Cortical representation of voluntary and non-voluntary motor rhythms [Abstract]

Background: Coupled bilateral cortical activity seems to be the basis for intermanual coordination, but its direct relation to the peripheral bimanual movements is still unclear. Methods: We analyzed corticomuscular coherence between 64-channel EEG and bilateral hand/finger extensor and flexor EMG and intermuscular coherence between left and right muscle activity in 18 healthy subjects during unilateral and bilateral fast rhythmic hand/finger movements and isometric contractions on both sides. Results: Partial coherence between two separated coherent areas and muscle and corticomusuclar/cortico-cortical delays were calculated. Bilateral voluntary rhythms of each hand showed coherence with lateral cortical areas on both sides in 60-80% of the recordings and occasionally with the frontal midline region (10-30%). They were always coherent between both hands. Unilateral rhythmic movements were represented in the ipsilateral cortex in only 20%-30% of the recordings tending to be more frequent with the left hand, paralleled by more frequent left-right muscle coherence. Partial corticomuscular coherence was most often abolished (p� 0.05) when the cortical signal contralateral to the coherent muscle was used as the predictor indicating that the ipsilateral and occasional frontomesial connection with the muscle was mainly indirect via the contralateral cortex. Cortico-cortical delays showed mainly bidirectional interaction at the movement frequency and were bimodally distributed ranging between 1-10 ms and 15-30 ms indicating direct cortical and subcortical routes. Corticomuscular delays ranged mainly between 12-25 ms indicating fast corticospinal projections, and musculocortical feedback showed similar delays. These corticomuscular delays were not significantly different for the 15-30 Hz coherence encountered in 60-70% of the recordings during isometric contractions. However this involuntary corticomuscular rhythm was strictly unilaterally represented and did not show coherence between left and right muscles. Conclusions: We conclude that there is a fundamental difference between the complex bilateral cortical network representing and controlling a voluntary motor rhythm and the cortical representation of non-voluntary 15-30 Hz rhythm as well as pathological non-voluntary rhythms likeorganic tremors

Cortical representation of different motor rhythms during bimanual movements

The cortical control of bimanual and unimanual movements involves complex facilitatory and inhibitory interhemispheric interactions. We analysed the part of the cortical network directly related to the motor output by corticomuscular (64 channel EEG–EMG) and cortico-cortical (EEG–EEG) coherence and delays at the frequency of a voluntarily maintained unimanual and bimanual rhythm and in the 15–30-Hz band during isometric contractions. Voluntary rhythms of each hand showed coherence with lateral cortical areas in both hemispheres and occasionally in the frontal midline region (60–80 % of the recordings and 10–30 %, respectively). They were always coherent between both hands, and this coherence was positively correlated with the interhemispheric coherence (p < 0.01). Unilateral movements were represented mainly in the contralateral cortex (60–80 vs. 10–30 % ipsilateral, p < 0.01). Ipsilateral coherence was more common in left-hand movements, paralleled by more left–right muscle coherence. Partial corticomuscular coherence most often disappeared (p < 0.05) when the contralateral cortex was the predictor, indicating a mainly indirect connection of ipsilateral/frontomesial representations with the muscle via contralateral cortex. Interhemispheric delays had a bimodal distribution (1–10 and 15–30 ms) indicating direct and subcortical routes. Corticomuscular delays (mainly 12–25 ms) indicated fast corticospinal projections and musculocortical feedback. The 15–30-Hz corticomuscular coherence during isometric contractions (60–70 % of recordings) was strictly contralaterally represented without any peripheral left–right coherence. Thus, bilateral cortical areas generate voluntary unimanual and bimanual rhythmic movements. Interhemispheric interactions as detected by EEG–EEG coherence contribute to bimanual synchronization. This is distinct from the unilateral cortical representation of the 15–30-Hz motor rhythm during isometric movements

Oscillating central motor networks in pathological tremors and voluntary movements: what makes the difference?

Parkinsonian tremor (PD), essential tremor (ET) and voluntarily mimicked tremor represent fundamentally different motor phenomena, yet, magnetoencephalographic and imaging data suggest their origin in the same motor centers of the brain. Using EEG–EMG coherence and coherent source analysis we found a different pattern of corticomuscular delays, time courses and central representations for the basic and double tremor frequencies typical for PD suggesting a wider range defective oscillatory activity. For the basic tremor frequency similar central representations in primary sensorimotor, prefrontal/premotor and diencephalic (e.g. thalamic) areas were reproduced for all three tremors. But renormalized partial directed coherence of the spatially filtered (source) signals revealed a mainly unidirectional flow of information from the diencephalon to cortex in voluntary tremor, e.g. a thalamocortical relay, as opposed to a bidirectional subcortico-cortical flow in PD and ET promoting uncontrollable, e.g. thalamocortical, loop oscillations. Our results help to understand why pathological tremors although originating from the physiological motor network are not under voluntary control and they may contribute to the solution of the puzzle why high frequency thalamic stimulation has a selective effect on pathological tremor leaving voluntary movement performance almost unaltered

Plasma S-adenosylmethionine, DNMT polymorphisms, and peripheral blood LINE-1 methylation among healthy Chinese adults in Singapore

10.1186/1471-2407-13-389BMC Cancer13-BCMA

An Integrated Model for User Attribute Discovery: A Case Study on Political Affiliation Identification

Discovering user demographic attributes from social media is a problem of considerable interest. The problem setting can be generalized to include three components - users, topics and behaviors. In recent studies on this problem, however, the behavior between users and topics are not effectively incorporated. In our work, we proposed an integrated unsupervised model which takes into consideration all the three components integral to the task. Furthermore, our model incorporates collaborative filtering with probabilistic matrix factorization to solve the data sparsity problem, a computational challenge common to all such tasks. We evaluated our method on a case study of user political affiliation identification, and compared against state-of-the-art baselines. Our model achieved an accuracy of 70.1% for user party detection task. ? 2014 Springer International Publishing.EI

Technologies for the global energy transition

The availability of reliable, affordable and mature technologies is at the basis of an effective decarbonization strategy, that should be in turn supported by timely and accurate policies. Due to the large differences across sectors and countries, there is no silver bullet to support decarbonization, but a combination of multiple technologies will be required to reach the challenging goal of decarbonizing the energy sector. This chapter presents a focus on the current technological solutions that are available in four main sectors: power generation, industry, transport and buildings. The aim of this work is to highlight the main strengths and weaknesses of the current technologies, to help the reader in understanding which are the main opportunities and challenges related to the development and deployment of each of them, as well as their potential contribution to the decarbonization targets. The chapter also provides strategies and policy recommendations from a technology point of view on how to decarbonize the global energy systems by mid-century and of the necessity to take a systems approach

Исследование методов измерения толщины стенки легкосплавных бурильных труб

Толщина стенки бурильной трубы из алюминиевого сплава измеряется вихретоковым методом, акустическим методом, магнитным методом, Радиaционным методом и визуально-оптическим методом. Принцип соответствующего инструмента также описывается с помощью принципа вышеупомянутого метода.Through the eddy current method, acoustic method, electromagnetic method, radiation method, visual optical method, to measure the thickness of the aluminum alloy drill pipe wall. The corresponding instrument principles are also described through the principles of the above methods