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At least 685 records · Page 38Linked to original sources
PubMed1990

[Interactions between saccades and vestibulo-ocular reflex during double gaze shifts].

After fixating the center, human subjects were required to track two visual targets (T1, T2) presented in the horizontal plane in a dark room. When T2 was lit 200-600 msec after T1, T2 was given and also second saccadic eye movement unsolicited at various positions of eye and head during the course of gaze (eye position in the orbit plus head position) shift toward T1. Under all circumstances, the final gaze reached T2 without significant difference from the trials made by eye movement alone, suggesting head and eye positions are perfectly monitored to adjust the amplitude of gaze. As head velocity increased, gaze velocity increased and duration decreased with little change in eye velocity, contrary to the previous assumption that vestibulo-ocular reflex adjusts the time course of gaze shift to be constant.

Adult↗
PubMed1989

Cervico-ocular eye movements in relation to different neck torsion velocities.

Rotation of the trunk with a fixed head causes isolated stimulation of cervical afferent input. Eleven patients with marked cervico-ocular reactions (COR) were selected. A neck torsion test (NTT) was performed with the help of a special apparatus. The resulting cervically induced eye movements consisted of two components. In addition to a cervical nystagmus, with its slow, compensatory phase, a deviation of the mean eye position (shift) in an anticompensatory direction, opposite to trunk rotation was observed. The COR in relation to different neck torsion velocities distinctly showed a tuning curve with maximum reactions between 4 degrees/s and 9 degrees/s. Above these values, a strong decrease in COR resulted. The optimal working range vastly differs from that of the vestibulo-ocular reflex (VOR).

Adult↗
PubMed1985

Evidence of early impairment of parasympathetic reflexes in insulin dependent diabetics without autonomic symptoms.

Cardiovascular (CV) autonomic functions were assessed in 50 insulin-dependent diabetic patients and in 30 controls using a battery of autonomic tests: Valsalva Manoeuvre (VR), Deep Breathing (DB), Lying-to-Standing (LS), Sustained Handgrip (SHG) and Postural Hypotension (PH). The results were compared with those obtained from a study of cardiac resting adjustment to different static postures (quiet lying and standing). 10 diabetics with abnormal responses to the majority of tests were considered affected by Diabetic Autonomic Neuropathy (DAN); 15 with some abnormal of borderline responses were defined much less than Borderlines much greater than. The remaining 25 diabetics, while displaying lower values than the controls in parasympathetic tests, had much less than normal much greater than autonomic responses. The VR mean (+/- SD) value was 1.71 +/- 31 in much less than normal much greater than diabetics and 2.01 +/- 0.29 in controls (p less than 0.001); the DB mean value was 20.6 +/- 87 and 28 +/- 8.13 (p less than 0.001), and the LS mean value 1.16 +/- 0.12 and 1.33 +/- 0.18 (p less than 0.001) respectively. No significant differences were found in the sympathetic tests (SHG, PH). However Heart Rate (HR) adjustment of diabetics with normal CV responses to immobile standing (RR mean 783 +/- 136 ms) and lying (RR mean increment of 25 +/- 11%; p less than 0.001) was similar to that of controls who had a resting HR standing (RR mean 749 +/- 104 ms) and lying (RR mean 884 +/- 116 ms) with a mean increment of 20.2 +/- 10.9% (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1981

Effect of lower body negative pressure upon local regulation of blood flow in human subcutaneous tissue.

Local regulation of subcutaneous blood flow in the forearm was studied during lower body negative pressure (LBNP) in 7 young healthy male subjects in supine position. Blood flow was measured on the forearm by the local 133Xe washout technique. LBNP of -40 and -60 mmHg induced a decrease in the 133Xe washout rate of 34 and 50% respectively. This response to LBNP could be blocked by proximal nervous blockade indicating that the vasoconstriction observed was due to a central sympathetic reflex mechanism. The vasoconstrictor response to increase in venous transmural pressure induced by lowering the arm (veno-arteriolar reflex mechanism) could not be demonstrated during 40 mmHg LBNP. The abolishment of this reflex is most likely due to centrally elicited increase in sympathetic activity as a normal veno-arteriolar reflex was elicited following proximal nervous blockade.

Adult↗
PubMed2000

Nicotine-induced nystagmus: three-dimensional analysis and dependence on head position.

Two- and three-dimensional analyses of nicotine-induced eye movements were performed in 53 subjects to evaluate whether they were primarily of vestibular or ocular motor origin. Nicotine-induced nystagmus was detected in 27 subjects (51%); in 25 of these (93%) it was modulated by otolith input. Three-dimensional analysis of nicotine-induced nystagmus revealed that it violates Listing's law. Taken together, these findings suggest that nicotine induces an imbalance in the vestibulo-ocular reflex.

Adult↗