Search results for "Saccule and Utricle"
showing 5 items of 5 documents
Cortical representation of saccular vestibular stimulation: VEMPs in fMRI
2006
Short tone bursts trigger a vestibular evoked myogenic potential (VEMP), an inhibitory potential which reflects a component of the vestibulocollic reflex (VCR). These potentials arise as a result of activation of the sacculus and are expressed through the vestibulo-collic reflex (VCR). Up to now, the ascending projections of the sacculus are unknown in humans, only the representation of the semicircular canals or the entire vestibular nerve has been demonstrated. The aim of this study was to determine whether a sacculus stimulus that evoked VEMPs could activate vestibular cortical areas in fMRI. To determine this, we studied the differential effects of unilateral VEMP stimulation in 21 heal…
Evidence of unilateral isolated utricular hypofunction
2010
The findings demonstrate that an enduring unilateral utricular dysfunction, possibly together with canal hypofunction, can occur after labyrinthine disease or injury. They also suggest that unilateral, isolated utricular dysfunction - or utricle paresis - can occur, representing a novel entity in the differential diagnosis of peripheral vestibular function. The occurrence of subjective visual vertical (SVV) asymmetry in the presence of symmetric vestibular evoked myogenic potentials (VEMPs) also confirms that the information from the utricles, rather than the saccules, dominates SVV estimation.To determine the incidence of unilateral utricular hypofunction.The retrospective clinical study d…
Influence of gravity vector on eye movement elicited by linear acceleration.
1991
When the body/head motion is sensed by otolith organs, they respond not only to the resultant acceleration of the motion but also to the gravitational force. We investigated the influence of the gravity vector on the otolithic-ocular reflex caused by motion in normal subjects. The sled type linear accelerator, moving back and forth with a frequency of 0.25 Hz and an amplitude of 2 m, generated right-left linear acceleration with a maximum magnitude of 0.5 g. We tested every subject under seven different postures: 1) 135 degrees forward tilted (F.T.), 2) 90 degrees F.T., 3) 45 degrees F.T., 4) upright sitting, 5) 45 degrees backward tilted (B.T.), 6) 90 degrees B.T., and 7) 135 degrees B.T. …
Testing utricular function by means of on-axis rotation
2005
Subjective visual vertical (SVV) estimation during on-axis rotation provides an efficient screening test of utricle function. The survey demonstrates that isolated disorders of peripheral utricular function can occur while SCC function appears normal.The present study aimed to investigate estimation of SVV during constant velocity yaw rotation (with the head held on-axis--to enhance any asymmetry between right and left utricular responses), as a useful screening test.In all, 230 patients were recruited from the dizziness clinic. For each patient, the SVV was estimated (a) while held stationary, and (b) during constant angular velocity (240 degrees/s), with the head centred on-axis. Bitherma…
European vestibular experiments on the Spacelab-1 mission: 7. Ocular counterrolling measurements pre- and post-flight.
1986
The static ocular counterrolling (OCR) of the four scientific crew members in the first Spacelab mission was measured during baseline-data-collection before and after the flight of SL-1. It was presumed that the modification of otolithic responses during spaceflight will be reflected in specific changes of the OCR-gain on the first days after recovery. The magnitude of OCR was determined analysing colour-transparencies of subjects right eyes that were produced in different positions of lateral body tilt. In general, one subject did not show any changes at all; three subjects exhibited a significant decrease of OCR-gain after exposure to weightlessness, whereby differences could be found bet…