Biomedical subjects

C Möller

Publications and source records attributed to C Möller.

148 records · Page 9Linked to original sources

PubMedDate not supplied

The plasticity of compensatory eye movements in rotatory tests. I. The effect of alertness and eye closure.

Fifteen voluntary subjects with a mean age of 26 years (17-39), participated in two rotatory experiments. The rotatory test used was sinusoidal harmonic acceleration (SHA) test at frequencies of 0.01-0.32 Hz. Compensatory eye movements were measured by means of EOG. Experiment A included rotation in darkness during alerting tasks (day 1), rotation in darkness with no tasks (day 2) and rotation in darkness during alerting tasks (day 3). In the alertness tests, the gain varied between 0.5 and 0.77. Phase values decreased with increasing frequency. The alertness results between days 1 and 3 did not differ in gain or phase. The gain of day 2 (no tasks) displayed significantly reduced gain at all frequencies, and a more pronounced decrease in phase than in the alertness tests. Experiment B comprised testing with eyes open (day 1) and eyes closed (day 2) during alerting tasks. These tests displayed significantly decreased gain at all frequencies with eyes closed compared with eyes open and with more negative phase at 0.08-0.32 Hz with eyes closed. The results indicate a central effect of the alertness level on compensatory eye movements, and the effect of eye closure might be explained by bio-mechanical and possibly even central effects on the eye movements. In low-frequency testing, as short a test time as possible should be used, and due to different alertness levels, the results should be evaluated with great caution.

Acceleration↗

PubMedDate not supplied

Plasticity of compensatory eye movements in rotatory tests. II. The effect of voluntary, visual, imaginary, auditory and proprioceptive mechanisms.

Two groups of 10 healthy volunteers each with a mean age of 28 years (17-39) were tested in low-frequency rotatory experiments (sinusoidal harmonic acceleration, SHA), at frequencies of 0.01-0.32 Hz. The purpose was to ascertain whether voluntary enhancement and reduction of gain and phase occurred with voluntary performances. The different tests were alertness in darkness, stationary and moving targets, imaginary stationary and moving targets in darkness, proprioceptive moving targets and acoustic stationary and moving targets. Alertness tests in darkness demonstrated a gain increase (0.5-0.7) at 0.01-0.32 Hz, and a decreasing phase lead (40-2 degrees) with increasing frequency. The alertness tests served as a reference for the other tests. In tests with stationary targets, the gain reached unity and the phase was almost 0 degrees. In imaginary stationary target tests, gain and phase were significantly increased compared with alertness. Stationary acoustic targets in darkness significantly enhanced the gain. An increased phase lead was also found. In visual suppression tests (moving target), the gain was near 0. In imaginary moving target tests, the gain decreased significantly. In darkness the gain was significantly more depressed with a proprioceptive moving target than during imaginary moving target. Testing with proprioceptive + acoustic moving target in darkness, displayed an additional gain depression and negative phase at 0.08 Hz. The conclusion is that the influence of non-vestibular mechanisms substantially affects low frequency sinusoidal rotatory testing.

Acoustic Stimulation↗

PubMedDate not supplied

Dynamic posturography in assessment of polyneuropathic disease.

Twenty-eight patients with polyneuropathy aged 49-82 years (mean 67 years) were assessed by dynamic posturography. The patient group was compared to a control group comprising 29 healthy controls aged 70 through 75 years (mean 73 years). The dynamic posturography method comprises a sensory organization part in which the platform and visual surround are either stable or referenced to the patient's sway; furthermore, the eyes are open or closed. In a movement coordination part the platform makes active movements. In the sensory organization part of the dynamic posturography the patient group showed significantly lower equilibrium performance compared to the control group in the test conditions with absent vision, sway-referenced surrounding, and, finally, sway referenced platform and surrounding. In these conditions the influx of somatosensory information is of paramount importance for stable posture. In the movement coordination test, the patient group showed prolonged muscular response latencies in both forward and backward platform perturbations compared to the control group. It is concluded that dynamic posturography is a valuable diagnostic tool in assessment of the dynamic equilibrium performance in patients with polyneuropathy.

Aged↗

PubMedDate not supplied

Effects of balance training in elderly evaluated by clinical tests and dynamic posturography.

All persons aged 70 through 75 years (N = 457) in a Swedish community were invited to participate in a 9 week balance training study. Out of 55 interested subjects, 15 were chosen at random for a study group; 15 matched controls were also selected. Before and after the investigation period the balance function was assessed by clinical balance tests and dynamic posturography. In the clinical balance tests, the training group significantly improved their balance standing on one leg with eyes closed as well as standing on one leg while shaking the head; they also walked 15 m back and forth faster. In the dynamic posturography the training group significantly improved their equilibrium scores in the 3 most difficult test conditions. The results of the control group were unchanged except for one test condition in the dynamic posturography. The differences in one-leg standing with head shaking, walking 2 x 15 m, and the equilibrium score using sway-referenced platform in dynamic posturography were proved to be attributable to the training. The first investigation in all 29 subjects formed normative dynamic posturography data for the age group 70 through 75 years. The normative posturographic data of this age group differed from previously obtained data in the age groups 20 through 59 and 60 through 69 years. It is concluded that elderly may improve their balance by regular balance training exercises for as short a period as 9 weeks. This might prove to be of great value in improving balance and thereby preventing accidental falls and subsequent fractures in elderly.

Aged↗