RESUMEN
The role of the cerebral cortex in self-initiated versus sensory-driven movements is central to understanding volitional action. Whether the differences in these two movement classes are due to specific cortical areas versus more cortex-wide engagement is debated. Using wide-field Ca2+ imaging, we compared neural dynamics during spontaneous and motorized treadmill locomotion, determining the similarities and differences in cortex-wide activation and functional connectivity (FC). During motorized locomotion, the cortex exhibits greater activation globally prior to and during locomotion starting compared to spontaneous and less during steady-state walking, during stopping, and after termination. Both conditions are characterized by FC increases in anterior secondary motor cortex (M2) nodes and decreases in all other regions. There are also cortex-wide differences; most notably, M2 decreases in FC with all other nodes during motorized stopping and after termination. Therefore, both internally- and externally-generated movements widely engage the cortex, with differences represented in cortex-wide activation and FC patterns.
Asunto(s)
Calcio , Locomoción , Corteza Motora , Corteza Motora/fisiología , Corteza Motora/diagnóstico por imagen , Calcio/metabolismo , Animales , Locomoción/fisiología , Masculino , Corteza Cerebral/fisiología , Corteza Cerebral/diagnóstico por imagen , Femenino , Mapeo Encefálico/métodos , Ratones , Caminata/fisiologíaRESUMEN
Stroke is an acute cerebrovascular disease in which sudden interruption of blood supply to the brain or rupture of cerebral blood vessels cause damage to brain cells and consequently impair the patient's motor and cognitive abilities. A novel rehabilitation training model integrating brain-computer interface (BCI) and virtual reality (VR) not only promotes the functional activation of brain networks, but also provides immersive and interesting contextual feedback for patients. In this paper, we designed a hand rehabilitation training system integrating multi-sensory stimulation feedback, BCI and VR, which guides patients' motor imaginations through the tasks of the virtual scene, acquires patients' motor intentions, and then carries out human-computer interactions under the virtual scene. At the same time, haptic feedback is incorporated to further increase the patients' proprioceptive sensations, so as to realize the hand function rehabilitation training based on the multi-sensory stimulation feedback of vision, hearing, and haptic senses. In this study, we compared and analyzed the differences in power spectral density of different frequency bands within the EEG signal data before and after the incorporation of haptic feedback, and found that the motor brain area was significantly activated after the incorporation of haptic feedback, and the power spectral density of the motor brain area was significantly increased in the high gamma frequency band. The results of this study indicate that the rehabilitation training of patients with the VR-BCI hand function enhancement rehabilitation system incorporating multi-sensory stimulation can accelerate the two-way facilitation of sensory and motor conduction pathways, thus accelerating the rehabilitation process.
Asunto(s)
Interfaces Cerebro-Computador , Electroencefalografía , Mano , Rehabilitación de Accidente Cerebrovascular , Realidad Virtual , Humanos , Mano/fisiología , Rehabilitación de Accidente Cerebrovascular/métodos , Rehabilitación de Accidente Cerebrovascular/instrumentación , Retroalimentación Sensorial , Interfaz Usuario-Computador , Corteza Motora/fisiologíaRESUMEN
A simple button press towards a prime stimulus enhances subsequent visual search for objects that match the prime. The present study investigated whether this action effect is a general phenomenon across different task domains, and the underlying neural mechanisms. The action effect was measured in an unspeeded size-matching task, with the presentation of the central target and the surrounding inducers of the Ebbinghaus illusion together to one eye or separately to each eye, and when repetitive TMS was applied over right primary motor cortex (M1). The results showed that a prior key-press significantly reduced the illusion effect compared to passive viewing. Notably, the action effect persisted with dichoptic presentation of the Ebbinghaus configuration, but disappeared with the right M1 disruption. These results suggest that action guides visual perception to influence human behavior, which mainly affects the late visual processing stage and probably relies on feedback projections from the motor cortex.
Asunto(s)
Corteza Motora , Desempeño Psicomotor , Percepción del Tamaño , Estimulación Magnética Transcraneal , Humanos , Masculino , Femenino , Adulto Joven , Adulto , Corteza Motora/fisiología , Percepción del Tamaño/fisiología , Desempeño Psicomotor/fisiología , Percepción Visual/fisiología , Estimulación LuminosaRESUMEN
The relationship between speech production and perception is a topic of ongoing debate. Some argue that there is little interaction between the two, while others claim they share representations and processes. One perspective suggests increased recruitment of the speech motor system in demanding listening situations to facilitate perception. However, uncertainties persist regarding the specific regions involved and the listening conditions influencing its engagement. This study used activation likelihood estimation in coordinate-based meta-analyses to investigate the neural overlap between speech production and three speech perception conditions: speech-in-noise, spectrally degraded speech and linguistically complex speech. Neural overlap was observed in the left frontal, insular and temporal regions. Key nodes included the left frontal operculum (FOC), left posterior lateral part of the inferior frontal gyrus (IFG), left planum temporale (PT), and left pre-supplementary motor area (pre-SMA). The left IFG activation was consistently observed during linguistic processing, suggesting sensitivity to the linguistic content of speech. In comparison, the left pre-SMA activation was observed when processing degraded and noisy signals, indicating sensitivity to signal quality. Activations of the left PT and FOC activation were noted in all conditions, with the posterior FOC area overlapping in all conditions. Our meta-analysis reveals context-independent (FOC, PT) and context-dependent (pre-SMA, posterior lateral IFG) regions within the speech motor system during challenging speech perception. These regions could contribute to sensorimotor integration and executive cognitive control for perception and production.
Asunto(s)
Percepción del Habla , Habla , Humanos , Percepción del Habla/fisiología , Habla/fisiología , Mapeo Encefálico , Funciones de Verosimilitud , Corteza Motora/fisiología , Corteza Cerebral/fisiología , Corteza Cerebral/diagnóstico por imagenRESUMEN
Episodic memory (EM) allows us to remember and relive past events and experiences and has been linked to cortical-hippocampal reinstatement of encoding activity. While EM is fundamental to establish a sense of self across time, this claim and its link to the sense of agency (SoA), based on bodily signals, has not been tested experimentally. Using real-time sensorimotor stimulation, immersive virtual reality, and fMRI we manipulated the SoA and report stronger hippocampal reinstatement for scenes encoded under preserved SoA, reflecting recall performance in a recognition task. We link SoA to EM showing that hippocampal reinstatement is coupled with reinstatement in premotor cortex, a key SoA region. We extend these findings in a severe amnesic patient whose memory lacked the normal dependency on the SoA. Premotor-hippocampal coupling in EM describes how a key aspect of the bodily self at encoding is neurally reinstated during the retrieval of past episodes, enabling a sense of self across time.
Asunto(s)
Hipocampo , Imagen por Resonancia Magnética , Memoria Episódica , Corteza Motora , Humanos , Hipocampo/fisiología , Masculino , Femenino , Corteza Motora/fisiología , Corteza Motora/diagnóstico por imagen , Adulto , Recuerdo Mental/fisiología , Adulto Joven , Amnesia/fisiopatología , Amnesia/psicología , Persona de Mediana EdadRESUMEN
Patellar tendinopathy (PT) typically affects jumping-sport athletes with functional impairments frequently observed. Alterations to the functional organization of corticomotor neurons within the motor cortex that project to working muscles are evident in some musculoskeletal conditions and linked to functional impairments. We aimed to determine if functional organization of corticomotor neuron projections differs between athletes with PT and asymptomatic controls, and if organization is associated with neuromuscular control. We used a cross-sectional design, and the setting was Monash Biomedical Imaging. Basketball and volleyball athletes with (n = 8) and without PT (n = 8) completed knee extension and ankle dorsiflexion force matching tasks while undergoing fMRI. We determined functional organization via identification of the location of peak corticomotor neuron activation during respective tasks (expressed in X, Y, and Z coordinates) and calculated force matching accuracy for both tasks to quantify neuromuscular control. We observed significant interactions between group and coordinate plane for functional organization of corticomotor projections to knee extensors (p < 0.001) and ankle dorsiflexors (p = 0.016). Compared to controls, PT group peak corticomotor activation during the knee extension task was 9.6 mm medial (p < 0.001) and 5.2 mm posterior (p = 0.036), and during the ankle dorsiflexion task 8.2 mm inferior (p = 0.024). In the PT group, more posterior Y coordinate peak activation location during the knee extension task was associated with greater task accuracy (r = 0.749, p = 0.034). Functional organization of corticomotor neurons differed in jumping athletes with PT compared to controls. Links between functional organization and neuromuscular control in the PT group suggest organizational differences may be relevant to knee extension neuromuscular control preservation.
Asunto(s)
Baloncesto , Imagen por Resonancia Magnética , Corteza Motora , Tendinopatía , Voleibol , Humanos , Voleibol/fisiología , Baloncesto/fisiología , Corteza Motora/fisiología , Corteza Motora/fisiopatología , Estudios Transversales , Tendinopatía/fisiopatología , Masculino , Adulto Joven , Femenino , Adulto , Neuronas Motoras/fisiología , Ligamento Rotuliano/fisiopatología , Ligamento Rotuliano/fisiología , Atletas , Estudios de Casos y ControlesRESUMEN
Many studies over the recent decades have attempted the modulation of motor learning using brain stimulation. Alternating currents allow for researchers not only to electrically stimulate the brain, but to further investigate the effects of specific frequencies, in and beyond the context of their endogenous associations. Transcranial alternating current stimulation (tACS) has therefore been used during motor learning to modulate aspects of acquisition, consolidation and performance of a learned motor skill. Despite numerous reviews on the effects of tACS, and its role in motor learning, there are few studies which synthesize the numerous frequencies and their respective theoretical mechanisms as they relate to motor and perceptual processes. Here we provide a short overview of the main stimulation frequencies used in motor learning modulation (e.g., alpha, beta, and gamma), and discuss the effect and proposed mechanisms of these studies. We summarize with the current state of the field, the effectiveness and variability in motor learning modulation, and novel mechanistic proposals from other fields.
Asunto(s)
Aprendizaje , Destreza Motora , Estimulación Transcraneal de Corriente Directa , Humanos , Estimulación Transcraneal de Corriente Directa/métodos , Aprendizaje/fisiología , Destreza Motora/fisiología , Corteza Motora/fisiologíaRESUMEN
Long-term electroencephalography (EEG) recordings have primarily been used to study resting-state fluctuations. These recordings provide valuable insights into various phenomena such as sleep stages, cognitive processes, and neurological disorders. However, this study explores a new angle, focusing for the first time on the evolving nature of EEG dynamics over time within the context of movement. Twenty-two healthy individuals were measured six times from 2 p.m. to 12 a.m. with intervals of 2 h while performing four right-hand gestures. Analysis of movement-related cortical potentials (MRCPs) revealed a reduction in amplitude for the motor and post-motor potential during later hours of the day. Evaluation in source space displayed an increase in the activity of M1 of the contralateral hemisphere and the SMA of both hemispheres until 8 p.m. followed by a decline until midnight. Furthermore, we investigated how changes over time in MRCP dynamics affect the ability to decode motor information. This was achieved by developing classification schemes to assess performance across different scenarios. The observed variations in classification accuracies over time strongly indicate the need for adaptive decoders. Such adaptive decoders would be instrumental in delivering robust results, essential for the practical application of BCIs during day and nighttime usage.
Asunto(s)
Electroencefalografía , Gestos , Mano , Humanos , Electroencefalografía/métodos , Masculino , Femenino , Mano/fisiología , Adulto , Adulto Joven , Movimiento/fisiología , Corteza Motora/fisiología , Interfaces Cerebro-ComputadorRESUMEN
The efficiency of motor skill acquisition is age-dependent, making it increasingly challenging to learn complex manoeuvres later in life. Zebra finches, for instance, acquire a complex vocal motor programme during a developmental critical period after which the learned song is essentially impervious to modification. Although inhibitory interneurons are implicated in critical period closure, it is unclear whether manipulating them can reopen heightened motor plasticity windows. Using pharmacology and a cell-type specific optogenetic approach, we manipulated inhibitory neuron activity in a premotor area of adult zebra finches beyond their critical period. When exposed to auditory stimulation in the form of novel songs, manipulated birds added new vocal syllables to their stable song sequence. By lifting inhibition in a premotor area during sensory experience, we reintroduced vocal plasticity, promoting an expansion of the syllable repertoire without compromising pre-existing song production. Our findings provide insights into motor skill learning capacities, offer potential for motor recovery after injury, and suggest avenues for treating neurodevelopmental disorders involving inhibitory dysfunctions.
Asunto(s)
Pinzones , Interneuronas , Aprendizaje , Vocalización Animal , Animales , Pinzones/fisiología , Vocalización Animal/fisiología , Masculino , Interneuronas/fisiología , Aprendizaje/fisiología , Estimulación Acústica , Optogenética , Plasticidad Neuronal/fisiología , Destreza Motora/fisiología , Período Crítico Psicológico , Corteza Motora/fisiología , FemeninoRESUMEN
This systematic review and meta-analysis assesses independently the acute effects of anodal and cathodal motor cortex transcranial direct current stimulation (tDCS) on athletic performance in healthy adults. Besides, it evaluates the unique and conjoint effects of potential moderators (i.e., stimulation parameters, exercise type, subjects' training status and risk of bias). Online database search was performed from inception until March 18th 2024 (PROSPERO: CRD42023355461). Forty-three controlled trials were included in the systematic review, 40 in the anodal tDCS meta-analysis (68 effects), and 9 (11 effects) in the cathodal tDCS meta-analysis. Performance enhancement between pre- and post-stimulation was the main outcome measure considered. The anodal tDCS effects on physical performance were small to moderate (g = .29, 95%CI [.18, .40], PI = -.64 to 1.23, I2 = 64.0%). Exercise type, training status and use of commercial tDCS were significant moderators of the results. The cathodal tDCS effects were null (g = .04, 95%CI [-.05, .12], PI = -.14 to .23, I2 = 0%), with a small to moderate heterogeneity entirely due to sampling error, thus impairing further moderator analysis. These findings hold significant implications for the field of brain stimulation and physical performance, as they not only demonstrate a small to moderate effect of acute tDCS but also identify specific categories of individuals, devices and activities that are more susceptible to improvements. By addressing the multidimensional factors influencing the mechanisms of tDCS, we also provide suggestions for future research.
Asunto(s)
Rendimiento Atlético , Corteza Motora , Estimulación Transcraneal de Corriente Directa , Estimulación Transcraneal de Corriente Directa/métodos , Humanos , Corteza Motora/fisiología , Rendimiento Atlético/fisiología , AdultoRESUMEN
Coordinated movement requires the nervous system to continuously compensate for changes in mechanical load across different conditions. For voluntary movements like reaching, the motor cortex is a critical hub that generates commands to move the limbs and counteract loads. How does cortex contribute to load compensation when rhythmic movements are sequenced by a spinal pattern generator? Here, we address this question by manipulating the mass of the forelimb in unrestrained mice during locomotion. While load produces changes in motor output that are robust to inactivation of motor cortex, it also induces a profound shift in cortical dynamics. This shift is minimally affected by cerebellar perturbation and significantly larger than the load response in the spinal motoneuron population. This latent representation may enable motor cortex to generate appropriate commands when a voluntary movement must be integrated with an ongoing, spinally-generated rhythm.
Asunto(s)
Locomoción , Corteza Motora , Neuronas Motoras , Animales , Corteza Motora/fisiología , Ratones , Neuronas Motoras/fisiología , Locomoción/fisiología , Miembro Anterior/fisiología , Masculino , Ratones Endogámicos C57BL , Movimiento/fisiología , Médula Espinal/fisiología , Femenino , Cerebelo/fisiologíaRESUMEN
Neurofeedback (NF) is a promising intervention for improvements in motor performance in Parkinson's disease. This NF pilot study in healthy participants aimed to achieve the following: (1) determine participants' ability to bi-directionally modulate sensorimotor beta power and (2) determine the effect of NF on movement performance. A real-time EEG-NF protocol was used to train participants to increase and decrease their individual motor cortex beta power amplitude, using a within-subject double-blind sham-controlled approach. Movement was assessed using a Go/No-go task. Participants completed the NASA Task Load Index and provided verbal feedback of the NF task difficulty. All 17 participants (median age = 38 (19-65); 10 females) reliably reduced sensorimotor beta power. No participant could reliably increase their beta activity. Participants reported that the NF task was challenging, particularly increasing beta. A modest but significant increase in reaction time correlated with a reduction in beta power only in the real condition. Findings suggest that beta power control difficulty varies by modulation direction, affecting participant perceptions. A correlation between beta power reduction and reaction times only in the real condition suggests that intentional beta power reduction may shorten reaction times. Future research should examine the minimum beta threshold for meaningful motor improvements, and the relationship between EEG mechanisms and NF learning to optimise NF outcomes.
Asunto(s)
Electroencefalografía , Neurorretroalimentación , Enfermedad de Parkinson , Humanos , Enfermedad de Parkinson/fisiopatología , Enfermedad de Parkinson/terapia , Femenino , Masculino , Persona de Mediana Edad , Anciano , Neurorretroalimentación/métodos , Adulto , Electroencefalografía/métodos , Movimiento/fisiología , Ritmo beta/fisiología , Adulto Joven , Proyectos Piloto , Tiempo de Reacción/fisiología , Corteza Motora/fisiopatología , Corteza Motora/fisiología , Método Doble CiegoRESUMEN
The primary motor cortex does not uniquely or directly produce alpha motoneurone (α-MN) drive to muscles during voluntary movement. Rather, α-MN drive emerges from the synthesis and competition among excitatory and inhibitory inputs from multiple descending tracts, spinal interneurons, sensory inputs, and proprioceptive afferents. One such fundamental input is velocity-dependent stretch reflexes in lengthening muscles, which should be inhibited to enable voluntary movement. It remains an open question, however, the extent to which unmodulated stretch reflexes disrupt voluntary movement, and whether and how they are inhibited in limbs with numerous multiarticular muscles. We used a computational model of a Rhesus Macaque arm to simulate movements with feedforward α-MN commands only, and with added velocity-dependent stretch reflex feedback. We found that velocity-dependent stretch reflex caused movement-specific, typically large and variable disruptions to arm movements. These disruptions were greatly reduced when modulating velocity-dependent stretch reflex feedback (i) as per the commonly proposed (but yet to be clarified) idealized alpha-gamma (α-γ) coactivation or (ii) an alternative α-MN collateral projection to homonymous γ-MNs. We conclude that such α-MN collaterals are a physiologically tenable propriospinal circuit in the mammalian fusimotor system. These collaterals could still collaborate with α-γ coactivation, and the few skeletofusimotor fibers (ß-MNs) in mammals, to create a flexible fusimotor ecosystem to enable voluntary movement. By locally and automatically regulating the highly nonlinear neuro-musculo-skeletal mechanics of the limb, these collaterals could be a critical low-level enabler of learning, adaptation, and performance via higher-level brainstem, cerebellar, and cortical mechanisms.
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Macaca mulatta , Neuronas Motoras , Reflejo de Estiramiento , Reflejo de Estiramiento/fisiología , Animales , Neuronas Motoras/fisiología , Movimiento/fisiología , Músculo Esquelético/fisiología , Corteza Motora/fisiología , Simulación por Computador , Modelos Neurológicos , Brazo/fisiologíaRESUMEN
Functional coactivation between human brain regions is partly explained by white matter connections; however, how the structure-function relationship varies by function remains unclear. Here, we reference large data repositories to compute maps of structure-function correspondence across hundreds of specific functions and brain regions. We use natural language processing to accurately predict structure-function correspondence for specific functions and to identify macroscale gradients across the brain that correlate with structure-function correspondence as well as cortical thickness. Our findings suggest structure-function correspondence unfolds along a sensory-fugal organizational axis, with higher correspondence in primary sensory and motor cortex for perceptual and motor functions, and lower correspondence in association cortex for cognitive functions. Our study bridges neuroscience and natural language to describe how structure-function coupling varies by region and function in the brain, offering insight into the diversity and evolution of neural network properties.
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Mapeo Encefálico , Encéfalo , Humanos , Encéfalo/fisiología , Encéfalo/diagnóstico por imagen , Mapeo Encefálico/métodos , Relación Estructura-Actividad , Imagen por Resonancia Magnética , Red Nerviosa/fisiología , Masculino , Femenino , Adulto , Sustancia Blanca/fisiología , Sustancia Blanca/diagnóstico por imagen , Procesamiento de Lenguaje Natural , Corteza Motora/fisiología , Corteza Motora/anatomía & histología , Cognición/fisiologíaRESUMEN
BACKGROUND: Repetitive Transcranial Magnetic Stimulation (rTMS) and EEG-guided neurofeedback techniques can reduce motor symptoms in Parkinson's disease (PD). However, the effects of their combination are unknown. Our objective was to determine the immediate and short-term effects on motor and non-motor symptoms, and neurophysiological measures, of rTMS and EEG-guided neurofeedback, alone or combined, compared to no intervention, in people with PD. METHODS: A randomized, single-blinded controlled trial with 4 arms was conducted. Group A received eight bilateral, high-frequency (10 Hz) rTMS sessions over the Primary Motor Cortices; Group B received eight 30-minute EEG-guided neurofeedback sessions focused on reducing average bilateral alpha and beta bands; Group C received a combination of A and B; Group D did not receive any therapy. The primary outcome measure was the UPDRS-III at post-intervention and two weeks later. Secondary outcomes were functional mobility, limits of stability, depression, health-related quality-of-life and cortical silent periods. Treatment effects were obtained by longitudinal analysis of covariance mixed-effects models. RESULTS: Forty people with PD participated (27 males, age = 63 ± 8.26 years, baseline UPDRS-III = 15.63 ± 6.99 points, H&Y = 1-3). Group C showed the largest effect on motor symptoms, health-related quality-of-life and cortical silent periods, followed by Group A and Group B. Negligible differences between Groups A-C and Group D for functional mobility or limits of stability were found. CONCLUSIONS: The combination of rTMS and EEG-guided neurofeedback diminished overall motor symptoms and increased quality-of-life, but this was not reflected by changes in functional mobility, postural stability or depression levels. TRIAL REGISTRATION: NCT04017481.
Asunto(s)
Electroencefalografía , Neurorretroalimentación , Enfermedad de Parkinson , Estimulación Magnética Transcraneal , Humanos , Enfermedad de Parkinson/terapia , Enfermedad de Parkinson/rehabilitación , Enfermedad de Parkinson/complicaciones , Masculino , Femenino , Persona de Mediana Edad , Estimulación Magnética Transcraneal/métodos , Neurorretroalimentación/métodos , Anciano , Electroencefalografía/métodos , Método Simple Ciego , Resultado del Tratamiento , Corteza Motora/fisiología , Corteza Motora/fisiopatología , Calidad de VidaRESUMEN
Hand visibility affects motor control, perception, and attention, as visual information is integrated into an internal model of somatomotor control. Spontaneous brain activity, i.e., at rest, in the absence of an active task, is correlated among somatomotor regions that are jointly activated during motor tasks. Recent studies suggest that spontaneous activity patterns not only replay task activation patterns but also maintain a model of the body's and environment's statistical regularities (priors), which may be used to predict upcoming behavior. Here, we test whether spontaneous activity in the human somatomotor cortex as measured using fMRI is modulated by visual stimuli that display hands vs. non-hand stimuli and by the use/action they represent. A multivariate pattern analysis was performed to examine the similarity between spontaneous activity patterns and task-evoked patterns to the presentation of natural hands, robot hands, gloves, or control stimuli (food). In the left somatomotor cortex, we observed a stronger (multivoxel) spatial correlation between resting state activity and natural hand picture patterns compared to other stimuli. No task-rest similarity was found in the visual cortex. Spontaneous activity patterns in somatomotor brain regions code for the visual representation of human hands and their use.
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Mapeo Encefálico , Mano , Imagen por Resonancia Magnética , Percepción Visual , Humanos , Mano/fisiología , Masculino , Femenino , Adulto , Percepción Visual/fisiología , Adulto Joven , Encéfalo/fisiología , Encéfalo/diagnóstico por imagen , Corteza Motora/fisiología , Corteza Motora/diagnóstico por imagen , Descanso/fisiología , Estimulación Luminosa , Corteza Visual/fisiología , Corteza Visual/diagnóstico por imagenRESUMEN
How cortical oscillations are involved in the coordination of functionally coupled muscles and how this is modulated by different movement contexts (static vs dynamic) remains unclear. Here, this is investigated by recording high-density electroencephalography (EEG) and electromyography (EMG) from different forearm muscles while healthy participants (n = 20) performed movement tasks (static and dynamic posture holding, and reaching) with their dominant hand. When dynamic perturbation was applied, beta band (15-35 Hz) activities in the motor cortex contralateral to the performing hand reduced during the holding phase, comparative to when there was no perturbation. During static posture holding, transient periods of increased cortical beta oscillations (beta bursts) were associated with greater corticomuscular coherence and increased phase synchrony between muscles (intermuscular coherence) in the beta frequency band compared to the no-burst period. This effect was not present when resisting dynamic perturbation. The results suggest that cortical beta bursts assist synchronisation of different muscles during static posture holding in healthy motor control, contributing to the maintenance and stabilisation of functional muscle groups. Theoretically, increased cortical beta oscillations could lead to exaggerated synchronisation in different muscles making the initialisation of movements more difficult, as observed in Parkinson's disease.
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Ritmo beta , Electromiografía , Corteza Motora , Músculo Esquelético , Postura , Humanos , Masculino , Músculo Esquelético/fisiología , Femenino , Ritmo beta/fisiología , Adulto , Corteza Motora/fisiología , Adulto Joven , Postura/fisiología , Electroencefalografía , Movimiento/fisiologíaRESUMEN
Cerebellar brain inhibition (CBI) is an inhibitory output from the cerebellum to the primary motor cortex, which is decreased in early motor learning. Transcranial random noise stimulation (tRNS) is a noninvasive brain stimulation to induce brain plastic changes; however, the effects of cerebellar tRNS on CBI and motor learning have not been investigated yet to our knowledge. In this study, whether cerebellar tRNS decreases CBI and improves motor learning was examined, and pupil diameter was measured to examine physiological changes due to the effect of tRNS on motor learning. Thirty-four healthy subjects were assigned to either the cerebellar tRNS group or the Sham group. The subjects performed visuomotor tracking task with ten trials each in the early and late learning stages while receiving the stimulus intervention. CBI and motor evoked potentials were measured before the learning task, after the early learning stage, and after the late learning stage, and pupil diameter was measured during the task. There was no change in CBI in both groups. No group differences in motor learning rates were observed at any learning stages. Pupil diameter was smaller in the late learning stage than in the early learning stage in both groups. The cerebellar tRNS was suggested not to induce changes in CBI and improvement in motor learning, and it did not affect pupil diameter.
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Cerebelo , Potenciales Evocados Motores , Aprendizaje , Desempeño Psicomotor , Pupila , Estimulación Transcraneal de Corriente Directa , Humanos , Masculino , Femenino , Pupila/fisiología , Cerebelo/fisiología , Aprendizaje/fisiología , Adulto Joven , Adulto , Potenciales Evocados Motores/fisiología , Desempeño Psicomotor/fisiología , Inhibición Neural/fisiología , Corteza Motora/fisiologíaRESUMEN
BACKGROUND: Ovarian hormones influence the propensity for short-term plasticity induced by repetitive transcranial magnetic stimulation (rTMS). Estradiol appears to enhance the propensity for neural plasticity. It is currently unknown how progesterone influences short-term plasticity induced by rTMS. OBJECTIVE: The present research investigates whether the luteal versus follicular phase of the menstrual cycle influence short-term plasticity induced by intermittent theta-burst stimulation (iTBS). We tested the hypothesis that iTBS would increase motor evoked potentials (MEPs) during the follicular phase. Further, we explored the effects of the luteal phase on iTBS-induced neural plasticity. METHOD: Twenty-nine adult females participated in a placebo-controlled study that delivered real and sham iTBS to the left primary motor cortex in separate sessions corresponding to the follicular phase (real iTBS), luteal phase (real iTBS), and a randomly selected day (sham iTBS). Outcomes included corticospinal excitability as measured by the amplitude of MEPs and short-interval intracortical inhibition (SICI) recorded from the right first dorsal interosseous muscle before and following iTBS (612 pulses). RESULTS: MEP amplitude was increased following real iTBS during the follicular condition. No significant changes in MEP amplitude were observed during the luteal or sham visits. SICI was unchanged by iTBS irrespective of menstrual phase. CONCLUSION: These findings suggest women experience a variable propensity for iTBS-induced short-term plasticity across the menstrual cycle. This information is important for designing studies aiming to induce plasticity via rTMS in women.
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Potenciales Evocados Motores , Ciclo Menstrual , Corteza Motora , Plasticidad Neuronal , Estimulación Magnética Transcraneal , Humanos , Femenino , Plasticidad Neuronal/fisiología , Potenciales Evocados Motores/fisiología , Adulto , Corteza Motora/fisiología , Adulto Joven , Ciclo Menstrual/fisiología , Electromiografía , Ritmo Teta/fisiología , Inhibición Neural/fisiologíaRESUMEN
BACKGROUND: Transcranial magnetic stimulation (TMS) is a valuable technique for assessing the function of the motor cortex and cortico-muscular pathways. TMS activates the motoneurons in the cortex, which after transmission along cortico-muscular pathways can be measured as motor-evoked potentials (MEPs). The position and orientation of the TMS coil and the intensity used to deliver a TMS pulse are considered central TMS setup parameters influencing the presence/absence of MEPs. NEW METHOD: We sought to predict the presence of MEPs from TMS setup parameters using machine learning. We trained different machine learners using either within-subject or between-subject designs. RESULTS: We obtained prediction accuracies of on average 77â¯% and 65â¯% with maxima up to up to 90â¯% and 72â¯% within and between subjects, respectively. Across the board, a bagging ensemble appeared to be the most suitable approach to predict the presence of MEPs. CONCLUSIONS: Although within a subject the prediction of MEPs via TMS setup parameter-based machine learning might be feasible, the limited accuracy between subjects suggests that the transfer of this approach to experimental or clinical research comes with significant challenges.