Search results for "Movement"
showing 10 items of 2021 documents
An ensemble analysis of electromyographic activity during whole body pointing with the use of support vector machines.
2011
Import JabRef | WosArea Life Sciences and Biomedicine - Other Topics; International audience; We explored the use of support vector machines (SVM) in order to analyze the ensemble activities of 24 postural and focal muscles recorded during a whole body pointing task. Because of the large number of variables involved in motor control studies, such multivariate methods have much to offer over the standard univariate techniques that are currently employed in the field to detect modifications. The SVM was used to uncover the principle differences underlying several variations of the task. Five variants of the task were used. An unconstrained reaching, two constrained at the focal level and two …
Investigating centre of mass stabilisation as the goal of posture and movement coordination during human whole body reaching
2000
In the light of experimental results showing significant forward centre of mass (CoM) displacements within the base of support, this study investigated if whole body reaching movements can be executed whilst keeping the CoM fixed in the horizontal axis. Using kinematic simulation techniques, angular configurations were recreated from experimental data imposing two constraints: a constant horizontal position of the CoM and an identical trajectory of the hand to grasp an object. The comparison between recorded and simulated trials showed that stabilisation of the CoM was associated with greater backward hip displacements, which became more marked with increasing object distance. This was in c…
Online detection of rem sleep based on the comprehensive evaluation of short adjacent eeg segments by artificial neural networks
1997
Abstract 1. 1. For scientific and clinical requirements the present objective is a robust automatic online algorithm to detect rapid eye movement (REM) steep from single channel sleep EEG data without using EMG or EOG information. 2. 2. For data preprocessing 20 seconds time periods of the continuous EEG activity are digitally filtered in 7 frequency bands. Then the RMS values of these filtered signals are calculated along segments of 2.5 seconds. The resulting matrix of RMS values is representing information on the power of the signal localized in time and frequency and serves as input to an artificial neural network. A pooled set of EEG data together with the corresponding manual evaluati…
Fatigue-related changes in technique emerge at different timescales during repetitive training
2017
Training consisting of numerous repetitions performed as closely as possible to ideal techniques is common in sports and every-day tasks. Little is known about fatigue-related technique changes that emerge at different timescales when repeating complex actions such as a karate front kick. Accordingly, 15 karatekas performed 600 kicks (1 pre-block and 9 blocks). The pre-block comprised 6 kicks (3 with each leg) at maximum intensity (K-100%). Each block comprised 60 kicks (10 with each leg) at 80% of their self-perceived maximum intensity (K-80%) plus 6 K-100%. In between blocks, the participants rested for 90 seconds. Right leg kinematics (peak joint angles, peak joint angular velocities, pe…
Relationship between isokinetic performance and ballistic movement
1983
The present experiments were carried out to assess the relationship between the mechanical behaviour of the leg extensor muscles in 12 male athletes during activities of a ballistic type and torque production, during: (1) torque production during isokinetic contraction: (2) ballistic type activities (vertical jumps from statis position = SJ, with counter-movement equal CMJ and after a fall from different heights equal DJ) and (3) a new anaerobic test (Bosco 1983a). This consisted of performing continuous jump work for a certain period of time (e.g., 60 s). Both ballistic activities and anaerobic power tests demonstrated the highest relationship with peak torques when this was developed resp…
Electromechanical delay in skeletal muscle under normal movement conditions.
1979
Electromechanical delays (EMD), the time from onset of EMG activity to change in acceleration or deceleration of the forearm, were studied in concentric and eccentric contractions of biceps and triceps brachii muscles. Horizontal flexion and extension movements were performed at varying speeds by 10 subjects. EMD time in concentric contractions for biceps was 41 +/- 13 ms and for triceps was 26 +/- 11 ms and was not influenced by the velocity of the movement. In eccentric contractions at the slow velocity the biceps EMD time was 38 +/- 13 ms and shortened to 28 +/- 10 ms at the faster velocity. The eccentric triceps EMD, however, was not significantly altered by movement velocity and averag…
Conventional and spectral power analysis of all-night sleep EEG after subchronic treatment with paroxetine in healthy male volunteers.
1998
Paroxetine is a selective and potent serotonin reuptake inhibitor with reported antidepressant properties. Since changes in the regular sleeping pattern were described as side effects under treatment with paroxetine, the impact of the drug on the sleep architecture is of major interest. The present study addressed the question of subchronic effects of paroxetine medication (30 mg/day) in eight healthy male volunteers in a double blind, placebo-controlled crossover-design. Conventional sleep EEG parameters and additionally computed spectral power analysis based on FFT of 20-s time epochs in the delta, theta, alpha, beta and gamma frequency range for different sleep stages after 4 weeks of tr…
Do palatal implants remain positionally stable under orthodontic load? A clinical radiologic study.
2009
Introduction The aim of this study was to determine the positional stability and success rate of palatally placed length-reduced temporary anchorage devices (LRTADs) (length, 4 or 6 mm). Methods Twenty-two patients (ages, 21-62 years; 14 women, 8 men) were enrolled in the study. Each received 1 LRTAD (Orthosystem, Straumann, Switzerland) placed in the midsagittal palate for multifunctional anchorage tasks. Standardized cephalograms were taken directly after implant placement and at the end of treatment to analyze any implant movements. The cephalometric tracings were superimposed on anterior nasal spine to posterior nasal spine in posterior nasal spine to analyze changes in implant angulati…
Kinematic and dynamic processes for the control of pointing movements in humans revealed by short-term exposure to microgravity.
2004
The generation of accurate motor commands requires implicit knowledge of both limb and environmental dynamics. The action of gravity on moving limb segments must be taken into account within the motor command, and may affect the limb trajectory chosen to accomplish a given motor task. Exactly how the CNS deals with these gravitoinertial forces remains an open question. Does the CNS measure gravitational forces directly, or are they accommodated in the motor plan by way of internal models of physical laws? In this study five male subjects participated. We measured kinematic and dynamic parameters of upward and downward arm movements executed at two different speeds, in both normal Earth grav…
Parafoveal versus foveal N400s dissociate spreading activation from contextual fit.
2009
Using concurrent electroencephalogram and eye movement measures to track natural reading, this study shows that N400 effects reflecting predictability are dissociable from those owing to spreading activation. In comparing predicted sentence endings with related and unrelated unpredicted endings in antonym constructions ('the opposite of black is white/yellow/nice'), fixation-related potentials at the critical word revealed a predictability-based N400 effect (unpredicted vs. predicted words). By contrast, event-related potentials time locked to the last fixation before the critical word showed an N400 only for the nonrelated unpredicted condition (nice). This effect is attributed to a parafo…