Visual-vestibular interaction during OVAR in the elderly

2002 ◽  
Vol 11 (6) ◽  
pp. 365-370 ◽  
Author(s):  
Joseph M. Furman ◽  
Mark S. Redfern
Keyword(s):  
Eye Movement ◽  
Visual Target ◽  
Vertical Axis ◽  
The Elderly ◽  
Otolith Organs ◽  
Fixation Target ◽  
Visual Vestibular Interaction ◽  
Older Subjects ◽  
Young Subjects ◽  
Axis Rotation

This study assessed visual-otolith interaction in healthy older humans and compared responses from older subjects to those of younger subjects. Using off-vertical axis rotation (OVAR) to stimulate the otolith organs, eye movement responses, measured using electro-oculography, were recorded during rotation in the dark, rotation with an earth-fixed lighted visual surround, and rotation with a subject-fixed fixation target. Results indicated that older subjects, like young subjects, exhibit a modulation component that was as large during rotation with a lighted earth-fixed visual surround as that seen in the dark and a modulation component during rotation with a subject-fixed visual target that was incompletely suppressed. The modulation component was, in general, larger in the older subjects. This study confirms findings from a previous study of visual-otolith interaction in young subjects and suggests that older subjects, like young subjects, have difficulty visually suppressing the modulation component induced by off-vertical axis rotation.

Off-Vertical Axis Rotational Responses in Patients with Unilateral Peripheral Vestibular Lesions

1993 ◽  
Vol 102 (2) ◽  
pp. 137-143 ◽  
Author(s):  
Joseph M. R. Furman ◽  
Robert H. Schor ◽  
Donald B. Kamerer
Keyword(s):  
Eye Movement ◽  
Semicircular Canal ◽  
Rotational Velocity ◽  
Angular Acceleration ◽  
Population Data ◽  
Vertical Axis ◽  
Normal Subjects ◽  
Otolith Organs ◽  
Rapid Decay ◽  
Axis Rotation

Off-vertical axis rotation (OVAR) stimulates the otolith organs in a manner that is suitable for assessment of the otolith-ocular reflex. To further assess the potential clinical usefulness of OVAR, the eye movement responses of seven patients with surgically confirmed unilateral peripheral vestibular lesions were compared with the eye movement responses of a group of age-matched, healthy, asymptomatic control subjects. Patients and controls were tested with constant velocity rotations that followed a brief period of angular acceleration (velocity trapezoid) using either earth-vertical axis (EVA) rotation or OVAR. Both EVA and OVAR sinusoidal velocity profiles were also performed. Results indicated that each patient had 1) an asymmetric OVAR response, ie, a bias component whose direction was opposite normal when rotating toward the lesioned ear, and 2) a normal modulation component. Population data suggested that patients had 1) a more rapid decay of response than normal subjects during OVAR velocity trapezoids, 2) an increased phase lead as compared to normal subjects during sinusoidal OVAR, and 3) like normal subjects, a less rapid decay of response during OVAR velocity trapezoids than during EVA rotational velocity trapezoids. Taken together, these findings suggest that patients with unilateral peripheral vestibular deficits have abnormal otolith-ocular and semicircular canal—ocular reflexes but that a single labyrinth appears to provide an otolithic signal sufficient for qualitatively normal semicircular canal—otolith interaction.

Nitric oxide and attenuated reflex cutaneous vasodilation in aged skin

2003 ◽  
Vol 284 (5) ◽  
pp. H1662-H1667 ◽  
Author(s):  
Lacy A. Holowatz ◽  
Belinda L. Houghton ◽  
Brett J. Wong ◽  
Brad W. Wilkins ◽  
Aaron W. Harding ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Core Temperature ◽  
The Elderly ◽  
Doppler Flowmetry ◽  
Cutaneous Vasodilation ◽  
Forearm Skin ◽  
Vascular Responsiveness ◽  
Older Subjects ◽  
Young Subjects ◽  
Reflex Cutaneous Vasodilation

Thermoregulatory cutaneous vasodilation is diminished in the elderly. The goal of this study was to test the hypothesis that a reduction in nitric oxide (NO)-dependent mechanisms contributes to the attenuated reflex cutaneous vasodilation in older subjects. Seven young (23 ± 2 yr) and seven older (71 ± 6 yr) men were instrumented with two microdialysis fibers in the forearm skin. One site served as control (Ringer infusion), and the second site was perfused with 10 mM N G-nitro-l-arginine methyl ester to inhibit NO synthase (NOS) throughout the protocol. Water-perfused suits were used to raise core temperature 1.0°C. Red blood cell (RBC) flux was measured with laser-Doppler flowmetry over each microdialysis fiber. Cutaneous vascular conductance (CVC) was calculated as RBC flux per mean arterial pressure, with values expressed as a percentage of maximal vasodilation (infusion of 28 mM sodium nitroprusside). NOS inhibition reduced CVC from 75 ± 6% maximal CVC (CVCmax) to 53 ± 3% CVCmax in the young subjects and from 64 ± 5% CVCmax to 29 ± 2% CVCmax in the older subjects with a 1.0°C rise in core temperature. Thus the relative NO-dependent portion of cutaneous active vasodilation (AVD) accounted for ∼23% of vasodilation in the young subjects and 60% of the vasodilation in the older subjects at this level of hyperthermia ( P < 0.001). In summary, NO-mediated pathways contributed more to the total vasodilatory response of the older subjects at high core temperatures. This suggests that attenuated cutaneous vasodilation with age may be due to a reduction in, or decreased vascular responsiveness to, the unknown neurotransmitter(s) mediating AVD.

Processing of center-embedded and right-branching relative clause sentences by normal elderly individuals

1993 ◽  
Vol 14 (1) ◽  
pp. 75-88 ◽  
Author(s):  
Shari R. Baum
Keyword(s):  
Lexical Decision ◽  
Lexical Decision Task ◽  
Relative Clause ◽  
Reaction Times ◽  
The Elderly ◽  
Elderly Subjects ◽  
Decision Task ◽  
Older Subjects ◽  
Young Subjects ◽  
Repetition Task

ABSTRACTTwo experiments were conducted to explore processing of relative clause structures by normal elderly adults. Four groups of subjects (aged 20–29 years, 60–69 years, 70–79 years, and 80–89 years) participated in a lexical decision task and a sentence repetition task. Results of the lexical decision task revealed longer reaction times and somewhat different patterns of performance for the older subjects as compared to the young subjects; on the repetition task, the oldest subjects performed more poorly overall. Findings are suggestive of a reduction in computational capacity in the elderly subjects, which may account for observed decrements in syntactic processing as compared to young adults.

scholarly journals AB0938 PARTICULARITIES OF INFECTIOUS SPONDYLODISCITIS IN THE ELDERLY: COMPARATIVE STUDY WITH THE YOUNG SUBJECT

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1768.2-1768
Author(s):  
L. Ben Ammar ◽  
A. Ben Tekaya ◽  
M. Ben Hammamia ◽  
O. Saidane ◽  
S. Bouden ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Compression ◽  
Cauda Equina ◽  
The Elderly ◽  
Cord Compression ◽  
Elderly Subjects ◽  
Significant Difference ◽  
Infectious Spondylodiscitis ◽  
Older Subjects ◽  
Young Subjects

Background:The incidence of infectious spondylodiscitis is steadily increasing. The prognosis depends on various parameters, including age.Objectives:To explore the differences in presentation and the results of further investigations and the prognosis of spondylodiscitis between young and elderly subjects.Methods:This is a retrospective study of 113 patients admitted to our department over a period of 20 years [1998-2018]. The epidemiological, clinical, biological, radiological and progressive aspects of spondylodiscitis in subjects over the age of 65 were compared to cases of spondylodiscitis in young subjects whose age is less than 65 years.Results:Of the 113 identified patients, 33 (29.2%) were classified as older, with male predominance in both groups (56.2 and 51.5% respectively; p=0.6). The presence of risk factors, particularly diabetes, was more frequent in the older subjects but without a statistically significant difference (p=0.2). Hepathopathies were also more frequent in the elderly but without statistically significant difference (p=0.3). The mean duration of progression was 3 months with no statistically significant difference between the two groups (4 and 5 months respectively, p=0.1).The presence of neurological symptoms, especially radiculalgia, was more frequently reported in younger subjects (p=0.01). Also, young subjects were more likely to have a fever (p=0.005). On the other hand, a biological inflammatory syndrome was more frequently encountered in older subjects (p=0.03).We found no statistically significant difference in the location of spondylodiscitis (p=0.4). Also, multifocal involvement was more frequent in older subjects but without a statistically significant difference.Radiologically, para-vertebral abscesses, epiduritis and spinal cord compression were more common in the elderly group (p=0.03; p=0.01 and p=0.01, respectively). While the frequency of intervertebral pinching and erosions was similar in both groups (p=0.1; p=0.8, respectively).Tuberculosis was the most involved germ in more than 50% of cases with no statistically significant difference between the two groups (57.5 and 51.5% respectively; p=0.5).All patients received targeted antibiotic therapy.The occurrence of immediate complications was more frequent in the elderly but without a statistically significant difference (p=0.1). They included neurological complications (spinal cord compression and Cauda equina syndrome) that occurred in 6.3% of cases in younger subjects versus 36.4% of cases in the elderly (p=0.07). Followed by treatment side effects dominated by disturbance of liver function due mainly to antituberculosis drugs occurring in 16.3% of cases in the younger group and 15.2% of cases in older subjects (p=0.8). Finally, there were 2 deaths in each group (p=0.5).Conclusion:Our series has shown that the picture of spondylodiscitis in the elderly is less noisy. However, the neurological damage is more pronounced on imaging. The misleading symptomatology in the elderly explains the delay in diagnosis and treatment, which leads to more frequent complications and excess mortality.Disclosure of Interests:None declared

Effect of aging on the otolith-ocular reflex

2001 ◽  
Vol 11 (2) ◽  
pp. 91-103
Author(s):  
Joseph M. Furman ◽  
Mark S. Redfern
Keyword(s):  
Semicircular Canal ◽  
Head Tilt ◽  
Vestibular Function ◽  
Vertical Axis ◽  
Ocular Reflex ◽  
Age Related ◽  
Vestibulo Ocular Reflex ◽  
Older Subjects ◽  
Axis Rotation ◽  
Reflex Time

We assessed the influence of age on the otolith-ocular reflex and semicircular canal-otolith interaction. Healthy young (n=30) and healthy older (n=60) subjects were rotated about an earth vertical axis, and about a 30 degree off-vertical axis. Eye movements during and following rotation were recorded using electro-oculography. Results indicated that there were statistically significant changes in the otolith-ocular reflex and semicircular canal-otolith interaction as a function of age. The modulation component during off-vertical axis rotation (OVAR) was greater in the older group compard to the young adults, whereas the bias component was smaller with advanced age. The foreshortening of the vestibulo-ocular reflex time constant induced by post-rotatory head tilt following cessation of rotation was less prominent in the older group. There were no consistent changes in the semicircular canal-ocular reflex. Overall, response parameters showed more variability in the older subjects. We conclude that age related changes in the otolith-ocular reflex and semicircular canal-otolith interaction are a result primarily of a degradation of central vestibular processing of otolith signals rather than a decline of peripheral vestibular function.

Coactivation to Reduce Variability in the Elderly

Motor Control ◽  
1998 ◽  
Vol 2 (4) ◽  
pp. 314-330 ◽  
Author(s):  
Rachael D. Seidler-Dobrin ◽  
jiping He ◽  
George E. Stelmach
Keyword(s):  
Muscle Activity ◽  
Visual Target ◽  
Model Simulation ◽  
Elbow Flexion ◽  
The Elderly ◽  
Elderly Subjects ◽  
Elderly Persons ◽  
Movement Variability ◽  
Burst Amplitude ◽  
Young Subjects

The aim of this experiment was to determine whether elderly persons exhibit reciprocal phasing of muscle activity and scale EMG burst amplitude in the same manner as young people. Seven young and 7 elderly adults performed 30° elbow flexion movements at 800 ms duration to a visual target against varying inertial loads. The elderly were not able to achieve the required movement duration as frequently and spent a greater portion of the movement accelerating than the young. The young and the elderly subjects scaled EMG burst amplitude to the increasing loads in the same fashion, although the elderly subjects coactivated the agonisthtagonist muscles more than did the young subjects and thus did not accelerate the limb as rapidly. We hypothesized that the elderly used coactivation to reduce movement variability, and we developed a single-joint model with two muscles to examine this hypothesis. The model simulation correctly predicted the variability reduction due to coactivation. It appears, however, that this reduces the capability to accelerate rapidly.

Human ocular counter-rolling and roll tilt perception during off-vertical axis rotation after spaceflight

2008 ◽  
Vol 17 (5-6) ◽  
pp. 209-215
Author(s):  
Gilles Clément ◽  
Pierre Denise ◽  
Millard F. Reschke ◽  
Scott J. Wood
Keyword(s):  
Head Tilt ◽  
Internal Representation ◽  
Vertical Axis ◽  
Body Tilt ◽  
Whole Body ◽  
Otolith Organs ◽  
Otolith Function ◽  
Significant Difference ◽  
Axis Rotation ◽  
Roll Tilt

Ocular counter-rolling (OCR) induced by whole body tilt in roll has been explored after spaceflight as an indicator of the adaptation of the otolith function to microgravity. It has been claimed that the overall pattern of OCR responses during static body tilt after spaceflight is indicative of a decreased role of the otolith function, but the results of these studies have not been consistent, mostly due to large variations in the OCR within and across individuals. By contrast with static head tilt, off-vertical axis rotation (OVAR) presents the advantage of generating a sinusoidal modulation of OCR, allowing averaged measurements over several cycles, thus improving measurement accuracy. Accordingly, OCR and the sense of roll tilt were evaluated in seven astronauts before and after spaceflight during OVAR at 45°/s in darkness at two angles of tilt (10° and 20°). There was no significant difference in OCR during OVAR immediately after landing compared to preflight. However, the amplitude of the perceived roll tilt during OVAR was significantly larger immediately postflight, and then returned to control values in the following days. Since the OCR response is predominantly attributed to the shearing force exerted on the utricular macula, the absence of change in OCR postflight suggests that the peripheral otolith organs function normally after short-term spaceflight. However, the increased sense of roll tilt indicates an adaptation in the central processing of gravitational input, presumably related to a re-weighting of the internal representation of gravitational vertical as a result of adaptation to microgravity.

UPPER BODY ACCELERATIONS DURING LOCOMOTION IN DIFFERENT AGE GROUPS AND GENDERS

2017 ◽  
Vol 17 (07) ◽  
pp. 1740026 ◽  
Author(s):  
HYEONG-MIN JEON ◽  
JI-WON KIM ◽  
YURI KWON ◽  
JAE-HOON HEO ◽  
EUI-BUM CHOI ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Balance Control ◽  
Age Groups ◽  
The Elderly ◽  
Upper Body ◽  
Head Acceleration ◽  
Leg Length ◽  
Sensor Position ◽  
Older Subjects ◽  
Young Subjects

Aim: The purpose of this study is to measure the acceleration of upper body (pelvis, shoulder and head) during walking and to investigate whether the acceleration patterns differ among age groups and genders. Methods: Twenty-nine old subjects and thirty young subjects participated in this study. Tri-axial accelerations were measured on the back of upper body (head, shoulder and pelvis). Subjects performed two trials of walking on a treadmill in their own comfortable speeds. Three-way ANOVA (repeated measures) was carried out for the root mean square of each directional acceleration with age, gender and sensor position as independent factors. Results: Age effect was significant on the RMS accelerations of the transverse plane. In the anteroposterior direction, the pelvis acceleration was greater in the younger group, while the head acceleration was greater in the older group ([Formula: see text]). In the mediolateral direction, the pelvis acceleration was comparable between age groups but the shoulder and head accelerations were greater in the older group ([Formula: see text]). The overall accelerations were greater in men than in women ([Formula: see text]). The phase-delay and attenuation of shoulder acceleration relative to the pelvis acceleration was smaller for the elderly in AP and ML directions ([Formula: see text]). Normalization of RMS accelerations by height, weight and leg length did not affect the age differences but negated the gender differences. Discussion: Greater head acceleration in older subjects were related to less attenuation of acceleration in the upper body, which may affect the sensory systems in the head and deteriorate balance control during locomotion.

Processing of Angular Motion and Gravity Information Through an Internal Model

2010 ◽  
Vol 104 (3) ◽  
pp. 1370-1381 ◽  
Author(s):  
Jean Laurens ◽  
Dominik Straumann ◽  
Bernhard J. M. Hess
Keyword(s):  
Internal Model ◽  
Semicircular Canals ◽  
Optimal Estimation ◽  
Vertical Axis ◽  
Head Orientation ◽  
Otolith Organs ◽  
Consistent Manner ◽  
Velocity Information ◽  
Axis Rotation ◽  
Base Of The Skull

The vestibular organs in the base of the skull provide important information about head orientation and motion in space. Previous studies have suggested that both angular velocity information from the semicircular canals and information about head orientation and translation from the otolith organs are centrally processed in an internal model of head motion, using the principles of optimal estimation. This concept has been successfully applied to model behavioral responses to classical vestibular motion paradigms. This study measured the dynamic of the vestibuloocular reflex during postrotatory tilt, tilt during the optokinetic afternystagmus, and off-vertical axis rotation. The influence of otolith signal on the VOR was systematically varied by using a series of tilt angles. We found that the time constants of responses varied almost identically as a function of gravity in these paradigms. We show that Bayesian modeling could predict the experimental results in an accurate and consistent manner. In contrast to other approaches, the Bayesian model also provides a plausible explanation of why these vestibulooculo motor responses occur as a consequence of an internal process of optimal motion estimation.

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