Search results for "imulation"
showing 10 items of 7271 documents
Maturation of near-field and far-field somatosensory evoked potentials after median nerve stimulation in children under 4 years of age
2000
Abstract Objectives : The maturation of subcortical SEPs in young children. Methods : Median nerve SEPs were recorded during sleep in 42 subjects aged 0–48 months. Active electrodes were at the ipsilateral Erb's point, the lower and upper dorsal neck, and the frontal and contralateral centroparietal scalp; reference electrodes were at the contralateral Erb's point, the ipsilateral earlobe and the frontal scalp; bandpass was 10–3000 Hz. The peaks were labelled by their latencies in adults. Results : The peak latencies of N9 (brachial plexus potential) decreased exponentially with age during the first year, but increased with height thereafter. The interpeak latencies (IPLs) N9–N11, which mea…
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 …
Heat-evoked vasodilatation in human hairy skin: axon reflexes due to low-level activity of nociceptive afferents.
1996
1. Spreading vasodilatation of the axon reflex type was evoked by contact heat stimulation of the hairy skin in the human forearm (13.3 cm2 stimulus area) and was detected by laser Doppler flowmetry at 8, 19 and 30 mm distance. 2. From a base temperature of 35 degrees C, rapidly rising short heat stimuli (4 degrees C s-1, 2 s plateau) elicited vasodilatation at an average threshold of 39.4 degrees C. For slowly rising sustained heat stimuli (64 s duration) the average threshold was 39.6 degrees C (n.s.) Laser Doppler flowmetry revealed a rapid onset within about 4 s, a long duration of several minutes beyond the end of the stimulus, and a rapid spread of vasodilatation to remote skin areas.…
Spectral Transmission of the Human Crystalline Lens in Adult and Elderly Persons: Color and Total Transmission of Visible Light
2012
Purpose To experimentally measure the spectral transmission of human crystalline lenses belonging to adult and elderly persons, and to determine the color and total transmission of visible light of such crystalline lenses. Methods The spectral transmission curve of 32 human crystalline lenses was measured using a PerkinElmer 800UV/VIS spectrometer. Total transmission of visible light and the chromatic coordinates of these crystalline lenses were determined from these curves for solar illumination. Results The crystalline lens that filters UV and its transmission in the visible spectrum decreases with age; such a decrease is greater for short wavelengths. The total transmission of visible li…
Distinct effects of positive and negative music on older adults' auditory target identification performances.
2014
Older adults, compared to younger adults, are more likely to attend to pleasant situations and avoid unpleasant ones. Yet, it is unclear whether such a phenomenon may be generalized to musical emotions. In this study, we investigated whether there is an age-related difference in how musical emotions are experienced and how positive and negative music influences attention performances in a target identification task. Thirty-one young and twenty-eight older adults were presented with 40 musical excerpts conveying happiness, peacefulness, sadness, and threat. While listening to music, participants were asked to rate their feelings and monitor each excerpt for the occurrence of an auditory tar…
Serum prolactin and tumors of the prostate: unchanged basal levels and lack of correlation to serum testosterone
1980
To investigate the possible role of circulatory levels of prolactin on the development of prostatic tumors, and to gain insight into the prolactin-androgen relationship, serum prolactin and testosterone were determined in 73 patients with newly diagnosed prostatic adenocarcinoma. Controls consisted of 32 patients with benign prostatic hyperplasia before treatment, 19 age-matched controls, and 21 young individuals. Hormones were measured under standardized conditions by highly specific and sensitive radioimmunoassays. There was no difference in prolactin in the elderly men regardless of prostate pathology, but a significant increment was found in young controls. Individual prolactin values d…
The development of involuntary and voluntary attention from childhood to adulthood: A combined behavioral and event-related potential study
2006
Abstract Objective This study investigated auditory involuntary and voluntary attention in children aged 6–8, 10–12 and young adults. The strength of distracting stimuli (20% and 5% pitch changes) and the amount of allocation of attention were varied. Methods In an auditory distraction paradigm event-related potentials (ERPs) and behavioral data were measured from subjects either performing a sound duration discrimination task or watching a silent video. Results Pitch changed sounds caused prolonged reaction times and decreased hit rates in all age groups. Larger distractors (20%) caused stronger distraction in children, but not in adults. The amplitudes of mismatch negativity (MMN), P3a, a…
Age-related changes in amplitude, latency and specialization of ERP responses to faces and watches
2020
Healthy aging is associated with impairments in face recognition. While earlier research suggests that these impairments arise during memory retrieval, more recent findings suggest that earlier mechanisms, at the perceptual stage, may also be at play. However, results are often inconsistent and very few studies have included a non-face control stimulus to facilitate interpretation of results with respect to the implication of specialized face mechanisms vs. general cognitive factors. To address these issues, P100, N170 and P200 event-related potentials (ERPs) were measured during processing of faces and watches. For faces, age-related differences were found for P100, N170 and P200 ERPs. For…
Sex-specific phenotypical and functional differences in peripheral human Vγ9/Vδ2 T cells
2006
Abstract Vγ9/Vδ2 T cells constitute a minor proportion of human peripheral blood T cells that can expand rapidly upon infection with microbial pathogens. Vγ9/Vδ2 T cell numbers change characteristically with age, rising from birth to puberty and gradually decreasing again beyond 30 years of age. In adults, female blood donors have significantly higher levels than males, implying that circulating Vγ9/Vδ2 T cells in women remain elevated for a longer period in life and drop less strikingly than in men. This loss in men is accompanied by a substantial depletion of CD27−CD45RA− and CD27−CD45RA+ effector T cells and a parallel increase in CD27+CD45RA− central memory T cells while in women, the d…
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 …