, timing between the two modalities was adjusted in increments of [1/4] time between pulses (16.5 ms). ResultsWhen TSS preceded FES, a larger force production was observed. We also determined several changes in muscle activation amplitude at different relative stimulus intervals, which help characterize our finding and indicate the facilitating and inhibitory effects of the modalities. ConclusionsUtilizing a delay ranging from 15 to 30 ms between stimuli resulted in higher mean force generation in both the knee and ankle joints, regardless of the selected FES location (Average; knee: 112.0%, ankle: 103.1%).

neuroscience↗

bioRxiv2021

Generating accurate 3D gaze vectors using synchronized eye tracking and motion capture

Assessing gaze behaviour during real-world tasks is difficult; dynamic bodies moving through dynamic worlds make gaze analysis difficult. Current approaches involve laborious coding of pupil positions. In settings where motion capture and mobile eye tracking are used concurrently in naturalistic tasks, it is critical that data collection be simple, efficient, and systematic. One solution is to combine eye tracking with motion capture to generate 3D gaze vectors. When combined with tracked or known object locations, 3D gaze vector generation can be automated. Here we use combined eye and motion capture and explore how linear regression models generate accurate 3D gaze vectors. We compare spatial accuracy of models derived from four short calibration routines across three pupil data inputs: the efficacy of calibration routines were assessed, a validation task requiring short fixations on taskrelevant locations, and a naturalistic object interaction task to bridge the gap between laboratory and "in the wild" studies. Further, we generated and compared models using spherical and cartesian coordinate systems and monocular (Left or Right) or binocular data. All calibration routines performed similarly, with the best performance (i.e., sub-centimetre errors) coming from the naturalistic task trials when the participant is looking at an object in front of them. We found that spherical coordinate systems generate the most accurate gaze vectors with no differences in accuracy when using monocular or binocular data. Overall, we recommend one-minute calibration routines using binocular pupil data combined with a spherical world coordinate system to produce the highest quality gaze vectors.

neuroscience↗

bioRxiv2019

Gaze and Movement Assessment (GaMA): Inter-site validation of a visuomotor upper limb functional protocol

BackgroundSuccessful hand-object interactions require precise hand-eye coordination with continual movement adjustments. Quantitative measurement of this visuomotor behaviour could provide valuable insight into upper limb impairments. The Gaze and Movement Assessment (GaMA) was developed to provide protocols for simultaneous motion capture and eye tracking during the administration of two functional tasks, along with data analysis methods to generate standard measures of visuomotor behaviour. The objective of this study was to investigate the reproducibility of the GaMA protocol across two independent groups of non-disabled participants, with different raters using different motion capture and eye tracking technology.\n\nMethodsTwenty non-disabled adults performed the Pasta Box Task and the Cup Transfer Task. Upper body and eye movements were recorded using motion capture and eye tracking, respectively. Measures of hand movement, angular joint kinematics, and eye gaze were compared to those from a different sample of twenty non-disabled adults who had previously performed the same protocol with different technology, rater and site.\n\nResultsParticipants took longer to perform the tasks versus those from the earlier study, although the relative time of each movement phase was similar. Measures that were dissimilar between the groups included hand distances travelled, hand trajectories, number of movement units, eye latencies, and peak angular velocities. Similarities included all hand velocity and grip aperture measures, eye fixations, and most peak joint angle and range of motion measures.\n\nDiscussionThe reproducibility of GaMA was confirmed by this study, despite a few differences introduced by learning effects, task demonstration variation, and limitations of the kinematic model. The findings from this study provide confidence in the reliability of normative results obtained by GaMA, indicating it accurately quantifies the typical behaviours of a non-disabled population. This work advances the consideration for use of GaMA in populations with upper limb sensorimotor impairment.

neuroscience↗