Increase In Electromyographic Activity Research Articles

Electromyographic Activity of Cervical Muscles in Patients with Neck Pain and Changes After Dry Needling: A Narrative Review

Neck pain can be associated with specific conditions, such as neurological disorders, vascular or inflammatory diseases, fractures, herniated discs, etc. However, the majority of neck pain cases cannot be attributed to a specific cause. The objective of this review is to describe the muscle dysfunctions associated with neck pain, as measured by electromyography, and to determine the effectiveness of dry needling in improving these muscular dysfunctions. The research was conducted using the following databases: PubMed, Alcorze, and Google Scholar. The next conclusions have been extracted after the revision of the 65 selected manuscripts. The current scientific evidence supports electromyographic pathological findings in individuals with chronic neck pain, especially during general upper limb movement, repetitive work, violin playing, cervical force, and cervical movement tasks. Dry needling applied to an active myofascial trigger point in the upper trapezius can be suggested as an intervention to enhance the performance in the cranio-cervical flexion. Dry needling applied to latent myofascial trigger points in the upper trapezius after typing tasks in healthy subjects resulted in decreased upper trapezius activity and fatigue in the short term. In women with trapezius myalgia, dry needling applied to the upper trapezius led to a lower increase in electromyography activity compared to no intervention.

Optogenetic activation of serotonergic neurons changes masticatory movement in freely moving mice

The serotonergic system modulates the neural circuits involved in jaw movement; however, the role of serotonin (5-HT) neurons in masticatory movement remains unclear. Here, we investigated the effect of selective activation of 5-HT neurons in the dorsal raphe nucleus (DRN), or the raphe obscurus nucleus (ROb), on voluntary masticatory movement using transgenic mice expressing the channelrhodopsin-2 (ChR2) mutant (C128S) in central 5-HT neurons. During voluntary mastication, DRN blue light illumination increased masticatory frequency and decreased the root mean square peak amplitude of electromyography (EMG) in the masseter muscles. DRN blue light illumination also decreased EMG burst duration in the masseter and digastric muscles. These changes were blocked by a 5-HT2A receptor antagonist. Conversely, ROb blue light illumination during voluntary mastication did not affect masticatory frequency and EMG bursts in the masseter and digastric muscles. DRN or ROb blue light illumination during the resting state did not induce rhythmic jaw movement such as mastication but induced an increase in EMG activity in masseter and digastric muscles. These results suggest that both DRN and ROb 5-HT neurons may facilitate jaw movement. Furthermore, DRN 5-HT neuron may contribute to changes in masticatory patterns during the masticatory sequence.

Basic characteristics of tongue pressure and electromyography generated by articulation of a syllable using the posterior part of the tongue

The basic function of the tongue in pronouncing diadochokinesis and other syllables is not fully understood. This study investigates the influence of sound pressure levels and syllables on tongue pressure and muscle activity in 19 healthy adults (mean age: 28.2 years; range: 22–33 years). Tongue pressure and activity of the posterior tongue were measured using electromyography (EMG) when the velar stops /ka/, /ko/, /ga/, and /go/ were pronounced at 70, 60, 50, and 40 dB. Spearman's rank correlation revealed a significant, yet weak, positive association between tongue pressure and EMG activity (ρ = 0.14, p < 0.05). Mixed-effects model analysis showed that tongue pressure and EMG activity significantly increased at 70 dB compared to other sound pressure levels. While syllables did not significantly affect tongue pressure, the syllable /ko/ significantly increased EMG activity (coefficient = 0.048, p = 0.013). Although no significant differences in tongue pressure were observed for the velar stops /ka/, /ko/, /ga/, and /go/, it is suggested that articulation is achieved by altering the activity of both extrinsic and intrinsic tongue muscles. These findings highlight the importance of considering both tongue pressure and muscle activity when examining the physiological factors contributing to sound pressure levels during speech.

Comparison of muscle response in patients treated with rigid and flexible fixed functional appliances.

The present study was undertaken to evaluate and compare muscle activity after the treatment with rigid and flexible fixed functional appliance. The study was conducted on 14 skeletal Class II malocclusion patients in the age group of 13-17 years, divided into two groups comprising 7 patients in each group. Group I was treated with a rigid fixed functional appliance (MPA IV), and Group II was treated with a flexible fixed functional appliance (Churro Jumper). Masseter and anterior temporalis muscle activities were recorded using needle electromyography (EMG) at postural rest, saliva swallowing, and clenching during five intervals (T0 to T4) during fixed functional appliance treatment. Unpaired t-test, Mann-Whitney U, and Wilcoxon sign rank test were applied for statistical analysis, and a P value of <.05 was considered statistically significant. Group I (MPA IV) showed a significant increase in EMG activity during postural rest position (P = 0.003, P = 0.001), swallowing (P = 0.013, P = 0.005), and clenching (P = 0.001, P = 0.002) in masseter and anterior temporalis muscle, respectively. Group II (Churro jumper) also showed a significant increase in EMG activity during postural rest position (P = 0.000, P = 0.000), swallowing (P = 0.001, P = 0.000), and clenching (P = 0.001, P = 0.000) in masseter and anterior temporalis muscle, respectively. Both rigid (MPA IV) and flexible (Churro Jumper) fixed functional appliances caused a significant increase in EMG activity of masseter and anterior temporalis muscle during postural rest position, swallowing, and clenching in 6 months of the observation period, but the flexible appliance (Churro Jumper) showed more significant increase.

Motor effects of fentanyl in isoflurane-anaesthetized pigs and the subsequent effect of ketanserin or naloxone

ObjectiveTo examine the effect of ketanserin and naloxone on fentanyl-induced motor activity in isoflurane-anaesthetized pigs. Study designRandomized, blinded, prospective two-group study. AnimalsA group of 12 crossbred pigs weighing 22–31 kg. MethodsFentanyl was administered to isoflurane-anaesthetized pigs at 7.5 μg kg–1 hour–1 for 40 minutes intravenously, followed by an intravenous injection of naloxone 0.1 mg kg–1 or ketanserin 1 mg kg–1. Electromyography (EMG) and accelerometry were used to record motor unit activity and tremors, respectively. To test the effect of drug administration on motor activity, data from a 5 minute period at baseline, immediately before and after antagonist injection were compared in a mixed model; p < 0.05. ResultsResults are reported with the median difference, 95% confidence intervals and corresponding p-values in brackets. Fentanyl significantly increased EMG activity [30.51 (1.84–81.02) μV, p = 0.004] and induced tremors [0.09 (0.02–0.18) m s–2, p < 0.001] in 10 of 12 pigs. Ketanserin significantly reduced EMG [32.22 (6.29–136.80) μV, p = 0.001] and tremor [0.10 (0.03–0.15) m s–2, p = 0.007] activity. No significant effect was found for naloxone on EMG [26.76 (–13.28–91.17) μV, p = 0.4] or tremors [0.08 (–0.01–0.19) m s–2, p = 0.08]. Conclusions and clinical relevanceFentanyl can induce motor activity in anaesthetized pigs, with a suggested link to the serotonergic system. This study shows that ketanserin can antagonize this activity, which supports the role of serotonin. This knowledge contributes to the general understanding of the motor effects of fentanyl and especially the problem of tremors in anaesthetized pigs.

The vestigial pinna-orienting system in humans briefly suppresses superior auricular muscle activity during reflexive orienting toward auditory stimuli.

The vestigial pinna-orienting system in humans is capable of increasing the activity of several auricular muscles in response to lateralized transient auditory stimuli. For example, transient increases in electromyographic activity in the posterior auricular muscle (PAM) to an attention-capturing stimulus have been documented. For the current study, surface electromyograms (EMGs) were recorded from the PAMs and superior auricular muscles (SAMs) of 10 normal-hearing participants. During the experiments, lateralized transient auditory stimuli, such as a crying baby, a shattering vase, or the participant's first names, were presented. These transient stimuli were either presented in silence or when participants actively listened to a podcast. Although ipsilateral PAM activity increased in response to transient stimuli, the SAM displayed the opposite behavior, i.e., a brief, ipsilateral suppression of activity. This suppression of ipsilateral SAM activity was more frequent on the right (75%) than left side (35%), whereas an ipsilateral PAM increase was roughly equal in prevalence on the two sides (left: 90%, right: 95%). During the active listening task, SAM suppression on the right ear was significantly larger in response to ipsilateral stimuli, compared with contralateral ones (P = 0.002), whereas PAM activity increased significantly (P = 0.002). Overall, this study provides evidence of a systematic transient suppression of the SAM during exogenous attention. This could suggest a more complex system than previously assumed, as the presence of synchronized excitatory and inhibitory components in different auricular muscles points toward a coordinated attempt at reflexively orienting the pinna toward a sound.NEW & NOTEWORTHY This study provides evidence that two auricular muscles in humans, the posterior and superior auricular muscles (PAM, SAM), react fundamentally different to lateralized transient auditory stimuli, especially during active listening. Although the PAM reacts with a transient increase in ipsilateral activity, ongoing ipsilateral SAM activity is briefly suppressed at the same time. This indicates the presence of a more complex and nuanced pinna-orienting system, with synchronized excitatory and inhibitory components in humans, than previously suspected.

Muscle Tension in Generalized Anxiety Disorder During a Stressful Mental Arithmetic Task

Introduction: The purpose of this study was to compare muscle tension between individuals with and without generalized anxiety disorder (GAD) during a resting state and a stressful mental arithmetic task. Methods: A total of 95 undergraduate students (68 females and 27 males; mean age=19.6, SD=3.5) completed an online survey on GAD symptoms and pathological worry, a diagnostic interview, and two laboratory tasks (resting and mental arithmetic tasks) while electromyography (EMG) signals were being recorded. Results: We found a significant main effect of condition, F(1,93) = 24.13, p&lt;.001, and group, F(1,93) = 4.55, p=.036. Furthermore, there was a significant interaction effect between condition and group, F(1,93) = 5.85, p=.017. A post-hoc analysis revealed that the increase in EMG activity from the resting period, 95% CI [.002398 .003474], to the mental arithmetic task, 95% CI [.003850 .005086], was significant for the GAD group, but not for the non-GAD group. Conclusions: Individuals with and without GAD did not show significant differences in physiologically measured muscle tension at baseline. However, the GAD group showed higher levels of muscle tension during stressful situations when compared to the non-GAD group.

Acute effects of blood flow restriction with whole-body vibration on sprint, muscle activation and metabolic accumulation in male sprinters.

Purpose: The aim of this study was to explore the acute effects of Blood Flow Restriction Training (BFRT), Whole-Body Vibration (WBV), and BFRT + WBV on the 20m sprint, muscle activation, and metabolic accumulation in male sprinters. Method: Sixteen male sprinters randomly performed BFRT, WBV, or BFRT + WBV interventions with 72h intervals. Electromyography (EMG) signals were collected before and during interventions. Fingertip blood was taken before, immediately after, and 15min after the intervention. 20m sprint was performed before and 3min after the intervention. Results: 1) 0-10m and 0-20m sprint performance were significantly improved after WBV and BFRT + WBV interventions (p < 0.05), 0-20m sprint performance was significantly improved after all three interventions (p < 0.05), 2) After BFRT + WBV intervention, the EMG amplitude of the vastus lateralis and soleus were significantly improved. Greater increases in EMG activity of the tibialis anterior muscle (p < 0.05)and blood lactate (p < 0.05)were observed following BFRT intervention compared to BFRT + WBV intervention. Conclusion: For sprint performance, BFRT and WBV had similar post-activation enhancement effects to BFRT + WBV, and the metabolic accumulation immediately following the BFRT were higher than that following BFRT + WBV in male sprinters.

Activation of upper limb muscles in subjects with scapular dyskinesis during bench-press and dumbbell fly on stable and unstable surfaces

Scapular dyskinesis has been associated with shoulder dysfunctions, and changes in electromyographic (EMG) activity have been reported during the execution of some exercises. To compare upper limb muscles EMG of asymptomatic subjects with and without scapular dyskinesis during bench-press and dumbbell fly exercise performed on different surface stability conditions. Twenty-eight physically active men were allocated into two groups: Control group (n= 14) and Dyskinesis group (n= 14). The participants performed six repetitions lasting three seconds of the bench press and dumbbell fly exercises with 50% of one-repetition maximum (1RM) on a bench and a Swiss ball. The EMG activity of the pectoralis major, serratus anterior, upper and lower trapezius, anterior deltoid, biceps and triceps muscles were recorded. No differences were found between groups, regardless of exercise or surface type. Inserting the unstable surface in the supine exercise promoted a slight increase in upper trapezius EMG activity for the control [4.32 (95% CI: 1.04 to 7.60)] and dyskinesis [3.30 (95% CI: 0.34 to 6.27)] groups. There is no difference in upper limb muscle EMG activity between subjects with and without scapular dyskinesis. In addition, inserting unstable surfaces did not modify EMG activity.

Pelvic floor muscle activity during coughing and valsalva maneuver in continent women and women with stress urinary incontinence: a systematic review

Background: Pelvic floor muscle (PFM) activation during efforts activities may predispose to urinary loss. However, there is unclear evidence on the behavior of PFM during situations of coughing and Valsalva maneuver. Objectives: Hence, the present review aimed to evaluate the current evidence on electromyographic (EMG) activity of PFM during coughing and Valsalva maneuver in continent women and women with stress urinary incontinence (SUI). Methods: The databases EMBASE, PubMed, Science Direct, Scopus and were searched up to August, 2021. Two independent reviewers conducted the selection process based on titles, abstracts, and full-text reading. In addition, studies reporting PFM EMG activity during coughing and/or the Valsalva maneuver with surface EMG were included. The methodological quality of the primary studies was assessed through the checklist proposed by the Joanna Briggs Institute for cross-sectional studies. Results: Seven cross-sectional studies were included in this review, four of which were on PFM activation of continent women, while the other three compared continent women versus women with SUI. During both Valsalva maneuver and coughing, an increase of PFM EMG activity compared to rest was observed for continent women and women with SUI. Limitations of the present systematic review are that comparison among studies and a meta-analysis were not possible due to heterogeneity of EMG techniques and devices used. Conclusions: Coughing and Valsalva maneuver lead to an increase in PFM electrical activity compared to rest. This increase was more prominent in women with SUI during Valsalva, with no differences during coughing.

Adding Vibration During Varied-Intensity Work Intervals Increases Time Spent Near Maximal Oxygen Uptake in Well-Trained Cyclists.

Previous research suggests that the percentage of maximal oxygen uptake attained and the time it is sustained close to maximal oxygen uptake (eg,>90%) can serve as a good criterion to judge the effectiveness of a training stimulus. The aim of this study was to investigate the acute effects of adding vibration during varied high-intensity interval training (HIIT) sessions on physiological and neuromuscular responses. Twelve well-trained cyclists completed a counterbalanced crossover protocol, wherein 2 identical varied HIIT cycling sessions were performed with and without intermittent vibration to the lower-intensity workloads of the work intervals (6 × 5-min work intervals and 2.5-min active recovery). Each 5-minute work interval consisted of 3 blocks of 40seconds performed at 100% of maximal aerobic power interspersed with 60-second workload performed at a lower power output, equal to the lactate threshold plus 20% of the difference between lactate threshold and maximal aerobic power. Oxygen uptake and electromyographic activity of lower and upper limbs were recorded during all 5-minute work intervals. Adding vibration induced a longer time ≥90% maximal oxygen uptake (11.14 [7.63] vs 8.82 [6.90] min, d = 0.64, P = .048) and an increase in electromyographic activity of lower and upper limbs during the lower-intensity workloads by 20% (16%) and 34% (43%) (d = 1.09 and 0.83; P = .03 and .015), respectively. Adding vibration during a varied HIIT session increases the physiological demand of the cardiovascular and neuromuscular systems, indicating that this approach can be used to optimize the training stimulus of well-trained cyclists.

Neuromuscular Control During Stair Descent and Artificial Tibial Translation After Acute ACL Rupture.

Background:Anterior cruciate ligament (ACL) rupture has direct effect on passive and active knee stability and, specifically, stretch-reflex excitability.Purpose/Hypothesis:The purpose of this study was to investigate neuromuscular activity in patients with an acute ACL deficit (ACL-D group) compared with a matched control group with an intact ACL (ACL-I group) during stair descent and artificially induced anterior tibial translation. It was hypothesized that neuromuscular control would be impaired in the ACL-D group.Study Design:Cross-sectional study; Level of evidence, 3.Methods:Surface electromyographic (EMG) activity of the vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), and semitendinosus (ST) muscles was recorded bilaterally in 15 patients with ACL-D (mean, 13.8 days [range, 7-21 days] since injury) and 15 controls with ACL-I during stair descent and artificially induced anterior tibial translation. The movements of stair descent were divided into preactivity, weight acceptance, and push-off phases. Reflex activity during anterior tibial translation was split into preactivity and short, medium, and late latency responses. Walking on a treadmill was used for submaximal EMG normalization. Kruskal-Wallis test and post hoc analyses with Dunn-Bonferroni correction were used to compare normalized root mean square values for each muscle, limb, movement, and reflex phase between the ACL-D and ACL-I groups.Results:During the preactivity phase of stair descent, the hamstrings of the involved leg of the ACL-D group showed 33% to 51% less activity compared with the matched leg and contralateral leg of the ACL-I group (P < .05). During the weight acceptance and push-off phases, the VL revealed a significant reduction (approximately 40%) in the involved leg of the ACL-D group compared with the ACL-I group. At short latency, the BF and ST of the involved leg of the ACL-D group showed a significant increase in EMG activity compared with the uninvolved leg of the ACL-I group, by a factor of 2.2 to 4.6.Conclusion:In the acute phase after an ACL rupture, neuromuscular alterations were found mainly in the hamstrings of both limbs during stair descent and reflex activity. The potential role of prehabilitation needs to be further studied.

Higher Leg and Trunk Muscle Activation during Balance Control in Copers versus People with Chronic Ankle Instability and Healthy Female Athletes.

HighlightsAthletes with a history of ankle sprain that do not suffer from ankle instability (copers) exhibit similar balance and neuromuscular control compared to healthy athletes.Athletes with chronic ankle instability show a deficit in neuromuscular control and balance, which may increase the risk of subsequent injuries.Athletes with chronic ankle instability are advised to use neuromuscular training in their rehabilitation program to improve balance and neuromuscular performance to reduce the risk of injury.More than 70% of people with ankle sprain experience chronic ankle instability. However, some people are well adapted to this damage (copers) and do not suffer from chronic ankle instability (CAI). This cross-sectional study involved 34 female athletes, who were classified into three groups (athletes with CAI, copers, and healthy athletes) and tested on a Biodex Balance System. Surface electromyography (EMG) and balance scores were monitored. The coper and healthy group exhibited higher medial gastrocnemius (MG) EMG activity during unstable balance conditions. The rectus abdominus (RA) in the coper group and rectus femoris (RF) in the healthy group showed greater EMG activity compared to CAI during unstable conditions. During stable conditions, the coper group showed greater RA EMG activity compared to CAI, as well as higher tibialis anterior (TA) EMG activity compared to the healthy group. Additionally, balance error scores were higher in the CAI group than those in the healthy group under unstable conditions. In conclusion, decreased EMG activity of the MG, RF, and RA in CAI athletes may contribute to impaired balance in these individuals. The increased EMG activity of the MG, TA, and RA in copers might result in more trunk and ankle stability.

High Estrogen Levels Cause Greater Leg Muscle Fatigability in Eumenorrheic Young Women after 4 mA Transcranial Direct Current Stimulation.

Transcranial direct current stimulation (tDCS) research has shown great outcome variability in motor performance tasks, with one possible source being sex differences. The goal of this study was to evaluate the effects of estrogen levels on leg muscle fatigability during a fatigue task (FT) after 4 mA tDCS over the left motor cortex (M1). Ten young, healthy eumenorrheic women received 4 mA anodal active or sham stimulation over the left M1 during periods of high and low estrogen levels. A fatigue index (FI) was calculated to quantify fatigability, and the electromyography (EMG) of the knee extensors and flexors was recorded during the FT. The findings showed that tDCS applied during high estrogen levels resulted in greater leg muscle fatigability. Furthermore, a significant increase in EMG activity of the right knee extensors was observed during periods of active stimulation, independent of estrogen level. These results suggest that estrogen levels should be considered in tDCS studies with young healthy women.

The Influence of Motoric Maneuvers on Cervical Vestibular Evoked Myogenic Potentials (cVEMPs).

The cervical vestibular evoked myogenic potential (cVEMP) is a vestibular response that is produced by the saccule in response to intense, often low-frequency, short-duration auditory stimuli, and is typically recorded from a contracted sternocleidomastoid (SCM) muscle. Previous research has shown that the amplitude of the cVEMP is related to the amount of SCM electromyographic (EMG) activity. The aim of this study was to determine the influence of various remote motoric maneuvers on the amplitude of the cVEMP, as well as whether they influence the level of SCM EMG activity. The cVEMP was recorded from the left SCM muscle to left ear stimulation, in response to the SCM condition, as well as three different motoric maneuvers (jaw clench, eye closure, and the Jendrassik maneuver). EMG activity was also varied between 50, 75, and 100% of maximal EMG activity. Data from 14 healthy subjects, with a mean age of 25.57 years (standard deviation = 5.93 years), was included in the present study. Mean latency and amplitude of the cVEMP were compared across the four conditions and varying magnitudes of EMG contraction. SPSS 26 was used to statistically analyze the results. cVEMP latency did not vary across condition. cVEMP amplitude decreased with decreasing EMG magnitude. SCM contraction with jaw clench produced the largest increase in cVEMP amplitude; however, this condition was not significantly different from the SCM condition alone. SCM contraction with the Jendrassik maneuver produced a cVEMP amplitude that was similar and not statistically different from SCM contraction alone, and the addition of the eye closure maneuver to SCM contraction resulted in the lowest cVEMP amplitude, which was found to be statistically different from the standard SCM condition at 100 and 75% EMG activity. The amplitude relationship across the conditions was not found to vary with changes in EMG activity; however, a significant increase in EMG amplitude was found during the 50% muscle contraction condition when subjects performed the Jendrassik maneuver in addition to the standard SCM contraction. The addition of the eye closure maneuver to SCM contraction resulted in a significant decrease in cVEMP amplitude, while the addition of the Jendrassik maneuver resulted in a significant increase in EMG activity at the lowest level of SCM activation (i.e., 50%). Additional research is necessary to determine how motoric maneuvers influence the cVEMP amplitude, and whether the results are also dependent on how SCM contraction is being produced (e.g., while supine vs. sitting).

Robust Torque Predictions From Electromyography Across Multiple Levels of Active Exoskeleton Assistance Despite Non-linear Reorganization of Locomotor Output.

Robotic exoskeletons can assist humans with walking by providing supplemental torque in proportion to the user's joint torque. Electromyographic (EMG) control algorithms can estimate a user's joint torque directly using real-time EMG recordings from the muscles that generate the torque. However, EMG signals change as a result of supplemental torque from an exoskeleton, resulting in unreliable estimates of the user's joint torque during active exoskeleton assistance. Here, we present an EMG control framework for robotic exoskeletons that provides consistent joint torque predictions across varying levels of assistance. Experiments with three healthy human participants showed that using diverse training data (from different levels of assistance) enables robust torque predictions, and that a convolutional neural network (CNN), but not a Kalman filter (KF), can capture the non-linear transformations in EMG due to exoskeleton assistance. With diverse training, the CNN could reliably predict joint torque from EMG during zero, low, medium, and high levels of exoskeleton assistance [root mean squared error (RMSE) below 0.096 N-m/kg]. In contrast, without diverse training, RMSE of the CNN ranged from 0.106 to 0.144 N-m/kg. RMSE of the KF ranged from 0.137 to 0.182 N-m/kg without diverse training, and did not improve with diverse training. When participant time is limited, training data should emphasize the highest levels of assistance first and utilize at least 35 full gait cycles for the CNN. The results presented here constitute an important step toward adaptive and robust human augmentation via robotic exoskeletons. This work also highlights the non-linear reorganization of locomotor output when using assistive exoskeletons; significant reductions in EMG activity were observed for the soleus and gastrocnemius, and a significant increase in EMG activity was observed for the erector spinae. Control algorithms that can accommodate spatiotemporal changes in muscle activity have broad implications for exoskeleton-based assistance and rehabilitation following neuromuscular injury.

Prochlorperazine Withdraws the Delayed Onset Tonic Activity of Unloaded Rat Soleus Muscle: A Pilot Study.

A gradual increase in rat soleus muscle electromyographic (EMG) activity is known to occur after 3–4 days of hindlimb suspension/unloading (HS). The physiological significance and mechanisms of such activity of motoneurons under unloading conditions are currently unclear. Since hyperactivity of motoneurons and muscle spasticity after spinal cord injury are associated with KCC2 downregulation, we hypothesized that a decrease in potassium (K+)/chloride (Cl−) co-transporter 2 (KCC2) in motoneurons would be responsible for an increase in soleus muscle EMG activity during HS. We aimed to investigate the effect of prochlorperazine (KCC2 activator) on the electrical activity of rat soleus muscle under HS. Wistar rats were divided into the following groups: (1) vivarium control (C), (2) 7-day HS group (7HS) and (3) 7-day HS group plus intraperitoneal injections of prochlorperazine (10 mg/kg, daily) (7HS + P). Expression of proteins in the motoneurons of the lumbar spinal cord was determined by Western blotting. An electromyogram of the rat soleus muscle was recorded using intramuscular electrodes. KCC2 content after 7-day HS significantly decreased by 34% relative to the control group. HS-induced decrease in KCC2 protein content was prevented by prochlorperazine administration. HS also induced a significant 80% decrease in KCC2 Ser940 phosphorylation; however prochlorperazine did not affect KCC2 phosphorylation. The treatment of the rats with prochlorperazine prevented a HS-induced increase in Na(+)/K(+)/(Cl−) co-transporter 1 (KCC2 antagonist) protein content. In parallel with the restoration of KCC2 content, prochlorperazine administration during HS partially prevented an increase in the soleus muscle tonic EMG activity. Thus, prochlorperazine administration during 7-day HS prevents a decrease in KCC2 protein expression in motoneurons and significantly reduces the level of HS-induced soleus muscle electrical activity.

To Regulate or Not to Regulate: Emotion Regulation in Participants With Low and High Impulsivity.

Successful emotion regulation plays a key role in psychological health and well-being. This study examines (1) whether cognitive control and corresponding neural connectivity are associated with emotion regulation and (2) to what extent external instructions can improve emotion regulation in individuals with low vs. high cognitive control capacity. For this, emotion regulation capabilities and the impact of emotion regulation on a subsequent emotional Stroop task was tested in participants with low (N = 25) vs. high impulsivity (N = 32). The classification according to impulsivity is based upon the stable correlation between high impulsivity and reduced cognitive control capacity. A negative emotion inducing movie scene was presented with the instruction to either suppress or allow all emotions that arose. This was followed by an emotional Stroop task. Electromyography (EMG) over the corrugator supercilii was used to assess the effects of emotion regulation. Neurophysiological mechanisms were measured using functional near-infrared spectroscopy over frontal brain areas. While EMG activation was low in the low-impulsive group independent of instruction, high-impulsive participants showed increased EMG activity when they were not explicitly instructed to suppress arising emotions. Given the same extent of functional connectivity within frontal lobe networks, the low-impulsive participants controlled their emotions better (less EMG activation) than the high-impulsive participants. In the Stroop task, the low-impulsive subjects performed significantly better. The emotion regulation condition had no significant effect on the results. We conclude that the cognitive control network is closely associated with emotion regulation capabilities. Individuals with high cognitive control show implicit capabilities for emotion regulation. Individuals with low cognitive control require external instructions (= explicit emotion regulation) to achieve similarly low expressions of emotionality. Implications for clinical applications aiming to improve emotion regulation are discussed.

Scoring of large muscle group movements during sleep: an International Restless Legs Syndrome Study Group position statement.

There is a gap in the manuals for scoring sleep-related movements because of the absence of rules for scoring large movements. A taskforce of the International Restless Legs Syndrome Study Group (IRLSSG) elaborated rules that define the detection and quantification of movements involving large muscle groups. Consensus on each of the criteria in this article was reached by testing the presence of consensus on a first proposal; if no consensus was achieved, the concerns were considered and used to modify the proposal. This process was iterated until consensus was reached. A preliminary analysis of the duration of movements involving large muscle groups was also carried out on data from two previous studies, which, however, used a visual analysis of video-polysomnographic (PSG) recordings obtained from children or adults. Technical specifications and scoring rules were designed for the detection and quantification of large muscle group movements during sleep with a duration between 3 and 45 seconds in adults or 3 and 30 seconds in children, characterized by an increase in electromyographic activity and/or the occurrence of movement artifact in any combination of at least two recommended channels and not meeting the criteria for any other type of movement. Large muscle group movements are often accompanied by sleep stage changes, arousals, awakenings, and heart rate rises. The absence of clear and detailed rules defining them has likely impeded the development of studies that might disclose their clinical relevance; these new rules fill this gap.

Evaluation of masticatory muscle response to clear aligner therapy using ambulatory electromyographic recording

Patients undergoing clear aligner therapy (CAT) report muscle tenderness and produce wear facets on their aligner trays. However, little is known about the masticatory muscle response to clear aligners. Here, we measured the activity of the masseter during CAT using ambulatory electromyography. We also explored whether psychological traits modulate the masticatory muscle response to CAT. Using portable data loggers, we recorded the electromyographic (EMG) activity in the right masseter muscle of 17 healthy adults without temporomandibular disorder (16 females, 1 male; mean age±standard deviation, 35.3±17.6years) commencing treatment with CAT over 4weeks, under the following conditions: week 1 without aligners (baseline), week 2 with a passive aligner (dummy), week 3 with their first active aligner (active1), and week 4 with their second active aligner (active2). We used a mixed-effect model to test differences in EMG activity over the 4-weeks and a general linear model to test the effect of psychological traits on EMG activity. The EMG activity of the masseter increased significantly with aligners compared with baseline. The largest relative increase in EMG activity was seen during the dummy (152%; P<0.001) and active1 (155%; P<0.001) stages. During active2, the activity of the masseter decreased significantly toward baseline levels. Participants' trait anxiety was positively associated with increases in EMG activity (P=0.027). CAT is associated with a transient increase in masticatory muscle activity, possibly because of an increase in wake-time parafunctional tooth clenching. Temporomandibular disorder-free patients adapt well to CAT as the masticatory muscle activity decreases toward baseline levels after 2weeks.