Biology subjects

Waltzing, B. M.

Publications and source records attributed to Waltzing, B. M..

8 recordsLinked to original sources

bioRxiv2026

'RMT-Finder': an automated procedure to determine the Resting Motor Threshold for Transcranial Magnetic Stimulation

BackgroundTranscranial Magnetic Stimulation (TMS) studies identify the Resting Motor Threshold (RMT) to calibrate stimulation intensity. However, this procedure is time-consuming and subject to variability. We developed an automated procedure to improve the efficiency and standardization of RMT determination. New methodWe developed an algorithm that measures MEP amplitudes and automatically adjusts stimulation intensity to determine the RMT. Experiment 1 compared this automated method with the manual procedure in terms of reliability and equivalence. Experiment 2 developed a "Fast" automated process, assessing it against both the manual and initial automated procedures. ResultsAcross both experiments the automated approach demonstrated excellent test-retest reliability and strong agreement with the manual method (Intraclass Correlation Coefficients [≥]0.95), giving estimates of RMT statistically equivalent to those of manual measurements within {+/-}3% MSO, with the majority of comparisons within {+/-}2% MSO. Experiment 2 optimized the procedure, allowing empirical determination of the RMT in an average of <3 minutes with only 33-34 pulses. Comparison with existing methods RMT-Finder provides a reliable and time-efficient alternative to manual approaches. To the best of our knowledge RMT-Finder presents the first closed-loop feedback approach to identify the RMT without manual intervention. This procedure can improve standardization and reproducibility in TMS studies. ConclusionsAutomating RMT assessment allows rapid and highly reproducible assessment of this standard TMS measurement, making it viable for inclusion in routine clinical applications that require standardized procedures.

neuroscience↗

bioRxiv2025

A comprehensive, open-source battery of movement imagery ability tests: Development and psychometric properties

Imagining actions is a covert and multidimensional skill difficult to quantify. Comprehensive assessments rarely combine measures of imagery generation, maintenance, and manipulation. We developed and validated a combination of tests to assess these processes of movement imagery, online. 180 healthy individuals completed the MIQ-RS questionnaire (generation), the Imagined Finger Sequence Task (iFST; maintenance), and the Hand Laterality Judgement Task (HLJT; manipulation). MIQ-RS showed a bifactorial structure (visual and kinesthetic modalities) according to confirmatory factor analysis, and its reliability (internal consistency) was good. In the iFST, internal validity analyses via generalized mixed models showed a clear effect of sequence complexity, stronger for execution than imagery. Reliability, estimated via signal-to-noise ratios (SNRs) using hierarchical Bayesian models, was also adequate (SNR [≥] 1.6). In the HLJT, expected effects of rotation angle, hand view, and their interaction, consistent with biomechanical constraints, were also found. Reliability was also adequate (SNR [≥] 1.75). Criterion validity across tests, assessed using Bayesian Spearmans correlations, showed that correlations were generally absent (BF01 [≥] 3), and when present, of small magnitude (r [≤] 0.27). Test-retest reliability (123 participants reassessed 6-8 days after), computed via Intraclass Correlation Coefficients (ICCs), was generally adequate (ICCs [≥] 0.67). We conclude that the online versions of these tests showed adequate structural/internal validity and (test-retest) reliability. However, weak criterion validity suggests individuals with high ability to generate movement imagery may not necessarily have high ability to maintain and/or manipulate movement imagery, underscoring the need for comprehensive assessment of this capacity.

neuroscience↗

bioRxiv2025

Comparing electromyography, accelerometry, and visual inspection to assess the resting motor threshold for transcranial magnetic stimulation

IntroductionElectromyography (EMG) remains the gold standard for estimating the Resting Motor Threshold (RMT) in Transcranial Magnetic Stimulation (TMS) studies, but its cost and limited accessibility often lead researchers to use visual inspection (VIS). However, VIS may introduce variability and systematic bias. Accelerometry (ACC) offers a cost-effective, objective alternative to capture TMS-evoked responses. ObjectiveTo compare the RMT as estimated using EMG, ACC, and VIS. MethodsFive participants underwent TMS while EMG, ACC, and video recordings were collected. Separately, 64 observers judged hand movement in videos to estimate RMT via VIS. RMTs were compared across the three methods using Bayesian model comparison, Bland-Altman analyses, and Intraclass Correlation Coefficients (ICCs). ResultsRMTs estimated via EMG were lower than those obtained using either ACC or VIS. Compared to EMG, VIS tended to overestimate RMT (mean bias = 5.23%, 95%CI = [1.00-11.00]), while ACC and VIS estimates were more closely aligned (mean bias = 0.43%, 95%CI = [-4.00 - 5.00]). ICC (2,1) values indicated moderate reliability for VIS vs EMG (mean = 0.580, 95%CI = [0.389 - 0.748]), and good-to-excellent reliability for VIS vs ACC (mean = 0.845). However, bootstrapped 95% confidence intervals identified significant variability in the estimates provided by visual inspection, ranging from +1 to +11 for VIS vs EMG, but as low as -4 to +5 for VIS vs ACC. ConclusionsEMG remains the most sensitive technique for estimating the RMT, but when EMG is not feasible, accelerometery provides a quantifiable, more objective, and less variable alternative than visual inspection. HighlightsO_LIVisual inspection introduces observer-related variability in RMT estimation C_LIO_LIVisual inspection & accelerometry systematically overestimate RMT compared to EMG C_LIO_LIEMG remains the most sensitive method for estimating RMT C_LIO_LIAccelerometry is an objective alternative to visual inspection if EMG is unavailable C_LI

neuroscience↗

bioRxiv2025

Information processing in the Hand Laterality Judgement Task: Fundamental differences between dorsal and palmar views revealed by a Forced Response paradigm

Imagining performing movements (motor imagery) has broad applications from fundamental neuroscience to sports and rehabilitation. However, measuring motor imagery ability is challenging due to its covert nature. While the Hand Laterality Judgement Task (HLJT) has been investigated as a measure of implicit motor imagery ability, our understanding of mechanisms underlying performance of the task is limited. We used a forced response paradigm to study the time-course of information processing in the HLJT. Participants (N=54) performed a modified HLJT where the time they had to process the stimulus was manipulated on a trial-by-trial basis, allowing us to reconstruct the time-course of information processing. Generalised Additive Mixed Models assessed the relationship between processing time and accuracy, which varied across rotation angles (0{degrees} to 180{degrees} in 45{degrees} steps), hand views (dorsal or palmar) or directions (medial or lateral). Stimulus rotation substantively increased the time needed to produce a correct response, although this effect was non-monotonic. Computational modelling confirmed a crucial interaction between hand view and rotation angle, identifying fundamental differences in processing for palmar stimuli with more extreme rotations ([≥]135{degrees}) compared to other stimuli. Finally, a biomechanical constraints effect (i.e. faster processing of medial vs laterally rotated stimuli) was present in both views, but was only statistically significant in palmar views, again suggesting differences in processing palmar and dorsal stimuli. These results improve our understanding of the cognitive processes underlying the HLJT and may have broader importance for our understanding of mental processes implicated in motor imagery.

neuroscience↗

bioRxiv2024

Development and validation of an open-source Hand Laterality Judgement Task for in-person and online studies

The Hand Laterality Judgement Task (HLJT) is considered a measure of the ability to manipulate motor images. The biomechanical constraints effect (longer reaction times for hand rotations towards anatomically difficult versus biomechanically easier movements) is considered the behavioural hallmark indicating motor imagery is being used. Previous work has used diverse HLJT paradigms, and there is no standardized procedure for the task. We developed an open-source, freely available version of the HLJT in PsychoPy2, which needs no programming skills and is highly customisable. Some studies suggest responding to the HLJT with the hands may interfere with performance, which would limit practical application of the task. We examined this potential issue using in-person and online versions. For the in-person version, 40 right-footed/handed individuals performed the HLJT with their feet or bimanually (N=20 each). For the online version, 60 right-handed individuals performed the task bimanually or unimanually (N=20 each). Bayesian mixed-effect analyses quantified the evidence for and against equivalence within and between the in-person and online versions. Both versions replicated previously described behavioural phenomena, including effects of angle, hand view, and the biomechanical constraints effect. While responding with different effectors modified overall reaction times, it did not interact with other factors analysed, and did not affect accuracy or the biomechanical constraints effect. There was also evidence for equivalence between in-person and online bimanual groups for all measures. We conclude that this open-source, standardized HLJT protocol (available at https://osf.io/8h7ec/) can reliably detect previously identified effects and works equally well in-person or online.

neuroscience↗

bioRxiv2023

Bilateral Intracortical Inhibition during Unilateral Motor Preparation and Sequence Learning

Motor sequence learning gradually quickens reaction time, suggesting that sequence learning alters motor preparation processes. Interestingly, evidence has shown that preparing sequence movements decreases short intracortical inhibition (SICI) in the contralateral motor cortex (M1), but also that sequence learning alters motor preparation processes in both the contralateral and ipsilateral M1s. Therefore, one possibility is that sequence learning alters the SICI decreases occurring during motor preparation in bilateral M1s. To examine this, two novel hypotheses were tested: unilateral sequence preparation would decrease SICI in bilateral M1s, and sequence learning would alter such bilateral SICI responses. Paired-pulse transcranial magnetic stimulation was delivered over the contralateral and ipsilateral M1s to assess SICI in an index finger muscle during the preparation of sequences initiated by either the right index or little finger. In the absence of sequence learning, SICI decreased in both the contralateral and ipsilateral M1s during the preparation of sequences initiated by the right index finger, suggesting that SICI decreases in bilateral M1s during unilateral motor preparation. As sequence learning progressed, SICI decreased in the contralateral M1 whilst it increased in the ipsilateral M1. Moreover, these bilateral SICI responses were observed at the onset of motor preparation, suggesting that sequence learning altered baseline SICI levels rather than the SICI decreases occurring during motor preparation per se. Altogether, these results suggest that SICI responses in bilateral M1s reflect two motor processes: an acute decrease of inhibition during motor preparation, and a cooperative but bidirectional shift of baseline inhibition levels as sequence learning progresses.

neuroscience↗

bioRxiv2023

Sub-Concussive Head Impacts From Heading Footballs Do Not Acutely Alter Brain Excitability As Compared to a Control Group

BackgroundRepeated sub-concussive head impacts are a growing brain health concern, but the possible mechanisms of trauma and plausible biomarkers remain elusive. One impediment is the lack of an experimental model to study the effects of sub-concussive head impacts on the brain. ObjectivesThis works objective was to provide an experimental model to study the acute effects of sub-concussive head impacts on the brain. To do so, this study aimed to replicate previous work from Di Virgilio et al. (2016) showing that head impacts from heading footballs acutely alter brain excitability by increasing corticomotor inhibition. MethodsScores from the Rivermead Post-Concussion Questionnaire and measurements of cortical silent period (CSP) duration - obtained using transcranial magnetic stimulation to assess corticomotor inhibition in the central nervous system - were taken before and after participants performed 20 football headings (Headings; n = 30) or control (Control; n = 30). ResultsThe results revealed increased headaches and dizziness symptoms in the Headings as compared to the Control group, revealing the qualitative experience of head impacts. The results then revealed that CSP duration similarly lengthened in both the Headings and Control groups, suggesting that head impacts did not cause the increased corticomotor inhibition. ConclusionsThe results show that head impacts from football headings did not acutely alter corticomotor inhibition as compared to a control group that did not experience head impacts, suggesting that excitability changes do not reflect acute sub-concussive brain injuries. Nonetheless, this work suggests that football headings can be used as an experimental model to study the effects of sub-concussive head impacts on brain health. Future work could use the present procedures to investigate additional biomarkers of brain injury.

neuroscience↗

bioRxiv2022

Consistent Under-reporting of Task Details in Motor Imagery Research

Motor Imagery is a subject of longstanding scientific interest. However, critical details of motor imagery protocols are not always reported in full, hampering direct replication and translation of this work. The present review provides a quantitative assessment of the prevalence of under-reporting in the recent motor imagery literature. Publications from the years 2018-2020 were examined, with 695 meeting the inclusion criteria for further examination. Of these studies, 64% (445/695) did not provide information about the modality of motor imagery (i.e., kinesthetic, visual, or a mixture of both) used in the study. When visual or mixed imagery was specified, the details of the visual perspective to be used (i.e., first person, third person, or combinations of both) were not reported in 24% (25/103) of studies. Further analysis indicated that studies using questionnaires to assess motor imagery reported more information than those that did not. We conclude that studies using motor imagery consistently under-report key details of their protocols, which poses a significant problem for understanding, replicating, and translating motor imagery effects.

neuroscience↗