Comfort in observing stereoscopic images reduced by vibration stimuli

Numerous studies have been conducted to illuminate the effect of image factors to reduce unexpected influence of stereoscopic images on healthy visual experience. In this paper, we introduce changes in the psychological and physiological indexes of observers of a stereo- scopic image disturbed by vibration stimuli. Forty-four healthy university students participated in the experiment. A programmable vibration table generated two types of vibrations (5 Hz and 20 Hz) and provided intermittent vibration stimuli to a stereoscopic projector installed on a vibration table. Our results showed that the frequency of vibration stimuli has a strong impact in evaluating the local comfort of subjects. Our results also showed that the indexes of visual fatigue increased after observation independent of the frequency. The activity status of the autonomic nervous system as a physiological index significantly increased after observing 3D images with vibration stimuli although the vibrational frequency did not have a significant effect on the activity status.

Psychological and physiological effects of stereoscopic movies of real-world scenes containing improper three-dimensional settings

By using psychological and physiological indicators, the effects on the body of three-dimensional (3D) movies containing improper settings were evaluated with 139 university students. The experiment consisted of two sessions: 1) a 3D movie containing improper 3D settings was compared with a 2D movie containing only the rightside images presented to both eyes, and 2) the original 3D movie was compared with the same 3D movie altered to contain improper 3D settings. The results of this experiment demonstrated clear deterioration of the subjective psychological indicators (degree of motion sickness after watching the movies and comfort level at 1-min intervals during the movie) with respect to the 3D movie containing improper settings. On the other hand, the physiological indicators (LF/HF ratio indicating the status of the autonomic nervous system) changed as a result of watching a 3D movie, but were unaffected by the presence or absence of improper 3D settings.

Development of Functional Interlaminar Pathways in the Mouse Superior Colliculus Revealed by Optical Imaging with Axonal Labeling

The superior colliculus (SC) is a laminated midbrain structure responsible for visual orientation behaviors. In the mature SC, neurons in the stratum griseum superficiale (SGS) receive visual inputs that contribute to exciting premotor neurons in the stratum griseum intermediale (SGI) through a dorsoventral pathway. SGI activation generates feedback signals to the SGS through a ventrodorsal pathway. However, the developmental changes in signal transmission within the SC around the time of eye opening are not yet well understood. We compared the functional connections between the SGS and SGI before and after eye opening by imaging the neuronal population responses using a voltage-sensitive absorption dye in mouse SC slices. Electrophoresis of a fluorescent dye from the stimulating electrodes was used to fill the cells in the stimulated site. We here show that the dorsoventral transmission is present both before and after eye opening. This is in contrast to our previous finding that the ventrodorsal transmission develops after eye opening. Functions of intrinsic inhibitory systems mediated by gamma-aminobutyric acid were also investigated with the antagonist. The processes stained by electrophoresis from stimulating electrodes before eye opening were confined within the respective stimulated layers. Whereas, after eye opening, the processes were widely extended especially dorsoventrally and ventrodorsally invading the SGI and SGS, respectively. These corresponded well to the early component of voltage responses that is known to reflect the activation of presynaptic elements, presumably the axonal arborizations and varicosities. Thus, the optically-revealed functional connections between the SGS and SGI were correlated to the morphology.