Decrease In Motor Performance Research Articles

STUDI OPTIMASI POMPA DISTRIBUSI SPAM KOTA PALANGKA RAYA UNTUK EFISIENSI ENERGI

SPAM of Palangka Raya City has a distribution unit which is powered by six pumps but only two pumps are functioning due to frequent damage to the pumps. The pumps that function is Pump III and Pump V. This research aims to evaluate pump efficiency and specific energy consumption (SEC) so that technical recommendations for optimizing existing distribution pumps are known. Pump III is installed with a VSD with a SEC value of 0.14 KWh/m3 with a pump efficiency of 70.41% so it does not require minor or major repairs but requires a new backup pump because it works 24 hours while Pump V has a SEC of 0.27 KWh/m3 with a pump efficiency of only 36.97% which requires a new pump replacement. Both pumps experienced the same problem, namely V-Unbalanced which reached 2.72-2.73%, causing a decrease in motor performance which could cause damage to the pump components and VSD, so a capacitor bank and voltage stabilizer were needed. The evaluation of energy loss in the distribution network was carried out by increasing the diameter of 57 pipe segments to reduce headloss to less than 10 m/km.

Physical Education and Development of Locomotion and Gross Motor Skills of Children with Autism Spectrum Disorder

Movement abnormalities are a common problem in children with autism spectrum disorder (ASD), which affect their fine and gross motor skills, locomotion, and eye movements, along with their ability to conduct more complex movement types. The purpose of this study was to determine whether regular exercises in physical education classes using the Test of Gross Motor Development Second Edition (TGMD-2) improve locomotion, gross motor skills, and overall movement performance in children with ASD and eliminate the occurrence of movement abnormalities. Twenty children aged 5–10 years (M ± SD; 7.51 ± 1.58 years) who were diagnosed with ASD participated in the research. The TGMD-2 training program was applied for a period of 8 weeks with a frequency setting of two times a week and a duration of 30 min under the guidance of a physical education teacher. Group A exercised according to TGMD-2 instructions, while Group B was the control group, then vice versa. The rest period between exercises was 13 weeks. The research results indicate that the use of exercises to develop the motor performance of children with ASD contributed to the significant development of their locomotion and gross motor skills. In both groups A and B, we noted an improvement in locomotion (p < 0.01) and gross motor skills (p < 0.01). The results demonstrated a significant improvement in gains between the control and experimental periods in groups A (p < 0.001) and B (p < 0.001). During the 13-week rest period between exercises, we found a decrease in the level of motor performance in both groups of children with ASD (p < 0.01). In group A, we found a decrease in motor performance (p < 0.01), locomotion (p < 0.01), and gross motor skills (p < 0.01), and in group B, a significant deterioration of motor performance in terms of the total TGMD-2 score (p < 0.05). Regular movement intervention is very important for children with ASD; otherwise, their level of motor performance can drop significantly. Therefore, we recommend implementing TGMD-2 exercises as part of the physical education of children with ASD and supporting the routine and healthy habits of children.

Performance-based assistance control for robot-mediated upper-limbs rehabilitation

Clinical research results demonstrated that robot-mediated training for the recovery of subjects after the stroke had the benefit of being able to carry out high-intensity repetitive and task-oriented tasks, which could effectively facilitate the rehabilitation effect. However, these subjects may have different training requirements as the disability levels vary from subject to subject at different stages of rehabilitation. Therefore, to meet the rehabilitation training needs of subjects in different rehabilitation stages, a performance-based assistance control strategy for safe robot-mediated therapy is proposed in this paper. The strategy contains three training modes that are switched by the trajectory tracking error, the zero interaction force mode (ZIF), assist-as-needed (AAN) mode, and restriction interaction region (RIR) mode. In ZIF mode, the subject can freely refer to their motion trajectory, and the robot will only offer fixed assistance only when the subject is slacking. In AAN mode, the robot would offer a variable level of assistance force by adjusting the stiffness coefficient to assist subjects in accordance with their motor abilities. To assure safety, a sizable assisting force is applied in RIR mode. To validate and evaluate the effectiveness and performance of the proposed assistance control strategy, a set of task-oriented continuous movement experiments based on an end-effector robot-mediated training system were performed by five able-bodied subjects. The preliminary experiment results demonstrated that the proposed control strategy works properly and could provide corresponding assistance and adjust the working modes according to the subject's motor performance. It was found that the robot provided more assistance as the increasing trajectory tracking error led to a decrease in motor performance. Additionally, adaptive adjustment of the stiffness coefficient allowed the proposed assistance control strategy to induce more active effort. It's worth noting that the parameters of the proposed strategy may be personalized and adjusted for different subjects to satisfy various requirements.

Targeting the frontoparietal network using bifocal transcranial alternating current stimulation during a motor sequence learning task in healthy older adults

BackgroundHealthy older adults show a decrease in motor performance and motor learning capacity as well as in working memory (WM) performance. WM has been suggested to be involved in motor learning processes, such as sequence learning. Correlational evidence has shown the involvement of the frontoparietal network (FPN), a network underlying WM processes, in motor sequence learning. However, causal evidence is currently lacking. Non-invasive brain stimulation (NIBS) studies have focused so far predominantly on motor-related areas to enhance motor sequence learning while areas associated with more cognitive aspects of motor learning have not yet been addressed. HypothesisIn this study, we aim to provide causal evidence for the involvement of WM processes and the underlying FPN in the successful performance of a motor sequence learning task by using theta transcranial alternating current stimulation (tACS) targeting the FPN during a motor sequence learning task. MethodsIn a cohort of 20 healthy older adults, we applied bifocal tACS in the theta range to the FPN during a sequence learning task. With the use of a double-blind, cross-over design, we tested the efficacy of active compared to sham stimulation. Two versions of the motor task were used: one with high and one with low WM load, to explore the efficacy of stimulation on tasks differing in WM demand. Additionally, the effects of stimulation on WM performance were addressed using an N-back task. The tACS frequency was personalized by means of EEG measuring the individual theta peak frequency during the N-back task. ResultsThe application of personalized theta tACS to the FPN improved performance during the motor sequence learning task with high WM load (p < .001), but not with low WM load. Active stimulation significantly improved both speed (p < .001), and accuracy (p = .03) during the task with high WM load. In addition, the stimulation paradigm improved performance on the N-back task for the 2-back task (p = .013), but not for 1-back and 3-back. ConclusionThe performance during a motor sequence learning task can be enhanced by means of personalized bifocal theta tACS to the FPN when WM load is high, indicating that the efficacy of this stimulation paradigm is dependent on the cognitive demand during the learning task. These data provide further causal evidence for the critical involvement of WM processes and the FPN during the execution of a motor sequence learning task in healthy older. These findings open new exciting possibilities to counteract the age-related decline in motor performance, learning capacity and WM performance.

Ciprofloxacin May Cause an Anxiety‐like Phenotype in a Rodent Model of Fluoroquinolone Associated Disability

Fluoroquinolones (FQ) are one of the most commonly prescribed antibiotics used to treat several infections including urinary tract infections, bacterial bronchitis, and bacterial gastroenteritis. However, the FDA has restricted their use to life‐threatening infections only, or for infections for which other antibiotics do not show therapeutic efficacy. The most frequent side‐effects reported include common gastrointestinal reactions (nausea, vomiting) and severe side effects, including Central Nervous System adverse reactions such as dizziness, insomnia, and severe mood disorders. For this reason, the existence of Fluoroquinolones‐Associated Disability has been proposed as the constellation of disabling side effects that may arise following administration of these antibiotics. Other preliminary data from our laboratory shows that administration of 20 mg/kg of ciprofloxacin (CPX), one of the most commonly prescribed FQs, permanently accelerates gastrointestinal transit. The goal of this study is to test whether the same dosage of CPX affects anxiety‐ and depression‐like behaviors in rats, and whether or not these behavioral changes are correlated to the observed gastrointestinal dysfunction. 3 males and 3 female rats received 20mg/kg of CPX through oral gavage once a day for 14 consecutive days. The Elevated plus‐maze test (EPM) and Sucrose Preference Test (SPT) were administered before the beginning of the treatment with CPX (baseline) and once weekly for a total of 4 weeks. At this dose, CPX did not affect the rats' preference for 1% sucrose water vs regular water in the SPT test. However, while we did not observe any differences in the time spent in the open or closed arm, nor in the number of entries in either arms, the EPM test showed that there was a significant difference in the time spent in the neutral zone for male CPX treated rats at 7, 21, and 28 testing days compared to baseline. This data shows that 20 mg/kg of CPX do not induce anhedonia, a measure of depression‐like behavior, but can induce an anxious phenotype in male rats only, which does not appear to be associated with the observed acceleration of gastrointestinal transit. Future experiments will determine whether this behavior is associated with an increase in anxiety, as observed in numerous clinical cases, or if it is caused by either a decrease in motor performance or cognitive abilities following CPX administration.

Changes in Motor Performance and BMI of Primary School Children over Time-Influence of the COVID-19 Confinement and Social Burden.

During the COVID-19 pandemic, physical inactivity and being overweight increased in children, especially those from lower socioeconomic backgrounds. Additionally, a decrease in motor performance has been increasingly reported; however, there is a lack of meaningful data on the relationship between these findings and socioeconomic status. Therefore, we examined the BMI, BMI z score, the prevalence of overweight/obesity, and motor performance (based on lateral jumping, the standing long jump, and the 6-min run) among three cohorts from timelines before (2016) and during the pandemic (2020, 2021), using a cohort sequential design. Our analysis revealed that all parameters examined showed a significant negative trend over time. For children with a low social burden, the trend was statistically detectable only for lateral jumping and the 6-min run. For children with a high social burden, the prevalence of overweight/obesity increased from 4.2% to 5.4% between 2016 and 2021. The prevalence of being underweight also increased from 3.4% to 4.3% during this time. Motor performance decreased from 11.3% to 12.3%, except in the standing long jump. Children with a high social burden showed significantly lower results (7.4% to 9.6%). Thus, our data confirm an increase in both measurements of overweight/obesity and underweight, as well as a decrease in motor performance under the pandemic conditions, especially in children from socioeconomically deprived backgrounds. These findings affirm the urgent need for action regarding health promotion measures, especially for children with high social burdens.

Surface Electromyography: What Limits Its Use in Exercise and Sport Physiology?

The aim of the present paper is to examine to what extent the application of surface electromyography (sEMG) in the field of exercise and, more in general, of human movement, is adopted by professionals on a regular basis. For this purpose, a brief history of the recent developments of modern sEMG techniques will be assessed and evaluated for a potential use in exercise physiology and clinical biomechanics. The idea is to understand what are the limitations that impede the translation of sEMG to applied fields such as exercise physiology. A cost/benefits evaluation will be drawn in order to understand possible causes that prevents sEMG from being routinely adopted. Among the possible causative factors, educational, economic and technical issues will be considered. Possible corrective interventions will be proposed. We will also give an overview of the parameters that can be extracted from the decomposition of the sHDEMG signals and how this can be related by professionals for assessing the health and disease of the neuromuscular system. We discuss how the decomposition of surface EMG signals might be adopted as a new non-invasive tool for assessing the status of the neuromuscular system. Recent evidences show that is possible to monitor the changes in neuromuscular function after training of longitudinally tracked populations of motoneurons, predict the maximal rate of force development by an individual via motoneuron interfacing, and identify possible causal relations between aging and the decrease in motor performance. These technologies will guide our understanding of motor control and provide a new window for the investigation of the underlying physiological processes determining force control, which is essential for the sport and exercise physiologist. We will also illustrate the challenges related to extraction of neuromuscular parameters from global EMG analysis (i.e., root-mean-square, and other global EMG metrics) and when the decomposition is needed. We posit that the main limitation in the application of sEMG techniques to the applied field is associated to problems in education and teaching, and that most of the novel technologies are not open source.

De novo phosphoinositide synthesis in zebrafish is required for triad formation but not essential for myogenesis.

Phosphoinositides (PIPs) and their regulatory enzymes are key players in many cellular processes and are required for aspects of vertebrate development. Dysregulated PIP metabolism has been implicated in several human diseases, including a subset of skeletal myopathies that feature structural defects in the triad. The role of PIPs in skeletal muscle formation, and particularly triad biogenesis, has yet to be determined. CDP-diacylglycerol-inositol 3-phosphatidyltransferase (CDIPT) catalyzes the formation of phosphatidylinositol, which is the base of all PIP species. Loss of CDIPT should, in theory, result in the failure to produce PIPs, and thus provide a strategy for establishing the requirement for PIPs during embryogenesis. In this study, we generated cdipt mutant zebrafish and determined the impact on skeletal myogenesis. Analysis of cdipt mutant muscle revealed no apparent global effect on early muscle development. However, small but significant defects were observed in triad size, with T-tubule area, inter terminal cisternae distance and gap width being smaller in cdipt mutants. This was associated with a decrease in motor performance. Overall, these data suggest that myogenesis in zebrafish does not require de novo PIP synthesis but does implicate a role for CDIPT in triad formation.

Investigation of engine performance and kit design for the usage of safflower oil as in diesel engine

In Turkey, the consumption of diesel oil is increasing both in transportation and in agricultural fields. In this study, the opportunities of the use of safflower oil, which grow originally in Turkey as a direct fuel in diesel engines, were researched to provide a new alternative for biofuel industry and to popularize the farming of oil crops.In this study, the kit design was completed first, and afterwards safflower oil was exposed to the process of neutralization and laundering, and then turned into standard fuel. For engine performance experiments, reference experiences were conducted by using diesel fuel by using safflower as a fuel in the engine with kit for 500 h; comparisons were made with regards to power, moment, diesel consumption, and exhaust emission.As a result, it was seen that when safflower was used as a fuel, there was a decrease in motor performance and emission, however specific fuel consumption increased. When safflower was used, there was not any residual on the engine that was found. The designed kit, which can be easily produced with national technology, did not cause any malfunction or negativity in the engine and it was successfully used.

Age related differences in functional synchronization of EEG activity as evaluated by means of TMS-EEG coregistrations

It was recently demonstrated that the characteristics of EEG rhythms preceding a transcranial magnetic stimulation (TMS) of the motor cortex (M1) influence the motor-evoked potential (MEP) amplitude with a peculiar pattern, thus reflecting the M1 functional state. As physiological aging is related to a decrease in motor performance and changes in excitability and connectivity strength within cerebral sensorimotor circuits, we aimed to explore whether aging affects EEG-MEP interactions. Using MRI-navigated TMS and multichannel EEG, we compared the EEG-MEP interactions observed in healthy aged subjects with those observed in young volunteers. We divided the MEPs amplitude into two different subgroups consisting of “high” and “low” MEPs, based on the 50th percentile of their amplitude distribution. Then we analysed the characteristics of the pre-stimulus EEG from M1 and correlated areas separately for the “high” and “low” MEPs, comparing the two conditions. In both young and old subjects, significantly larger MEPs were evoked when the stimulated M1 was coupled in the beta-2 band with the homolateral prefrontal cortex. Conversely, only in young participants was the MEP size modulated when the M1 and homolateral parieto-occipital cortices were coupled in the delta band. The elderly didn’t show this kind of pattern. Importantly, this coupling was significantly higher in elderly brains than in young brains, both for high and low MEPs. Our results suggest an age-related significant influence of time-varying coupling of spatially patterned EEG rhythms on motor cortex excitability in response to TMS.

Acute exercise and motor memory consolidation: Does exercise type play a role?

A single bout of high-intensity exercise can augment off-line gains in skills acquired during motor practice. It iscurrently unknown if the type of physical exercise influences the effect on motor skill consolidation. This study investigated the effect of three types of high-intensity exercise following visuomotor skill acquisition on the retention of motor memory in 40 young (25.3±3.6years), able-bodied male participants randomly assigned to one of four groups either performing strength training (STR), circuit training (CT), indoor hockey (HOC) or rest (CON). Retention tests of the motor skill were performed 1 (R1h) and 24h (R1d) post acquisition. For all exercise groups, mean motor performance scores decreased at R1h compared to post acquisition (POST) level; STR (P=0.018), CT (P=0.02), HOC (P=0.014) and performance scores decreased for CT compared to CON (P=0.049). Mean performance scores increased from POST to R1d for all exercise groups; STR (P=0.010), CT (P=0.020), HOC (P=0.007) while performance scores for CON decreased (P=0.043). Changes in motor performance were thus greater for STR (P=0.006), CT (P<0.001) and HOC (P<0.001) compared to CON from POST to R1d. The results demonstrate that high-intensity, acute exercise can lead to a decrease in motor performance assessed shortly after motor skill practice (R1h), but enhances offline effects promoting long-term retention (R1d). Given that different exercise modalities produced similar positive off-line effects on motor memory, we conclude that exercise-induced effects beneficial to consolidation appear to depend primarily on the physiological stimulus rather than type of exercise and movements employed.

Role of the dorsolateral prefrontal cortex in context-dependent motor performance.

Context-dependent motor performance is a phenomenon in which people perform better in the environmental context where they originally practised a task. Some animal and computer simulation studies have suggested that context-dependent performance may be associated with neural activation of the dorsolateral prefrontal cortex (DLPFC). This study aimed to determine the role of the DLPFC in context-dependent motor performance by perturbing the neural processing of the DLPFC with repetitive transcranial magnetic stimulation (rTMS) in healthy adults. Thirty healthy adults were recruited into the Control, rTMS DLPFC and rTMS Vertex groups. The participants practised three finger sequences associated with a specific incidental context (a coloured circle and a location on the computer screen). One day following practice, the rTMS groups received 1 Hz rTMS prior to the testing conditions in which the sequence-context associations remained the same as practice (SAME) or changed (SWITCH). All three groups improved significantly over practice on day 1. The second day testing results showed that the DLPFC group had a significantly lower decrease in motor performance under the SWITCH condition than the Control and Vertex groups. This finding suggests a specific role of the DLPFC in context-dependent motor performance.

Central fatigue induced by short-lasting finger tapping and isometric tasks: A study of silent periods evoked at spinal and supraspinal levels

The neural substrates of fatigue induced by muscular activity have been addressed in depth in relation to isometric tasks. For these activities, when fatigue develops, it has been noted that the duration of the silent periods (SPs) increases in response to both transcranial magnetic stimulation (TMS) of primary motor cortex or electric cervicomedullary stimulation (CMS). However, fatigue is known to be task-dependent and the mechanisms giving rise to a decrease in motor performance during brief, fast repetitive tasks have been less studied. We hypothesized that fatigue induced by repetitive fast finger tapping may have physiological mechanisms different from those accounting for fatigue during an isometric contraction, even in cases of matched effort durations. In these tasks, we examined the contribution of spinal and supraspinal motor circuits to the production of fatigue. The tapping rate and maximal voluntary contractions (MVC), and TMS- and CMS-evoked SPs were obtained at the time of fatigue, and while subjects maintained maximal muscle activation after fast finger-tapping (or isometric activity) of different durations (10 or 30s). Results showed different mechanisms of fatigue triggered by isometric contraction and repetitive movements, even of short duration. Short-lasting repetitive movements induce fatigue within intracortical inhibitory circuits. They increased TMS-SPs, but not CMS-SPs. On the other hand, isometric contraction had a clear impact on spinal circuits. The consideration of these differences might help to optimize the study of fatigue in physiological conditions and neurological disorders.

Reduced Dual-Task Performance in MS Patients Is Further Decreased by Muscle Fatigue

Background. Multiple sclerosis (MS) can be accompanied by motor, cognitive, and sensory impairments. Additionally, MS patients often report fatigue as one of their most debilitating symptoms. It is, therefore, expected that MS patients will have difficulties in performing cognitive-motor dual tasks (DTs), especially in a fatiguing condition. Objective. To determine whether MS patients are more challenged by a DT than controls in a fatiguing and less-fatiguing condition and whether DT performance is associated with perceived fatigue. Methods. A group of 19 MS patients and 19 age-, sex-, and education-matched controls performed a cognitive task (2-choice reaction time task) separately or concurrent with a low-force or a high-force motor task (index finger abduction at 10% or 30% maximal voluntary contraction). Results. MS patients performed less well on a cognitive task than controls. Cognitive task performance under DT conditions decreased more for MS patients. Moreover, under high-force DT conditions, cognitive performance declined in both groups but to a larger degree for MS patients. Besides a decline in cognitive task performance, MS patients also showed a stronger decrease in motor performance under high-force DT conditions. DT costs were positively related to perceived fatigue as measured by questionnaires. Conclusions. Compared with controls, MS patients performed less well on DTs as demonstrated by a reduction in both cognitive and motor performances. This performance decrease was stronger under fatiguing conditions and was related to the sense of fatigue of MS patients. These data illustrate problems that MS patients may encounter in daily life because of their fatigue.

CNS-targeted glucocorticoid reduces pathology in mouse model of amyotrophic lateral sclerosis.

BackgroundHallmarks of CNS inflammation, including microglial and astrocyte activation, are prominent features in post-mortem tissue from amyotrophic lateral sclerosis (ALS) patients and in mice overexpressing mutant superoxide dismutase-1 (SOD1G93A). Administration of non-targeted glucocorticoids does not significantly alter disease progression, but this may reflect poor CNS delivery. Here, we sought to discover whether CNS-targeted, liposomal encapsulated glucocorticoid would inhibit the CNS inflammatory response and reduce motor neuron loss. SOD1G93A mice were treated with saline, free methylprednisolone (MP, 10 mg/kg/week) or glutathione PEGylated liposomal MP (2B3-201, 10 mg/kg/week) and compared to saline treated wild-type animals. Animals were treated weekly with intravenous injections for 9 weeks from 60 days of age. Weights and motor performance were monitored during this period. At the end of the experimental period (116 days) mice were imaged using T2-weighted MRI for brainstem pathology; brain and spinal cord tissue were then collected for histological analysis.ResultsAll SOD1G93A groups showed a significant decrease in motor performance, compared to baseline, from ~100 days. SOD1G93A animals showed a significant increase in signal intensity on T2 weighted MR images, which may reflect the combination of neuronal vacuolation and glial activation in these motor nuclei. Treatment with 2B3-201, but not free MP, significantly reduced T2 hyperintensity observed in SOD1G93A mice. Compared to saline-treated and free-MP-treated SOD1G93A mice, those animals given 2B3-201 displayed significantly improved histopathological outcomes in brainstem motor nuclei, which included reduced gliosis and neuronal loss.ConclusionsIn contrast to previous reports that employed free steroid preparations, CNS-targeted anti-inflammatory agent 2B3-201 (liposomal methylprednisolone) has therapeutic potential, reducing brainstem pathology in the SOD1G93A mouse model of ALS. 2B3-201 reduced neuronal loss and vacuolation in brainstem nuclei, and reduced activation preferentially in astrocytes compared with microglia. These data also suggest that other previously ineffective therapies could be of therapeutic value if delivered specifically to the CNS.

Comparison of the somatic state and the level of motor performance of boys between the ages of seven and fifteen in the Olomouc region (Czech Republic) and in Opole (Poland)

BACKGROUND: Recent years have seen a decrease in habitual movement activity in children and youth, which is being replaced by the predominance of a sedentary lifestyle. A reflection of these negative trends is also seen in the decrease in motor performance. OBJECTIVE: The aim of this research is to analyze the level of the motor skills of contemporary 7 to 15 year olds in Olomouc and in Opole and to compare the physical parameters of Olomouc and Opole boys with the 6th Nation- Wide Anthropological Survey of Children and Adolescents 2001 Czech Republic (the 6th CAV 2001). METHODS: The research was carried out in both the Olomouc (695 boys) and Opole (313 boys) regions. For the diagnostics of the level of the motor performance of the boys, standardized motoric tests were used: the standing long jump with legs together, one-minute sit-ups, the 4 × 10 meter shuttle run, and throwing a medicine ball using both hands, as well as the testing battery UNIFITTEST (6-60). For the statistical evaluation of the results, Student's t-test, Z-scores and the non-parametric χ^2-test were used. RESULTS: The results have shown that, in height and weight, both boys from Olomouc and from Opole are in accordance with parameters, which correspond also to the reference data of the 6th CAV 2001. An identical performance level was reached by both sets of boys in the 4 × 10 m shuttle run and in the standing long jump with legs together. In throwing the medicine ball with both hands, the Olomouc boys scored lower than the boys from Opole. During the period of their earlier school years, Olomouc boys scored higher in the one-minute sit-up test. The evaluation of individual motoric performance of boys in accordance with the testing battery UNIFITTEST (6-60) showed overall that 39% of the Olomouc boys and 42% of the Opole boys had less than average or even below average motoric performance levels. A comparison of the tested results of contemporary Olomouc and Opole boys with referential data for the Olomouc boys dating to 2001 and 2002 indicated a decrease in the speed, endurance and strength of their abdominal musculature and the dynamic-explosive capability of their upper and lower extremities. CONCLUSIONS: The decrease in the motoric performance level of Olomouc and Opole boys probably reflects a decrease in habitual movement activity and the prevalence of a sedentary lifestyle.

Oscillatory entrainment of subthalamic nucleus neurons and behavioural consequences in rodents and primates

We investigated the functional role of oscillatory activity in the local field potential (LFP) of the subthalamic nucleus (STN) in the pathophysiology of Parkinson's disease (PD). It has been postulated that beta (15-30 Hz) oscillatory activity in the basal ganglia induces PD motor symptoms. To assess this hypothesis, an LFP showing significant power in the beta frequency range (23 Hz) was used as a stimulus both in vitro and in vivo. We first demonstrated in rat brain slices that STN neuronal activity was driven by the LFP stimulation. We then applied beta stimulation to the STN of 16 rats and two monkeys while quantifying motor behaviour. Although stimulation-induced behavioural effects were observed, stimulation of the STN at 23 Hz induced no significant decrease in motor performance in either rodents or primates. This study is the first to show LFP-induced behaviour in both rats and primates, and highlights the complex relationship between beta power and parkinsonian symptoms.

Mapping of functional brain activity in freely behaving rats during voluntary running using manganese-enhanced MRI: Implication for longitudinal studies

Magnetic resonance imaging (MRI) is widely used in basic and clinical research to map the structural and functional organization of the brain. An important need of MR research is for contrast agents that improve soft-tissue contrast, enable visualization of neuronal tracks, and enhance the capacity of MRI to provide functional information at different temporal scales. Unchelated manganese can be such an agent, and manganese-enhanced MRI (MEMRI) can potentially be an excellent technique for localization of brain activity (for review see Silva et al., 2004). Yet, the toxicity of manganese presents a major limitation for employing MEMRI in behavioral paradigms. We have tested systematically the voluntary wheel running behavior of rats after systemic application of MnCl2 in a dose range of 16–80 mg/kg, which is commonly used in MEMRI studies. The results show a robust dose-dependent decrease in motor performance, which was accompanied by weight loss and decrease in food intake. The adverse effects lasted for up to 7 post-injection days. The lowest dose of MnCl2 (16 mg/kg) produced minimal adverse effects, but was not sufficient for functional mapping. We have therefore evaluated an alternative method of manganese delivery via osmotic pumps, which provide a continuous and slow release of manganese. In contrast to a single systemic injection, the pump method did not produce any adverse locomotor effects, while achieving a cumulative concentration of manganese (80 mg/kg) sufficient for functional mapping. Thus, MEMRI with such an optimized manganese delivery that avoids toxic effects can be safely applied for longitudinal studies in behaving animals.

Altered neuronal activities in the motor cortex with impaired motor performance in adult rats observed after infusion of cerebrospinal fluid from amyotrophic lateral sclerosis patients

Although definite evidences are available to state that, neuronal activity is a prime determinant of animal behavior, the specific relationship between local field potentials of the motor cortex after intervention with CSF from human patients and animal behavior have remained opaque. The present study has investigated whether cerebrospinal fluid from sporadic amyotrophic lateral sclerosis (sALS) patients could disrupt neuronal activity of the motor cortex, which could be associated with disturbances in the motor performance of adult rats. CSF from ALS patients (ALS-CSF) was infused into the lateral ventricle of Wistar rats. After 24 h, the impact of ALS-CSF on the local field potentials (LFPs) of the motor cortex and on the motor behavior of animals were examined. The results indicate that ALS-CSF produced a bivariate distribution on the relative power values of the LFPs of the motor cortex 24 h following infusion. However, the behavioral results did not show bimodality, instead showed consistent decrease in motor performance: on rotarod and grip strength meter. The neuronal activity of the motor cortex negatively correlated with the duration of ALS symptoms at the time of lumbar puncture. Although the effect of ALS-CSF was more pronounced at 24 h following infusion, the changes observed in LFPs and motor performance appeared to revert to baseline values at later time points of testing. In the current study, we have shown that, ALS-CSF has the potential to perturb neuronal activity of the rat motor cortex which was associated with poor performance on motor function tests.

Identification of critical areas for motor function recovery in chronic stroke subjects using voxel-based lesion symptom mapping

IntroductionPrevious stroke studies using fMRI or lesion characterization methods to study the preservation of motor performance have been limited in defining anatomical structure critical for functional performance. This study attempts to overcome this limitation by using voxel-based lesion symptom mapping (VLSM) to identify specific anatomical regions required for preservation of motor function. MethodsForty-one moderate to moderately severe stroke subjects (upper extremity Fugl-Meyer between 28 and 50, Arm Motor Ability Test >35) were imaged with a 1 mm isotropic T1-weighted volumetric sequence, and their motor performance was assessed. The T1 volume images were normalized to a symmetric template using SPM5 and oriented so the lesion appeared in the left hemisphere. The lesioned areas were manually segmented on the normalized T1 image. All 3D lesion maps were entered into the VLSM analysis. Areas showing significant correlations with functional performance measures were identified using the false discovery rate corrected at p≤0.05. ResultsThe areas most correlated with a decrease in motor performance were at the junction of the corona radiata leading into the corticospinal tract. The Arm Motor Ability Test scores produced the most significant results, while the other measures showed similar anatomical patterns. ConclusionThe use of lesion symptom mapping in conjunction with behavioral measures produced anatomically specific results demonstrating that the area leading from the corticospinal tract to cortical motor areas is critical for maintaining hand motor performance after a stroke. This area may represent the joining of parallel redundant tracts that, when damaged, limit recovery potential.