Plasticity changes in dorsolateral prefrontal cortex associated with procedural sequence learning are hemisphere-specific.

Corticocortical neuroplastic changes from higher-order cortices to primary motor cortex (M1) have been described for procedural sequence learning. The dorsolateral prefrontal cortex (DLPFC) plays critical roles in cognition, including in motor learning and memory. However, neuroplastic changes in the DLPFC and their influence on M1 and on motor learning are not well understood. The present study examined bilateral DLPFC-M1 changes in plasticity induced by procedural motor sequence learning in a serial reaction time task. DLPFC plasticity induced by procedural sequence learning was examined by comparing before vs. after training assessments of ipsilateral/contralateral DLPFC-M1 interactions between sequence order and random order trials performed using either the left or right hand. Intra-hemispheric (inter-stimulus interval [ISI] = 10 ms) and inter-hemispheric (ISI = 10 or 50 ms) DLPFC-M1 interactions and single-pulse motor-evoked potentials (MEPs) were measured with transcranial magnetic stimulation (TMS). The reaction times of participants measured during motor training were faster for sequence learning than for random learning with either hand. Paired-pulse TMS induced DLPFC-M1 interactions that were disinhibited after motor sequence learning, especially for left DLPFC-left M1 interactions with right hand task performance and for left DLPFC-right M1 interactions with left hand task performance. These findings indicate that motor sequence learning induces neuroplastic changes to enhance DLPFC-M1 interactions. This manifestation of plasticity showed hemispheric specificity, favoring the left DLPFC. DLPFC plasticity may be a useful index of DLPFC function and may be a treatment target for enhancing DLPFC function and motor learning.

Cognitive motor intervention for gait and balance in Parkinson's disease: systematic review and meta-analysis.

OBJECTIVE: We performed a systematic review and meta-analysis to assess the effect of cognitive motor intervention (CMI) on gait and balance in Parkinson's disease. DATA SOURCES: PubMed, Embase, Cochrane Library, CINAHL, Web of Science, PEDro, and China Biology Medicine disc. METHODS: We included randomized controlled trials (RCTs) and non RCTs. Two reviewers independently evaluated articles for eligibility and quality and serially abstracted data. A standardized mean difference ± standard error and 95% confidence interval (CI) was calculated for each study using Hedge's g to quantify the treatment effect. RESULTS: Nine trials with 181 subjects, four randomized controlled trials, and five single group intervention studies were included. The pooling revealed that cognitive motor intervention can improve gait speed (Hedge's g = 0.643 ± 0.191; 95% CI: 0.269 to 1.017, P = 0.001), stride time (Hedge's g = -0.536 ± 0.167; 95% CI: -0.862 to -0.209, P = 0.001), Berg Balance Scale (Hedge's g = 0.783 ± 0.289; 95% CI: 0.218 to 1.349, P = 0.007), Unipedal Stance Test (Hedge's g = 0.440 ± 0.189; 95% CI: 0.07 to 0.81, P =0.02). CONCLUSIONS: The systematic review demonstrates that cognitive motor intervention is effective for gait and balance in Parkinson's disease. However, the paper is limited by the quality of the included trials.

Cognitive motor interference for preventing falls in older adults: a systematic review and meta-analysis of randomised controlled trials.

OBJECTIVE: We conducted a systematic review to determine the effect of cognitive motor interference (CMI) for the prevention of falls in older adults. METHODS: We searched studies through Medline, Embase, the Cochrane Library, Web of Science, CINAHL, PEDro and the China Biology Medicine disc. Only randomised controlled trials examining the effects of CMI for older people were included. The primary outcome measure was falls; the secondary outcome measures included gait, balance function and reaction time. RESULTS: A total of 30 studies of 1,206 participants met the inclusion criteria, and 27 studies of 1,165 participants were used as data sources for the meta-analyses. The pooling revealed that CMI was superior to control group for fall rate [standard mean difference (SMD) (95% CI)=-3.03 (-4.33, -1.73), P<0.0001], gait speed [SMD (95% CI)=0.36 (0.07, 0.66), P=0.01], step length [SMD (95% CI)=0.48 (0.16, 0.80), P=0.003], cadence [SMD (95% CI)=0.19 (0.01, 0.36), P=0.03], timed up and go test [SMD (95% CI)=-0.22 (-0.38, -0.06), P=0.007], centre of pressure displacement [SMD (95% CI)=-0.32 (-1.06, 0.43), P=0.04] and reaction time [SMD (95% CI)=-0.47 (-0.86, -0.08), P=0.02]. CONCLUSION: The systematic review demonstrates that CMI is effective for preventing falls in older adults in the short term. However, there is, as yet, little evidence to support claims regarding long-term benefits. Hence, future studies should investigate the long-term effectiveness of CMI in terms of fall prevention in older adults.

Approach-avoidance behavior and motor-specific modulation towards smoking-related cues in smokers.

AIMS: By performing three transcranial magnetic stimulation (TMS) experiments, we measured the motor-specific modulatory mechanisms in the primary motor cortex (M1) at both the intercortical and intracortical levels when smokers actively approach or avoid smoking-related cues. DESIGN, SETTING AND PARTICIPANTS: For all experiments, the design was group (smokers versus non-smokers) × action (approach versus avoidance) × image type (neutral versus smoking-related). The study was conducted at the Shanghai University of Sport, CHN, TMS Laboratory. For experiment 1, 30 non-smokers and 30 smokers; for experiment 2, 16 non-smokers and 16 smokers; for experiment 3, 16 non-smokers and 16 smokers. MEASUREMENTS: For all experiments, the reaction times were measured using the smoking stimulus-response compatibility task. While performing the task, single-pulse TMS was applied to the M1 in experiment 1 to measure the excitability of the corticospinal pathways, and paired-pulse TMS was applied to the M1 in experiments 2 and 3 to measure the activity of intracortical facilitation (ICF) and short-interval intracortical inhibition (SICI) circuits, respectively. FINDINGS: Smokers had faster responses when approaching smoking-related cues (F1,58 = 36.660, P < 0.001, η p 2 = 0.387), accompanied by higher excitability of the corticospinal pathways (F1,58 = 10.980, P = 0.002, η p 2 = 0.159) and ICF circuits (F1,30 = 22.187, P < 0.001, η p 2 = 0.425), while stronger SICI effects were observed when they avoided these cues (F1,30 = 10.672, P = 0.003, η p 2 = 0.262). CONCLUSIONS: Smokers appear to have shorter reaction times, higher motor-evoked potentials and stronger intracortical facilitation effects when performing approach responses to smoking-related cues and longer reaction times, a lower primary motor cortex descending pathway excitability and a stronger short-interval intracortical inhibition effect when avoiding them.

Bilateral motor cortex functional differences in left-handed approaching-avoiding behavior.

Automatic action tendencies occur at behavioral and neurophysiological levels during task performance with the dominant right hand, with shorter reaction times (RTs) and higher excitability of the contralateral primary motor cortex (M1) during automatic vs. regulated behavior. However, effects associated with the non-dominant left-hand in approaching-avoiding behavior remain unclear. Here, we used transcranial magnetic stimulation during the performance by 18 participants of an approaching-avoiding task using the non-dominant left hand. Single-pulse transcranial magnetic stimulation was applied over left or right M1 at 150 and 300 ms after the onset of an emotional stimulus. RTs and motor-evoked potentials (MEPs) were recorded. Significant automatic action tendencies were observed at the behavioral level. Higher MEP amplitudes were detected 150 ms after stimulus onset from the right hand (non-task hand, corresponding to left M1) during regulated behavior compared with during automatic behavior. However, no significant modulation was found for MEP amplitudes from the left hand (task hand, corresponding to right M1). These findings suggested that left M1 may play a principal role in the early phase of mediating left-handed movement toward an emotional stimulus.

The superior response speed of table tennis players is associated with proactive inhibitory control.

Objective: To explore the mechanism behind the faster volitional reaction time (RT) of open skill sports athletes from the perspective of proactive inhibitory control, with the hypothesis that the superior response speed of athletes from open skill sports is related to their enhanced capacity for releasing inhibition. Methods: Participants were divided into two groups, an experimental group of 27 table tennis players and a control group of 27 non-athletes. By manipulating cue-target onset asynchrony (CTOA) in a simple cue-target detection task, the timing of target presentation occurred in different phases of the disinhibition process. The time needed for disinhibition were compared between groups. Results: For the experimental group, RT varied with CTOA at delays less than 200 ms; for CTOAs greater than 200 ms, RTs were not significantly different. For the control group, RT varied with CTOA for delays as long as 300 ms. Conclusions: Table tennis players took less time (200 ms) than non-athletes (300 ms) to complete the disinhibition process, which might partly explain their rapid response speed measured in unpredictable contexts. Significance: The study provided evidence for disinhibition speed as a new index to assess the capacity of proactive inhibitory control, and provided a new perspective to explore the superior RT of athletes from open skill sports. We also offered support for the fundamental cognitive benefits of table tennis training.

Selective effects of exercise on reactive and proactive inhibition in Parkinson's disease.

Objective: Patients with Parkinson's disease (PD) have an obvious motor inhibition disorder, which is closely related to their motor symptoms. Although previous studies have shown that exercise can improve their inhibition deficits, the effect of exercise on different types of inhibition (proactive and reactive inhibition) has not been addressed. Methods: We used a behavioral paradigm combined with a series of questionnaires to explore the effect of long-term exercise on different types of motor inhibition in 59 patients with PD aged 55-75 years. According to the intensity and frequency of exercise, the participants were divided into regular-exercise and no-exercise groups. To obtain the average reference value for inhibition ability at the same age, we also recruited 30 healthy elderly people as controls. Results: The main defect in the motor inhibition of PD is reactive inhibition, while proactive inhibition has no obvious differences compared with healthy controls. Additionally, compared with the non-exercise group, PD in the exercise group showed significantly better reaction speeds and reactive control ability, fewer motor symptoms and negative emotions. Conclusions: Taken together, the motor inhibition defects of patients with PD affect only reactive inhibition. In addition, PD with exercise reported fewer negative emotions than that of the non-exercise group, indicating that exercise can relieve negative emotions and improve behavioral symptoms and quality of life in PD to a certain extent. We demonstrate for the first time that exercise has and can improve reactive inhibition in PD patients and has no effect on proactive inhibition.

Effects of Wu Qin Xi exercise on reactive inhibition in Parkinson's disease: A randomized controlled clinical trial.

Objective: Motor symptom in patients with Parkinson's disease (PD) are related to reduced motor inhibitory ability (proactive and reactive inhibition). Although exercise has been shown to improve this ability, its effects on different levels of motor inhibition have not been determined. Materials and methods: Sixty patients with PD aged 55-75 years were allocated randomly to 24-week exercise interventions [Wu Qin Xi exercise (WQX) and stretching exercise (SE)]. The stop signal task and questionnaires were administered pre and post interventions. Twenty-five age-matched healthy controls were recruited to obtain reference values for inhibition. Results: Compared to healthy controls, patients with PD showed motor inhibition deficits in reactive inhibition, but not in proactive inhibition. Post-intervention, the WQX group showed significant improvement in reactive inhibition compared to the SE group. In both the WQX and SE groups, movement speed was improved post-intervention, accompanied by reduction in negative emotions, stable improvement of sleep quality, and high self-reported satisfaction levels. Conclusion: This study demonstrated that Wu Qin Xi exercise can improve the reactive inhibition of patients with PD. Our results provide theoretical support for the formulation of reasonable and effective exercise prescriptions for PD rehabilitation. Clinical trial registration: [http://www.chictr.org.cn], identifier [ChiCTR2000038517].

The Feasibility and Positive Effects of Wuqinxi Exercise on the Cognitive and Motor Functions of Patients with Parkinson's Disease: A Pilot Study.

INTRODUCTION: Parkinson's disease (PD) is a chronic degenerative disease of the central nervous system common in middle-aged and elderly people, which has a serious impact on patients' cognitive and motor functions. Exercise can improve the nonmotor symptoms of PD patients, but the optimal type of exercise for the cognitive function of patients is unclear. Therefore, the purpose of this study is the impact of 12 weeks of Wuqinxi exercise on the cognitive and motor function in PD patients. METHODS: Thirty PD patients participated in the study and were randomly assigned to two groups: Wuqinxi group (n = 15) or stretching group (n = 15). All the participants performed a 12-week exercise program twice a week, 90 min/session. The assessments were conducted before and after exercise intervention, included cognitive function (frontal assessment battery (FAB); Stroop test I and II), motor functions (Unified Parkinson's Disease Rating Scale Part III (UPDRS-III); timed up and go (TUG)). RESULTS: We found the FAB and Stroop I scores were significantly higher in the Wuqinxi group than in the stretching group. Participants in the Wuqinxi group significantly improved their UPDRS-III (17.73 ± 9.88) and TUG (10.50 ± 1.79) score after 12 weeks of training intervention. CONCLUSION: The results show that the use of Wuqinxi for rehabilitation therapy for cognition is feasible, widely accepted, and effective in patients with Parkinson's disease. This study provides preliminary evidence for further large-scale and controlled studies.

Intermittent theta burst stimulation facilitates functional connectivity from the dorsal premotor cortex to primary motor cortex.

BACKGROUND: Motor information in the brain is transmitted from the dorsal premotor cortex (PMd) to the primary motor cortex (M1), where it is further processed and relayed to the spinal cord to eventually generate muscle movement. However, how information from the PMd affects M1 processing and the final output is unclear. Here, we applied intermittent theta burst stimulation (iTBS) to the PMd to alter cortical excitability not only at the application site but also at the PMd projection site of M1. We aimed to determine how PMd iTBS-altered information changed M1 processing and the corticospinal output. METHODS: In total, 16 young, healthy participants underwent PMd iTBS with 600 pulses (iTBS600) or sham-iTBS600. Corticospinal excitability, short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) were measured using transcranial magnetic stimulation before and up to 60 min after stimulation. RESULTS: Corticospinal excitability in M1 was significantly greater 15 min after PMd iTBS600 than that after sham-iTBS600 (p = 0.012). Compared with that after sham-iTBS600, at 0 (p = 0.014) and 15 (p = 0.037) min after iTBS600, SICI in M1 was significantly decreased, whereas 15 min after iTBS600, ICF in M1 was significantly increased (p = 0.033). CONCLUSION: Our results suggested that projections from the PMd to M1 facilitated M1 corticospinal output and that this facilitation may be attributable in part to decreased intracortical inhibition and increased intracortical facilitation in M1. Such a facilitatory network may inform future understanding of the allocation of resources to achieve optimal motion output.

Modulation of hand motor skill performance induced by motor practice combined with matched or mismatched hand posture motor imagery.

Motor imagery (MI), the mental rehearsal of a movement without muscle activation, combined with motor practice (MP) improves the performance of athletes and promotes rehabilitation of motor function among patients with brain injury. The actual hand posture influences the mental simulation of hand movements such that the ability of MI to affect corticospinal excitability is enhanced when the actual hand posture is consistent with the imagined movement of the hand. However, how MP combined with matched or mismatched hand posture MI modulates hand motor skill performance and the underlying neural mechanisms remain unclear. Thus, we first investigated whether MI hand posture that was compatible or incompatible with the actual MP influenced motor performance and corticospinal excitability induced by MI combined with MP. Twenty-eight healthy young adults repeatedly imagined either (1) closing their right hand into a fist with the thumb on top of the fingers and then opening the hand before actually performing that exact motor action or (2) performing the same motor skill but first imagining the right thumb touching the little finger before opening the hand . Changes in the peak acceleration of the hand grasp were measured to assess motor performance. The amplitudes of motor-evoked potentials (MEPs) in a target muscle were obtained using transcranial magnetic stimulation to assess corticospinal activation, a measure of primary cortex stimulation, before, immediately after, and 20 min after the performance. When the results of two-way repeated-measures analyses of variance assessing the effects of the protocols and time on the various measurements were found to be significant, post hoc paired t tests with Bonferroni corrections for multiple comparisons were applied. The results showed that both peak grasp acceleration and corticospinal excitability significantly increased immediately and 20 min after task completion (p < 0.05 for all) only when the MI hand posture matched with that of the actual MP. We then determined whether this increased corticospinal activity was associated with decreased short-interval intracortical inhibition, as measured using paired-pulse transcranial magnetic stimulation. Similar to our previous results, we found that short-interval intracortical inhibition was significantly decreased immediately and 20 min after task completion (p < 0.05 for both) only when MI matched MP. We concluded that the increased motor performance and corticospinal excitability induced by MI and MP depended on the match between the hand posture in the MI and MP, and that this increased corticospinal excitability was associated with disinhibition of the primary motor cortex activity.

Neural efficiency in basketball players is associated with bidirectional reductions in cortical activation and deactivation during multiple-object tracking task performance.

Although sports expertise has been shown to have transferable cognitive benefits, it is unclear how motor expertise influences brain activity during perceptual-cognitive tasks. The aim of the present study was to investigate whether improved perceptual-cognitive behavioral task performance in individuals with well-developed motor skills is associated with characteristic cortical activation and deactivation. Blood oxygenation-level dependent (BOLD) functional MRI (fMRI) was conducted in 23 athletes and 24 age- and education-matched non-athletes performing a multiple object tracking (MOT) task with graded levels of attentional load (two, three, or four targets). Compared to non-athletes, athletes had better performance in the three- and four-target conditions of the MOT task. Less activation of the left frontal eye field (FEF) and bilateral anterior intraparietal sulcus (aIPS) and less deactivation in the bilateral medial superior frontal gyrus (mSFG) were observed in athletes compared to non-athletes. Importantly, as the attentional load was increased, differences in deactivation of the left middle temporal gyrus (MTG) between athletes and non-athletes became larger. Behavioral performance in the high attentional load condition correlated negatively with activation in the left FEF and right aIPS, and correlated positively with that in the mSFG and left MTG. Better performance in elite athletes may transfer from the sport domain to a general cognitive domain owing to higher neural efficiency, which may be represented by a bidirectional reduction phenomenon encompassing both reduced activation of areas associated with task execution and reduced deactivation of areas associated with irrelevant information processing.

Effect of acupuncture at ST36 on motor cortical excitation and inhibition.

BACKGROUND: Acupuncture at Zusanli (ST36) is often used to facilitate motor recovery after stroke. However, the effect of acupuncture at ST36 on motor cortical excitation and inhibition remains unclear. This study aimed to explore the effect of acupuncture at ST36 on motor cortical excitation and inhibition. METHODS: Twenty healthy volunteers were recruited to receive acupuncture treatment. We selected the acupoint ST36 and its respective sham point as the experimental acupoint. Transcranial magnetic stimulation (TMS) was used to measure motor-evoked potentials (MEP) at 7 time points-before acupuncture (Pre), acupuncture (T0), 4 and 8 min after acupuncture (T4; T8), needle removal (T12), 4 and 8 min after needle removal (T16; T20). Simultaneously, paired TMS (pTMS) was employed to measure short- and long-interval intracortical inhibition (SICI [short latency intracortical inhibition]; LICI [long latency intracortical inhibition]), respectively, at three time points-before acupuncture (Pre), acupuncture (T0), needle removal (T12). After removing the acupuncture needle, all subjects were asked to quantify their Deqi sensation using a Gas table. RESULTS: The average Deqi sensation score of all subjects during acupuncture at ST36 was higher than that observed at the sham point. With acupuncture at ST36, the MEP amplitude was higher at three time points (T0, T4, T8) than at Pre, although the MEP amplitude tended toward Pre after needle removal. The MEP amplitude was also higher at the same time points (T0, T4, T8) than at the sham point. Furthermore, the Deqi sensation score was correlated with MEP amplitude. With acupuncture at ST36, SICI and LICI at T0 were higher than those at Pre, and SICI and LICI at T0 were higher than those at the sham point. CONCLUSION: Acupuncture at ST36 increased motor cortical excitation and had an effect on the remaining needle phase. Deqi sensation was correlated with MEP amplitude. Acupuncture at ST36 also decreased motor cortical inhibition.

Motor learning enhanced by combined motor imagery and noninvasive brain stimulation is associated with reduced short-interval intracortical inhibition.

BACKGROUND: Motor imagery (MI) improves motor skill learning, which is further enhanced when MI is paired with primary motor cortex transcranial brain stimulation or with electrical stimulation of the peripheral median nerve. Applying both stimulation types (here with 25 ms intervals) is called paired associative stimulation (PAS25). The final primary motor cortex output is determined by combined excitatory and intracortical inhibitory circuits, and reducing the latter is associated with enhanced synaptic transmission and efficacy. Indeed, short-interval intracortical inhibition (SICI) inhibits motor evoked potentials (MEPs), and motor learning has been associated with decreased SICI and increased cortical excitability. Here, we investigated whether cortical excitability and SICI are altered by PAS25 applied after MI-induced modulation of motor learning. METHODS: Peak acceleration of a hand-grasping movement and MEPs and SICI were measured before and after MI alone, PAS25 alone, and MI followed by PAS25 in 16 healthy participants to evaluate changes in motor learning, corticospinal excitability, and intracortical inhibition. RESULTS: After PAS25 alone, MEP amplitude increased while peak acceleration was unchanged. However, PAS25 applied following MI not only significantly enhanced both peak acceleration (p = 0.011) and MEP amplitude (p = 0.004) but also decreased SICI (p = 0.011). Moreover, we found that this decrease in SICI was significantly correlated with both the peak acceleration (r = 0.49, p = 0.029) and the MEP amplitude (r = 0.56, p = 0.013). CONCLUSIONS: These results indicate that brain function altered by PAS25 of the motor cortex enhances MI-induced motor learning and corticospinal excitability and decreases SICI, suggesting that SICI underlies, at least in part, PAS25 modulation of motor learning.

Motor skill learning induces brain network plasticity: A diffusion-tensor imaging study.

Motor skills and the acquisition of brain plasticity are important topics in current research. The development of non-invasive white matter imaging technology, such as diffusion-tensor imaging and the introduction of graph theory make it possible to study the effects of learning skills on the connection patterns of brain networks. However, few studies have characterized the brain network topological features of motor skill learning, especially open skill. Given the need to interact with environmental changes in real time, we hypothesized that the brain network of high-level open-skilled athletes had higher transmission efficiency and stronger interaction in attention, visual and sensorimotor networks. We selected 21 high-level basketball players and 25 ordinary individuals as control subjects, collected their DTI data, built a network of brain structures, and used graph theory to analyze and compare the network properties of the two groups at global and regional levels. In addition, we conducted a correlation analysis on the training years of high-level athletes and brain network nodal parameters on the regional level to assess the relationship between brain network topological characteristics and skills learning. We found that on the global-level, the brain network of high-level basketball players had a shorter path length, small-worldness, and higher global efficiency. On the regional level, the brain nodes of the high-level athletes had nodal parameters that were significantly higher than those of control groups, and were mainly distributed in the visual network, the default mode network, and the attention network. The changes in brain node parameters were significantly related to the number of training years.

Visual and Action-control Expressway Associated with Efficient Information Transmission in Elite Athletes.

Effective information transmission for open skill performance requires fine-scale coordination of distributed networks of brain regions linked by white matter tracts. However, how patterns of connectivity in these anatomical pathways may improve global efficiency remains unclear. In this study, we hypothesized that the feeder edges in visual and motor systems have the potential to become "expressways" that increase the efficiency of information communication across brain networks of open skill experts. Thirty elite athletes and thirty novice subjects were recruited to participate in visual tracking and motor imagery tasks. We collected structural imaging data from these subjects, and then resolved structural neural networks using deterministic tractography to identify streamlines connecting cortical and subcortical brain regions of each participant. We observed that superior skill performance in elite athletes was associated with increased information transmission efficiency in feeder edges distributed between orbitofrontal and basal ganglia modules, as well as among temporal, occipital, and limbic system modules. These findings suggest that there is an expressway linking visual and action-control system of skill experts that enables more efficient interactions of peripheral and central information in support of effective performance of an open skill.

Influence of sports expertise level on attention in multiple object tracking.

BACKGROUND: This study aimed to investigate whether performance in a multiple object tracking (MOT) task could be improved incrementally with sports expertise, and whether differences between experienced and less experienced athletes, or non-athletes, were modulated by load. METHODS: We asked 22 elite and 20 intermediate basketball players, and 23 non-athletes, to perform an MOT task under three attentional load conditions (two, three, and four targets). Accuracies were analyzed to examine whether different levels of sports expertise influence MOT task performance. RESULTS: The elite athletes displayed better tracking performance compared with the intermediate or non-athletes when tracking three or four targets. However, no significant difference was found between the intermediate athletes and the non-athletes. Further, no differences were observed among the three groups when tracking two targets. DISCUSSION: The results suggest that the effects of expertise in team ball sports could transfer to a non-sports-specific attention task. These transfer effects to general cognitive functions occur only in elite athletes with extensive training under higher attentional load.

Motor experience with a sport-specific implement affects motor imagery.

The present study tested whether sport-specific implements facilitate motor imagery, whereas nonspecific implements disrupt motor imagery. We asked a group of basketball players (experts) and a group of healthy controls (novices) to physically perform (motor execution) and mentally simulate (motor imagery) basketball throws. Subjects produced motor imagery when they were holding a basketball, a volleyball, or nothing. Motor imagery performance was measured by temporal congruence, which is the correspondence between imagery and execution times estimated as (imagery time minus execution time) divided by (imagery time plus execution time), as well as the vividness of motor imagery. Results showed that experts produced greater temporal congruence and vividness of kinesthetic imagery while holding a basketball compared to when they were holding nothing, suggesting a facilitation effect from sport-specific implements. In contrast, experts produced lower temporal congruence and vividness of kinesthetic imagery while holding a volleyball compared to when they were holding nothing, suggesting the interference effect of nonspecific implements. Furthermore, we found a negative correlation between temporal congruence and the vividness of kinesthetic imagery in experts while holding a basketball. On the contrary, the implement manipulation did not modulate the temporal congruence of novices. Our findings suggest that motor representation in experts is built on motor experience associated with specific-implement use and thus was subjected to modulation of the implement held. We conclude that sport-specific implements facilitate motor imagery, whereas nonspecific implements could disrupt motor representation in experts.

Inhibitory and facilitatory connections from dorsolateral prefrontal to primary motor cortex in healthy humans at rest-An rTMS study.

BACKGROUND: The human motor system consists of several divisions in the frontal lobes. The physiological function of projections from the dorsolateral prefrontal cortex (DLPFC) to the primary motor cortex (M1) remains elusive. Here, we introduce theta burst stimulation (TBS)-based protocols to target inhibitory and facilitatory connections in the DLPFC-M1 network. METHODS: Intermittent and continuous TBS with 600 pulses (iTBS600/cTBS600) were applied to the left DLPFC. Resting motor threshold (RMT), motor-evoked potential (MEP), and short-interval intracortical inhibition (SICI) were measured with transcranial magnetic stimulation to the ipsilateral M1. RESULTS: iTBS600 to the DLPFC decreased MEP amplitude in M1. Conversely, cTBS600 to the DLPFC increased MEP amplitude in M1. The peak decrease in MEP amplitude after iTBS600 was negatively correlated with the peak increase in MEP amplitude after cTBS600. There were no significant effects in the control group with the sham stimulation. DISCUSSION: These results provide insight into the regulation of inhibitory and facilitatory balance from the local DLPFC to M1. TBS modulation in one brain region will induce interactions within other remote cortical areas. Our results enable better understanding of how cognitive resources are allocated to achieve optimal control of motor output.

Differences between motor execution and motor imagery of grasping movements in the motor cortical excitatory circuit.

BACKGROUND: Both motor imagery (MI) and motor execution (ME) can facilitate motor cortical excitability. Although cortical excitability is modulated by intracortical inhibitory and excitatory circuits in the human primary motor cortex, it is not clear which intracortical circuits determine the differences in corticospinal excitability between ME and MI. METHODS: We recruited 10 young healthy subjects aged 18-28 years (mean age: 22.1 ± 3.14 years; five women and five men) for this study. The experiment consisted of two sets of tasks involving grasp actions of the right hand: imagining and executing them. Corticospinal excitability and short-interval intracortical inhibition (SICI) were measured before the interventional protocol using transcranial magnetic stimulation (baseline), as well as at 0, 20, and 40 min (T0, T20, and T40) thereafter. RESULTS: Facilitation of corticospinal excitability was significantly greater after ME than after MI in the right abductor pollicis brevis (APB) at T0 and T20 (p < 0.01 for T0, and p < 0.05 for T20), but not in the first dorsal interosseous (FDI) muscle. On the other hand, no significant differences in SICI between ME and MI were found in the APB and FDI muscles. The facilitation of corticospinal excitability at T20 after MI correlated with the Movement Imagery Questionnaire (MIQ) scores for kinesthetic items (Rho = -0.646, p = 0.044) but did not correlate with the MIQ scores for visual items (Rho = -0.265, p = 0.458). DISCUSSION: The present results revealed significant differences between ME and MI on intracortical excitatory circuits of the human motor cortex, suggesting that cortical excitability differences between ME and MI may be attributed to the activation differences of the excitatory circuits in the primary motor cortex.