scholarly journals Oscillatory neural responses evoked by natural vestibular stimuli in humans

2016 ◽  
Vol 115 (3) ◽  
pp. 1228-1242 ◽  
Author(s):  
Steven Gale ◽  
Mario Prsa ◽  
Aaron Schurger ◽  
Annietta Gay ◽  
Aurore Paillard ◽  
...  
Keyword(s):  
Constant Velocity ◽  
Human Subjects ◽  
Whole Body ◽  
Alpha Power ◽  
Alpha Band ◽  
Experimental Conditions ◽  
Healthy Human ◽  
Vestibular Loss ◽  
Bilateral Vestibular Loss ◽  
Cortical Oscillations

While there have been numerous studies of the vestibular system in mammals, less is known about the brain mechanisms of vestibular processing in humans. In particular, of the studies that have been carried out in humans over the last 30 years, none has investigated how vestibular stimulation (VS) affects cortical oscillations. Here we recorded high-density electroencephalography (EEG) in healthy human subjects and a group of bilateral vestibular loss patients (BVPs) undergoing transient and constant-velocity passive whole body yaw rotations, focusing our analyses on the modulation of cortical oscillations in response to natural VS. The present approach overcame significant technical challenges associated with combining natural VS with human electrophysiology and reveals that both transient and constant-velocity VS are associated with a prominent suppression of alpha power (8–13 Hz). Alpha band suppression was localized over bilateral temporo-parietal scalp regions, and these alpha modulations were significantly smaller in BVPs. We propose that suppression of oscillations in the alpha band over temporo-parietal scalp regions reflects cortical vestibular processing, potentially comparable with alpha and mu oscillations in the visual and sensorimotor systems, respectively, opening the door to the investigation of human cortical processing under various experimental conditions during natural VS.

Factors affecting determinations of manganese in serum by atomic absorption spectrometry

1991 ◽  
Vol 37 (5) ◽  
pp. 723-728 ◽  
Author(s):  
J Nève ◽  
N Leclercq
Keyword(s):  
Atomic Absorption Spectrometry ◽  
Atomic Absorption ◽  
Human Subjects ◽  
Graphite Furnace ◽  
Absorption Spectrometry ◽  
Calibration Graph ◽  
Manganese Concentration ◽  
Experimental Conditions ◽  
Healthy Human ◽  
Physiological Concentration

Abstract A method was developed for the routine determination of manganese in serum from healthy human subjects by graphite furnace atomic absorption spectrometry. We controlled the experimental conditions rigorously, from sampling to analysis, to minimize contamination and to conserve diluted samples. We optimized the procedure with two serum Reference Materials, one of which had a manganese concentration very close to what is thought to be the physiological concentration in humans. The best analytical performance was obtained by directly injecting into the furnace serum diluted with an equal volume of a solution containing Triton X-100 and sodium EDTA and calibrating by the standard additions procedure or by a calibration graph constructed in a similar matrix. The Zeeman background correction produced better accuracy and precision than did the classical deuterium correction. Within-run CV for a manganese concentration of 12.7 nmol/L in serum was 7.9%, and between-run precision was 16.1%. The mean (SD) serum manganese concentration in 31 healthy adults was 10.8 (SD 3.0) nmol/L. Sex and age of subjects did not affect concentrations.

scholarly journals Prevalence of Vestibular Disorders in Independent People Over 50 That Experience Dizziness

2021 ◽  
Vol 12 ◽  
Author(s):  
William V. C. Figtree ◽  
Jasmine C. Menant ◽  
Allan T. Chau ◽  
Patrick P. Hübner ◽  
Stephen R. Lord ◽  
...  
Keyword(s):  
Time Constant ◽  
High Frequency ◽  
Constant Velocity ◽  
Vestibular Function ◽  
Community Dwelling ◽  
Whole Body ◽  
Head Impulse Test ◽  
Vestibular Loss ◽  
Vestibulo Ocular Reflex ◽  
The Impact

People aged over 50 are the most likely to present to a physician for dizziness. It is important to identify the main cause of dizziness in order to develop the best treatment approach. Our goal was to determine the prevalence of benign paroxysmal positional vertigo (BPPV), and peripheral and central vestibular function in people that had experienced dizziness within the past year aged over 50. One hundred and ninety three community-dwelling participants aged 51–92 (68 ± 8.7 years; 117 females) were tested using the clinical and video head impulse test (cHIT and vHIT) to test high-frequency vestibular organ function; the head thrust dynamic visual acuity (htDVA) test to test high-frequency visual-stability; the dizziness handicap inventory (DHI) to measure the impact of dizziness; as well as sinusoidal and unidirectional rotational chair testing to test low- to mid-frequency peripheral and central vestibular function. From these assessments we computed the following measures: HIT gain; htDVA score; DHI score; sinusoidal (whole-body; 0.1–2 Hz with 30°/s peak-velocity) vestibulo-ocular reflex (VOR) gain and phase; transient (whole-body, 150°/s2 acceleration to 50°/s constant velocity) VOR gain and time constant; optokinetic nystagmus (OKN) gain and time constant (whole-body, 50°/s constant velocity rotation). Our study showed that BPPV, and peripheral or central vestibular hypofunction were present in 34% of participants, suggesting a vestibular cause to their dizziness. Over half (57%) of these with a likely vestibular cause had BPPV, which is more than twice the percentage reported in other dizzy clinic studies. Our findings suggest that the physical DHI score and VOR time constant were best at detecting those with non-BPPV vestibular loss, but should always be used in conjunction with cHIT or vHIT, and that the htDVA score and vHIT gain were best at detecting differences between ipsilesional and contralesional sides.

Pulse-step-sine rotation test for the identification of abnormal vestibular function

2005 ◽  
Vol 15 (5-6) ◽  
pp. 291-311
Author(s):  
Robert J. Peterka
Keyword(s):  
Human Subjects ◽  
Vestibular Function ◽  
Semicircular Canals ◽  
Large Change ◽  
Sine Wave ◽  
Slow Phase ◽  
Vestibular Loss ◽  
Bilateral Vestibular Loss ◽  
Discharge Rates ◽  
Response Measures

This study illustrates the use of a novel "pulse-step-sine" (PSS) rotational stimulus to identify abnormal function of the horizontal semicircular canals in human subjects with unilateral and bilateral vestibular deficits. The cyclic PSS stimulus includes a "bias component" and a "probe component". The bias component, consisting of a short duration pulse of acceleration followed by an acceleration step, is designed to produce a large change in canal afferent discharge rates that silences the neural activity in one canal during the step portion of the PSS stimulus. The pulse and step components are then repeated with opposite sign to silence afferent activity in the opposite canal. The probe component, consisting of a ∼1 Hz sine wave superimposed on the step portions of the stimulus, is designed to test the ability of canal afferents in the excited canal to encode the probe stimulus. Various response measures are developed that characterize the horizontal slow phase eye movements evoked by the PSS stimulus. Results show that these measures can distinguish subjects with normal vestibular function from those with unilateral and bilateral vestibular loss, can identify the side-of-lesion in subjects with well compensated unilateral vestibular loss, and can possibly identify the side-of-greater-loss in subjects with asymmetric bilateral loss.

scholarly journals Intense light as anticoagulant therapy in humans

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244792
Author(s):  
Yoshimasa Oyama ◽  
Sydney Shuff ◽  
Pavel Davizon-Castillo ◽  
Nathan Clendenen ◽  
Tobias Eckle
Keyword(s):  
Myocardial Ischemia ◽  
Human Subjects ◽  
Light Therapy ◽  
Whole Body ◽  
Ischemia And Reperfusion ◽  
Ischemia And Reperfusion Injury ◽  
Novel Therapy ◽  
Healthy Human ◽  
Myocardial Ischemia And Reperfusion ◽  
Intense Light

Blood coagulation is central to myocardial ischemia and reperfusion (IR) injury. Studies on the light elicited circadian rhythm protein Period 2 (PER2) using whole body Per2-/- mice found deficient platelet function and reduced clotting which would be expected to protect from myocardial IR-injury. In contrast, intense light induction of PER2 protected from myocardial IR-injury while Per2 deficiency was detrimental. Based on these conflicting data, we sought to evaluate the role of platelet specific PER2 in coagulation and myocardial ischemia and reperfusion injury. We demonstrated that platelets from mice with tissue-specific deletion of Per2 in the megakaryocyte lineage (Per2loxP/loxP-PF4-CRE) significantly clot faster than platelets from control mice. We further found increases in infarct sizes or plasma troponin levels in Per2loxP/loxP-PF4-CRE mice when compared to controls. As intense light increases PER2 protein in human tissues, we also performed translational studies and tested the effects of intense light therapy on coagulation in healthy human subjects. Our human studies revealed that intense light therapy repressed procoagulant pathways in human plasma samples and significantly reduced the clot rate. Based on these results we conclude that intense light elicited PER2 has an inhibitory function on platelet aggregation in mice. Further, we suggest intense light as a novel therapy to prevent or treat clotting in a clinical setting.

Dissociated Hysteresis of Static Ocular Counterroll in Humans

2006 ◽  
Vol 95 (4) ◽  
pp. 2222-2232 ◽  
Author(s):  
A. Palla ◽  
C. J. Bockisch ◽  
O. Bergamin ◽  
D. Straumann
Keyword(s):  
Second Harmonic ◽  
Human Subjects ◽  
Body Position ◽  
Three Dimensional ◽  
Upright Position ◽  
Whole Body ◽  
Eye Position ◽  
Healthy Human ◽  
Ocular Counterroll ◽  
Head Roll

In stationary head roll positions, the eyes are cyclodivergent. We asked whether this phenomenon can be explained by a static hysteresis that differs between the eyes contra- (CE) and ipsilateral (IE) to head roll. Using a motorized turntable, healthy human subjects ( n = 8) were continuously rotated about the earth-horizontal naso-occipital axis. Starting from the upright position, a total of three full rotations at a constant velocity (2°/s) were completed (acceleration = 0.05°/s2, velocity plateau reached after 40 s). Subjects directed their gaze on a flashing laser dot straight ahead (switched on 20 ms every 2 s). Binocular three-dimensional eye movements were recorded with dual search coils that were modified (wires exiting inferiorly) to minimize torsional artifacts by the eyelids. A sinusoidal function with a first and second harmonic was fitted to torsional eye position as a function of torsional whole body position at constant turntable velocity. The amplitude and phase of the first harmonic differed significantly between the two eyes (paired t-test: P < 0.05): on average, counterroll amplitude of IE was larger [CE: 6.6 ± 1.6° (SD); IE: 8.1 ± 1.7°), whereas CE showed more position lag relative to the turntable (CE: 12.5 ± 10.7°; IE: 5.1 ± 8.7°). We conclude that cyclodivergence observed during static ocular counterroll is mainly a result of hysteresis that depends on whether eyes are contra- or ipsilateral to head roll. Static hysteresis also explains the phenomenon of residual torsion, i.e., an incomplete torsional return of the eyes when the first 360° whole body rotation was completed and subjects were back in upright position (extorsion of CE: 2.0 ± 0.10°; intorsion of IE: 1.4 ± 0.10°). A computer model that includes asymmetric backlash for each eye can explain dissociated torsional hysteresis during quasi-static binocular counterroll. We hypothesize that ocular torsional hysteresis is introduced at the level of the otolith pathways because the direction-dependent torsional position lag of the eyes is related to the head roll position and not the eye position.

Brain SPECT imaging and whole-body biodistribution with [123I]ADAM — a serotonin transporter radiotracer in healthy human subjects

2006 ◽  
Vol 33 (2) ◽  
pp. 193-202 ◽  
Author(s):  
Kun-Ju Lin ◽  
Chia-Yih Liu ◽  
Shiaw-Pyng Wey ◽  
Ing-Tsung Hsiao ◽  
Jay Wu ◽  
...  
Keyword(s):  
Serotonin Transporter ◽  
Human Subjects ◽  
Brain Spect ◽  
Spect Imaging ◽  
Whole Body ◽  
Healthy Human ◽  
Healthy Human Subjects

Vertical Divergence and Counterroll Eye Movements Evoked by Whole-Body Position Steps About the Roll Axis of the Head in Humans

2001 ◽  
Vol 85 (2) ◽  
pp. 671-678 ◽  
Author(s):  
A. A. Kori ◽  
A. Schmid-Priscoveanu ◽  
D. Straumann
Keyword(s):  
Eye Movements ◽  
Human Subjects ◽  
Body Position ◽  
Semicircular Canals ◽  
Whole Body ◽  
Healthy Human ◽  
Vertical Divergence ◽  
Roll Axis ◽  
Otolith Stimulation ◽  
Dynamic Gain

In healthy human subjects, a head tilt about its roll axis evokes a dynamic counterroll that is mediated by both semicircular canal and otolith stimulation, and a static counterroll that is mediated by otolith stimulation only. The vertical ocular divergence associated with the static counterroll too is otolith-mediated. A previous study has shown that, in humans, there is also a vertical divergence during dynamic head roll, but this report was not conclusive on whether this response was mediated by the semicircular canals only or whether the otoliths made a significant contribution. To clarify this issue, we applied torsional whole-body position steps (amplitude 10°, peak acceleration of 90°/s2, duration 650 ms) about the earth-vertical (supine body position) and earth-horizontal (upright body position) axis to healthy human subjects who were monocularly fixating a straight-ahead target. Eye movements were recorded binocularly with dual search coils in three dimensions. The dynamic parameters were determined 120 ms after the beginning of the turntable movement, i.e., before the first fast phase of nystagmus. The static parameters were measured 4 s after the beginning of the turntable movement. The dynamic gain of the counterroll was larger in upright (average gain: 0.48 ± 0.10 SD) than in supine (0.36 ± 0.10) position. The static gain of the counterroll in the upright position (0.21 ± 0.06) was smaller than the dynamic gain. Divergent eye movements (intorting eye hypertropic) evoked during the dynamic phase were not significantly different between supine (average vergence velocity: 0.87 ± 0.51°/s) and upright (0.84 ± 0.64°/s) positions. The static vertical divergence in upright position was 0.32 ± 0.14°. The results indicate that the dynamic vertical divergence in contrast to the dynamic ocular counterroll is not enhanced by otolith input. These results can be explained through the different patterns of connectivity between semicircular canals and utricles to the eye muscles. Alternatively, we hypothesize that the small dynamic vertical divergence represents the remaining vertical error necessary to drive an adaptive control mechanism that normally maintains a vertical eye alignment.

scholarly journals Biodistribution and radiation dosimetry of the positron emission tomography probe for AMPA receptor, [11C]K-2, in healthy human subjects

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mai Hatano ◽  
Tomoyuki Miyazaki ◽  
Yoshinobu Ishiwata ◽  
Waki Nakajima ◽  
Tetsu Arisawa ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Effective Dose ◽  
Human Subjects ◽  
Whole Body ◽  
Single Subject ◽  
Radiation Doses ◽  
Healthy Human ◽  
Positron Emission ◽  
Healthy Human Subjects ◽  
Human Brains

Abstract[11C]K-2, a radiotracer exhibiting high affinity and selectivity for α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs), is suitable for the quantification of AMPARs in living human brains and potentially useful in the identification of epileptogenic foci in patients. This study aimed to estimate the radiation doses of [11C]K-2 in various organs and calculate the effective dose after injection of [11C]K-2 in healthy human subjects. Twelve healthy male subjects were registered and divided into two groups (370 or 555 MBq of [11C]K-2), followed by 2 h whole-body scans. We estimated the radiation dose of each organ and then calculated the effective dose for each subject. The highest uptake of [11C]K-2 was observed in the liver, while the brain also showed relatively high uptake. The urinary bladder exhibited the highest radiation dose. The kidneys and liver also showed high radiation doses after [11C]K-2 injections. The effective dose of [11C]K-2 ranged from 5.0 to 5.2 μSv/MBq. Our findings suggest that [11C]K-2 is safe in terms of the radiation dose and adverse effects. The injection of 370–555 MBq (10 to 15 mCi) for PET studies using this radiotracer is applicable in healthy human subjects and enables serial PET scans in a single subject.

scholarly journals Dissociating vestibular and somatosensory contributions to spatial orientation

2016 ◽  
Vol 116 (1) ◽  
pp. 30-40 ◽  
Author(s):  
Bart B. G. T. Alberts ◽  
Luc P. J. Selen ◽  
Giovanni Bertolini ◽  
Dominik Straumann ◽  
W. Pieter Medendorp ◽  
...  
Keyword(s):  
Tilt Angle ◽  
Spatial Orientation ◽  
The Body ◽  
Substantial Contribution ◽  
Otolith Organs ◽  
Noise Levels ◽  
Healthy Human ◽  
Vestibular Loss ◽  
Bilateral Vestibular Loss ◽  
Noise Characteristics

Inferring object orientation in the surroundings heavily depends on our internal sense of direction of gravity. Previous research showed that this sense is based on the integration of multiple information sources, including visual, vestibular (otolithic), and somatosensory signals. The individual noise characteristics and contributions of these sensors can be studied using spatial orientation tasks, such as the subjective visual vertical (SVV) task. A recent study reported that patients with complete bilateral vestibular loss perform similar as healthy controls on these tasks, from which it was conjectured that the noise levels of both otoliths and body somatosensors are roll-tilt dependent. Here, we tested this hypothesis in 10 healthy human subjects by roll tilting the head relative to the body to dissociate tilt-angle dependencies of otolith and somatosensory noise. Using a psychometric approach, we measured the perceived orientation, and its variability, of a briefly flashed line relative to the gravitational vertical (SVV). Measurements were taken at multiple body-in-space orientations (−90 to 90°, steps of 30°) and head-on-body roll tilts (30° left ear down, aligned, 30° right ear down). Results showed that verticality perception is processed in a head-in-space reference frame, with a systematic SVV error that increased with larger head-in-space orientations. Variability patterns indicated a larger contribution of the otolith organs around upright and a more substantial contribution of the body somatosensors at larger body-in-space roll tilts. Simulations show that these findings are consistent with a statistical model that involves tilt-dependent noise levels of both otolith and somatosensory signals, confirming dynamic shifts in the weights of sensory inputs with tilt angle.

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