Biology subjects

Lundbye-Jensen, J.

Publications and source records attributed to Lundbye-Jensen, J..

10 recordsLinked to original sources

bioRxiv2026

Age-Related Differences in Bimanual Coordination Are Associated with Increased Cerebellar Activity and Reduced Frontal Recruitment

Bimanual coordination declines in late adulthood, but the neural mechanisms underlying these changes remain unclear. Age-related differences in brain activity have been interpreted either as compensatory recruitment of frontal cognitive control regions or as a shift toward feedback-based control, supported by sensory and cerebellar processing systems. To investigate these hypotheses, we examined brain activity, using fMRI in twenty-three younger and twenty-three older adults performing a bimanual visuomotor pinch-force task with different task complexities. Behaviourally, older adults showed lower accuracy than younger adults, particularly when task demands increased. Neuroimaging results revealed general age-dependent increases in activity within posterior cerebellar lobules VI-VII, regions overlapping with the classical oculomotor vermis and implicated in visuomotor adaptation, movement calibration, and error-based motor learning. In addition, during the more demanding task condition, older adults showed a greater increase in activation of anterior cerebellar lobules IV-V and a decrease in activation of the medial frontal pole (BA10). No consistent age-related increases or decreases in task related activation was observed in parieto-frontal regions. Moreover, better task performance across age groups was associated with lower activation in frontal cognitive control regions, including the superior medial frontal gyrus and right inferior frontal gyrus. Together, these results suggest increased feedback- and error-related sensorimotor processing in older adults involving the cerebellum and frontal cortex.

neuroscience↗

bioRxiv2026

Transcranial Direct Current Stimulation enhances long-term retention after 5 days of lower-limb motor skill learning

Transcranial direct current stimulation (tDCS) holds the potential to affect behavior by modulating ongoing neural activity, and tDCS paired with hand motor practice can enhance motor learning. While augmenting the behavioral benefits of motor practice is relevant for neurorehabilitation following central and peripheral lesions to the motor system, as well as in sports, the short- and long-term effects of tDCS targeting the mesial motor cortex (M1-Leg) during lower-limb motor skill practice remain unexplored. We tested whether five days of anodal tDCS over M1-Leg during training of a sequential visuomotor tracking task improves within- and between-session learning and one-week retention. Participants were randomized to skill practice with active tDCS, skill practice with sham stimulation, or volume-matched non-skilled ankle movements with sham stimulation. Changes in corticospinal excitability accompanying skill and nonskill motor practice with real and sham tDCS, were assessed as motor evoked potential amplitudes recorded from the tibialis anterior muscle at rest. Compared to non-skill practice, motor skill practice yielded robust sequence-specific performance gains, which were transferred to the untrained leg and persisted for at least one week after practice ended. Concurrent tDCS did not increase learning within or between training sessions, but it did lead to improved one-week retention compared to sham stimulation. Corticospinal excitability did not increase after practice and was unaffected by tDCS. These findings suggest that combining lower-limb motor skill practice with tDCS over M1-Leg can strengthen retention of skill learning without measurable changes in resting corticospinal excitability. This is relevant for motor practice scheduling in neurorehabilitation. Key pointsO_LITranscranial direct current stimulation (tDCS) is a weak electrical brain stimulation that may boost learning when paired with motor practice; however, its effects during lower-limb skill training are not well known. C_LIO_LIWe tested whether stimulation over the leg area of the motor cortex during 5 days of ankle skill training improves learning, consolidation, and delayed retention. C_LIO_LIAnkle skill training produced clear sequence-specific improvements that transferred to the untrained leg and were still present 1 week later. C_LIO_LIStimulation did not increase short-term learning, but it did improve 1-week retention compared to sham stimulation. C_LIO_LICorticospinal excitability assessed based on motor evoked potentials elicited by transcranial magnetic stimulation did not change with motor training or stimulation, suggesting that the observed positive effect of tDCS on delayed retention may arise from other brain network processes relevant to long-term motor learning and memory. C_LI

neuroscience↗

bioRxiv2025

No Evidence for Stronger Brain-Behavior Associations in the Bimanual Motor Network of Older Adults

Bimanual motor performance declines with age, is accompanied by cortical thinning and alterations in white matter microstructure within motor control networks. Aging is also associated with increased interindividual variability in behavioural and structural markers, and some studies report stronger brain-behaviour associations in older compared to younger adults. However, evidence for this remains mixed, and it is unclear whether young adults express similar relationships under comparable task demands. We tested whether bimanual performance is related differently to structural brain properties in younger and older adults. Twenty-three younger (22-27 years) and twenty-three older adults (65-70 years) performed a visually guided bimanual pinch-force task and underwent whole-brain structural magnetic resonance imaging (MRI). Fractional anisotropy (FA) and cortical thickness (CTh) were extracted from a pre-defined bilateral visuo-motor network and compared between groups. In regions showing significant age-related differences, we tested whether and how FA and CTh values correlates with bimanual performance within each age group. Older adults showed lower FA in the anterior portions of the bilateral superior longitudinal fasciculus (SLF) III and right inferior fronto-occipital fasciculus (IFOF), and lower CTh across most visuomotor regions, along with lower bimanual performance compared to young adults. Structure-function analyses in these areas revealed that bimanual performance correlated positively with FA in the anterior segment of the right SLF III in younger but not older adults. Furthermore, larger hemispheric asymmetries in cortical thickness between the dominant and non-dominant SMA correlated positively with larger intermanual performance differences between the dominant and non-dominant hand in younger but not older adults. These findings suggest that intrahemispheric white-matter integrity and interhemispheric cortical balance support efficient bimanual control in early adulthood, but they provide no evidence that structure-function relationships increase with age.

neuroscience↗

bioRxiv2025

Wearable MEG data recorded during human stepping

Non-invasive spatiotemporal imaging of brain activity during large-scale, whole body movement is a significant methodological challenge for the field of movement neuroscience. Here, we present a dataset recorded using a new imaging modality - optically-pumped magnetoencephalography (OP-MEG) - to record brain activity during human stepping. Participants (n=3) performed a visually guided stepping task requiring precise foot placement while dual-axis and triaxial OP-MEG and leg muscle activity (electromyography, EMG) were recorded. The dataset also includes a structural MRI for each participant and foot kinematics. We validate the fidelity of the OPM data by showing movement-related beta band desynchronization source localised to the primary motor cortex. This multimodal dataset offers a resource for methodological development and testing for OPM data (e.g., movement-related interference rejection), within-subject analyses, and exploratory analyses to generate hypotheses for further work on the neural control of human stepping.

neuroscience↗

bioRxiv2024

Force, angle, and velocity parameters of finger movements are reflected in corticospinal excitability

Identifying which movement parameters are reflected in the corticospinal excitability (CSE) will improve our understanding human motor control. Change in CSE measured with transcranial magnetic stimulation (TMS)-induced motor evoked potentials (MEPs) can probe the content of the signal from primary motor cortex (M1) through the corticospinal pathway and spinal motoneurons to the muscle. Here we used MEPs to investigate which movement-related parameters are reflected in CSE in 33 healthy adults. In three separate tasks, we evaluated which movement parameter(s), force, angle, and velocity, are reflected in the MEP amplitude during movement preparation and movement execution. Bayesian model comparison in a forward feature selection framework identified force and velocity measures as reflected in the MEP amplitude during movement preparation, and force, angle, and velocity measures as reflected in the MEP amplitude during movement execution. Importantly, we included measures of electromyography (EMG) in the forward feature selection, and the parameter measures are included only if they add explanatory power of MEP amplitude in addition to the EMG. These findings show that when taking EMG measures into account, all three movement parameters force, angle, and velocity are reflected in CSE. These findings propose a flexible and task-dependent form of signaling in the motor system that allows parameter-specific modulation of CSE to accurately control finger movements. Key pointsO_LIPrior research show that the primary motor cortex activity reflects movement parameters. C_LIO_LIMeasures of the response to a magnetic stimulation, the motor evoked potential (MEP), can be used to assess the content of the signal sent to the muscle. C_LIO_LIWe use Bayesian model comparison to test whether movement parameters are reflected in the models best describing the MEP amplitude modulations. C_LIO_LIWe show that the MEP amplitude reflects all tested movement parameters, force, angle, and velocity. C_LIO_LIOur results indicate a task-dependent form of signaling not only in M1, but also in the corticospinal pathway and spinal motor neurons propagating the signal to the muscle. C_LI

neuroscience↗

bioRxiv2023

Hebbian priming of human spinal motor learning

Learning or relearning of motor skills requires plasticity in relevant neural circuits. Motor recovery following lesions to the corticospinal system can be augmented through neuromodulation techniques targeting the affected or compensatory neural circuits. By repeatedly pairing transcranial magnetic stimulation of the primary motor cortex (M1) and motoneuronal electrical stimulation (i.e., paired corticomotoneuronal stimulation, PCMS) timed to arrive at the corticomotoneuronal (CM) synapses in close temporal proximity, spike-timing-dependent bidirectional changes in CM transmission can be induced in humans (Taylor & Martin, 2009). PCMS-induced increases in CM transmission have been demonstrated to transiently improve motor control in patients with spinal cord injury (Bunday & Perez 2012), whereas effects on the malleability of neural circuits are entirely unexplored. We hypothesized that PCMS can prime mechanisms of subsequent motor learning exclusively when directed to the neural circuitry underpinning the motor behavior. In three experiments, we provide the first evidence ( Experiment I) and a double-blinded, sham-controlled replication ( Experiment II) that PCMS targeting the spinal CM synapses can prime subsequent learning of rapid finger movements relying on spinal neuroplasticity. Finally, we demonstrate that the effects of PCMS are circuit-specific and bidirectional. When PCMS was timed to arrive at a facilitatory interval in M1 but an inhibitory interval at the CM synapses subsequent learning was transiently impeded ( Experiment III). Taken together, our results provide proof-of-principle that non-invasively induced plasticity governed by Hebbian learning rules interacts with experience-dependent plasticity in the spinal cord with positive implications for motor learning. Our results offer a mechanistic rationale for priming sensorimotor training with individualized PCMS to enhance the effects of motor practice in neurorehabilitation. HighlightsO_LIPaired corticomotoneuronal stimulations (PCMS) promote ballistic motor learning and facilitate corticospinal excitability compared to rest and sham protocols. C_LIO_LIA double-blinded sham experiment replicates priming effects of PCMS on ballistic motor learning and demonstrates long-term benefits of combined PCMS and motor practice. C_LIO_LIThe facilitating effect of PCMS on ballistic motor learning is circuit-specific with superior effects on ballistic motor learning after facilitating PCMS compared to control protocols. C_LI

neuroscience↗

bioRxiv2022

Visuomotor skill learning in young adults with Down syndrome

BackgroundIndividuals with Down syndrome (DS) have impaired general motor skills compared to typically developed (TD) individuals. AimsTo gain knowledge on how young adults with DS learn and retain new motor skills. Methods and ProceduresA DS-group (mean age = 23.9 {+/-} 3 years, N = 11), and an age- matched TD-group (mean age 22.8 {+/-} 1.8, N= 14) were recruited. The participants practiced a sequence visuomotor accuracy tracking task (VATT). Online and offline effects of practice were assessed in immediate and 7-day retention tests. Participants practiced the task in seven blocks (10.6 minutes). Outcomes and ResultsThe TD-group performed better than the DS-group in all blocks (all P < 0.001). Both groups improved VATT-performance online from baseline to immediate retention (all P < 0.001). The DS-groups performance at 7-day retention was at the same level as the immediate retention tests ({Delta}DS). An offline decrease in performance was found in the TD-group ({Delta}TD, P < 0.001). A between-group difference was observed in the offline effect on the sequence task ({Delta}TD - {Delta}DS, P = 0.04). Conclusions and ImplicationsThe motor performance of adults with DS is lower compared to their TD peers. However, adults with DS display significant online performance improvement during training, and offline consolidation following motor learning. What this paper addsLearning new motor skills is fundamental throughout our lifespan. Persons with Down syndrome have other prerequisites for learning new tasks, related to psychological, physiological, and anatomical factors imposed by the syndrome. This study is the first to investigate online and offline learning effects of a single motor skill training session in adults with DS. Our results show generally lower motor performance in DS individuals compared to the typically developed population, but with equal online learning effects. Both groups demonstrate retention, i.e., offline stabilisation but while TD demonstrate negative offline effects, this was not the case for DS. These results should be taken into consideration when planning training of motor and general life skills for adults with DS. This work lays the ground for further investigations of the trajectory of the early learning processes and the mechanisms involved when this target group acquires new skills.

neuroscience↗

bioRxiv2021

Behavioural variability and cortical electrophysiological signals depend on recent outcomes during human reinforcement motor learning

The history of our actions and the outcomes of these represent important information, which can inform choices, and efficiently guide future behaviour. While unsuccessful (S-) outcomes are expected to lead to more explorative motor states and increased behavioural variability, successful (S+) outcomes lead to reinforcement of the previous action and thus exploitation. Here, we show that during reinforcement motor learning, humans attribute different values to previous actions when they experience S- vs. S+ outcomes. Behavioural variability after S- outcomes is influenced more by the previous outcomes compared to what is observed after S+ outcomes. Using electroencephalography, we show that neural oscillations of the prefrontal cortex encode the level of reinforcement (high beta frequencies) and reflect the detection of reward prediction errors (theta frequencies). The results suggest that S+ experiences overwrite previous motor states to a greater extent than S- experiences and that modulations in neural oscillations in the prefrontal cortex play a potential role in encoding the (changes in) movement variability state during reinforcement motor learning.

neuroscience↗

bioRxiv2020

Development of functional corticomuscular connectivity from childhood to adulthood during precision grip with the dominant and non-dominant hand

How does the neural control of manual movements mature from childhood to adulthood? Here, we investigated developmental differences in functional corticomuscular connectivity using coherence techniques in 91 individuals recruited from four different age groups covering the age range 8-30y. EEG and EMG were recorded while participants performed a unimanual visual force-tracing task requiring fine control of the force produced in a precision grip with both the dominant and non-dominant hand. Using beamforming methods, we reconstructed source activity from EEG data displaying peak coherence with the active FDI muscle during the task in order to assess functional corticomuscular connectivity. Our results revealed that coherence was greater in adolescents and adults than in children and that the difference in coherence between children and adults was driven by a greater magnitude of descending (cortex-to-muscle) coherence. This was paralleled by the observation of a posterior-to-anterior shift in the cortical sources displaying corticomuscular coherence within the contralateral hemisphere from late adolescence. Finally, we observed that corticomuscular coherence was higher on the non-dominant compared to the dominant hand across age groups. These findings provide a detailed characterization of differences in task-related corticomuscular connectivity for individuals at different stages of typical ontogenetic development that may be related to the maturational refinement of dexterous motor control. Key points- Fine motor control is gradually refined during human motor development, but little is known about the underlying neurophysiological mechanisms. - Here, we used EEG and EMG to investigate functional corticomuscular connectivity during a precision grip with the dominant and non-dominant hand in 91 typically developed children, adolescents and adults (age range 8-30y). - We show that older adolescents and adults are characterized by greater levels of corticomuscular coherence compared to children and that this is mainly driven by greater magnitudes of descending coherence (cortex-to-muscle). This is paralleled by a more anterior cortical site of coherence in older adolescents and adults compared to younger individuals. - These results help us better understand the ontogenetic development of task-related functional connectivity in sensorimotor networks.

neuroscience↗

bioRxiv2019

Directed connectivity between primary and premotor areas underlying ankle force control in young and older adults

The control of ankle muscle force is an integral component of walking and postural control. Aging impairs the ability to produce force steadily and accurately, which can compromise functional capacity and quality of life. Here, we hypothesized that reduced force control in older adults would be associated with altered cortico-cortical communication within a network comprising the primary motor area (M1), the premotor cortex (PMC), parietal, and prefrontal regions. We examined electroencephalographic (EEG) responses from fifteen younger (20-26 yr) and fifteen older (65-73 yr) participants during a unilateral dorsiflexion force-tracing task. Dynamic Causal Modelling (DCM) and Parametric Empirical Bayes (PEB) were used to investigate how directed connectivity between contralateral M1, PMC, parietal, and prefrontal regions was related to age group and precision in force production. DCM and PEB analyses revealed that the strength of connections between PMC and M1 were related to ankle force precision and differed by age group. For young adults, bidirectional PMC-M1 coupling was negatively related to task performance: stronger backward M1-PMC and forward PMC-M1 coupling was associated with worse force precision. The older group exhibited deviations from this pattern. For the PMC to M1 coupling, there were no age-group differences in coupling strength; however, within the older group, stronger coupling was associated with better performance. For the M1 to PMC coupling, older adults followed the same pattern as young adults - with stronger coupling accompanied by worse performance - but coupling strength was lower than in the young group. Our results suggest that bidirectional M1-PMC communication is related to precision in ankle force production and that this relationship changes with aging. We argue that the observed age-related differences reflect compensatory mechanisms whereby older adults maintain performance in the face of declines in the sensorimotor system.

neuroscience↗