Search results for "electric [mass]"
showing 10 items of 1101 documents
Neuromuscular performance in voluntary bilateral and unilateral contraction and during electrical stimulation in men at different ages.
1995
A group of 33 men divided into three different age groups, M30 years (n = 11), M50 years (n = 12) and M70 years (n = 10) volunteered as subjects for examination of their maximal voluntary isometric bilateral and unilateral forces and force-time curves of the knee extensor muscle group as well as electromyogram activity of the vastus lateralis, vastus medialis and rectus femoris muscles of the right and/or left leg contractions. Electrical stimulation (ES) of 50 Hz was also given by two surface tin electrodes for each subject and each leg separately with the maximal tolerable intensity for recording the isometric force evoked. The maximal force produced by the voluntary isometric unilateral …
Application of intermittent galvanic vestibular stimulation reveals age-related constraints in the multisensory reweighting of posture
2014
In this study we examined the effects of intermittent short-duration Galvanic Vestibular Stimulation (GVS) during a multisensory perturbation of posture in young and elderly adults. Twelve young (24.91 +/- 6.44 years) and eleven elderly (74.8 +/- 6.42 years) participants stood upright under two task conditions: (a) quiet standing and (b) standing while receiving pseudo-randomly presented bipolar 2 s GVS pulses. In both conditions, sensory reweighting was evoked by visual surround oscillations (20 cm, 0.3 Hz) and Achilles tendon vibration (3 mm, 80 Hz), concurrently delivered during the middle 60 s of standing. Intermittent GVS decreased the excessive postural sway induced by the concurrent …
Psychophysical evidence for long-term potentiation of C-fiber and Adelta-fiber pathways in humans by analysis of pain descriptors.
2007
Long-term potentiation of human pain perception (nociceptive LTP) to single electrical test stimuli was induced by high-frequency stimulation (HFS) of cutaneous nociceptive afferents. Numerical pain ratings and a list of sensory pain descriptors disclosed the same magnitude of nociceptive LTP (23% increase for >60 min, P < 0.001), whereas affective pain descriptors were not significantly enhanced. Factor analysis of the sensory pain descriptors showed that facilitation was restricted to two factors characterized by hot and burning (+41%) and piercing and stinging (+21%, both P < 0.01), whereas a factor represented by throbbing and beating was not significantly increased (+9%, P = …
Illusory contours and specific regions of human extrastriate cortex: evidence from rTMS.
2003
Functional magnetic resonance imaging studies showed that perception of illusory contours is associated with extrastriate cortex activation prevailing on the right side. 1 Hz repetitive transcranial magnetic stimulation (rTMS) is able to induce lasting inhibition of cortical activity. The objective of the study was to investigate the role of extrastriate cortex in illusory contour perception inducing 1 Hz rTMS interference in healthy subjects. Eight healthy subjects underwent 1 Hz rTMS (600 pulses) through a figure-of-eight coil over right and left occipital cortex (O1 and O2 of 10/20 EEG system); sham magnetic stimulation on the same sites and right motor cortex rTMS (in three subjects) we…
Topodiagnostic value of blink reflex R1 changes: a digital postprocessing MRI correlation study.
2001
The aim of the study was to investigate the relation of the blink reflex R1 arc to known anatomical brainstem structures. Acute vascular brainstem lesions as identified by magnetic resonance imaging (MRI) of patients with isolated R1 pathology were superimposed into a stereotactic anatomical atlas using a new method of digital postprocessing. Isolated acute brainstem lesions were documented by diffusion-weighted MRI in 12 of 24 patients with unilateral R1 pathology. The lesions were located in the ipsilateral mid- to lower pons. In three patients only, the lesion had partial contact with the principal sensory nucleus of the trigeminal nerve (PSN) on at least one level. In two patients, the …
Vulnerability of the right ventricle to cathodal, anodal, and bipolar stimulation at double diastolic threshold strength
1984
The repetitive ventricular response (RVR) to three stimulation techniques (bipolar, cathodal and anodal) was investigated in 35 patients. 26 patients suffered from coronary heart disease and 9 patients from dilative cardiomyopathy. The stimulation study was performed at a ventricular driving rate of 120/min with one and two premature ventricular extrastimuli. We used rectangular impulses of 1.8 ms duration at duable diastolic threshold strength. RVR was scored as follows: 0: no RVR, 1: one nonstimulated RVR, 2: two nonstimulated RVR, 3: three nonstimulated RVR, 4: four to ten nonstimulated RVR, 5: more than ten nonstimulated RVR lasting less than 2 minutes, 6: sustained ventricular tachycar…
Increased facilitation of the primary motor cortex following 1 Hz repetitive transcranial magnetic stimulation of the contralateral cerebellum in nor…
2005
Connections between the cerebellum and the contralateral motor cortex are dense and important, but their physiological significance is difficult to measure in humans. We have studied a group of 10 healthy subjects to test whether a modulation of the excitability of the left cerebellum can affect the excitability of the contralateral motor cortex. We used repetitive transcranial magnetic stimulation (rTMS) at 1 Hz frequency to transiently depress the excitability of the left cerebellar cortex and paired-pulse TMS testing of intracortical inhibition (ICI) and intracortical facilitation (ICF) to probe the excitability of cortico-cortical connections in the right motor cortex. The cortical sile…
Modulatory effects of 1 Hz rTMS over the cerebellum on motor cortex excitability
2005
Clinical observations and data from animal experiments point to a physiological facilitatory influence of the deep cerebellar structures on the motor system through the cerebello-thalamo-cortical pathways. The aim of the present study was to explore the long-term effects of low-frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) over the cerebellum on short intracortical inhibition (SICI) and facilitation (ICF) of the motor cortex in normal subjects. Eight healthy subjects (mean age 26.9 +/- 3.1) underwent 1 Hz frequency rTMS delivered on the right cerebellar hemisphere. Before and after cerebellar rTMS, SICI and ICF were assessed in the motor cortex contralateral to the st…
Role of the cerebellum in time perception: A TMS study in normal subjects
2007
The aim of this study was to investigate the role of the cerebellum in a temporal-discrimination task without movement production in healthy subjects. Ten healthy subjects underwent a time-perception task with somatosensory stimuli. Two pairs of electrical stimuli: the first considered the reference pair (rp) with a standard interval of 400 ms and the second, the test pair (tp), with variable intervals ranging from 300 to 500 ms, were applied by surface electrodes on the right forearm. Subjects were instructed to compare time intervals of rp and tp and to estimate whether the tp interval was shorter than, equal to, or longer than that of rp. The task was performed in baseline and after 1 Hz…
A ventral striatal prediction error signal in human fear extinction learning.
2021
Animal studies have shown that the prediction error (PE) signal that drives fear extinction learning is encoded by phasic activity of midbrain dopamine (DA) neurons. Thus, the extinction PE resembles the appetitive PE that drives reward learning. In humans, fear extinction learning is less well understood. Using computational neuroimaging, a previous study from our group reported hemodynamic activity in the left ventral putamen, a subregion of the ventral striatum (VS), to correlate with a PE function derived from a formal associative learning model. The activity was modulated by genetic variation in a DA-related gene. To conceptually replicate and extend this finding, we here asked whether…