Gender differences in the use of cardiovascular interventions in HIV-positive persons; the D:A:D Study

Peer reviewe

Visually evoked slow eye movements, visual-vestibular interaction, and infratentorial lesions

The maximum velocity gain of smooth pursuit and optokinetic, vestibular, and optovestibular slow phases was examined in 15 patients with pontine, 10 with medullary, 10 with cerebellar, and 5 with combined cerebello-brain stem disorders. Marked dissociations were observed between smooth pursuit and optokinetic slow phases, especially in medullary disease. A cerebellar deficit enhanced slow phase velocity gain during rotation in darkness, whereas the corresponding gain during rotation in light was normal

Retention of habituation of vestibulo-ocular reflex and sensation of rotation in humans.

International audienceIn humans, habituation of vestibulo-ocular reflex (VOR) by repeated caloric or rotational stimulation has been well documented. However, less attention has been directed to the effect of habituation on the sensation of self-rotation and little is known about the retention duration of vestibular habituation. To investigate these characteristics, subjects were exposed to ten sessions of angular velocity steps in yaw, with a chair rotating either alternatively in both CW and CCW directions (bidirectional protocol) or always in the same direction (unidirectional protocol), i.e., CW or CCW. The retention of habituation of VOR and sensation of rotation induced by both protocols was studied for a period up to 8 months following the end of the habituation protocols. There was a progressive decline in the VOR peak slow phase velocity and time constant throughout the sessions during both protocols. These parameters then followed an exponential recovery with a time constant of about 1 month. The duration of the sensation of rotation also habituated during repeated angular velocity steps, but it was shorter for both directions of stimulation, including after the unidirectional protocol. Sinusoidal VOR gain was not affected by vestibular habituation to velocity steps, but sinusoidal VOR phase showed an increase in phase lead at 0.02 and 0.04 Hz, which also returned to baseline values within about 1 month. We conclude that vestibular habituation is a long-lasting phenomenon. These results may be helpful for designing and scheduling the protocols for drug studies using crossover design, rehabilitation of balance disorder patients, and for the application of intermittent artificial gravity during space missions