Search results for "STIMULATION"

Effects of tetraethylammonium ions on frequency-dependent vasopressin release from the rat neurohypophysis.

1988

1. Isolated rat neurohypophyses were fixed by their stalks to a platinum wire electrode and superfused with oxygenated Krebs-HEPES solution. Vasopressin release into the medium was determined by radioimmunoassay. Vasopressin secretion was increased by electrical stimulation at different frequencies (3-30 Hz) and different train lengths (75-900 pulses). The effects of tetraethylammonium (TEA) ions and of enhanced calcium were tested. 2. Electrical stimulation at 7.5 or 15 Hz evoked a markedly larger release of vasopressin than stimulation at 3 Hz. During continuous stimulation at 7.5 and 15 Hz the evoked vasopressin release per pulse declined rapidly, but with similar time constants for both…

Arginine Vasopressin Enhances Sympathetic Constriction Through the V1 Vasopressin Receptor in Human Saphenous Vein

1998

Background—Arginine vasopressin (AVP) not only acts directly on blood vessels through V1 receptor stimulation but also may modulate adrenergic-mediated responses in animal experiments in vivo and in vitro. The aim of the present study was to investigate whether AVP can contribute to an abnormal adrenergic constrictor response of human saphenous veins. Methods and Results—Saphenous vein rings were obtained from 32 patients undergoing coronary artery bypass surgery. The vein rings were suspended in organ bath chambers for isometric recording of tension. AVP (331029 mol/L) enhanced the contractions elicited by electrical field stimulation at 1, 2, and 4 Hz (by 80%, 70%, and 60%, respectively) …

Comparison of anterior cingulate vs. insular cortex as targets for real-time fMRI regulation during pain stimulation

2014

© 2014 Emmert Breimhorst Bauermann Birklein Van De Ville and Haller. Real time functional magnetic resonance imaging (rt fMRI) neurofeedback allows learning voluntary control over specific brain areas by means of operant conditioning and has been shown to decrease pain perception. To further increase the effect of rt fMRI neurofeedback on pain we directly compared two different target regions of the pain network notably the anterior insular cortex (AIC) and the anterior cingulate cortex (ACC). Participants for this prospective study were randomly assigned to two age matched groups of 14 participants each (7 females per group) for AIC and ACC feedback. First a functional localizer using bloc…

A suggested role for secondary flow in the stimulation of the cochlear hair cell

1985

The mammalian Corti organ and the reptilian basilar papilla are structures with a curved surface, which vibrate in a fluid medium. This paper is concerned with the role played by the geometric shape of these organs in cochlear hydrodynamics. In association with vibrating structures such as these organs, it can be expected that a stationary current will be initiated due to a nonlinear phenomenon in the boundary layer known as secondary flow. This phenomenon may explain the source of the mechanical nonlinearity in the cochlea.

Functional brain imaging of peripheral and central vestibular disorders.

2008

This review summarizes our current knowledge of multisensory vestibular structures and their functions in humans. Most of it derives from brain activation studies with PET and fMRI conducted over the last decade. The patterns of activations and deactivations during caloric and galvanic vestibular stimulations in healthy subjects have been compared with those in patients with acute and chronic peripheral and central vestibular disorders. Major findings are the following: (1) In patients with vestibular neuritis the central vestibular system exhibits a spontaneous visual-vestibular activation–deactivation pattern similar to that described in healthy volunteers during unilateral vestibular sti…

Sensory system interactions during simultaneous vestibular and visual stimulation in PET

2002

The patterns of regional cerebral blood flow (rCBF) increases and decreases in PET were compared for unimodal vestibular, unimodal visual, and for simultaneous vestibular and visual stimulation. Thirteen healthy volunteers were exposed to a) caloric vestibular stimulation, b) small-field visual motion stimulation in roll, c) simultaneous caloric vestibular and visual pattern stimulation. Unimodal vestibular stimulation led to activations of vestibular cortex areas, in particular the parieto-insular vestibular cortex (PIVC), and concurrent deactivations of visual cortical areas [Brodmann area (BA) 17-19]. Unimodal visual motion stimulation led to activations of the striate visual cortex and …

Comparative study of the effect of gentamicin on the vestibulo-ocular and visual vestibulo-ocular reflexes in the cat.

1991

The ototoxic effect of an aminoglycoside, gentamicin, on the vestibular system was investigated in cats given daily doses of 40 mg/kg i.m. for 14 days. Periodically, measurements were made of the vestibulo-ocular reflex (VOR) and visual vestibulo-ocular reflex (ViVOR) responses induced by rotatory stimuli at various frequencies from 0.0125 Hz to 0.8 Hz. After the cessation of drug administration, a progressively declining response to VOR stimuli continued, manifested by gain (ratio of peak response to peak stimulus amplitude) and phase relationships. The ViVOR was affected only in the gain measurements. The changes in the response amplitude (gain) were greater for the VOR than for the ViVOR…

Three Determinants of Vestibular Hemispheric Dominance during Caloric Stimulation: A Positron Emission Tomography Study

2003

FV 2. Modulation of the cortical vestibular network by means of rTMS and its neural correlate

2016

Repetitive transcranial magnetic stimulation (rTMS) has been applied to sensory research and for the treatment of disorders in psychiatry and neurology since 1993 ( Wassermann and Zimmermann, 2012 ). The widespread cortical vestibular system, however, has to date not been targeted. Aim of our study was to manipulate vestibular regions in the human cortex by temporary virtual lesioning through rTMS and analyse the changes in the perception of a galvanic vestibular stimulation (GVS) as well as the differing activation patterns in functional neuroimaging. The effects of rectangular and sinusoidal bimastoidal GVS were studied in 16 healthy volunteers (8 F; mean age 23 years) in a 3T scanner. Da…

Effects of different lower-limb sensory stimulation strategies on postural regulation-a Systematic review and metaanalysis

2017

Systematic reviews of balance control have tended to only focus on the effects of single lower-limb stimulation strategies, and a current limitation is the lack of comparison between different relevant stimulation strategies. The aim of this systematic review and meta-analysis was to examine evidence of effects of different lower-limb sensory stimulation strategies on postural regulation and stability. Moderate- to high-pooled effect sizes (Unbiased (Hedges' g) standardized mean differences (SMD) = 0.31-0.66) were observed with the addition of noise in a Stochastic Resonance Stimulation Strategy (SRSS), in three populations (i.e., healthy young adults, older adults, and individuals with low…