Biology subjects

Kraeutner, S. N.

Publications and source records attributed to Kraeutner, S. N..

6 recordsLinked to original sources

bioRxiv2025

Females versus males exhibit greater brain activation in sensorimotor regions during motor imagery after stroke

Motor imagery (MI; the mental rehearsal of movement) activates sensorimotor regions, providing the basis for its effectiveness as an intervention for motor recovery after stroke. Yet, the impact of biological sex on MI-related brain activation after stroke is unexplored. Here, we investigated sex-related differences in MI-related brain activation after stroke and explored associations between questionnaire-based MI ability and MI-related brain activation. Thirty-four individuals with chronic stroke performed MI of a complex, upper-limb movement using their paretic arm/hand. Brain activation was captured using functional magnetic resonance imaging (fMRI). Individual differences in MI ability were also assessed prior to the scan using an established MI questionnaire. MI-related brain activation was observed across sensorimotor regions. Yet, group-level contrasts revealed greater activation in sensorimotor regions for females vs. males, while greater activation in the cerebellar and parietal regions was noted in males vs. females. Females also recruited greater ipsilesional regions vs. males. Questionnaire-based MI ability was associated with brain activation localized to occipital regions. Our findings suggest that females and males may respond differently to MI-based tasks. Further, we did not find a relationship between questionnaire-based data and activity in sensorimotor regions. This finding suggests that multiple measures of MI may be needed to assess its impact. Overall, this work informs the use of MI after stroke.

neuroscience↗

bioRxiv2024

Motor Imagery Improves Force Control in Older and Young Females

Motor imagery training (MIT) is the mental rehearsal of a motor task with no overt movement that enhances physical performance through adaptations in neural excitability. MIT may prime the motor system for physical execution. In older adults, with physical practice, force steadiness (FS) improves and changes are related to improved performance of functional tasks, and associated with adaptations in neural excitability. The purpose of this study was to determine if one session of MIT influences corticospinal excitability and improves FS of isometric elbow flexion contractions in young and older female adults. To test the hypotheses that MIT would increase corticospinal excitability and improve isometric elbow flexion FS to a greater extent in older compared to young females fourteen older (67-89 years old) and twenty-two younger (19-33 years old) participants were randomly assigned to a MIT group or Control group. Participants, in a block design, performed isometric elbow flexion contractions at 10% of maximal force prior to and following MIT (training group) or no training (Control group). Elbow flexion contractions were performed in blocks 1, 3, and 5. MIT or documentary viewing was performed in blocks 2 and 4. Motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation were collected within the last five seconds of each submaximal contraction. The MEPs were reduced in the older MIT group from block 1 to block 5 (p=0.039) but not the young MIT group (p=0.761). Force steadiness in the older (p=0.005) and young (p=0.001) females improved from baseline after 20 minutes of MIT. Older females improved force steadiness relative to the baseline to a greater extent than young females (older 8.44% and young 5.0%), and the improvements were significant in older females in the first 10 minutes. In older females, MIT primes the motor system and improves FS earlier and to a greater extent than in young females.

neuroscience↗

bioRxiv2023

Concurrent action observation but not motor imagery modulates interhemispheric inhibition during physical execution

Motor control relies on an inhibitory connection between the motor cortices of the brain, known as interhemispheric inhibition (IHI). This phenomenon is well established during the execution of unilateral motor tasks. It is unknown if the neurophysiological effects associated with IHI during physical execution (PE) also occur during action observation (AO) and motor imagery (MI) and/or if the addition of these covert processes to PE moderates IHI; speaking to differences in neurophysiology and functional equivalence. Participants (N=23) performed unilateral concentric wrist contractions (50% maximum voluntary contraction) under three conditions: PE alone, concurrent PE+AO, and concurrent PE+MI. To index IHI, we induced an ipsilateral silent period (iSP) and assessed iSP duration during each condition via neuro-navigated single-pulse transcranial magnetic stimulation (TMS) over the ipsilateral motor cortex. Relative to PE alone, iSP decreased during PE+AO, yet only when this condition preceded PE+MI. iSP duration was not modulated during PE+MI. Together, these data suggest that PE+AO promotes bilateral recruitment and interhemispheric cooperation rather than inhibition. AO and MI differentially impact interhemispheric coordination, serving to suppress inhibition only when AO is primed by MI.

neuroscience↗

bioRxiv2023

Quantifying similarities between MediaPipe and a known standard for tracking 2D hand trajectories

Marker-less motion tracking methods have promise for use in a range of domains, including clinical settings where traditional marker-based systems for human pose estimation is not feasible. MediaPipe is an artificial intelligence-based system that offers a markerless, lightweight approach to motion capture, and encompasses MediaPipe Hands, for recognition of hand landmarks. However, the accuracy of MediaPipe for tracking fine upper limb movements involving the hand has not been explored. Here we aimed to evaluate 2-dimensional accuracy of MediaPipe against a known standard. Participants (N = 10) performed trials in blocks of a touchscreen-based shape-tracing task. Each trial was simultaneously captured by a video camera. Trajectories for each trial were extracted from the touchscreen and compared to those predicted by MediaPipe. Specifically, following re-sampling, normalization, and Procrustes transformations, root mean squared error (RMSE; primary outcome measure) was calculated for coordinates generated by MediaPipe vs. the touchscreen computer. Resultant mean RMSE was 0.28 +/-0.064 normalized px. Equivalence testing revealed that accuracy differed between MediaPipe and the touchscreen, but that the true difference was between 0-0.30 normalized px (t(114) = -3.02, p = 0.002). Overall, we quantify similarities between MediaPipe and a known standard for tracking fine upper limb movements, informing applications of MediaPipe in a domains such as clinical and research settings. Future work should address accuracy in 3-dimensions to further validate the use of MediaPipe in such domains.

bioengineering↗

bioRxiv2022

Experience-dependent learning and myelin plasticity in individuals with stroke

BackgroundInjury to brain myelin disrupts motor performance and learning, however it is not clear if myelination is modulated by skilled motor practice or by recovery after stroke. Multi-component relaxation imaging can be used to measure water trapped between myelin bilayers which is expressed as myelin water fraction. The purpose of this study was to examine the effect of experience-dependent learning on myelin plasticity using multi-component relaxation imaging in individuals with stroke. MethodsThirty-two individuals with chronic stroke (>6 months) and twenty-seven healthy controls completed 4 weeks of skilled motor practice using a complex, gamified reaching task. Multi-component relaxation imaging-derived myelin water fraction was obtained before and after training. Seven brain regions associated with motor learning and sensorimotor function were investigated. ResultsAll participants improved task-specific reaching movements after training. In individuals with stroke: 1) pre-training myelin water fraction was lower in motor brain regions but higher in the cingulum compared to controls, 2) pre-training myelin water fraction in motor and sensorimotor regions was positively associated with learning rate, and 3) myelin water fraction was increased in the ipsilesional (contralateral to the trained arm) superior longitudinal fasciculus following skilled motor practice. ConclusionsFindings indicate that after stroke, myelin water fraction is related to measures of motor learning and modulated by 4 weeks of skilled motor practice with the paretic limb. Myelin water fraction can be enhanced in the chronic stage of stroke and may be an important target for upper-limb motor recovery.

neuroscience↗

bioRxiv2021

Multiple bouts of high-intensity interval exercise reverse age-related functional connectivity disruptions without affecting motor learning in older adults

Exercise has emerged as an intervention that may mitigate age-related resting state functional connectivity and sensorimotor declines. Here, 42 healthy older adults rested or completed 3 sets of high-intensity interval exercise for a total of 23 minutes, then immediately practiced an implicit motor task with their non-dominant hand across five separate sessions. Participants completed resting stage functional MRI before the first and after the fifth day of practice; they also returned 24-hours and 35-days later to complete short- and long-term retention. Independent component analysis of resting state functional MRI revealed increased connectivity in the frontoparietal, the dorsal attentional, and cerebellar networks and group. seed-based analysis showed strengthened connectivity between the limbic system and right cerebellum, and between the right cerebellum and bilateral middle temporal gyri in the exercise group. There was no motor learning advantage for the exercise group. Our data suggest that exercise paired with an implicit motor learning task in older adults can augment resting state functional connectivity without enhancing behaviour beyond that stimulated by skilled motor practice. Impact statementFive separate bouts of exercise paired with skilled motor practice strengthens resting state networks in brain regions that are susceptible to declines in older adults without affecting motor acquisition or learning.

neuroscience↗