Characteristics of EEG reactivity changes during the performance of dual tasks in healthy subjects (voluntary postural control and calculation)

Comprehensive EEG and stabilography investigation with separate and simultaneous performance of motor (voluntary postural control) and cognitive (calculation) tasks has been performed in 20 healthy subjects (22 ± 0.7 years). Specific spatial and frequency reactive changes have been found during motor task performance. These included an increase in coherence in the EEG α band for distant derivation pairs in the right hemisphere, as well as in symmetric parietal-occipital areas in both hemispheres. Cognitive task performance was accompanied by an increase in coherence for the slow bands (δ and θ) with a higher activation in the left hemisphere and frontal cortex areas. In performing the dual task, one could observe activation of spatial and frequency changes including both motor and cognitive tasks. In the dual tasks where both components were performed worse as compared to the control, reactive reorganization of EEG coherence was less pronounced than during the performance of separate tasks. A decrease in the coherence of the α₁ band in the frontal areas appeared as a zone of “conflict of interest” or interference. In dual tasks with better performance of each component as compared to the control, EEG coherence increased in each specific area, as well as in the areas of “conflict of interests.”     

Unexpected Dual Task Benefits on Cycling in Parkinson Disease and Healthy Adults: A Neuro-Behavioral Model

BackgroundWhen performing two tasks at once, a dual task, performance on one or both tasks typically suffers. People with Parkinson’s disease (PD) usually experience larger dual task decrements on motor tasks than healthy older adults (HOA). Our objective was to investigate the decrements in cycling caused by performing cognitive tasks with a range of difficulty in people with PD and HOAs.MethodsTwenty-eight participants with Parkinson’s disease and 20 healthy older adults completed a baseline cycling task with no secondary tasks and then completed dual task cycling while performing 12 tasks from six cognitive domains representing a wide range of difficulty.ResultsCycling was faster during dual task conditions than at baseline, and was significantly faster for six tasks (all p<.02) across both groups. Cycling speed improved the most during the easiest cognitive tasks, and cognitive performance was largely unaffected. Cycling improvement was predicted by task difficulty (p<.001). People with Parkinson’s disease cycled slower (p<.03) and showed reduced dual task benefits (p<.01) than healthy older adults.ConclusionsUnexpectedly, participants’ motor performance improved during cognitive dual tasks, which cannot be explained in current models of dual task performance. To account for these findings, we propose a model integrating dual task and acute exercise approaches which posits that cognitive arousal during dual tasks increases resources to facilitate motor and cognitive performance, which is subsequently modulated by motor and cognitive task difficulty. This model can explain both the improvement observed on dual tasks in the current study and more typical dual task findings in other studies.     

Electroencephalographic markers of the spontaneous recovery of the vertical posture in patients with consequences of traumatic brain injury

Nine patients (mean age, 23.6 ± 3.15 years) with a severe traumatic brain injury (TBI) associated with a loss of the ability to maintain vertical posture were enrolled in a comprehensive clinical and electroencephalographic study during the spontaneous recovery of vertical posture (VP). The patients were divided into three groups according to their functional deficit assessed on the international MPAI, FIM, and MMSE scales, which was determined by the severity of the TBI. The EEG data were compared to those of ten healthy subjects (mean age, 22.8 ± 0.67 years). In patients with a moderate impairment of the brain and a rapid recovery of VP (over two weeks), a change in the sitting position revealed EEG signs similar to reactive EEG restructurings of healthy individuals during the maintenance of VP in the form of a predominant EEG coherence increase in the right hemisphere for most of the rhythm bands; however, at this stage of VP recovery, the EEG restructurings retained pathological signs. In patients with a more severe functional deficit, spontaneous recovery of VP was accompanied by hyperreactive EEG restructurings for all rhythm bands without regional specificity. This finding showed up irrespective of the lateralization of the brain injury, which could be considered as a marker of positive dynamics of VP recovery. In patients with the most severe impairment and functional deficit and long-term (more than three months) absence of spontaneous VP recovery, the absence of reactive EEG restructurings was revealed in their passive verticalization, which could be used as a marker of negative prognosis.     

Peculiarities of changes of EEG reactivity during performance of dual tasks in healthy subjects (voluntary postural control and calculation)

Complex EEG and stabilography investigation with separate and simultaneous performance of motor (voluntary postural control) and cognitive (calculation) tasks has been performed in 20 healthy subjects (22 +/- 0.7 yo.). Specific spatial and frequency reactive changes have been revealed during motor task performance. These included increase of coherence in alpha-band for long pair of channels in right hemisphere as well as in symmetric parietal-occipital regions in both hemispheres. Cognitive task performance has been accompanied by coherence increase for low bands (delta- and theta-) with higher activation in left hemisphere and frontal regions. In dual tasks where both components were performed worse comparing to control, performance led to reactive spatial and frequency changes of both--motor and cognitive--tasks, though these changes were less than during separate task performance. Decrease of coherence in alphal-band in frontal areas appeared as a zone of "conflict of interest - interferention". In dual tasks with better performance of each component comparing to control EEG coherence increased in each specific area as well as in areas of "conflict of interest".     

Psychological and stabilographic features of healthy persons with different capabilities of performing dual tasks

A dual task study including control of postural balance and counting was conducted on 40 healthy subjects (with an average age of 29.8 ± 2.47 years) along with a psychological examination that included estimation of the working memory, attention, and the time of attention switch. Three types of dual task performance were observed: worsening of either one or both components of the dual task, improvement of one component, and improvement of both components of the dual task. 30% of participants performed a dual task better than isolated tasks. Successful performance in the dual task correlated with the higher volume of spatial and working memory, attention, and a rapid switch of attention. The speed of sway of the center of pressure (CoP) negatively correlated with the speed of attention switch, while the amplitude of the CoP shift in the frontal plane negatively correlated with the volume of spatial and working memory. These data suggest involvement of the cognitive resources in controlling the upright balance and a high degree of motor automatism when the dual tasks are successfully performed. Our experimental paradigm is expected to be helpful in predicting individual performance in situations with high information loads.     

Corticomuscular coherence with and without additional task in the elderly

Aging and dual-task paradigms often degrade fine motor performance, but the effects of aging on correlated neural activity between motor cortex and contracting muscle are unknown during dual tasks requiring fine motor performance. The purpose of this study was to compare corticomuscular coherence between young and elderly adults during the performance of a unilateral fine motor task and concurrent motor and cognitive tasks. Twenty-nine healthy young (18-38 yr) and elderly (61-75 yr) adults performed unilateral motor, bilateral motor, concurrent motor-cognitive, and cognitive tasks. Peak corticomuscular coherence between the electroencephalogram from the primary motor cortex and surface electromyogram from the first dorsal interosseous muscle was compared during steady abduction of the index finger with visual feedback. In the alpha-band (8-14 Hz), corticomuscular coherence was greater in elderly than young adults especially during the motor-cognitive task. The beta-band (15-32 Hz) corticomuscular coherence was higher in elderly than young adults across unilateral motor and dual tasks. In addition, beta-band corticomuscular coherence in the motor-cognitive task was negatively correlated with motor output error across young but not elderly adults. The results suggest that 1) corticomuscular coherence was increased in senior age with a greater influence of an additional cognitive task in the alpha-band and 2) individuals with greater beta-band corticomuscular coherence may exhibit more accurate motor output in young, but not elderly adults, during steady contraction with visual feedback.     

Neural Activation in Humans during a Simple Motor Task Differs between BDNF Polymorphisms

The BDNF Val66Met polymorphism has been linked to decreased synaptic plasticity involved in motor learning tasks. We investigated whether individual differences in this polymorphism may promote differences in neural activity during a two-alternative forced-choice motor performance. In two separate sessions, the BOLD signal from 22 right-handed healthy men was measured during button presses with the left and right index finger upon visual presentation of an arrow. 11 men were Val66Val carriers (ValVal group), the other 11 men carried either the Val66Met or the Met66Met polymorphism (Non-ValVal group). Reaction times, resting and active motor thresholds did not differ between ValVal and Non-ValVal groups. Compared to the ValVal group the Non-ValVal group showed significantly higher BOLD signals in the right SMA and motor cingulate cortex during motor performance. This difference was highly consistent for both hands and across all four sessions. Our finding suggests that this BDNF polymorphism may not only influence complex performance during motor learning but is already associated with activation differences during rather simple motor tasks. The higher BOLD signal observed in Non-ValVal subjects suggests the presence of cumulative effects of the polymorphism on the motor system, and may reflect compensatory functional activation mediating equal behavioral performance between groups.     

Risk Taking in Hospitalized Patients with Acute and Severe Traumatic Brain Injury

Rehabilitation can improve cognitive deficits observed in patients with traumatic brain injury (TBI). However, despite rehabilitation, the ability of making a choice often remains impaired. Risk taking is a daily activity involving numerous cognitive processes subserved by a complex neural network. In this work we investigated risk taking using the Balloon Analogue Risk Task (BART) in patients with acute TBI and healthy controls. We hypothesized that individuals with TBI will take less risk at the BART as compared to healthy individuals. We also predicted that within the TBI group factors such as the number of days since the injury, severity of the injury, and sites of the lesion will play a role in risk taking as assessed with the BART. Main findings revealed that participants with TBI displayed abnormally cautious risk taking at the BART as compared to healthy subjects. Moreover, healthy individuals showed increased risk taking throughout the task which is in line with previous work. However, individuals with TBI did not show this increased risk taking during the task. We also investigated the influence of three patients’ characteristics on their performance at the BART: Number of days post injury, Severity of the head injury, and Status of the frontal lobe. Results indicate that performance at the BART was influenced by the number of days post injury and the status of the frontal lobe, but not by the severity of the head injury. Reported findings are encouraging for risk taking seems to naturally improve with time postinjury. They support the need of conducting longitudinal prospective studies to ultimately identify impaired and intact cognitive skills that should be trained postinjury.     

双任务事件中脑电信号的熵计算

采用复杂性分析中的样品熵算法,计算并分析了受试者在单任务事件以及双任务事件活动过程中的神经电生理数据.在利用样品熵算法对短时程（秒）脑电数据的复杂度和规则度进行计算之前,首先应用了代替数据分析法,以排除所分析的实验数据是由线性加随机部分构成.所有的实验数据分别在单任务和双任务等不同的生理条件下采集.其中单任务为一个听觉辨别任务;双任务有两种形式,分别为听觉任务和不同的震动任务的结合.计算结果显示,任何一种双任务过程中脑电信号的熵值都明显的低于单任务状态时脑电信号的熵值（P＜0.05～0.001）.研究表明对应于受试者仅仅进行单任务工作而言,当受试者处于双任务工作状态时大脑的神经信息传递可能会受到某种程度的削弱,神经信息流通的范围也可能更为孤立.结果进一步说明对于短时程（秒）脑电信号分析,样品熵算法是有效的非线性分析方法.     

Integrating role of voluntary postural control recovery during rehabilitation of patients with traumatic brain injury

Results of complex clinical, stabilographic and electroencephalographic (EEG) examination of 20 patients (28 +/- 6.9 years) suffered a severe traumatic brain injury (STBI) are presented. The examination was carried out in early terms after the STBI before and after a course of stabilographic training (ST) with a visual feedback as compared to a group of 18 healthy volunteers (26 +/- 5.8 years). The 4- to 6-week course of ST consisted of 8-15 sessions. Before the course, the patients experienced problems in different kinds of activity, maximum in the motor sphere. The EEG study revealed a decrease in the power and coherence of the alpha rhythm and an increase in the power of the slow spectral bands (delta). The ST restored not only the postural control of patients, but also reduced the defects in other spheres. The EEG study showed an increase in the alpha-rhythm power maximum in the occipital-parietal areas and a tendency to normalization of its regional specificity. In all examined patients, the interhemispheric coherence increased for different EEG-rhythms, especially of the alpha-band, in the central and parietal brain areas. The described EEG changes can be a marker of the integrating role of postural control and an important stage in restoration of integrative brain activity in early terms after the STBI accompanied by improvement of damaged functions.     

Organisation of the motor cortex differs between people with and without knee osteoarthritis

IntroductionThe aim of this study was to investigate possible differences in the organisation of the motor cortex in people with knee osteoarthritis (OA) and whether there is an association between cortical organisation and accuracy of a motor task.MethodsfMRI data were collected while 11 participants with moderate/severe right knee OA (6 male, 69 ± 6 (mean ± SD) years) and seven asymptomatic controls (5 male, 64 ± 6 years) performed three visually guided, variable force, force matching motor tasks involving isolated isometric muscle contractions of: 1) quadriceps (knee), 2) tibialis anterior (ankle) and, 3) finger/thumb flexor (hand) muscles. fMRI data were used to map the loci of peak activation in the motor cortex during the three tasks and to assess whether there were differences in the organisation of the motor cortex between the groups for the three motor tasks. Root mean square of the difference between target and generated forces during muscle contraction quantified task accuracy.ResultsA 4.1 mm anterior shift in the representation of the knee (p = 0.03) and swap of the relative position of the knee and ankle representations in the motor cortex (p = 0.003) were found in people with knee OA. Poorer performance of the knee task was associated with more anterior placement of motor cortex loci in people with (p = 0.05) and without (p = 0.02) knee OA.ConclusionsDifferences in the organisation of the motor cortex in knee OA was demonstrated in relation to performance of knee and ankle motor tasks and was related to quality of performance of the knee motor task. These results highlight the possible mechanistic link between cortical changes and modified motor behavior in people with knee OA.     

Reliability of assessing trunk motor control using position and force tracking and stabilization tasks

System-based methods have been applied to assess trunk motor control in people with and without back pain, although the reliability of these methods has yet to be established. Therefore, the goal of this study was to quantify within- and between-day reliability using systems-based methods involving position and force tracking and stabilization tasks. Ten healthy subjects performed six tasks, involving tracking and stabilizing of trunk angular position in the sagittal plane, and trunk flexion and extension force. Tracking tasks involved following a one-dimensional, time-varying input signal displayed on a screen by changing trunk position (position tracking) or trunk force (force tracking). Stabilization tasks involved maintaining a constant trunk position (position stabilization) or constant trunk force (force stabilization) while a sagittal plane disturbance input was applied to the pelvis using a robotic platform. Time and frequency domain assessments of error (root mean square and H₂ norm, respectively) were computed for each task on two separate days. Intra-class correlation coefficients (ICC) for error and coefficients of multiple correlations (CMC) for frequency response curves were used to quantify reliability of each task. Reliability for all tasks was excellent (between-day ICC≥0.8 and CMC>0.75, within-day CMC>0.85). Therefore, position and force control tasks used to assess trunk motor control can be deemed reliable.     

tBHQ和SFN在创伤性脑损伤小鼠中的疗效比较性分析

目的:探讨叔丁基对苯二酚(t BHQ)和莱菔硫烷(SFN)在患有创伤性脑损伤大鼠的疗效差异性。方法:80只健康成年的雄性SD大鼠分为假手术组、常规损伤组、t BHQ治疗组和SFN治疗组,使用电子颅脑损伤仪(e CCI)制备TBI模型。其中t BHQ治疗组在伤前24 h大鼠腹腔注射三次t BHQ(50 mg/kg),每8 h一次;SFN治疗组在伤后15 min给予腹腔注射SFN(5 mg/kg)。给药24 h后,采用m NSS方法评价各组大鼠神经功能缺损状况,利用干湿称量法计算脑含水量,Western blot和ELISA方法分别测定大鼠脑组织的NOX2和Nrf2的表达水平。结果:损伤发生后第24 h,t BHQ治疗组和SFN治疗组在m NSS评分((4.5±0.71)vs(9.2±0.79),(6.0±0.82)vs(9.2±0.79))、脑水肿(79.4%vs 85.6%,80.3%vs 85.6%)、NOX2和Nrf2(0.93 ng/m L vs 0.81 ng/m L,0.87 ng/m L vs 0.81 ng/m L)表达上与常规损伤组差异明显,而t BHQ治疗组和SFN治疗组间在m NSS评分((4.5±0.71)vs(6.0±0.82))、NOX2和Nrf2(0.93 ng/m L vs 0.87 ng/m L)表达上差异显著。结论:在大鼠TBI模型中,t BHQ和SFN均可以有效的降低机体自身的氧化应激作用,并改善神经功能,但t BHQ的疗效要好于SFN。     

The Microstructural Status of the Corpus Callosum Is Associated with the Degree of Motor Function and Neurological Deficit in Stroke Patients

Human neuroimaging studies and animal models have suggested that white matter damage from ischemic stroke leads to the functional and structural reorganization of perilesional and remote brain regions. However, the quantitative relationship between the transcallosal tract integrity and clinical motor performance score after stroke remains unexplored. The current study employed a tract-based spatial statistics (TBSS) analysis on diffusion tensor imaging (DTI) to investigate the relationship between white matter diffusivity changes and the clinical scores in stroke patients. Probabilistic fiber tracking was also used to identify structural connectivity patterns in the patients. Thirteen ischemic stroke patients and fifteen healthy control subjects participated in this study. TBSS analyses showed that the corpus callosum (CC) and bilateral corticospinal tracts (CST) in the stroke patients exhibited significantly decreased fractional anisotropy and increased axial and radial diffusivity compared with those of the controls. Correlation analyses revealed that the motor and neurological deficit scores in the stroke patients were associated with the value of diffusivity indices in the CC. Compared with the healthy control group, probabilistic fiber tracking analyses revealed that significant changes in the inter-hemispheric fiber connections between the left and right motor cortex in the stroke patients were primarily located in the genu and body of the CC, left anterior thalamic radiation and inferior fronto-occipital fasciculus, bilateral CST, anterior/superior corona radiate, cingulum and superior longitudinal fasciculus, strongly suggesting that ischemic induces inter-hemispheric network disturbances and disrupts the white matter fibers connecting motor regions. In conclusion, the results of the present study show that DTI-derived measures in the CC can be used to predict the severity of motor skill and neurological deficit in stroke patients. Changes in structural connectivity pattern tracking between the left and right motor areas, particularly in the body of the CC, might reflect functional reorganization and behavioral deficit.     

Effect of group size and maize silage dietary levels on behaviour,health, carcass and meat quality of Mediterranean buffaloes

The effects of different dietary levels of maize silage (10% v. 36% DM) and group size (7 v. 14 animals) were assessed on growth performance and in vivo digestibility of 28 male fattening buffaloes. In addition, the effects of diet on meat quality and group size on behaviour and immune response were separately evaluated. Animals were weighed and assigned to three groups. The high silage – low size group (HL) was fed a total mixed ration (TMR) containing 36% DM of maize silage and consisted of seven animals (age 12.7±2.6 months; BW 382.2±67.7 kg at the start of the study). The low silage – low size group (LL) was fed a TMR containing 10% DM of maize silage and consisted of seven animals (age 13.0±2.7 months; BW 389.4±72.3 kg). The high silage – high size group (HH) was fed the 36% maize silage DM diet and consisted of 14 animals (age 13.9±3.25 months; BW 416.5±73.9 kg). Total space allowance (3.2 indoor+3.2 outdoor m²/animal) was kept constant in the three groups, as well as the ratio of animals to drinkers (seven animals per water bowl) and the manger space (70 cm per animal). Growth performance, carcass characteristics and digestibility were influenced neither by dietary treatment nor by group size, even if the group fed 36% maize silage diet showed a higher fibre digestibility. No effect of diet was found on meat quality. Group size did not affect the behavioural activities with the exception of drinking (1.04±0.35% v. 2.60±0.35%; P<0.01 for groups HL and HH, respectively) and vigilance (2.58±0.46% v. 1.20±0.46%; P<0.05 for groups HL and HH, respectively). Immune responses were not affected by group size.     

Deficit in Motor Training-Induced Clustering,but Not Stabilization,of New Dendritic Spines in fmr1 Knock-Out Mice

Fragile X Syndrome is the most common inherited intellectual disability, and Fragile X Syndrome patients often exhibit motor and learning deficits. It was previously shown that the fmr1 knock-out mice, a common mouse model of Fragile X Syndrome, recapitulates this motor learning deficit and that the deficit is associated with altered plasticity of dendritic spines. Here, we investigated the motor learning-induced turnover, stabilization and clustering of dendritic spines in the fmr1 knock-out mouse using a single forelimb reaching task and in vivo multiphoton imaging. We report that fmr1 knock-out mice have deficits in motor learning-induced changes in dendritic spine turnover and new dendritic spine clustering, but not the motor learning-induced long-term stabilization of new dendritic spines. These results suggest that a failure to establish the proper synaptic connections in both number and location, but not the stabilization of the connections that are formed, contributes to the motor learning deficit seen in the fmr1 knock-out mouse.     

Extreme Levels of Noise Constitute a Key Neuromuscular Deficit in the Elderly

Fluctuations during isometric force production tasks occur due to the inability of musculature to generate purely constant submaximal forces and are considered to be an estimation of neuromuscular noise. The human sensori-motor system regulates complex interactions between multiple afferent and efferent systems, which results in variability during functional task performance. Since muscles are the only active component of the motor system, it therefore seems reasonable that neuromuscular noise plays a key role in governing variability during both standing and walking. Seventy elderly women (including 34 fallers) performed multiple repetitions of isometric force production, quiet standing and walking tasks. No relationship between neuromuscular noise and functional task performance was observed in either the faller or the non-faller cohorts. When classified into groups with either nominal (group NOM, 25^th –75^th percentile) or extreme (either too high or too low, group EXT) levels of neuromuscular noise, group NOM demonstrated a clear association (r²>0.23, p<0.05) between neuromuscular noise and variability during task performance. On the other hand, group EXT demonstrated no such relationship, but also tended to walk slower, and had lower stride lengths, as well as lower isometric strength. These results suggest that neuromuscular noise is related to the quality of both static and dynamic functional task performance, but also that extreme levels of neuromuscular noise constitute a key neuromuscular deficit in the elderly.     

Deficit of learning of posture voluntary control in patients with cortical lesions of various locations: cortical mechanisms of posture regulation

Forty two hemiparetic patients after cerebrovascular accidents were trained to change the position of the center of pressure according to a target on the screen with the visual feedback control. The learning was substantially impaired in comparison with the group of healthy subjects. Patients with the right-hemispheric lesions showed somewhat greater learning deficit than patients with lesions in the left hemisphere. Lesion localization also affected the process of learning. The learning was disturbed to a greater extent in patients with lesions involving not only motor but also premotor and parietal cortical areas. In patients with parieto-temporal lesions the learning reached a very low level after three initial days of training, possibly, because of the deficit of sensory integration and of body scheme in the extra-personal space. Patients with combined lesions of the motor, premotor, and parietal areas showed the lowest results. The learning was shown to depend on the deficit of proprioception and extent of postural disturbances (asymmetry of body weight distribution and amplitude of the center of pressure oscillations) rather than on the extent of motor deficit (paresis and spasticity). However, the learning itself improved some motor disturbances.     

Comparative Analysis of Serum Zinc, Copper, Manganese, Iron, Calcium, and Magnesium Level and Complexity of Interelement Relations in Generalized Anxiety Disorder Patients

The purpose of the study was to determine the concentration of serum trace and other essential elements of generalized anxiety disorder patients and to find out the relationship between element levels and nutritional status or socioeconomic factors. The study was conducted among 50 generalized anxiety disorder patients and 51 healthy volunteers. Patients were selected and recruited in the study with the help of a clinical psychologist by random sampling. The concentrations of serum trace elements (Zn, Cu, Mn, and Fe) and other two essential elements (Ca and Mg) were determined by graphite furnace and flame atomic absorption spectroscopy. Data were analyzed by independent t test, Pearson’s correlation analysis, regression analysis, and analysis of variance. The serum concentrations of Zn, Cu, Mn, Fe, Ca, and Mg in generalized anxiety disorder patients were 1.069?±?0.40, 1.738?±?0.544, 1.374?±?0.750, 3.203?±?2.065, 108.65?±?54.455, and 21?±?4.055 mg/L, while those were 1.292?±?0.621, 0.972?±?0.427, 0.704?±?0.527, 1.605?±?1.1855, 101.849?±?17.713, and 21.521?±?3.659 mg/L in control subjects. Significantly decreased (p?<?0.05) serum Zn concentration was found in the patient group compared to the control group while serum level of Cu, Mn, and Fe was significantly (p?<?0.05) higher, but the differences of the concentration of Ca and Mg between the patient and control groups were not significant (p?>?0.05). Socioeconomic data revealed that most of the patients were in the lower middle class group and middle-aged. Mean BMI of the control group (23.63?±?3.91 kg/m²) and the patient group (23.62?±?3.77 kg/m²) was within the normal range (18.5–25.0 kg/m²). The data obtained from different interelement relations in the generalized anxiety disorder patients and control group strongly suggest that there is a disturbance in the element homeostasis. So changes in the serum trace element level in generalized anxiety disorder patients occur independently and they may provide a prognostic tool for the diagnosis and treatment of this disease.