EEG and EMG Sensorimotor Measurements to Assess Proprioception Following ACL Reconstruction

The Anterior Cruciate Ligament (ACL) is the primary source of rotational stability in the knee by preventing the tibia from sliding in front of the femur. When the ACL is torn, it typically must be repaired through reconstructive surgery which results in proprioceptive deficiencies in the knee. Proprioception plays an important role in understanding where one’s knee is in space, sensing movement and reacting accordingly. This study examines an alternative method of measuring proprioceptive responses to a stimulus (motion) by using electromyogram (EMG) and electroencephalogram (EEG) signals to observe muscle and brain activity. Two participants (one with an ACL reconstruction and a second with healthy knees) were tested three times over a six week period. Repeated measures allowed for an initial examination of how proprioception may vary over time in an individual with healthy knees and with an ACL reconstruction. This measurement strategy can examine the process of proprioception recovery after an ACL reconstruction. It has the potential to help physicians and physical therapists decide when a person can return to normal or strenuous activity as well as provide insight into whether uninjured patients have a proprioceptive deficit which may indicate an increased risk of injury

Methods of power line interference elimination in EMG signals

Electromyogram (EMG) recordings are often corrupted by the wide range of artifacts, which one of them is power line interference (PLI). The study focuses on some of the well-known signal processing approaches used to eliminate or attenuate PLI from EMG signal. The results are compared using signal-to-noise ratio (SNR), correlation coefficients and Bland-Altman analysis for each tested method: notch filter, adaptive noise canceller (ANC) and wavelet transform (WT). Thus, the power of the remaining noise and shape of the output signal are analysed. The results show that the ANC method gives the best output SNR and lowest shape distortion compared to the other methods.Web of Science40706

Using Scalp Electrical Biosignals to Control an Object by Concentration and Relaxation Tasks: Design and Evaluation

In this paper we explore the use of electrical biosignals measured on scalp and corresponding to mental relaxation and concentration tasks in order to control an object in a video game. To evaluate the requirements of such a system in terms of sensors and signal processing we compare two designs. The first one uses only one scalp electroencephalographic (EEG) electrode and the power in the alpha frequency band. The second one uses sixteen scalp EEG electrodes and machine learning methods. The role of muscular activity is also evaluated using five electrodes positioned on the face and the neck. Results show that the first design enabled 70% of the participants to successfully control the game, whereas 100% of the participants managed to do it with the second design based on machine learning. Subjective questionnaires confirm these results: users globally felt to have control in both designs, with an increased feeling of control in the second one. Offline analysis of face and neck muscle activity shows that this activity could also be used to distinguish between relaxation and concentration tasks. Results suggest that the combination of muscular and brain activity could improve performance of this kind of system. They also suggest that muscular activity has probably been recorded by EEG electrodes.Comment: International Conference of the IEEE EMBS (2011

Sleep Disorders and Genes

Versão preprintThe sleep-wake cycle is a neurobiological phenomenon that shows intervals of activity alternating with restfulness that appears with a periodicity approximating the 24h day-night cycle. The sleep-wake cycle is under the control of diverse neuroanatomical and neurochemical systems, including monoaminergic, cholinergic, adenosinergic among many other systems. In addition, neuroanatomical centers linked to sleep promotion, such as hypothalamus, project to the cerebral cortex, subcortical relays and brainstem. In addition, the sleep-wake cycle has been associated to aberrant features known as sleep disorders. Here, we will discuss the role of specific gene expression on sleep disturbances. Given the expansion of the knowledge in the sleep-wake cycle area, it is indeed ambitious to describe all the genetics involved in the sleep modulation. However, in this chapter we reviewed the current understanding of the sleep disorders and gene expression.info:eu-repo/semantics/publishedVersio

Strengthening Your Hip Muscles: Some Exercises May Be Better Than Others

Weak hip muscles lead to poor hip motion, and poor hip motion can cause knee, hip, and back pain. Strengthening hip muscles that control how hips move may reduce pain in these parts of the body. This undergraduate research project compared hip abductor muscle activity during selected exercises using electromyography in order to determine which exercises are best for activating the gluteus medius and the superior portion of the gluteus maximus, while minimizing activity of the tensor fascia lata. Participants in this study included nine healthy female soccer players between the ages of 18 and 21. Using an electromyogram (EMG), the muscle activity of the nine subjects was recorded during the following 11 exercises: hip abduction in sidelying, clam with elastic resistance around thighs, bilateral bridge, unilateral bridge, hip extension in quadruped on elbows with knee extending, hip extension in quadruped on elbows with knee flexed, forward lunge with erect trunk, squat, sidestep with elastic resistance in a squatted position, hip hike, and forward step-up. At this time, data collection and analysis continues; however, it is hypothesized that both gluteal muscles were significantly more active than the TFL in unilateral and bilateral bridging, quadruped hip extension, the clam, sidestepping, and squatting

Cross-spectral analysis of physiological tremor and muscle activity. I. Theory and application to unsynchronized EMG

We investigate the relationship between the extensor electromyogram (EMG) and tremor time series in physiological hand tremor by cross-spectral analysis. Special attention is directed to the phase spectrum and the effects of observational noise. We calculate the theoretical phase spectrum for a second order linear stochastic process and compare the results to measured tremor data recorded from subjects who did not show a synchronized EMG activity in the corresponding extensor muscle. The results show that physiological tremor is well described by the proposed model and that the measured EMG represents a Newtonian force by which the muscle acts on the hand.Comment: 9 pages, 6 figures, to appear in Biological Cybernetic

Gills as Possible Accessory Circulatory Pumps in Limulus polyphemus

Heart electrical activity (ECGs), gill closer muscle potentials (EMGs), and blood pressures in the heart and the branchiocardiac canals, were measured in adult horseshoe crabs (Limulus polyphemus) during various activities. During ventilation, hyperventilation, and swimming, large transient increases in pressures (10-35 cm H2O) occur in the branchiocardiac canals, which carry blood from the gills to the heart. These pulses of positive pressure are related to, and apparently caused by, gill plate closing. During quiescent periods, with no ventilatory activity, there are no pressure pulses in the canals, but the pressure is still greater than zero. We found covariation of heart and ventilation rates during intermittent ventilation, hyperventilation, gill cleaning, and swimming, as well as evidence of transient periods of phasic coordination. The heart appears to be weakly entrained to the gill rhythm by phasic cardioregulatory nerve input. The preferred phase of heartbeats, with respect to gill rhythm, was 0.5, or 180 degrees out of phase. In some animals, intra-cardiac pressures were enhanced when the heart and gill rhythms were entrained. We suggest that rhythmic movements of the gill plates enhance the flow of low pressure blood returning from the body to the heart. Thus, ventilatory appendage movements may constitute an accessory blood pumping mechanism in Limulus