Biomedical subjects

Cunguo Wang

Publications and source records attributed to Cunguo Wang.

3 recordsLinked to original sources

PubMed2005

Diazepam-induced changes of optokinetic nystagmus fast phase.

Since specific benzodiazepine (Bz) binding sites have been found in the vision and oculomotor control areas of the central nervous system (CNS), the fast phases of optokinetic nystagmus (OKN) should be affected by Bz administration. In this study, we examine the effects of Bzs on OKN fast phases under closed- and open-loop experimental conditions. Six normal subjects participated in the experiments. The eye movements were measured by the magnetic field, search coil technique, 90 min after diazepam or placebo administration. The study was performed in a randomized, double-blind fashion. After diazepam, the mean amplitude (MAmp) and mean peak velocity (MVel) of OKN fast phases decreased significantly under both experimental conditions. The percentage decreases in MAmp and MVel under the open-loop condition were significantly larger than those under the closed-loop condition. The results indicate that the fast phases of OKN could sensitively reflect the pharmacodynamic effects of Bzs on the CNS.

Adult↗

PubMed2005

Effects of diazepam on the latency of saccades for luminance and binocular disparity defined stimuli.

Saccadic latency is composed of separate sensory and motor processing delays. Therefore, any alteration in the sensory processing should effect the saccadic latency. Because the highest density of benzodiazepine (Bz) binding sites is located in cerebral cortex, sensory processing of stimuli in this cortical area is expected to be substantially effected by administration of Bzs. It is well known that sensory processing of binocular disparity occurs in the cerebral cortical areas and therefore the latency of saccades to stimuli defined by binocular disparity should be substantially affected by Bz intake. In this study, we tested this prediction by comparing the latency of saccadic eye movements for binocular disparity defined stimuli (stereo stimuli) with those for luminance contrast defined stimuli (luminance stimuli), after diazepam or placebo. Eye movements were mainly recorded by use of the magnetic search coil technique, and the study was performed in a randomized, double-blind way. Although diazepam prolonged the latency of saccades for stereo and luminance stimuli, the percentage increases in saccadic latency for the stereo stimuli were significantly larger than those for the luminance stimuli. Saccadic peak velocity, and saccadic amplitude, also significantly decreased after diazepam under conditions of stereo and luminance stimuli. However, there was no significant difference for either saccadic peak velocity or amplitude between the two types of target. The results suggest that the latency of saccades to binocular disparity defined random-dot stimuli could more sensitively reflect the pharmacodynamic effects of Bzs on the cerebral cortex.

Adult↗

PubMed2003

Interocular motion combination for dichoptic moving stimuli.

When gratings moving in different directions are presented separately to the two eyes, we typically perceive periods of the combination of motion in the two eyes as well as periods of one or the other monocular motions. To investigate whether such interocular motion combination is determined by the intersection-of-constraints (IOC) or vector average mechanism, we recorded both optokinetic nystagmus eye movements (OKN) and perception during dichoptic presentation of moving gratings and random-dot patterns with various differences of interocular motion direction. For moving gratings, OKN alternately tracks not only the direction of the two monocular motions but also the direction of their combined motion. The OKN in the combined motion direction is highly correlated with the perceived direction of combined motion; its velocity complies with the IOC rule rather than the vector average of the dichoptic motion stimuli. For moving random-dot patterns, both OKN and perceived motion alternate only between the directions of the two monocular motions. These results suggest that interocular motion combination in dichoptic gratings is determined by the IOC and depends on their form.

Adult↗