Primary motor cortex and movement prevention: Where Stop meets Go

Acute aerobic exercise modulates cognition and cortical excitability in adults with attention-deficit hyperactivity disorder (ADHD) and healthy controls

Evidence suggests aerobic exercise has beneficial effects on cognitive performance in adults with attention-deficit hyperactivity disorder (ADHD). The underlying mechanisms might depend on mechanisms of exercise-mediated brain physiology. The study aims to investigate the effects of acute aerobic exercise on cortical excitability and cognitive performance, and the correlation between these phenomena in adults with ADHD. Twenty-six drug-naïve ADHD adults, and twenty-six age-, and gender-matched healthy controls were assessed with respect to cortical excitability and cognitive performance before and after acute aerobic exercise (a single session for 30 min) or a control intervention. The results show significantly enhanced intracortical facilitation (ICF) and decreased short intracortical inhibition (SICI) after aerobic exercise in healthy subjects. In contrast, SICI was significantly enhanced following acute aerobic exercise in ADHD. In ADHD, furthermore inhibitory control and motor learning were significantly improved after the acute aerobic exercise intervention. Alterations of SICI induced by aerobic exercise, and inhibitory control and motor learning improvement were significantly positively correlated in the ADHD group. Aerobic exercise had partially antagonistic effects in healthy controls, and ADHD patients. Furthermore, aerobic exercise-induced cognition-enhancing effects in ADHD depend on specific alterations of brain physiology, which differ from healthy humans.

Selective cancellation of reactive or anticipated movements: Differences in speed of action reprogramming, but not stopping

The ability to inhibit movements is an essential component of a healthy executive control system. Two distinct but commonly used tasks to assess motor inhibition are the stop signal task (SST) and the anticipated response inhibition (ARI) task. The SST and ARI tasks are similar in that they both require cancelation of a prepotent movement; however, the SST involves cancelation of a speeded reaction to a temporally unpredictable signal, while the ARI task involves cancelation of an anticipated response that the participant has prepared to enact at a wholly predictable time. 33 participants (mean age = 33.3 years, range = 18-55 years) completed variants of the SST and ARI task. In each task, the majority of trials required bimanual button presses, while on a subset of trials a stop signal indicated that one of the presses should be cancelled (i.e., motor selective inhibition). Additional variants of the tasks also included trials featuring signals which were to be ignored, allowing for insights into the attentional component of the inhibitory response. Electromyographic (EMG) recordings allowed detailed comparison of the characteristics of voluntary action and cancellation. The speed of the inhibitory process was not influenced by whether the enacted movement was reactive (SST) or anticipated (ARI task). However, the ongoing (non-cancelled) component of anticipated movements was more efficient than reactive movements, as a result of faster action reprogramming (i.e., faster ongoing actions following successful motor selective inhibition). Older age was associated with both slower inhibition and slower action reprogramming across all reactive and anticipated tasks.

Uncovering brain functional connectivity disruption patterns of lung cancer-related pain

Pain is a pervasive symptom in lung cancer patients during the onset of the disease. This study aims to investigate the connectivity disruption patterns of the whole-brain functional network in lung cancer patients with cancer pain (CP+). We constructed individual whole-brain, region of interest (ROI)-level functional connectivity (FC) networks for 50 CP+ patients, 34 lung cancer patients without pain-related complaints (CP-), and 31 matched healthy controls (HC). Then, a ROI-based FC analysis was used to determine the disruptions of FC among the three groups. The relationships between aberrant FCs and clinical parameters were also characterized. The ROI-based FC analysis demonstrated that hypo-connectivity was present both in CP+ and CP- patients compared to HC, which were particularly clustered in the somatomotor and ventral attention, frontoparietal control, and default mode modules. Notably, compared to CP- patients, CP+ patients had hyper-connectivity in several brain regions mainly distributed in the somatomotor and visual modules, suggesting these abnormal FC patterns may be significant for cancer pain. Moreover, CP+ patients also showed increased intramodular and intermodular connectivity strength of the functional network, which could be replicated in cancer stage IV and lung adenocarcinoma. Finally, abnormal FCs within the prefrontal cortex and somatomotor cortex were positively correlated with pain intensity and pain duration, respectively. These findings suggested that lung cancer patients with cancer pain had disrupted connectivity in the intrinsic brain functional network, which may be the underlying neuroimaging mechanisms.

Long-lasting negativity in the left motoric brain structures during word memory inhibition in the Think/No-Think paradigm

In this study, we investigated the electrical brain responses in a high-density EEG array (64 electrodes) elicited specifically by the word memory cue in the Think/No-Think paradigm in 46 participants. In a first step, we corroborated previous findings demonstrating sustained and reduced brain electrical frontal and parietal late potentials elicited by memory cues following the No-Think (NT) instructions as compared to the Think (T) instructions. The topographical analysis revealed that such reduction was significant 1000 ms after memory cue onset and that it was long-lasting for 1000 ms. In a second step, we estimated the underlying brain generators with a distributed method (swLORETA) which does not preconceive any localization in the gray matter. This method revealed that the cognitive process related to the inhibition of memory retrieval involved classical motoric cerebral structures with the left primary motor cortex (M1, BA4), thalamus, and premotor cortex (BA6). Also, the right frontal-polar cortex was involved in the T condition which we interpreted as an indication of its role in the maintaining of a cognitive set during remembering, by the selection of one cognitive mode of processing, Think, over the other, No-Think, across extended periods of time, as it might be necessary for the successful execution of the Think/No-Think task.

Acute aerobic exercise at different intensities modulates inhibitory control and cortical excitability in adults with attention-deficit hyperactivity disorder (ADHD)

BACKGROUND

This study aimed to investigate the effects of different aerobic exercise intensities on inhibitory control and cortical excitability in adults with attention-deficit/hyperactivity disorder (ADHD).

METHODS

The study was conducted in a within-subject design. Twenty-four adults with ADHD completed a stop signal task and received cortical excitability assessment by transcranial magnetic stimulation (TMS) before and after a single session of low-, moderate-, high-intensity aerobic exercise or a control intervention.

RESULTS

Acute moderate-, and high-intensity aerobic exercise improved inhibitory control in adults with ADHD. Moreover, the improving effect was similar between moderate-, and high-intensity aerobic exercise conditions. As shown by the brain physiology results, short interval intracortical inhibition was significantly increased following both, moderate- and high-intensity aerobic exercise intervention conditions. Additionally, the alteration of short interval intracortical inhibition and inhibitory control improvement were positively correlated.

CONCLUSIONS

The moderate-, and high-intensity aerobic exercise-dependent alterations of cortical excitability in adults with ADHD might partially explain the inhibitory control-improving effects of aerobic exercise in this population.

Anodal transcranial direct current stimulation enhances response inhibition and attention allocation in fencers

Background

The aim of this study is to investigate the acute effects of anodal transcranial direct current stimulation (tDCS) on reaction time, response inhibition and attention in fencers.

Methods

Sixteen professional female fencers were recruited, and subjected to anodal tDCS and sham stimulation in the primary motor area (M1) one week apart in a randomized, crossover, single-blind design. A two-factor analysis of variance with repeated measures was used to analyze the effects of stimulation conditions (anodal stimulation, sham stimulation) and time (pre-stimulation, post-stimulation) on reaction time, response inhibition, and attention in fencers.

Results

The study found a significant improvement in response inhibition and attention allocation from pre-stimulation to post-stimulation following anodal tDCS but not after sham stimulation. There was no statistically significant improvement in reaction time and selective attention.

Conclusions

A single session of anodal tDCS could improve response inhibition, attention allocation in female fencers. This shows that tDCS has potential to improve aspects of an athlete's cognitive performance, although we do not know if such improvements would transfer to improved performance in competition. However, more studies involving all genders, large samples, and different sports groups are needed in the future to further validate the effect of tDCS in improving the cognitive performance of athletes.

The phase of tACS-entrained pre-SMA beta oscillations modulates motor inhibition

Inhibitory control has been linked to beta oscillations in the fronto-basal ganglia network. Here we aim to investigate the functional role of the phase of this oscillatory beta rhythm for successful motor inhibition. We applied 20 Hz transcranial alternating current stimulation (tACS) to the pre-supplementary motor area (pre-SMA) while presenting stop signals at 4 (Experiment 1) and 8 (Experiment 2) equidistant phases of the tACS entrained beta oscillations. Participants showed better inhibitory performance when stop signals were presented at the trough of the beta oscillation whereas their inhibitory control performance decreased with stop signals being presented at the oscillatory beta peak. These results are consistent with the communication through coherence theory, in which postsynaptic effects are thought to be greater when an input arrives at an optimal phase within the oscillatory cycle of the target neuronal population. The current study provides mechanistic insights into the neural communication principles underlying successful motor inhibition and may have implications for phase-specific interventions aimed at treating inhibitory control disorders such as PD or OCD.

Corticospinal excitability reductions during action preparation and action stopping in humans: Different sides of the same inhibitory coin?

Motor functions and cognitive processes are closely associated with each other. In humans, this linkage is reflected in motor system state changes both when an action must be prepared and stopped. Single-pulse transcranial magnetic stimulation showed that both action preparation and action stopping are accompanied by a reduction of corticospinal excitability, referred to as preparatory and response inhibition, respectively. While previous efforts have been made to describe both phenomena extensively, an updated and comprehensive comparison of the two phenomena is lacking. To ameliorate such deficit, this review focuses on the role and interpretation of single-coil (single-pulse and paired-pulse) and dual-coil TMS outcome measures during action preparation and action stopping in humans. To that effect, it aims to identify commonalities and differences, detailing how TMS-based outcome measures are affected by states, traits, and psychopathologies in both processes. Eventually, findings will be compared, and open questions will be addressed to aid future research.

The role of dorsal premotor cortex in joint action inhibition

Behavioral interpersonal coordination requires smooth negotiation of actions in time and space (joint action-JA). Inhibitory control may play a role in fine-tuning appropriate coordinative responses. To date, little research has been conducted on motor inhibition during JA and on the modulatory influence that premotor areas might exert on inhibitory control. Here, we used an interactive task in which subjects were required to reach and open a bottle using one hand. The bottle was held and stabilized by a co-actor (JA) or by a mechanical holder (vice clamp, no-JA). We recorded two TMS-based indices of inhibition (short-interval intracortical inhibition-sICI; cortical silent period-cSP) during the reaching phase of the task. These reflect fast intracortical (GABAa-mediated) and slow corticospinal (GABAb-mediated) inhibition. Offline continuous theta burst stimulation (cTBS) was used to interfere with dorsal premotor cortex (PMd), ventral premotor cortex (PMv), and control site (vertex) before the execution of the task. Our results confirm a dissociation between fast and slow inhibition during JA coordination and provide evidence that premotor areas drive only slow inhibitory mechanisms, which in turn may reflect behavioral co-adaptation between trials. Exploratory analyses further suggest that PMd, more than PMv, is the key source of modulatory drive sculpting movements, according to the socio-interactive context.

A voxel-level resting-state fMRI study on patients with alcohol use disorders based on a power spectrum slope analysis method

Background

Earlier neuroimaging investigations showed that abnormal brain activity in patients with alcohol use disorder (AUD) was frequency dependent. However, there is lacking of a comprehensive method to capture the amplitude of multi-frequency bands directly. Here, we used a new method, the power spectrum slope (PSS) to explore abnormal spontaneous activity of brain in patients with AUD.

Methods

Thirty-three AUD patients and 29 healthy controls (HCs) enrolled in this study. The coefficient b and the power-law slope b' were calculated and compared between two groups. We also used the receiver operating characteristic (ROC) curve to examine the ability of the PSS analysis to distinguish between AUD and HCs. We next examined the correlation between PSS difference in the brain areas and the severity of alcohol dependence.

Results

Thirty AUD patients and 26 HCs were retained after head motion correction. The two metrics of PSS values increased in the left precentral gyrus in AUD patients. The area under the curve values of PSS differences in the specific brain area were respectively 0.836 and 0.844, with sensitivities of 86.7% and 83.3% and specificities of 73.1% and 76.9%. The Michigan Alcoholism Screening Test (MAST) and Alcohol drinking scale (ADS) scores were not significantly correlated with the PSS values in the specific brain area.

Conclusion

As a novel method, the PSS can well detect abnormal local brain activity in the AUD patients and may offer new insights for future fMRI studies.

Effects of glabellar botulinum toxin injections on resting-state functional connectivity in borderline personality disorder

Meta-analyses suggest a sustained alleviation of depressive symptoms through glabellar botulinum toxin (BTX) injections. This can be explained by the disruption of facial feedback loops, which may moderate and reinforce the experience of negative emotions. Borderline personality disorder (BPD) is characterized by excessive negative emotions. Here, a seed-based resting-state functional connectivity (rsFC) analysis following BTX (N = 24) or acupuncture (ACU, N = 21) treatment in BPD is presented on areas related to the motor system and emotion processing. RsFC in BPD using a seed-based approach was analyzed. MRI data were measured before and 4 weeks after treatment. Based on previous research, the rsFC focus was on limbic and motor areas as well as the salience and default mode network. Clinically, after 4 weeks both groups showed a reduction of borderline symptoms. However, the anterior cingulate cortex (ACC) and the face area in the primary motor cortex (M1) displayed aberrant rsFC after BTX compared to ACU treatment. The M1 showed higher rsFC to the ACC after BTX treatment compared to ACU treatment. In addition, the ACC displayed an increased connectivity to the M1 as well as a decrease to the right cerebellum. This study shows first evidence for BTX-specific effects in the motor face region and the ACC. The observed effects of BTX on rsFC to areas are related to motor behavior. Since symptom improvement did not differ between the two groups, a BTX-specific effect seems plausible rather than a general therapeutic effect.

Alterations of brain activity in patients with alcohol use disorder: a resting-state fMRI study

BACKGROUND

Alcohol use disorder (AUD) has a negative impact on one's health and wastes a lot of societal resources since it damages one's brain tissue. Yet the knowledge of the neural mechanisms underlying alcohol addiction still remains limited. This study aims to investigate the neural mechanisms underlying alcohol addiction by using voxel-wise binarized degree centrality (DC), weighted DC and functional connectivity (FC) methods to analyze brain network activity in individuals with AUD.

METHODS

Thirty-three AUD patients and 29 healthy controls (HC) participated in this study. Binarized and weighted DC approach coupled with a second seed-based FC algorithm was used to assess the abnormal intrinsic hub features in AUD. We also examined the correlation between changes in functional network nodes and the severity of alcohol dependence.

RESULTS

Thirty AUD patients and 26 HC were retained after head motion correction. The spatial distribution maps of the binarized DC and weighted DC for the AUD and HC groups were roughly similar. In comparison to HC, the AUD group had decreased binarized DC and decreased weighted DC in the left precentral gyrus (PreCG) and the left inferior parietal lobule (IPL). Significantly different brain regions in the DC analysis were defined as seed points in the FC analysis. Compared with HC, changes in FC within the right inferior temporal gyrus (ITG), right middle temporal gyrus (MTG), left dorsolateral superior frontal gyrus (SFGdor), bilateral IPL, left precuneus (PCUN), left lingual gyrus (LING), right cerebellum_crus1/ITG/inferior occipital gyrus (IOG) and right superior parietal gyrus (SPG) were observed. The correlation analysis revealed that FC of right MTG-right PreCG was negatively correlated with MAST scores, and FC of right IPL-left IPL was positively correlated with ADS scores.

CONCLUSIONS

Alcohol use disorder is associated with aberrant regional activities in multiple brain areas. Binarized DC, weighted DC and FC analyses may be useful biological indicators for the detection of regional brain activities in patients with AUD. Intergroup differences in FC have also been observed in AUD patients, and these variations were connected to the severity of the symptoms. The AUD patients with lower FC value of the right IPL - left IPL has a lighter dependence on alcohol. This difference in symptom severity may be a compensation for cognitive impairment, indicating a difference in pathological pathways. Future AUD research will now have a fresh path thanks to these discoveries.

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.

The effect of acute exercise on cognitive and motor inhibition - Does fitness moderate this effect?

BACKGROUND

Given the extensive evidence on improvements in cognitive inhibition immediately following exercise, and the literature indicating that cognitive and motor inhibitory functions are mediated by overlapping brain networks, the aim of this study was to assess, for the first time, the effect of moderate intensity acute aerobic exercise on multi-limb motor inhibition, as compared to cognitive inhibition.

METHOD

Participants were 36 healthy adults aged 40-60 years old (mean age 46.8 ± 5.7), who were randomly assigned to experimental or control groups. One-to-two weeks following baseline assessment, participants were asked to perform a three-limb (3-Limb) inhibition task and a vocal version of the Stroop before and after either acute moderate-intense aerobic exercise (experimental group) or rest (control).

RESULTS

Similar rates of improvement were observed among both groups from baseline to the pre-test. Conversely, a meaningful, yet non-significant trend was seen among the experimental group in their pretest to posttest improvement in both cognitive and motor tasks. In addition, exploratory analysis revealed significant group differences in favor of the experimental group among highly fit participants on the 3-Limb task. A significant correlation was indicated between the inhibition conditions, i.e., choice in the motor inhibition and color/word (incongruent) in the cognitive inhibition, especially in the improvement observed following the exercise.

DISCUSSION

Moderate-intensity acute aerobic exercise is a potential stimulator of both multi-limb motor inhibition and cognitive inhibition. It appears that high-fit participants benefit from exercise more than low-fit people. Additionally, performance on behavioral tasks that represent motor and cognitive inhibition is related. This observation suggests that fitness levels and acute exercise contribute to the coupling between cognitive and motor inhibition. Neuroimaging methods would allow examining brain-behavior associations of exercise-induced changes in the brain.

Is cortical inhibition in primary motor cortex related to executive control?

Recent research using paired-pulse transcranial magnetic stimulation (TMS) has shown that the speed with which people can stop an action is linked to GABAergic inhibitory activity in the motor system. Specifically, a significant proportion of the variance in stop signal reaction time (SSRT; a widely used measure of inhibitory control) is accounted for by short-interval cortical inhibition (SICI). It is still unclear whether this relationship reflects a broader link between GABAergic processes and executive functions, or a specific link between GABAergic processes and motor stopping ability. The current study sought to replicate the correlation between SSRT and SICI while investigating whether this association generalises to other measures of inhibitory control and working memory, and to long-interval cortical inhibition (LICI). Participants completed a battery of inhibition (Stop-Signal, Stroop, Flanker) and working memory (n-back, Digit Span, and Operation Span) tasks. We replicated the correlation between SICI and SSRT but found no other correlations between behavioural measures of executive control and the two cortical measures of inhibition. These findings indicate that the relationship between SSRT and SICI is specific to a particular property of response inhibition and likely reflects the function of local inhibitory networks mediated by GABA_A.

Effective connectivity analysis reveals the time course of the Stroop effect in manual responding

Investigations of the time course of the Stroop effect have contributed to understanding of the mechanisms of cognitive control. However, previous studies have not reached a consistent conclusion regarding such mechanisms. The current study clarified the controversy by adopting a modified stimulus onset asynchrony (SOA) manual Stroop task combined with effective connectivity analysis based on task-related functional magnetic resonance imaging data. The behavioral results showed a decreasing Stroop effect when the distractor was presented before the target stimulus. In addition, significant effective connectivity related to inhibitory control was observed, which decreased with the time interval between stimuli, including the connection from the right inferior frontal gyrus (rIFG) to the pre-supplementary motor area (pre-SMA) and from the pre-SMA to the primary motor cortex (M1). Diversity of active patterns between different congruency types was also detected. The current results revealed that inhibitory control could be actively performed in response to distractors to reduce their interference and further decrease the Stroop effect, and that inhibition is more efficient the earlier it is started.

Response inhibition in children with different subtypes/presentations of attention deficit hyperactivity disorder: A near-infrared spectroscopy study

Background

Executive dysfunction in children with attention deficit hyperactivity disorder (ADHD) is thought to be closely related to the prefrontal cortex (PFC). However, there is controversy over the activation of the PFC in children with ADHD. Differences could be related to the subtype. Meanwhile, no study to date has used functional near-infrared spectroscopy (fNIRS) to explore the differences between subtypes. Thus, this study aimed to explore the activation of the PFC in children with different subtypes of ADHD during executive function task.

Methods

Participants in this study include typically developing (TD) children (n = 28), ADHD-predominantly inattentive (ADHD-PI) (n = 39) and ADHD-combined (ADHD-C) (n = 24). To examine the executive function of ADHD, the Go/No-go task is chosen to assess the response inhibition function. The activation of PFC in all participants during the Go/No-go task was recorded by fNIRS. Meanwhile, behavioral data were also recorded.

Results

Both TD and ADHD children activated the right PFC [middle frontal gyrus (MFG) and inferior frontal gyrus (IFG)] during response inhibition. However, the range and degree of activation differed among these groups. Compared with TD children, those with ADHD-PI had a smaller extent of activation in the right PFC, and those with ADHD-C only had a tendency to enhance activation. In addition, children with ADHD-PI and ADHD-C had impaired activation of the temporal gyrus. Besides, compared with ADHD-C and TD, those with ADHD-PI also had impaired activation of the right precentral gyrus (PG), and the supplementary motor area (SMA). Compared with ADHD-PI, ADHD-C showed decreased activation of the right MFG. The activation of Ch34 (BA44, rPFC) in children with ADHD-PI and ADHD-C was negatively correlated with their clinical symptoms.

Conclusion

The activation of the PFC in children with different subtypes of ADHD has both commonalities and differences. The degree of activation of the right PFC Ch34 in children with ADHD is negatively correlated with clinical symptoms. fNIRS could be served as a candidate hemodynamic biomarker for the diagnosis of ADHD.

Individual differences in beta-band oscillations predict motor-inhibitory control

Objective

The ability of motor-inhibitory control is critical in daily life. The physiological mechanisms underlying motor inhibitory control deficits remain to be elucidated. Beta band oscillations have been suggested to be related to motor performance, but whether they relate to motor-inhibitory control remains unclear. This study is aimed at systematically investigating the relationship between beta band oscillations and motor-inhibitory control to determine whether beta band oscillations were related to the ability of motor-inhibitory control.

Methods

We studied 30 healthy young adults (age: 21.6 ± 1.5 years). Stop-signal reaction time (SSRT) was derived from stop signal task, indicating the ability of motor-inhibitory control. Resting-state electroencephalography (EEG) was recorded for 12 min. Beta band power and functional connectivity (including global efficiency) were calculated. Correlations between beta band oscillations and SSRT were performed.

Results

Beta band EEG power in left and right motor cortex (MC), right somatosensory cortex (SC), and right inferior frontal cortex (IFC) was positively correlated with SSRT (P's = 0.031, 0.021, 0.045, and 0.015, respectively). Beta band coherence between bilateral MC, SC, and IFC was also positively correlated with SSRT (P's < 0.05). Beta band global efficiency was positively correlated with SSRT (P = 0.01).

Conclusion

This is the first study to investigate the relationship between resting-state cortical beta oscillations and response inhibition. Our findings revealed that individuals with better ability of motor inhibitory control tend to have less cortical beta band power and functional connectivity. This study has clinical significance on the underlying mechanisms of motor inhibitory control deficits.

Transcranial Magnetic Stimulation Following a Paired Associative Stimulation Protocol Based on a Video Game Neuromodulates Cortical Excitability and Motor Behavior

Transcranial Magnetic Stimulation (TMS) can be used to modulate cortico-spinal excitability following a paired associative stimulation (PAS) protocol. Movement-related cortical stimulation (MRCS) is a PAS protocol based on the synchronization of a single-pulse TMS with a movement task. However, plasticity and motor performance potentiation due to MRCS has been related exclusively to single-movement tasks. In order to unveil the effects of an MRCS protocol in complex movements, we applied PAS synchronized with a movement-related dynamic task (MRDT) with a customized video game. In 22 healthy subjects, we measured the reaction time (RT), trajectory error (TE), and the number of collected and avoided items when playing the custom video game to evaluate the task motor performance. Moreover, we assessed the recruitment curve of Motor Evoked Potentials (MEPs) with five different intensities to evaluate the motor corticospinal excitability. MEPs were recorded in Abductor Pollicis Brevis (APB) and Abductor Digiti Minimi (ADM), before, right after, and 30 min after the PAS intervention, in an active versus sham experimental design. The MRCS PAS intervention resulted in RT reduction, and motor corticospinal excitability was modulated, reflected as significant MEP amplitude change at 110% RMT intensity in ADM and at 130% RMT intensity in APB. RTs and ADM MEP amplitudes correlated positively in specific time and intensity assessments. We conclude that the proposed PAS protocol facilitated RT performance in a complex task. This phenomenon might be useful to develop neurorehabilitation strategies with complex movements, similar to activities of daily living.

Neuronal effects of glabellar botulinum toxin injections using a valenced inhibition task in borderline personality disorder

Previous studies have indicated that glabellar botulinum toxin (BTX) injections may lead to a sustained alleviation of depression. This may be accomplished by the disruption of a facial feedback loop, which potentially mitigates the experience of negative emotions. Accordingly, glabellar BTX injection can attenuate amygdala activity in response to emotional stimuli. A prototypic condition with an excess of negative emotionality and impulsivity accompanied by elevated amygdala reactivity to emotional stimuli is borderline personality disorder (BPD). In order to improve the understanding of how glabellar BTX may affect the processing of emotional stimuli and impulsivity, we conducted a functional magnetic resonance imaging (fMRI) study. Our hypotheses were (1) glabellar BTX leads to increased activation in prefrontal areas during inhibition performance and (2) BTX decreases amygdala activity during the processing of emotional stimuli in general. Using an emotional go-/no-go paradigm during fMRI, the interference of emotion processing and impulsivity in a sample of n = 45 women with BPD was assessed. Subjects were randomly assigned to BTX treatment or serial acupuncture (ACU) of the head. After 4 weeks, both treatments led to a reduction in the symptoms of BPD. However, BTX treatment was specifically associated with improved inhibition performance and increased activity in the motor cortex. In addition, the processing of negative emotional faces was accompanied by a reduction in right amygdala activity. This study provides the first evidence that glabellar BTX injections may modify central neurobiological and behavioural aspects of BPD. Since the control treatment produced similar clinical effects, these neurobiological findings may be specific to BTX and not a general correlate of symptomatic improvement.

Motor Imagery Combined With Physical Training Improves Response Inhibition in the Stop Signal Task

Background

Motor imagery training has a similar effect to that of physical training on motor performance. The objective of this study was to investigate the short-term effectiveness of motor imagery training on response inhibition using the stop signal task (SST).

Methods

Participants were divided into a physical training group (PT, n = 17), a motor imagery training group (MIT, n = 17), and a motor imagery combined with physical training group (MIPT, n = 17). All participants performed 10 SST training sessions over 5 days. Both stop signal reaction time (SSRT) and non-signal reaction time (NSRT) were measured before and after SST training.

Results

There were significant interaction (time × group) and time effects, although the group effect was not statistically significant. Bonferroni post hoc analysis showed that MIPT group revealed a significantly greater change in SSRT than PT and MIT groups, while there was no significant difference between PT and MIT groups. SSRT significantly decreased after training in all groups. In NSRT, there was a significant effect of time, but there was no significant interaction effect (time × group) or group effect.

Conclusion

Response inhibition could be enhanced via training, and it was most effective when motor imagery and physical training were combined. We demonstrate that motor imagery training significantly improves response inhibition and should be accompanied by physical training when performing SST.

Repetitive Transcranial Magnetic Stimulation of the Primary Motor Cortex beyond Motor Rehabilitation: A Review of the Current Evidence

Transcranial magnetic stimulation (TMS) has emerged as a novel technique to stimulate the human brain through the scalp. Over the years, identifying the optimal brain region and stimulation parameters has been a subject of debate in the literature on therapeutic uses of repetitive TMS (rTMS). Nevertheless, the primary motor cortex (M1) has been a conventional target for rTMS to treat motor symptoms, such as hemiplegia and spasticity, as it controls the voluntary movement of the body. However, with an expanding knowledge base of the M1 cortical and subcortical connections, M1-rTMS has shown a therapeutic efficacy that goes beyond the conventional motor rehabilitation to involve pain, headache, fatigue, dysphagia, speech and voice impairments, sleep disorders, cognitive dysfunction, disorders of consciousness, anxiety, depression, and bladder dysfunction. In this review, we summarize the latest evidence on using M1-rTMS to treat non-motor symptoms of diverse etiologies and discuss the potential mechanistic rationale behind the management of each of these symptoms.

The role of the primary motor cortex in motor imagery: A theta burst stimulation study

While mentally simulated actions activate similar neural structures to overt movement, the role of the primary motor cortex (PMC) in motor imagery remains disputed. The aim of the study was to use continuous theta burst stimulation (cTBS) to modulate corticospinal activity to investigate the putative role of the PMC in implicit motor imagery in young adults with typical and atypical motor ability. A randomized, double blind, sham‐controlled, crossover, offline cTBS protocol was applied to 35 young adults. During three separate sessions, adults with typical and low motor ability (developmental coordination disorder [DCD]), received active cTBS to the PMC and supplementary motor area (SMA), and sham stimulation to either the PMC or SMA. Following stimulation, participants completed measures of motor imagery (i.e., hand rotation task) and visual imagery (i.e., letter number rotation task). Although active cTBS significantly reduced corticospinal excitability in adults with typical motor ability, neither task performance was altered following active cTBS to the PMC or SMA, compared to performance after sham cTBS. These results did not differ across motor status (i.e., typical motor ability and DCD). These findings are not consistent with our hypothesis that the PMC (and SMA) is directly involved in motor imagery. Instead, previous motor cortical activation observed during motor imagery may be an epiphenomenon of other neurophysiological processes and/or activity within brain regions involved in motor imagery. This study highlights the need to consider multi‐session theta burst stimulation application and its neural effects when probing the putative role of motor cortices in motor imagery.

A controlled continuous theta burst stimulation protocol was adopted to examine the role of the primary motor cortex in motor imagery. While corticospinal excitability was suppressed in individuals with typical motor ability, no changes in imagery performance were detected after applying active stimulation to the motor regions. This suggests that motor regions may not be causally implicated in motor imagery and/or that multiple stimulation sessions may be required when inducing cognitive‐behavioral changes.

Data-driven study on resting-state functional magnetic resonance imaging during early abstinence of alcohol dependence in male patients and its predictive value for relapse

BACKGROUND

Alcohol dependence is a mental disorder with a high relapse rate. However, specific neuroimaging biomarkers have not been determined for alcohol dependence and its relapse. We conducted data-driven research to investigate resting-state functional magnetic resonance imaging (rs-fMRI) during early abstinence from alcohol dependence and its potential ability to predict relapse.

METHODS

Participants included 68 alcohol-dependent patients and 68 healthy controls (HCs). The regional homogeneity (ReHo) and fractional amplitude of low-frequency fluctuations (fALFF) were compared between the alcohol dependence group and the HCs and between the relapse group and the nonrelapse group. The brain regions that presented significantly different ReHo and/or fALFF between the alcohol-dependent patients and HCs and/or between the relapsed and nonrelapsed patients were selected as the seeds to calculate the functional connectivities (FCs).

RESULTS

During a 6-month follow-up period, 52.24% of alcohol-dependent patients relapsed. A regression model for differentiating alcohol-dependent patients and HCs showed that reductions in ReHo in the left postcentral region, fALFF in the right fusiform region, and FC in the right fusiform region to the right middle cingulum were independently associated with alcohol dependence, with an area under the receiver operating characteristic curve (AUC) of 0.841. The baseline FC of the left precentral to the left cerebellum of the relapse group was significantly lower than that of the nonrelapse group. The AUC of this FC to predict relapse was 0.774.

CONCLUSIONS

Our findings contribute to advancing research on the neurobiological etiology and predictive biomarkers for relapse associated with alcohol dependence.

Dynamic targeting enables domain-general inhibitory control over action and thought by the prefrontal cortex

Over the last two decades, inhibitory control has featured prominently in accounts of how humans and other organisms regulate their behaviour and thought. Previous work on how the brain stops actions and thoughts, however, has emphasised distinct prefrontal regions supporting these functions, suggesting domain-specific mechanisms. Here we show that stopping actions and thoughts recruits common regions in the right dorsolateral and ventrolateral prefrontal cortex to suppress diverse content, via dynamic targeting. Within each region, classifiers trained to distinguish action-stopping from action-execution also identify when people are suppressing their thoughts (and vice versa). Effective connectivity analysis reveals that both prefrontal regions contribute to action and thought stopping by targeting the motor cortex or the hippocampus, depending on the goal, to suppress their task-specific activity. These findings support the existence of a domain-general system that underlies inhibitory control and establish Dynamic Targeting as a mechanism enabling this ability.

Multiple Brain Sources Are Differentially Engaged in the Inhibition of Distinct Action Types

Most studies contributing to identify the brain network for inhibitory control have investigated the cancelation of prepared-discrete actions, thus focusing on an isolated and short-lived chunk of human behavior. Aborting ongoing-continuous actions is an equally crucial ability but remains little explored. Although discrete and ongoing-continuous rhythmic actions are associated with partially overlapping yet largely distinct brain activations, it is unknown whether the inhibitory network operates similarly in both situations. Thus, distinguishing between action types constitutes a powerful means to investigate whether inhibition is a generic function. We, therefore, used independent component analysis (ICA) of EEG data and show that canceling a discrete action and aborting a rhythmic action rely on independent brain components. The ICA showed that a delta/theta power increase generically indexed inhibitory activity, whereas N2 and P3 ERP waves did so in an action-specific fashion. The action-specific components were generated by partially distinct brain sources, which indicates that the inhibitory network is engaged differently when canceling a prepared-discrete action versus aborting an ongoing-continuous action. In particular, increased activity was estimated in precentral gyri and posterior parts of the cingulate cortex for action canceling, whereas an enhanced activity was found in more frontal gyri and anterior parts of the cingulate cortex for action aborting. Overall, the present findings support the idea that inhibitory control is differentially implemented according to the type of action to revise.

Dynamic functional network connectivity reveals the brain functional alterations in lung cancer patients after chemotherapy

This study aimed to investigate alterations of brain functional network connectivity (FNC) in lung cancer patients after chemotherapy and explore links between these FNC differences and cognitive impairment. Twenty-two lung cancer patients receiving chemotherapy and 26 healthy controls (HCs) underwent resting-state functional MRI (rs-fMRI) and neuropsychological testing. Group independent component analysis (GICA) was applied to rs-fMRI data to extract whole-brain resting state networks (RSNs). Static and dynamic FNC (dFNC) were constructed to reveal RSNs connectivity alterations between lung cancer patients and HCs group, and the correlations between the group differences in RSNs and cognitive performance were analyzed. Our findings revealed that chemotherapeutics can produce widespread connectivity abnormalities in RSNs, mainly focused on default mode network (DMN) and executive control network. Furthermore, the dFNC analysis help identify network configurations of each state and capture more chemotherapy-induced disorders of interactions between and within RSNs, which mainly includes sensorimotor network, attentional network and auditory network. In addition, after chemotherapy, the lung cancer patients spend shorter mean dwell time (MDT) in state 2. The decreased dFNC between DMN [independent component 5 (IC5)] and DMN (IC6) in the lung cancer patients after chemotherapy in state 4 was negatively correlated with Montreal Cognitive Assessment (MoCA) scores (r=-0.447, p=0.042). The dFNC analysis enrich our understanding of the neural mechanisms underlying the chemobrain, and suggested that the temporal dynamics of FNC could be a potential effective method to detect cognitive changes in lung cancer patients receiving chemotherapy.

The Pause-then-Cancel model of human action-stopping: Theoretical considerations and empirical evidence

The ability to stop already-initiated actions is a key cognitive control ability. Recent work on human action-stopping has been dominated by two controversial debates. First, the contributions (and neural signatures) of attentional orienting and motor inhibition after stop-signals are near-impossible to disentangle. Second, the timing of purportedly inhibitory (neuro)physiological activity after stop-signals has called into question which neural signatures reflect processes that actually contribute to action-stopping. Here, we propose that a two-stage model of action-stopping - proposed by Schmidt and Berke (2017) based on subcortical rodent recordings - may resolve these controversies. Translating this model to humans, we first argue that attentional orienting and motor inhibition are inseparable because orienting to salient events like stop-signals automatically invokes broad motor inhibition, reflecting a fast-acting, ubiquitous Pause process. We then argue that inhibitory signatures after stop-signals differ in latency because they map onto two sequential stages: the salience-related Pause and a slower, stop-specific Cancel process. We formulate the model, discuss recent supporting evidence in humans, and interpret existing data within its context.

Exploring cortico-cortical interactions during action preparation by means of dual-coil transcranial magnetic stimulation: A systematic review

Action preparation is characterized by a set of complex and distributed processes that occur in multiple brain areas. Interestingly, dual-coil transcranial magnetic stimulation (TMS) is a relevant technique to probe effective connectivity between cortical areas, with a high temporal resolution. In the current systematic review, we aimed at providing a detailed picture of the cortico-cortical interactions underlying action preparation focusing on dual-coil TMS studies. We considered four theoretical processes (impulse control, action selection, movement initiation and action reprogramming) and one task modulator (movement complexity). The main findings highlight 1) the interplay between primary motor cortex (M1) and premotor, prefrontal and parietal cortices during action preparation, 2) the varying (facilitatory or inhibitory) cortico-cortical influence depending on the theoretical processes and the TMS timing, and 3) the key role of the supplementary motor area-M1 interactions that shape the preparation of simple and complex movements. These findings are of particular interest for clinical perspectives, with a need to better characterize functional connectivity deficiency in clinical population with altered action preparation.

Anatomo-Functional Origins of the Cortical Silent Period: Spotlight on the Basal Ganglia

The so-called cortical silent period (CSP) refers to the temporary interruption of electromyographic signal from a muscle following a motor-evoked potential (MEP) triggered by transcranial magnetic stimulation (TMS) over the primary motor cortex (M1). The neurophysiological origins of the CSP are debated. Previous evidence suggests that both spinal and cortical mechanisms may account for the duration of the CSP. However, contextual factors such as cortical fatigue, experimental procedures, attentional load, as well as neuropathology can also influence the CSP duration. The present paper summarizes the most relevant evidence on the mechanisms underlying the duration of the CSP, with a particular focus on the central role of the basal ganglia in the "direct" (excitatory), "indirect" (inhibitory), and "hyperdirect" cortico-subcortical pathways to manage cortical motor inhibition. We propose new methods of interpretation of the CSP related, at least partially, to the inhibitory hyperdirect and indirect pathways in the basal ganglia. This view may help to explain the respective shortening and lengthening of the CSP in various neurological disorders. Shedding light on the complexity of the CSP's origins, the present review aims at constituting a reference for future work in fundamental research, technological development, and clinical settings.

Short intracortical facilitation associates with motor-inhibitory control

The ability of motor-inhibitory control is important in daily life. Inhibitory control deficits are commonly observed in psychiatric conditions with enhanced impulsivity. The physiological mechanisms underlying the inhibitory control deficits are not well elucidated. We systematically investigated the relationship between resting-state intracortical inhibition or facilitation and inhibitory control (indicated by stop signal reaction time, SSRT) to determine whether reduced intracortical inhibition or increased intracortical facilitation was related to the poorer inhibitory control. Thirty-three healthy subjects (age: 21.46 ± 1.40 years) participated in this study. We used paired-pulse transcranial magnetic stimulation to induce short intracortical inhibition, intracortical facilitation, long intracortical inhibition, and short intracortical facilitation at rest. SSRT was derived from stop signal task. We performed all measurements in two repeat sessions conducted two weeks apart. A negative correlation between short intracortical inhibition and SSRT was only observed in session 1; however, the correlation did not persist after controlling for short intracortical facilitation. Positive correlation between short intracortical facilitation and SSRT was observed in both sessions, indicating that individuals with greater resting-state short intracortical facilitation tend to have less efficient stopping performance. Our results help explain the inconsistency with respect to the relationship between short intracortical inhibition and SSRT in the existing literature. Short intracortical facilitation may be used as a potential physiological biomarker for motor-inhibitory control, which may have clinical implications for disorders associated with inhibitory control deficits.

The "when" and "where" of the interplay between attentional capture and response inhibition during a Go/NoGo variant

Inhibitory control relies on attention, inhibition, and other functions that are integrated across neural networks in an interactive manner. Functional MRI studies have provided excellent spatial mapping of the involved regions. However, finer temporal resolution is needed to capture the underlying neural dynamics and the pattern of their functional contributions. Here, we used anatomically-constrained magnetoencephalography (aMEG) which combines MEG with structural MRI to examine how the spatial ("where") and temporal ("when") processing stages and interregional co-oscillations unfold in real time to contribute to inhibitory control. Healthy participants completed a modified Go/NoGo paradigm in which a subset of stimuli was modified to be visually salient (SAL). Compared to the non-modified condition, the SAL manipulation facilitated response withholding on NoGo trials and hindered responding to Go stimuli, reflecting attentional capture effectuated by an orienting response to SAL stimuli. aMEG source estimates indicate SAL stimuli elicited the attentional "circuit breaker" effect through early activity within a right-lateralized network centered around the lateral temporal cortex with additional activity in the pre-supplementary motor area (preSMA) and anterior insula (aINS/FO). Activity of the bilateral inferior frontal cortex responded specifically to inhibitory demands and was generally unaffected by the attentional manipulation. In contrast, early aINS/FO activity was sensitive to stimulus salience while subsequent activity was specific to inhibitory control. Activity estimated to the medial prefrontal cortex including the dorsal anterior cingulate cortex and preSMA reflected an integrative role that was sensitive to both inhibitory and attentional stimulus properties. At the level of neurofunctional networks, neural synchrony in the theta band (4-7 Hz) revealed interactions between principal cortical regions subserving attentional and inhibitory processes. Together, these results underscore the dynamic, integrative processing stages underlying inhibitory control.

Unexpected Sounds Nonselectively Inhibit Active Visual Stimulus Representations

The brain's capacity to process unexpected events is key to cognitive flexibility. The most well-known effect of unexpected events is the interruption of attentional engagement (distraction). We tested whether unexpected events interrupt attentional representations by activating a neural mechanism for inhibitory control. This mechanism is most well characterized within the motor system. However, recent work showed that it is automatically activated by unexpected events and can explain some of their nonmotor effects (e.g., on working memory representations). Here, human participants attended to lateralized flickering visual stimuli, producing steady-state visual evoked potentials (SSVEPs) in the scalp electroencephalogram. After unexpected sounds, the SSVEP was rapidly suppressed. Using a functional localizer (stop-signal) task and independent component analysis, we then identified a fronto-central EEG source whose activity indexes inhibitory motor control. Unexpected sounds in the SSVEP task also activated this source. Using single-trial analyses, we found that subcomponents of this source differentially relate to sound-induced SSVEP changes: While its N2 component predicted the subsequent suppression of the attended-stimulus SSVEP, the P3 component predicted the suppression of the SSVEP to the unattended stimulus. These results shed new light on the processes underlying fronto-central control signals and have implications for phenomena such as distraction and the attentional blink.

Abnormal regional homogeneity and its relationship with symptom severity in cervical dystonia: a rest state fMRI study

BACKGROUND

Although several brain networks play important roles in cervical dystonia (CD) patients, regional homogeneity (ReHo) changes in CD patients have not been clarified. We investigated to explore ReHo in CD patients at rest and analyzed its correlations with symptom severity as measured by Tsui scale.

METHODS

A total of 19 CD patients and 21 gender-, age-, and education-matched healthy controls underwent fMRI scans at rest state. Data were analyzed by ReHo method.

RESULTS

Patients showed increased ReHo in the right cerebellum crus I and decreased ReHo in the right superior medial prefrontal cortex (MPFC). Moreover, the right precentral gyrus, right insula, and bilateral middle cingulate gyrus also showed increased ReHo values. A significantly positive correlation was observed between ReHo value in the right cerebellum crus I and symptom severity (p < 0.05).

CONCLUSIONS

Our investigation suggested abnormal ReHo existed in brain regions of the "pain matrix" and salience network (the right insula and bilateral middle cingulate gyrus), the motor network (the right precentral gyrus), the cerebellum and MPFC and further highlighted the significance of these networks in the pathology of CD.

Behavioral and Neurophysiological Aspects of Inhibition-The Effects of Acute Cardiovascular Exercise

This review summarizes behavioral and neurophysiological aspects of inhibitory control affected by a single bout of cardiovascular exercise. The review also examines the effect of a single bout of cardiovascular exercise on these processes in young adults with a focus on the functioning of prefrontal pathways (including the left dorsolateral prefrontal cortex (DLPFC) and elements of the prefrontal-basal ganglia pathways). Finally, the review offers an overview on the potential effects of cardiovascular exercise on GABA-ergic and glutamatergic neurotransmission in the adult brain and propose mechanisms or processes that may mediate these effects. The main findings show that a single bout of cardiovascular exercise can enhance inhibitory control. In addition, acute exercise appears to facilitate activation of prefrontal brain regions that regulate excitatory and inhibitory pathways (specifically but not exclusively the prefrontal-basal-ganglia pathways) which appear to be impaired in older age. Based on the reviewed studies, we suggest that future work examine the beneficial effects of exercise on the inhibitory networks in the aging brain.

Voxel-Wise Brain-Wide Functional Connectivity Abnormalities in Patients with Primary Blepharospasm at Rest

Background

Primary blepharospasm (BSP) is one of the most common focal dystonia and its pathophysiological mechanism remains unclear. An unbiased method was used in patients with BSP at rest to observe voxel-wise brain-wide functional connectivity (FC) changes.

Method

A total of 48 subjects, including 24 untreated patients with BSP and 24 healthy controls, were recruited to undergo functional magnetic resonance imaging (fMRI). The method of global-brain FC (GFC) was adopted to analyze the resting-state fMRI data. We designed the support vector machine (SVM) method to determine whether GFC abnormalities could be utilized to distinguish the patients from the controls.

Results

Relative to healthy controls, patients with BSP showed significantly decreased GFC in the bilateral superior medial prefrontal cortex/anterior cingulate cortex (MPFC/ACC) and increased GFC in the right postcentral gyrus/precentral gyrus/paracentral lobule, right superior frontal gyrus (SFG), and left paracentral lobule/supplement motor area (SMA), which were included in the default mode network (DMN) and sensorimotor network. SVM analysis showed that increased GFC values in the right postcentral gyrus/precentral gyrus/paracentral lobule could discriminate patients from controls with optimal accuracy, specificity, and sensitivity of 83.33%, 83.33%, and 83.33%, respectively.

Conclusion

This study suggested that abnormal GFC in the brain areas associated with sensorimotor network and DMN might underlie the pathophysiology of BSP, which provided a new perspective to understand BSP. GFC in the right postcentral gyrus/precentral gyrus/paracentral lobule might be utilized as a latent biomarker to differentiate patients with BSP from controls.

Abnormal Spatial Patterns of Intrinsic Brain Activity in Osteonecrosis of the Femoral Head: A Resting-State Functional Magnetic Resonance Imaging Study

Objective: Osteonecrosis of the femoral head (ONFH) is a common condition that is encountered in clinical practice, and yet, little is known about its characteristics and manifestations in the brain. Therefore, in this study, we aimed to use resting-state functional magnetic resonance imaging (rs-fMRI) to investigate the spatial patterns of spontaneous brain activity in the brain of ONFH patients.

Methods: The study included ONFH patients and healthy controls. The pattern of intrinsic brain activity was measured by examining the amplitude of low-frequency fluctuations (ALFF) of blood oxygen level-dependent signals using rs-fMRI. Meanwhile, we also used Harris hip scores to evaluate the functional performance of ONFH patients and healthy controls.

Result: Ten ONFH patients and 10 health controls were investigated. We found global ALFF differences between the two groups throughout the occipital, parietal, frontal, prefrontal, and temporal cortices. In the ONFH patients, altered brain activity was found in the brain regions in the sensorimotor network, pain-related network, and emotion and cognition network. The results of the correlation investigations also demonstrated that the regions with ALFF changes had significant correlations with the functional performance of the patients evaluated by Harris hip scores.

Conclusions: Our study has revealed the abnormal pattern of brain activity in ONFH patients, and our findings could be used to aid in understanding the mechanisms behind the gait abnormality and intractable pain associated with ONFH at the central level.

Optimal stimulation site for rTMS to improve motor function: Anatomical hand knob vs. hand motor hotspot

Repetitive transcranial magnetic stimulation (rTMS) is used to modulate neuronal excitability of the human brain. Distant effects on contralateral corticomotor excitability can be exerted by interhemispheric modulation by low-frequency rTMS on ipsilateral hemisphere. To modulate corticospinal excitability, accurate determination of the stimulation site is important to maximize the effects of rTMS. In the present study, we investigated the difference in the distant effect of 1 Hz rTMS with respect to inducing functional improvement in the non-dominant hand by inhibiting the dominant hemisphere depending on cortical target areas. Ten healthy right-handed volunteers without any neurological disorders were enrolled. The anatomical hand knob (HK) identified from individual magnetic resonance imaging and the transcranial magnetic stimulation (TMS) induced hand motor hotspot (hMHS) by recording motor evoked potentials (MEPs) in the contralateral first dorsal interosseous muscle were determined. All participants underwent three conditions of 1 Hz rTMS on left hemisphere intervention; rTMS application over the HK, rTMS application over the hMHS, and sham-rTMS. Before and after each intervention, all participants undergone motor function assessments with their left hand. The cortical mapping showed that the hMHS was located anteriorly and laterally compared to the HK. Motor function tests showed the most significant improvements after the hMHS stimulation. When we compared the distant effects of target site on corticospinal excitability and motor behavior, delivering 1 Hz rTMS to the hMHS was more effective than delivering it to the HK for improving corticomotor excitability, motor skill, and dexterity. These results suggest that TMS-induced hMHS is an optimal target area to induce distant effect of low-frequency rTMS in motor function.

Stop Signal Task Training Strengthens GABA-mediated Neurotransmission within the Primary Motor Cortex

We have recently shown that the efficiency in stopping a response, measured using the stop signal task, is related to GABAA-mediated short-interval intracortical inhibition (SICI) in the primary motor cortex. In this study, we conducted two experiments on humans to determine whether training participants in the stop signal task within one session (Experiment 1) and across multiple sessions (Experiment 2) would increase SICI strength. For each experiment, we obtained premeasures and postmeasures of stopping efficiency and resting-state SICI, that is, during relaxed muscle activity (Experiment 1, n = 45, 15 male participants) and SICI during the stop signal task (Experiment 2, n = 44, 21 male participants). In the middle blocks of Experiment 1 and the middle sessions of Experiment 2, participants in the experimental group completed stop signal task training, whereas control participants completed a similar task without the requirement to stop a response. After training, the experimental group showed increased resting-state SICI strength (Experiment 1) and increased SICI strength during the stop signal task (Experiment 2). Although there were no overall behavioral improvements in stopping efficiency, improvements at an individual level were correlated with increases in SICI strength at rest (Experiment 1) and during successful stopping (Experiment 2). These results provide evidence of neuroplasticity in resting-state and task-related GABAA-mediated SICI in the primary motor cortex after response inhibition training. These results also suggest that SICI and stopping efficiency are temporally linked, such that a change in SICI between time points is correlated with a change in stopping efficiency between time points.

Neurometabolic Correlates of Reactive and Proactive Motor Inhibition in Young and Older Adults: Evidence from Multiple Regional 1H-MR Spectroscopy

Suboptimal inhibitory control is a major factor contributing to motor/cognitive deficits in older age and pathology. Here, we provide novel insights into the neurochemical biomarkers of inhibitory control in healthy young and older adults and highlight putative neurometabolic correlates of deficient inhibitory functions in normal aging. Age-related alterations in levels of glutamate–glutamine complex (Glx), N-acetylaspartate (NAA), choline (Cho), and myo-inositol (mIns) were assessed in the right inferior frontal gyrus (RIFG), pre-supplementary motor area (preSMA), bilateral sensorimotor cortex (SM1), bilateral striatum (STR), and occipital cortex (OCC) with proton magnetic resonance spectroscopy (¹H-MRS). Data were collected from 30 young (age range 18–34 years) and 29 older (age range 60–74 years) adults. Associations between age-related changes in the levels of these metabolites and performance measures or reactive/proactive inhibition were examined for each age group. Glx levels in the right striatum and preSMA were associated with more efficient proactive inhibition in young adults but were not predictive for reactive inhibition performance. Higher NAA/mIns ratios in the preSMA and RIFG and lower mIns levels in the OCC were associated with better deployment of proactive and reactive inhibition in older adults. Overall, these findings suggest that altered regional concentrations of NAA and mIns constitute potential biomarkers of suboptimal inhibitory control in aging.

Age-related alterations in the modulation of intracortical inhibition during stopping of actions

We investigated the effect of age on the ability to modulate GABA_A-ergic and GABA_B-ergic inhibitory activity during stopping of action (reactive inhibition) and preparation to stop (proactive inhibition). Twenty-five young and twenty-nine older adults performed an anticipated response version of the stop-signal task with varying levels of stop-signal probability. Paired-pulse transcranial magnetic stimulation was applied to left primary motor cortex to assess the modulation of GABA_A-mediated short-interval intracortical inhibition (SICI) during stopping and GABA_B-mediated long-interval intracortical inhibition (LICI) during the anticipation of a stop-signal. At the behavioral level, reactive inhibition was affected by aging as indicated by longer stop-signal reaction times in older compared to young adults. In contrast, proactive inhibition was preserved at older age as both groups slowed down their go response to a similar degree with increasing stop-signal probability. At the neural level, the amount of SICI was higher in successful stop relative to go trials in young but not in older adults. LICI at the start of the trial was modulated as a function of stop-signal probability in both young and older adults. Our results suggest that specifically the recruitment of GABA_A-mediated intracortical inhibition during stopping of action is affected by aging.

Modulation of vestibular-evoked responses prior to simple and complex arm movements

During destabilizing, voluntary arm movements, the vestibular system provides sensory cues related to head motion that are necessary to preserve upright balance. Although sensorimotor processing increases in accordance with task complexity during the preparation phase of reaching, it is unclear whether vestibular signals are also enhanced when maintaining postural control prior to the execution of a voluntary movement. To probe whether vestibular cues are a component of complexity-related increases in sensorimotor processing during movement preparation, vestibular-evoked responses to stochastic (0-25 Hz; root mean square = 1 mA) binaural, bipolar electrical vestibular stimulation (EVS) were examined. These responses were assessed using cumulant density function estimates in the upper and lower limbs prior to ballistic arm movements of varying complexity in both standing (experiment 1) and seated (experiment 2) conditions. In experiment 1, EVS-electromyography (EMG) cumulant density estimates surpassed 95% confidence intervals for biceps and triceps brachii, as well as the left and right medial gastrocnemius. For the latter two muscles, the responses were enhanced 10-18% with increased movement complexity. In experiment 2, the EVS-EMG cumulant density estimates also surpassed 95% confidence intervals in the upper limb, confirming the presence of vestibular-evoked responses while seated; however, the amplitude was significantly less than standing. This study demonstrates the vestibular system contributes to postural stability during the preparation phase of reaching. As such, vestibular-driven signals may be used to update an internal model for upcoming reaching tasks or to prepare for imminent postural disturbances.

Tuning the Corticospinal System: How Distributed Brain Circuits Shape Human Actions

Interactive behaviors rely on the operation of several processes allowing the control of actions, including their selection, withholding, and cancellation. The corticospinal system provides a unique route through which multiple brain circuits can exert control over bodily motor acts. In humans, the influence of these modulatory circuits on the corticospinal system can be probed using various transcranial magnetic stimulation (TMS) protocols. Here, we review neural data from TMS studies at the basis of our current understanding of how diverse pathways—including intra-cortical, trans-cortical, and subcortico-cortical circuits—contribute to action control by tuning the activity of the corticospinal system. Critically, when doing so, we point out important caveats in the field that arise from the fact that these circuits, and their impact on the corticospinal system, have not been considered equivalently for action selection, withholding, and cancellation. This has led to the misleading view that some circuits or regions are specialized in specific control processes and that they produce particular modulatory changes in corticospinal excitability (e.g., generic vs. specific modulation of corticospinal excitability). Hence, we point to the need for more transversal research approaches in the field of action control.

Reduced Global-Brain Functional Connectivity and Its Relationship With Symptomatic Severity in Cervical Dystonia

Background: Altered functional connectivity (FC) is related to pathophysiology of patients with cervical dystonia (CD). However, inconsistent results may be obtained due to different selected regions of interest. We explored voxel-wise brain-wide FC changes in patients with CD at rest in an unbiased manner and analyzed their correlations with symptomatic severity using the Tsui scale.

Method: A total of 19 patients with CD and 21 sex- and age-matched healthy controls underwent resting-state functional magnetic resonance imaging scans. Global-brain FC (GFC) was applied to analyze the images. Support vector machine was used to distinguish the patients from the controls.

Results: Patients with CD exhibited decreased GFC in the right precentral gyrus and right supplementary motor area (SMA) that belonged to the M1-SMA motor network. Significantly negative correlation was observed between GFC values in the right precentral gyrus and symptomatic severity in the patients (r = −0.476, p = 0.039, uncorrected). Decreased GFC values in these two brain regions could be utilized to differentiate the patients from the controls with good accuracies, sensitivities and specificities (83.33, 85.71, and 80.95% in the right precentral gyrus; and 87.59, 89.49, and 85.71% in the right SMA).

Conclusions: Our investigation suggests that patients with CD show reduced GFC in brain regions of the M1-SMA motor network and provides further insights into the pathophysiology of CD. GFC values in the right precentral gyrus and right SMA may be used as potential biomarkers to recognize the patients from the controls.

Connectivity of the Frontal Cortical Oscillatory Dynamics Underlying Inhibitory Control During a Go/No-Go Task as a Predictive Biomarker in Major Depression

BACKGROUND

Major depressive disorder (MDD) is characterized by core functional deficits in cognitive inhibition, which is crucial for emotion regulation. To assess the response to ruminative and negative mood states, it was hypothesized that MDD patients have prolonged disparities in the oscillatory dynamics of the frontal cortical regions across the life course of the disease.

METHOD

A "go/no-go" response inhibition paradigm was tested in 31 MDD patients and 19 age-matched healthy controls after magnetoencephalography (MEG) scanning. The use of minimum norm estimates (MNE) examined the changes of inhibitory control network which included the right inferior frontal gyrus (rIFG), pre-supplementary motor area (preSMA), and left primary motor cortex (lM1). The power spectrum (PS) within each node and the functional connectivity (FC) between nodes were compared between two groups. Furthermore, Pearson correlation was calculated to estimate the relationship between altered FC and clinical features.

RESULT

PS was significantly reduced in left motor and preSMA of MDD patients in both beta (13-30 Hz) and low gamma (30-50 Hz) bands. Compared to the HC group, the MDD group demonstrated higher connectivity between lM1 and preSMA in the beta band (t = 3.214, p = 0.002, FDR corrected) and showed reduced connectivity between preSMA and rIFG in the low gamma band (t = -2.612, p = 0.012, FDR corrected). The FC between lM1 and preSMA in the beta band was positively correlated with illness duration (r = 0.475, p = 0.005, FDR corrected), while the FC between preSMA and rIFG in the low gamma band was negatively correlated with illness duration (r = -0.509, p = 0.002, FDR corrected) and retardation factor scores (r = -0.288, p = 0.022, uncorrected).

CONCLUSION

In this study, a clinical neurophysiological signature of cognitive inhibition leading to sustained negative affect as well as functional non-recovery in MDD patients is highlighted. Duration of illness (DI) plays a key role in negative emotional processing, heighten rumination, impulsivity, and disinhibition.

The Cortico-Basal Ganglia-Cerebellar Network: Past, Present and Future Perspectives

Much of our present understanding of the function and operation of the basal ganglia rests on models of anatomical connectivity derived from tract-tracing approaches in rodents and primates. However, the last years have been characterized by promising step forwards in the in vivo investigation and comprehension of brain connectivity in humans. The aim of this review is to revise the current knowledge on basal ganglia circuits, highlighting similarities and differences across species, in order to widen the current perspective on the intricate model of the basal ganglia system. This will allow us to explore the implications of additional direct pathways running from cortex to basal ganglia and between basal ganglia and cerebellum recently described in animals and humans.

Between-hand coupling during response inhibition

Response inhibition reflects the process of terminating inappropriate preplanned or ongoing movements. When one hand is cued to stop after preparing a bimanual response (Partial trial), there is a substantial delay on the responding side. This delay is termed the interference effect and identifies a constraint that limits selective response inhibition. γ-Aminobutyric acid (GABA)-mediated networks within primary motor cortex (M1) may have distinct roles during response inhibition. In this study we examined whether the interference effect is the consequence of between-hand "coupling" into a unitary response and whether this is reflected in GABAergic intracortical inhibition within M1. Eighteen healthy right-handed participants performed a bimanual synchronous and asynchronous anticipatory response inhibition task. Electromyographic recordings were obtained from the first dorsal interosseous muscle bilaterally. Motor evoked potentials were elicited by single- and paired-pulse transcranial magnetic stimulation over right M1. As expected, Go trial performance was better with the synchronous compared with the asynchronous version of the task. Paradoxically, response delays during Partial trials were longer with the synchronous compared with the asynchronous task. Although task difficulty did not modulate GABAergic intracortical inhibition, there was a trend for between-hand coupling on asynchronous trials to be associated with greater GABA_B receptor-mediated inhibition and lesser recruitment of GABA_A receptor-mediated inhibition. The novel findings indicate that the interference effect is in part a consequence of between-hand coupling into a unitary response during movement preparation. The ability to respond independently with the two hands may rely on modulation of distinct inhibitory processes.NEW & NOTEWORTHY The temporal dynamics of an anticipated response task were manipulated to effect the difficulty of behavioral stopping and the underlying effects on motor neurophysiology. There were large response delays during trials where a subcomponent of an upcoming bimanual response was cued to stop in conditions where the anticipated action of the hands were synchronous, but not when asynchronous. Response delays reflected the integration of actions of both hands into a unitary response.