Hand differences in aiming task: A complementary spatial approach and analysis of dynamic brain networks with EEG

Left and right-hand exhibit differences in the execution of movements. Particularly, it has been shown that manual goal-directed aiming is more accurate with the right hand than with the left, which has been explained through the shorter time spent by the right hand in the feedback phase (FB). This explanation makes sense for the temporal aspects of the task; however, there is a lack of explanations for the spatial aspects. The present study hypothesizes that the right hand is more associated with the FB, while the left hand is more strongly associated with the pre-programming phase (PP). In addition, the present study aims to investigate differences between hands in functional brain connectivity (FBC). We hypothesize an increase in FBC of the right hand compared to the left hand. Twenty-two participants performed 20 trials of the goal-directed aiming task with both hands. Overall, the results confirm the study's hypotheses. Although the right hand stopped far from the target at the PP, it exhibited a lower final position error than the left hand. These findings imply that during the FB, the right hand compensates for the higher error observed in the PP, using the visual feedback to approach the target more closely than the left hand. Conversely, the left hand displayed a lower error at the PP than the right. Also, the right hand displayed greater FBC within and between brain hemispheres. This heightened connectivity in the right hand might be associated with inhibitory mechanisms between hemispheres.

Statistical evaluation of tongue capability with visual feedback

BACKGROUND

Analysis of tongue movement would benefit from a reference showcasing healthy tongue capability. We aimed to develop a reference of tongue capability and evaluated the role of visual feedback on the expression of movement.

METHODS

Using a wireless tracking intraoral wearable device, we composed probability distributions of the tongue tip as subjects were asked to explore the entire sensing surface area. Half of the 32 subjects received live visual feedback of the location of the center of the tongue tip contact.

RESULTS

We observed that the visual feedback group was 51.0% more consistent with each other in the position domain, explored 21.5% more sensing surface area, and was 50.7% more uniformly distributed. We found less consistent results when we evaluated velocity and acceleration.

CONCLUSION

Visual feedback best established a healthy capability reference which can be used for designing new interfaces, quantifying tongue ability, developing new diagnostic and rehabilitation techniques, and studying underlying mechanisms of tongue motor control.

Measuring the nonselective effects of motor inhibition using isometric force recordings

Inhibition is a key cognitive control mechanism humans use to enable goal-directed behavior. When rapidly exerted, inhibitory control has broad, nonselective motor effects, typically demonstrated using corticospinal excitability measurements (CSE) elicited by transcranial magnetic stimulation (TMS). For example, during rapid action-stopping, CSE is suppressed at both stopped and task-unrelated muscles. While such TMS-based CSE measurements have provided crucial insights into the fronto-basal ganglia circuitry underlying inhibitory control, they have several downsides. TMS is contraindicated in many populations (e.g., epilepsy or deep-brain stimulation patients), has limited temporal resolution, produces distracting auditory and haptic stimulation, is difficult to combine with other imaging methods, and necessitates expensive, immobile equipment. Here, we attempted to measure the nonselective motor effects of inhibitory control using a method unaffected by these shortcomings. Thirty male and female human participants exerted isometric force on a high-precision handheld force transducer while performing a foot-response stop-signal task. Indeed, when foot movements were successfully stopped, force output at the task-irrelevant hand was suppressed as well. Moreover, this nonselective reduction of isometric force was highly correlated with stop-signal performance and showed frequency dynamics similar to established inhibitory signatures typically found in neural and muscle recordings. Together, these findings demonstrate that isometric force recordings can reliably capture the nonselective effects of motor inhibition, opening the door to many applications that are hard or impossible to realize with TMS.

Effect of psychostimulant medications on functional balance performance in persons with Attention-Deficit/Hyperactivity Disorder: A systematic review

RATIONALE

Balance impairments are highly prevalent and underscreened in individuals with Attention-deficit/hyperactivity disorder (ADHD). Psychostimulant medications, used to treat ADHD symptoms, may improve balance performance in this population as demonstrated by a growing literature; however, there has not been a systematic investigation to understand the effects of psychostimulant medications on balance performance in individuals with ADHD. This systematic review examined the existing evidence to determine if psychostimulant medications improve balance performance in this population.

METHODS

We searched PubMed, CINAHL, SPORTDiscus, Scopus, Embase and Cochrane in March 2021 and in January 2022 to locate articles relevant to the topic. Two reviewers evaluated the methodological quality of included articles using the Study Quality Assessment Tools and the PEDro scale. The reviewers rated articles for the level of evidence based on the American Academy of Neurology (AAN) criteria. The reviewers further offered recommendations for research and clinical practice based on the strength of the reviewed articles using the AAN criteria. Additionally, the reviewers gleaned important characteristics from each article, such as study design, balance domain and study results.

RESULTS

Nine articles addressed the role of psychostimulant medications on balance outcomes. These articles included two Class II studies, two Class III studies and five Class IV studies. Based on study quality, this systematic review indicated low confidence in the use of psychostimulant medications for improving balance performance based on AAN criteria.

CONCLUSION

Psychostimulant medications trends to enhance balance performance in individuals with ADHD. However, the lack of well-designed studies and heterogeneity of balance measures warrant additional research.

Electrophysiological responses to Kabat motor control re-education on Bell's Palsy: A randomized controlled study

OBJECTIVES

to investigate the Electrophysiological responses post-Kabat Motor Control Re-education in Bell's palsy which might restore the neuromuscular circuit and normal function of the nerve.

METHODS

Thirty children diagnosed with Bell's palsy were equally divided into two groups; the study group that received Kabat Motor Control Re-education and the physical therapy selected designed program, and the control group that received physical therapy selected designed program. The outcomes included Electroneurography (ENoG) measuring distal latency, amplitude, and percentage of degenerations, and the Sunnybrook facial grading system (SFGS), as pre and post-treatment, all parameters were evaluated.

RESULTS

The ENoG findings approved that post-intervention there was a significant improvement in the study group more than the control group (p<0.05), as the percent of change of latency, amplitude, and percent of degeneration for both frontalis and orbicularis oris of the study group was 18.12-13.6%, 88.3-107.8%, and 74.4-78.9% respectively and that of the control group was 10.8-7.7%, 63.4-69.4%, and 54.9-54.8% respectively, also the percent of change of SFGS post-treatment, for study and control groups was 234.1% and 209.1% respectively.

CONCLUSION

The Electrophysiological responses approved that the advanced Kabat rehabilitation combined with motor control re-education training using extrinsic feedback cues had a valuable effect in the treatment of Bell's Palsy.

CLINICAL TRIALS

gov ID: NCT04894513.

A novel application of entropy analysis for assessing changes in movement variability during cumulative tackles in young elite rugby league players

The aim of this study was to identify between-position (forwards vs. backs) differences in movement variability in cumulative tackle events training during both attacking and defensive roles. Eleven elite adolescent male rugby league players volunteered to participate in this study (mean ± SD, age; 18.5 ± 0.5 years, height; 179.5 ± 5.0 cm, body mass; 88.3 ± 13.0 kg). Participants performed a drill encompassing four blocks of six tackling (i.e. tackling an opponent) and six tackled (i.e. being tackled by an opponent while carrying a ball) events (i.e. 48 total tackles) while wearing a micro-technological inertial measurement unit (WIMU, Realtrack Systems, Spain). The acceleration data were used to calculate sample entropy (SampEn) to analyse the movement variability during tackles performance. In tackling actions SampEn showed significant between-position differences in block 1 (p = 0.0001) and block 2 (p = 0.0003). Significant between-block differences were observed in backs (block 1 vs 3, p = 0,0021; and block 1 vs 4, p = 0,0001) but not in forwards. When being tackled, SampEn showed significant between-position differences in block 1 (p = 0.0007) and block 3 (p = 0.0118). Significant between-block differences were only observed for backs in block 1 vs 4 (p = 0,0025). Movement variability shows a progressive reduction with cumulative tackle events, especially in backs and when in the defensive role (tackling). Forwards present lower movement variability values in all blocks, particularly in the first block, both in the attacking and defensive role. Entropy measures can be used by practitioners as an alternative tool to analyse the temporal structure of variability of tackle actions and quantify the load of these actions according to playing position.

Real World Evidence for Restorative Neurostimulation in Chronic Low Back Pain- a Consecutive Cohort Study

OBJECTIVE

Neuromuscular instability of the lumbar spine resulting from impaired motor control and degeneration of the multifidus muscle is a known root cause of refractory chronic low back pain (CLBP). An implantable neurostimulation system that aims to restore multifidus motor control by stimulating the L2 medial branch of the dorsal ramus (ReActiv8, Mainstay Medical) and thereby relieving pain and reducing disability has demonstrated clinically significant benefits in the clinical trial setting. The 1-year results of a single site real-world cohort study are presented here.

METHODS

Forty-four consecutive patients with refractory, predominantly nociceptive axial CLB, evidence of multifidus dysfunction and no surgical indications or history of surgical intervention for CLBP were recruited at a single site in Germany. Each patient was implanted with a neurostimulation device. Pain (NRS), disability (ODI) and quality of life (EQ-5D-5L) outcomes were collected at baseline, 3-, 6- and 12-months post-activation.

RESULTS

Statistically significant improvements in pain, disability, and quality of life from baseline were seen at all assessment times points. At 12 months post-activation, mean (±SE) NRS was reduced from 7.6±0.2 to 3.9±0.4 (p<0.001), mean ODI (±SE) from 43.0±2.8 to 25.8±3.9 (p<0.001) and mean EQ-5D-5L (±SE) index improved from 0.504±0.034 to 0.755±0.039 (p<0001). No lead migrations were observed. One patient required revision due to lead fracture.

CONCLUSIONS

Restorative neurostimulation is a new treatment option for well selected patients with refractory CLBP. The clinically meaningful improvements in pain, disability, and quality of life demonstrated in routine clinical practice are consistent with the published results of controlled trials.

Transcranial Direct Current Stimulation (tDCS) modulates motor execution in a limb reaching task

The majority of human activities show a trade-off between movement speed and accuracy. Here we tested 16 participants in a quick pointing action after 20 minutes (2mA) of transcranial Direct Current Stimulation (tDCS) delivered at the Supplementary Motor Area (SMA) in a single-blind crossover design study for testing the feedforward components in the control of action. tDCS stimuli were delivered in three randomized sessions of stimulations as anodal, cathodal and sham as a control. The task performed Pre and Post tDCS stimulation, was to point as fast and as precise as possible with the big toe to targets having different sizes (2 and 8 cm; Width) and positioned at different Distances (20 and 60 cm; Distance). An optoelectronic motion capture system was used to collect the kinematics of movement. Result indicates that individuals after receiving anodal stimulation decreased their movement time and increased their movement speed while the opposite happened after receiving a cathodal stimulation. The scarcity of studies in this area invites us to plan a research that aims at the trade-off especially in the clinical settings.

Pay attention! The influence of coach-, content-, and player-related factors on focus of attention statements during tennis training

It is well established that adopting an external focus of attention (EF) enhances motor learning when contrasted to an internal focus (IF) or a neutral condition. Despite consistent evidence for this performance-enhancing effect of an EF, recent studies show that coaches predominantly induce an IF in the communication with athletes. It remains, however, unknown whether and to what degree coach-, content- or player-related factors have an impact on the focus of attention during youth tennis training. Therefore, we recorded all statements from 10 tennis coaches during six training sessions with a total of 87 youth athletes aged 18 years or younger. All statements were categorized according to the focus they induced (IF, EF, neutral, best place to hit the ball, mix, no focus) and the form of communication (instruction, feedback). Of the relevant statements (n=3049), 45.1% promoted an EF, whereas 33.1% induced an IF. Evaluation of coaches-, player- and content-specific features (education, age of coach/player, training content, skill level) showed that more statements with an IF were given when training beginners. The data also show more statements with an EF for instructions (59.0%) compared to feedback (43.0%). Our results contrast with other sports where instructions with an IF predominate. Thus, instrumented sports with external targets (e.g. tennis) might be better suited for inducing an EF. The data also show that coaches are more likely to use IF when communicating with beginners. Consequently, an EF should not be induced in every possible situation, even if this is often communicated so far.

Motor skill learning decreases movement variability and increases planning horizon

We investigated motor skill learning using a path tracking task, where human subjects had to track various curved paths at a constant speed while maintaining the cursor within the path width. Subjects' accuracy increased with practice, even when tracking novel untrained paths. Using a "searchlight" paradigm, where only a short segment of the path ahead of the cursor was shown, we found that subjects with a higher tracking skill differed from the novice subjects in two respects. First, they had lower movement variability, in agreement with previous findings. Second, they took a longer section of the future path into account when performing the task, i.e. had a longer planning horizon. We estimate that between one third and one half of the performance increase in the expert group was due to the longer planning horizon. An optimal control model with a fixed horizon (receding horizon control) that increases with tracking skill quantitatively captured the subjects' movement behaviour. These findings demonstrate that human subjects not only increase their motor acuity but also their planning horizon when acquiring a motor skill.

A machine learning approach to characterize sequential movement-related states in premotor and motor cortices

Non-human primate (NHP) movement kinematics have been decoded from spikes and local field potentials (LFPs) recorded during motor tasks. However, the potential of LFPs to provide network-like characterizations of neural dynamics during planning and execution of sequential movements requires further exploration. Is the aggregate nature of LFPs suitable to construct informative brain state descriptors of movement preparation and execution? To investigate this, we developed a framework to process LFPs based on machine learning classifiers and analyzed LFP from a primate, implanted with several microelectrode arrays covering the premotor cortex in both hemispheres and the primary motor cortex on one side. The primate performed a reach and grasp task, consisting of five consecutive states, starting from rest until a rewarding target (food) was attained. We use this five-state task to characterize brain activity and connectivity within eight frequency bands, using spectral amplitude and pair-wise correlations across electrodes as features. Our results show that we could best distinguish all five movement-related states using the highest frequency band (200-500Hz), yielding an 87% accuracy with spectral amplitude, and 60% with pair-wise electrode correlation. Further analyses characterized each movement-related state, showing differential neuronal population activity at above-gamma frequencies during the various stages of movement. In summary, our results show that the concerted use of novel machine-learning techniques with coarse grained queue broad signals such as LFPs may be successfully used to track and decode fine reach and grasp movement aspects across several brain regions.

Motivating Selective Motor Control of Infants at High Risk of Cerebral Palsy Using an In-Home Kicking-Activated Mobile Task: A Pilot Study

OBJECTIVE

Decreased selective motor control limits gait function of children with spastic cerebral palsy (CP). Infants at high risk of CP demonstrate decreased selective motor control by 1 month of age. To motivate more selective hip-knee control, infants at high risk of CP participated in an in-home kicking-activated mobile task. The purpose of this study was to determine whether infants at high risk of CP and infants with typical development (TD) demonstrated increased selective hip-knee control during 2-minute intervals of the mobile task when they demonstrated learning of the association between their leg movement and mobile activation vs during 2-minute intervals when they did not demonstrate learning.

METHODS

Participants in this cohort study included 10 infants at high risk of CP based on neuroimaging and 11 infants with TD at 3.5 to 4.5 months of age. Each infant participated in the in-home kicking-activated mobile task for 8 to 10 min/d, 5 d/wk, for 6 weeks. Over 80,000 kicks were extracted and classified for each infant as occurring during 2-minute intervals of the task when the infant demonstrated learning vs not learning based on mobile activation time above baseline.

RESULTS

Infants demonstrated kicks with more selective hip-knee control during 2-minute intervals of the mobile task when they demonstrated learning compared with when they did not demonstrate learning for 4 of 6 weeks in the cohort at high risk of CP and for 2 of 6 weeks in the cohort with TD.

CONCLUSION

Participation in the in-home kicking-activated mobile task may motivate more selective hip-knee control of infants at high risk of CP.

IMPACT

This study is a first step toward developing an intervention to promote selective hip-knee control of infants at high risk of CP, with the ultimate goal of optimizing future walking function.

LAY SUMMARY

This study showed that playing with an in-home infant kicking-activated mobile may motivate infants at high risk of CP to produce more age-appropriate leg movements.

Exploration of Vibrotactile Biofeedback Strategies to Induce Stance Time Asymmetries

BACKGROUND

Gait symmetry is the degree of equality of biomechanical parameters between limbs within a gait cycle. Human gait is highly symmetrical; however, in the presence of pathology, gait often lacks symmetry. Biofeedback (BFB) systems have demonstrated the potential to reduce gait asymmetry, improve gait function, and benefit overall long-term musculoskeletal health.

OBJECTIVES

The aim of this study was to develop a BFB system and evaluate three unique BFB strategies, including bidirectional control - constant vibration (BC), bidirectional control - variable vibration (BV), and unidirectional control - variable vibration (UV) relevant to gait symmetry. The assessed feedback strategies were a combination of vibration frequency/amplitude levels, vibration thresholds, and vibrotactile stimuli from one and two vibrating motors (tactors). Learning effect and short-term retention were also assessed.

METHODOLOGY

Testing was performed using a custom BFB system that induces stance time asymmetries to modulate temporal gait symmetry. The BFB system continuously monitors specific gait events (heel-strike and toe-off) and calculates the symmetry ratio, based on the stance time of both limbs to provide real-time biomechanical information via the vibrating motors. Overall walking performance of ten (n=10) able-bodied individuals (age 24.8 ± 4.4 years) was assessed via metrics of symmetry ratio, symmetry ratio error, walking speed, and motor's vibration percentages.

FINDINGS

All participants utilized BFB somatosensory information to modulate their symmetry ratio. UV feedback produced a greater change in symmetry ratio, and it came closer to the targeted symmetry ratio. Learning or short-term retention effects were minimal. Walking speeds were reduced with feedback compared to no feedback; however, UV walking speeds were significantly faster compared to BV and BC.

CONCLUSION

The outcomes of this study provide new insights into the development and implementation of feedback strategies for gait retraining BFB systems that may ultimately benefit individuals with pathological gait. Future work should assess longer-term use and long-term learning and retention effects of BFB systems in the populations of interest.

Shoulder position and handedness differentially affect excitability and intracortical inhibition of hand muscles

Individuals with stroke show distinct differences in hand function impairment when the shoulder is in adduction, within the workspace compared to when the shoulder is abducted, away from the body. To better understand how shoulder position affects hand control, we tested the corticomotor excitability and intracortical control of intrinsic and extrinsic hand muscles important for grasp in twelve healthy individuals. Motor evoked potentials (MEP) using single and paired-pulse transcranial magnetic stimulation were elicited in extensor digitorum communis (EDC), flexor digitorum superficialis (FDS), first dorsal interosseous (FDI), and abductor pollicis brevis (APB). The shoulder was fully supported in horizontal adduction (ADD) or abduction (ABD). Separate mixed-effect models were fit to the MEP parameters using shoulder position (or upper-extremity [UE] side) as fixed and participants as random effects. In the non-dominant UE, EDC showed significantly greater MEPs in shoulder ABD than ADD. In contrast, the dominant side EDC showed significantly greater MEPs in ADD compared to ABD; %facilitation of EDC on dominant side showed significant stimulus intensity x position interaction, EDC excitability was significantly greater in ADD at 150% of the resting threshold. Intrinsic hand muscles of the dominant UE received significantly more intracortical inhibition (SICI) when the shoulder was in ADD compared to ABD; there was no position-dependent modulation of SICI on the non-dominant side. Our findings suggest that these resting-state changes in hand muscle excitabilities reflect the natural statistics of UE movements, which in turn may arise from as well as shape the nature of shoulder-hand coupling underlying UE behaviors.

Motor control times and strategies in left- and right-handed participants: Behavioral evidence for the hemispheric distribution of motor planning

Background: There is conflicting evidence in favor of the hemispheric distribution of motor planning. Some studies supported the left-hemisphere-dominance hypothesis for motor planning and claimed that the left-hemisphere has a crucial function in motor control even in left-handers. The present study aimed to compare the right- and left-handed participants on motor planning ability and to investigate the performance of their dominant hands in a specific action selection task. Also, the effect of task complexity was assessed. Methods: Twenty right-handers and 20 left-handers performed an action selection task. The participants had to grasp a hexagonal knob with their dominant hand and consequently rotated it 60° or 180 ° clockwise or counterclockwise. Depending on our objects, we used mixed factorial ANOVA and the groups were examined in terms of the planning time, grasping time, releasing time and planning pattern for initial grip selection. The SPSS 19 was used for analyzing the data and p≤0.05 was considered as the significant level. Results: No significant differences were observed between the two groups. The movement-related measures revealed a main effect of rotation (p˂0.001). However, a significant interaction between direction × planning pattern × group (p˂0.001) indicated a preferential bias for rotatory movements in the medial direction which is consistent with the "medial over lateral advantage". Conclusion: Both left- and right-handed participants had a similar motor planning ability while performing a planning task with their dominant hands. Because our study was behavioral, it only provided a test of the left-hemisphere hypothesis of motor planning.

Rapid muscle activation changes across a competitive collegiate female soccer season

OBJECTIVE

The purpose of this study was to examine the effects of a competitive soccer season on rapid activation properties of the knee extensors and flexors in Division II female soccer players.

METHODS

Eighteen collegiate female soccer players participated in the present study, however, due to injuries during the season a final sample of 16 players were included for study analysis. Participants performed two maximal voluntary isometric contractions (MVICs) of the knee extensors and flexors before, during, and at the end of a competitive college soccer season. Electromyography root mean square (EMG RMS; μV), rate of EMG rise (RER; %Peak EMG•s^-1), and electromechanical delay (EMD; ms) were examined on both legs for the knee extensors and flexors.

RESULTS

EMG RMS at early time intervals (0-50, 0-100, and 50-100 ms) and RER at 0-75 ms for the knee extensors and flexors significantly increased from the pre-season to the end of the season (P≤0.010-0.026, η²=0.36-0.81). EMD of the knee flexors significantly decreased at the mid-season and the end of the season compared to the pre-season (P<0.001, η²=0.95).

CONCLUSIONS

These findings may have important implications for monitoring improvements on thigh neuromuscular activation and developing lower extremity injury prevention strategies during a competitive collegiate female soccer season.

The role(s) of "Simultaneous Postural Adjustments" (SPA) during Single Step revealed with the Lissajous method

Dynamical phenomena in the postural chain occur before, during and after the voluntary movement. These phenomena correspond to anticipatory (APA), simultaneous (SPA), and consecutive (CPA) postural adjustments, respectively. APA and, more recently, CPA, have been extensively investigated in the literature. SPA have surprisingly received much less attention. The aim of the present study was to examine the role(s) of SPA associated with a single step task (SST). Ten healthy young adults performed series of SST on a force-plate. A 2-DOF mechanical model was used to separate the dynamics of the swing leg and the dynamics of the rest of the body, corresponding to the focal and the postural component of the SST, respectively. The postural component was plotted against the focal one during SPA (from heel-off to foot-contact), and this plot was modelled as a Lissajous ellipse. Result showed that this ellipse systematically ran through the same three quadrants of the diagram. For each of these quadrants, the role of the postural component in regards to the focal one was interpreted according to the relative orientation of the postural and focal dynamics. Results thus showed that SPA ensured the following successive roles: counter-perturbation of swing leg dynamics following heel-off, propulsion of swing leg, counter-perturbation of swing leg dynamics again, and then braking swing leg movement. These new findings contribute to a better knowledge of postural adjustments properties, and may provide new insights for understanding balance troubles with aging and in neurological patients (e.g. people with Parkinson's disease).

Motor Function and Perception of Health in Women with Provoked Vestibulodynia

BACKGROUND

Provoked vestibulodynia (PVD) is a prevalent and disabling condition in women that may be associated with reduced quality of life and impairment of physical functioning.

AIM

To investigate whether women with PVD have different motor functions, posture and breathing patterns, and whether they perceive their physical health differently, compared with asymptomatic controls.

METHODS AND MAIN OUTCOME MEASURE

The Standardized Mensendieck Test (SMT) and the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) were used to assess differences between 35 women with PVD and 35 healthy controls.

RESULTS

There were no statistically significant differences in any of the 5 motor domains of the SMT between the women with PVD and those without PVD: standing posture, 4.0 (0.6) vs 5.0 (0.6); gait, 4.7 (0.6) vs 4.8 (0.6); movement, 4.8 (0.8) vs 5.1 (0.6); sitting posture, 4.7 (1.0) vs 4.9 (0.8); respiration, 4.7 (1.0) vs 4.7 (0.9). Women with PVD scored significantly lower in all domains on the SF-36 (adjusted Bonferroni P = .002) except physical functioning.

CLINICAL IMPLICATIONS

Given the lack of difference in the SF-36 physical functioning domain and in all 5 domains of the SMT between women with PVD and those without PVD, the value of interventions focusing on general physical function is unclear.

STRENGTHS & LIMITATIONS

A study strength is the use of an assessor-blinded case-control design, trained physiotherapists to conduct the tests, and valid and reliable outcome measures. A limitation is the homogeneity of the sample of young nulliparous women, which limits the generalizability of our findings to other study populations.

CONCLUSION

Young nulliparous women with PVD did not score differently from a group of healthy controls on assessment of overall physical functioning or on standing posture, gait, movement, sitting posture, and respiration. However, the score for perception of general health was lower in the women with PVD compared with controls. I. Næss, H.C. Frawley, K. Bø. Motor Function and Perception of Health in Women with Provoked Vestibulodynia. J Sex Med 2019;16:1060-1067.

Learning spinal manipulation: Gender and expertise differences in biomechanical parameters, accuracy, and variability

OBJECTIVE:

The purpose of this study was to investigate gender differences and expertise effects on biomechanical parameters as well as force accuracy and variability for students learning spinal manipulation.

METHODS:

A total of 137 fourth- and fifth-year students were recruited for the study. Biomechanical parameters (preload, time to peak force, peak force, rate of force), as well as accuracy and variability of thoracic spine manipulation performance, were evaluated during 5 consecutive trials using a force-sensing table and a target force of 450 N. Gender, expertise differences on biomechanical parameters, as well as constant, variable, and absolute error were assessed using 2-way analysis of variance.

RESULTS:

Analyses showed significant gender differences for several biomechanical parameters, as well as significant gender differences in accuracy and variability. Although women showed lower time to peak force and rate of force values, they were more precise and showed less variability than men when performing thoracic spine manipulations. Students with clinical expertise (fifth-year students) used less force and were more precise.

CONCLUSION:

Our results showed that gender differences in spinal manipulation performance exist and that these differences seem to be mainly explained by alternative motor strategies. To develop gender-specific teaching methods, future studies should explore why men and women approach spinal manipulation tasks differently.

Alcohol-Induced Impairment of Balance is Antagonized by Energy Drinks

BACKGROUND

The acute administration of alcohol reliably impairs balance and motor coordination. While it is common for consumers to ingest alcohol with other stimulant drugs (e.g., caffeine, nicotine), little is known whether prototypical alcohol-induced balance impairments are altered by stimulant drugs. The purpose of this study was to examine whether the coadministration of a high-caffeine energy drink with alcohol can antagonize expected alcohol-induced increases in body sway.

METHODS

Sixteen social drinkers (of equal gender) participated in 4 separate double-blind dose administration sessions that involved consumption of alcohol and energy drinks, alone and in combination. Following dose administration, participants completed automated assessments of balance stability (both eyes open and eyes closed) measured using the Biosway Portable Balance System. Participants completed several subjective measures including self-reported ratings of sedation, stimulation, fatigue, and impairment. Blood pressure and pulse rate were recorded repeatedly.

RESULTS

The acute administration of alcohol increased body sway, and the coadministration of energy drinks antagonized this impairment. When participants closed their eyes, alcohol-induced body sway was similar whether or not energy drinks were ingested. While alcohol administration increased ratings of sedation and fatigue, energy drink administration increased ratings of stimulation and reduced ratings of fatigue. Modest increases in systolic and diastolic blood pressure following energy drink administration were also observed.

CONCLUSIONS

Visual assessment of balance impairment is frequently used to indicate that an individual has consumed too much alcohol (e.g., as part of police-standardized field sobriety testing or by a bartender assessing when someone should no longer be served more alcohol). The current findings suggest that energy drinks can antagonize alcohol-induced increases in body sway, indicating that future work is needed to determine whether this observation regarding neuromotor functioning applies to alcohol in combination with all types of stimulant drugs.

Relationship between margin of stability and deviations in spatiotemporal gait features in healthy young adults

Increased variability of spatio-temporal features while walking is related to increased risk of falls. It is thought that variability in foot placement and timing reflects responses to mechanical instability while walking. The purpose of this study was to determine whether 'extreme' values of step length, width and time follow transient periods of low mechanical stability during the single support phase of gait in healthy young adults. We conducted secondary analysis of a portion of an existing dataset. Eleven healthy adults walked on an instrumented treadmill. Participants were outfitted with reflective markers and completed two 1-min periods of walking at each of 3 speeds (0.8m/s, 1.2m/s, and 1.6m/s). Margins of stability were calculated relative to the anterior, posterior, lateral, and medial boundaries of the base of support, and the value at heel strike and the minimum value during the first half of each single-support phase were extracted. Step length, swing time, and step width were calculated from motion capture and ground reaction force data. Extreme values for consecutive steps were identified using Poincaré plots, and margins of stability in each direction were compared between 'normal' and 'extreme' steps. Margins of stability in both the anterior and medial direction were lower prior to long and wide steps, respectively. Margins of stability in the anterior and medial directions were lower prior to quick steps, and margins of stability in the posterior and lateral directions were lower prior to slow steps. There were either no significant differences in margin of stability between 'normal' and 'extreme' steps at heel strike, or the direction of the relationship was reversed to that observed during single support. These data suggest that spatio-temporal variability may reflect adjustments in step placement and timing to compensate for transient periods of low mechanical stability when walking.

Modeling motor learning using heteroskedastic functional principal components analysis

We propose a novel method for estimating population-level and subject-specific effects of covariates on the variability of functional data. We extend the functional principal components analysis framework by modeling the variance of principal component scores as a function of covariates and subject-specific random effects. In a setting where principal components are largely invariant across subjects and covariate values, modeling the variance of these scores provides a flexible and interpretable way to explore factors that affect the variability of functional data. Our work is motivated by a novel dataset from an experiment assessing upper extremity motor control, and quantifies the reduction in motion variance associated with skill learning.

An exploratory examination of the association between altered lumbar motor control, joint mobility and low back pain in athletes

Background:

Low back pain (LBP) is a common cause of lost playing time and can be a challenging clinical condition in competitive athletes. LBP in athletes may be associated with joint and ligamentous hypermobility and impairments in activation and coordination of the trunk musculature, however there is limited research in this area.

Objectives:

To determine if there is an association between altered lumbar motor control, joint mobility and low back pain (LBP) in a sample of athletes.

Materials and Methods:

Fifteen athletes with LBP were matched by age, gender and body mass index (BMI) with controls without LBP. Athletes completed a questionnaire with questions pertaining to demographics, activity level, medical history, need to self-manipulate their spine, pain intensity and location. Flexibility and lumbar motor control were assessed using: active and passive straight leg raise, lumbar range of motion (ROM), hip internal rotation ROM (HIR), Beighton ligamentous laxity scale, prone instability test (PIT), observation of lumbar aberrant movements, double leg lowering and Trendelenburg tests. Descriptive statistics were compiled and the chi square test was used to analyze results.

Results:

Descriptive statistics showed that 40% of athletes with LBP exhibited aberrant movements (AM), compared to 6% without LBP. 66% of athletes with LBP reported frequently self-manipulating their spine compared to 40% without LBP. No significant differences in motor control tests were found between groups. Athletes with LBP tended to have less lumbar flexion (63 ± 11°) compared to those without LBP (66 ± 13°). Chi-Square tests revealed that the AM were more likely to be present in athletes with LBP than those without (X2 = 4.66, P = 0.03).

Conclusions:

The presence of aberrant movement patterns is a significant clinical finding and associated with LBP in athletes.

Tricks in dystonia: ordering the complexity

Sensory tricks are various manoeuvres that can ameliorate dystonia. Common characteristics are well known, but their variety is wide, sensory stimulation is not necessarily the critical feature, and their physiology is unknown. To enumerate the various forms of sensory tricks and describe their nature, research findings and theories that may elucidate their neurophysiologic mechanism, we reviewed the literature pertaining to sensory tricks, including variants like motor tricks, imaginary tricks, forcible tricks and reverse sensory tricks. On the basis of this information, we propose a new classification of sensory tricks to include its variants. We highlight neurophysiologic evidence suggesting that sensory tricks work by decreasing abnormal facilitation. We tie this with established dystonia pathogenesis and postulate that sensory tricks decrease abnormally increased facilitation to inhibition ratios in the dystonic brain. It appears worthwhile for patients to search for possible sensory tricks.

Effects of deep brain stimulation of the subthalamic nucleus on freezing of gait in Parkinson's disease: a prospective controlled study

BACKGROUND

Freezing of gait (FOG) is a debilitating gait disorder in Parkinson's disease (PD) with partial responsiveness to dopaminergic medication. To date, notions about the effects of subthalamic deep brain stimulation (STN-DBS) on FOG remain controversial.

OBJECTIVES

To compare the effects of bilateral STN-DBS and continued best medical treatment (BMT) on FOG occurrence, FOG severity and clinical outcomes in PD patients at 6 and 12 months follow-up.

METHODS

In this prospective, controlled study, 41 PD patients with at least 5 years disease duration participated. Twenty-four subjects (20 with FOG) were treated with STN-DBS and seventeen (15 with FOG) continued BMT. The primary outcome was the New Freezing of Gait Questionnaire (NFOGQ) at 6 months postsurgery. Other outcomes were the NFOGQ at 12 months and clinical outcomes (Unified Parkinson's Disease Rating Scale III (UPDRS III), timed gait, falls and quality of life) at both time points.

RESULTS

STN-DBS increased the likelihood to convert from being a freezer to a non-freezer at 6 and 12 months follow-up (relative risk reduction=0.4). However, 45% of baseline freezers still experienced FOG 6 and 12 months postsurgery although with reduced severity. Three baseline non-freezers (1/2 BMT-treated, 2/4 STN-DBS-treated) developed FOG during follow-up. STN-DBS-induced benefits on FOG were mostly mediated by baseline levodopa equivalent dose, altered medication-intake and reduced motor fluctuations.

CONCLUSIONS

In contrast to continued BMT, STN-DBS reduced FOG occurrence and severity at 6 months postsurgery with largely sustained effects at 12 months follow-up. Longer follow-up periods are needed to test whether FOG improvements after STN-DBS persist with disease progression.

Facial bradykinesia

The aim of this paper is to summarise the main clinical and pathophysiological features of facial bradykinesia in Parkinson's disease (PD) and in atypical parkinsonism. Clinical observation suggests that reduced spontaneous and emotional facial expressions are features of facial bradykinesia in PD and atypical parkinsonism. In atypical parkinsonism, facial bradykinesia is complicated by additional dystonic features. Experimental studies evaluating spontaneous and emotional facial movements demonstrate that PD is characterised by a reduction in spontaneous blinking and emotional facial expression. In PD, neurophysiological studies show that voluntary orofacial movements are smaller in amplitude and slower in velocity. In contrast, movements of the upper face (eg, voluntary blinking) are normal in terms of velocity and amplitude but impaired in terms of switching between the closing and opening phases. In progressive supranuclear palsy (PSP), voluntary blinking is not only characterised by a severely impaired switching between the closing and opening phases of voluntary blinking, but is also slow in comparison with PD. In conclusion, in PD, facial bradykinesia reflects abnormalities of spontaneous, emotional and voluntary facial movements. In PSP, spontaneous and voluntary facial movements are abnormal but experimental studies on emotional facial movements are lacking. Data on facial bradykinesia in other atypical parkinsonism diseases, including multiple system atrophy and corticobasal degeneration, are limited. In PD, facial bradykinesia is primarily mediated by basal ganglia dysfunction whereas in PSP, facial bradykinesia is a consequence of a widespread degeneration involving the basal ganglia, cortical and brainstem structures.

Optogenetic insights into striatal function and behavior

Recent breakthroughs in optogenetic technologies to alter neuronal firing and function with light, combined with cell type-specific transgenic animal lines, has led to important insights into the function of distinct neuronal cell subtypes and afferent connections in the heterogeneously complex striatum. A vital part of the basal ganglia, the striatum is heavily implicated in both motor control and motivation-based behavior; as well as in neurological disorders and psychiatric diseases including Parkinson's Disease, Huntington's Disease, drug addiction, depression, and schizophrenia. Researchers are able to manipulate firing and cell signaling with temporal precision using optogenetics in the two striatal medium spiny neuron (MSN) subpopulations, the striatal interneurons, and striatal afferents. These studies confirmed the classical hypothesis of movement control and reward seeking behavior through direct versus indirect pathway MSNs; illuminated a selective role for TANs in cocaine reward; dissected the roles of glutamatergic and dopaminergic inputs to striatum in reward; and highlighted a role for striatal signaling molecules including an adrenergic G-protein coupled receptor in reward and the rho-GTPase Rac1 in cocaine reward and cocaine induced structural plasticity. This review focuses on how the evolving optogenetic toolbox provides insight into the distinct behavioral roles of striatal cell subpopulations and striatal afferents, which has clinically relevant implications into neurological disorders and psychiatric disease.

Ultrasonographic measurement of neck muscle recruitment: a preliminary investigation

Chronic cervical pain is a common source of disability in society, and evidence suggests that individuals with neck pain have impairment of the deep cervical flexor (DCF) muscles. This study investigated the recruitment pattern of the neck muscles, particularly the DCF, during the Craniocervical Flexion Test (CCFT), using ultrasound measurement of muscle activity in asymptomatic subjects. In a cross-sectional design, 10 subjects, of both sexes, with no history of neck pain participated in the study. Participants were instructed to perform the CCFT, and changes in thickness from resting baseline values during the five incremental stages of the test were obtained for DCF and sternocleidomastoid (SCM) muscles using ultrasonography. The most significant changes found in DCF thickness were between phase 1 and phases 4 (p<0.001) and 5 (p= <0.001). For SCM, differences were most significant between phases 1 and 3 (p<0.001), 4 (p<0.001), and 5 (p<0.001); and between phases 3 and 5 (p<0.003). No differences were found between DCF and SCM muscles. The present study confirms the evidence that CCFT increases DCF recruitment. However, the ultrasonography test protocol did not identify differences in recruitment between deep and superficial neck muscles. The present study confirms the evidence that the CCFT challenges the cervical spine and that DCF activity is increased during this maneuver.

Screening methods, epidemiology and evaluation of intervention in DAMP in preschool children

This report describes a population-based study of deficits in attention, motor control and perception (DAMP) in six-year-old Swedish urban children. The point prevalance was 2.8% and the boy:girl ratio 5.3∶1. A questionnaire and motor examination screening device is described and evaluated. In a group of 25 children with DAMP, interventions of various kinds were made when the children were 6-7 years old. These cases were followed up at age 10-11 years and compared with 42 cases who had received no intervention. The follow-up study was fraught with problems and the data obtained could only be used for highly preliminary conclusions. However, it appears that information to parents, children and teachers about the nature of the child's condition might be helpful.