PubMed · 4421029
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R I Kohut. 1974. Vertical linear acceleration (otolithic-ocular responses).. https://doi.org/10.1288/00005537-197410000-00002
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BACKGROUND AND PURPOSE: Cerebral vasomotor reactivity can easily be assessed reliably by measuring vasodilatory response to acetazolamide by transcranial Doppler sonography. The aim of this study was to confirm the hypothesis that female sex is associated with an increased cerebrovascular flow reserve. METHODS: Blood flow velocity of the middle cerebral artery was measured by transcranial Doppler sonography in 36 healthy sex- and age-matched subjects. After the initial blood flow velocities were recorded, the subjects received 14.3 mg/kg body wt acetazolamide, ie, 1 g/70 kg, intravenously. The measurements were repeatedly performed at 5-minute intervals starting 10 minutes after injection and lasting for 30 minutes. The highest measured flow velocities were used for further analysis. RESULTS: In both groups mean blood flow velocity increased significantly after acetazolamide (women, from 60.2 +/- 12.5 to 89.9 +/- 14.4 cm/s, P < .006; men, from 54.5 +/- 18.8 to 75.7 +/- 24.5 cm/s, P < .02). The difference in mean blood flow velocity after acetazolamide between groups of women and men was statistically significant (P < .02). CONCLUSIONS: Female subjects show an increased vasodilatory response to the acetazolamide test compared with men.
In order to determine whether short and middle latency vestibular evoked potentials (VsEPs) can be recorded in humans in response to angular acceleration stimuli in the vertical plane, a drum, head-holder, and stepper motor were designed to deliver upward acceleration impulses of 10,000 degrees/s2 (1.8 degrees displacement) to the human head. Forehead and mastoid electrodes recorded electrical activity that was filtered, differentially amplified, and averaged in short (12.7 milliseconds) and middle (63.5 milliseconds) latency time frames. Control recordings were used to eliminate various types of artifact. Recordings were conducted in 7 normal subjects and in 4 control patients with congenital, profound hearing loss and absence of caloric responses. Short and middle latency VsEPs with high intrasubject and intersubject consistency were recorded in normal subjects and not in control patients. The middle latency responses were larger in amplitude than the short latency responses. The effects of stimulus intensity and repetition rate on VsEP waveform, latency, and amplitude studied. Experiments have shown that the responses are not electrical artifact, nor are they contaminated by auditory, somatosensory, or passive eye movement potentials.
The ability to evaluate traveled distance is common to most animal species. Head trajectory in space is measured on the basis of the converging signals of the visual, vestibular, and somatosensory systems, together with efferent copies of motor commands. Recent evidence from human studies has shown that head trajectory in space can be stored in spatial memory. A fundamental question, however, remains unanswered: How is movement stored? In this study, humans who were asked to reproduce passive linear whole-body displacement distances while blindfolded were also able to reproduce velocity profiles. This finding suggests that a spatiotemporal dynamic pattern of motion is stored and can be retrieved with the use of vestibular and somesthetic cues.