Fumiya Kinoshita

Effects of Two-Minute Stereoscopic Viewing on Human Balance Function

Recently, with the rapid progress in image processing and three-dimensional (3D) technologies, stereoscopic images are not only available on television but also in theaters, on game machines, and elsewhere. In contrast to two-dimensional (2D) films that project flat images, stereoscopic films elicit the feeling of being at a live performance. However, asthenopia and visually-induced motion sickness (VIMS) can result from the exposure to these films. Even though various hypotheses exist, the pathogenesis of VIMS is still unclear. There is not enough knowledge on the effects of stereoscopic images on the living body, and the accumulation of basic research is thus important. The aim of this paper is to accumulate information relevant to VIMS and to examine whether the exposure to 3D video clips affects the human equilibrium functions. We evaluated body sway by conducting stabilometry studies. As a result, we verified that 3D viewing effects on our equilibrium function depends on exposure time.

Changes in Brain Blood Flow by the Use of 2D/3D Games

Recently, with the rapid progress in image processing and three-dimensional (3D) technology, stereoscopic images are not only seen on television but also in theaters, on game machines, etc. However, symptoms such as eye fatigue and 3D sickness may be experienced when viewing 3D films on displays and visual environments. The influence of stereoscopic vision on the human body has been insufficiently understood; therefore, it is important to consider the safety of viewing virtual 3D content. In this study, we examine whether exposure to 3D video clips affects the human body such as brain blood flow. Subjects viewed 3D video clips on the display of portable game machines, and time series data of their brain blood flow was measured by near-infrared spectroscopy (NIRS) with use of FOIRE-3000 (Shimazu Co. Ltd., Kyoto). Our results showed oxyhemoglobin tended to increase throughout the cerebral cortex while operating the game machines on the 3D display in comparison with the 2D display.

Changes of Potential Functions While Maintaining Upright Postures After Exposure to Stereoscopic Video Clips

Asthenopia and visually induced motion sickness (VIMS) is a well-known phenomenon in viewing video, playing video games and others. In previous studies, we pointed out peripherally viewing as a pathogenesis of the VIMS whose evidence was also shown and described the anomalous sway by using mathematical models. Stochastic differential equations are known to be a mathematical model of the body sway. We herein discuss the metamorphism in the potential functions to control the standing posture during/after the exposure to stereoscopic video clips.

Analysis of the Body Sway While/After Viewing Visual Target Movement Synchronized with Background Motion

Stereoscopic imaging techniques have also become used for not only amusement but also in the industrial, medical care, and educational fields, however, symptoms due to the stereopsis have been reported. In this study, we especially focus on the effect of background motions on the equilibrium function. The body sway was recorded while/after viewing a sphere as a visual target synchronized/unsynchronized with periodic motion of the view point. Statistical analysis was conducted for the stabilograms.

Analysis of Electrogastrograms During Exercise Loads

A percutaneous electrogastrogram (EGG) is a simple and low-restraint way to measure the electrical activity of the gastrointestinal tract. An electrogastrogram examination is a noninvasive method of evaluating gastrointestinal motility and autonomic nervous system activity. However, EGGs are not as widely used in clinical settings as electrocardiograms (ECGs) or electroencephalographs (EEGs) because an EGG can be impacted by electrical activity from the myocardium and diaphragm (due to respiration), and there is no method to relate the functions of the stomach to the data obtained. This paper examines the effect of exercise on gastric electrical activity using two exercise intensities to confirm the basic biological response of an EGG. It was found that after high-intensity exercising the spectrum density at the normal frequency band of the stomach (2.4–3.7 cpm) decreased, which may indicate a decline in gastric activity during exercise. Exercise intensity is thought to affect the electrical activity of not only the gastrointestinal tract but also other organs.

Electromyography Analysis of Rapid Eye Movement Sleep Behavior Disorder

Polysomnography (PSG), which records physiological phenomena including brain waves, breathing status, and muscle tonus, is useful for the diagnosis of sleep disorders as a gold standard. However, measurement and analysis are complex for several specific sleep disorders, such as rapid eye movement (REM) sleep behavior disorder (RBD). Usually, brain waves during REM sleep indicate an awakening pattern under relaxed conditions of skeletal and antigravity muscles. However, these muscles are activated during REM sleep when patients suffer from RBD. These activated muscle movements during REM, so-called REM without atonia (RWA) recorded by PSG, may be related to a neurodegenerative disease such as Parkinsons disease. Thus, careful analysis of RWA is significant not only physically, but also clinically. Commonly, manual viewing measurement analysis of RWA is time-consuming. Therefore, quantitative studies on RWA are rarely reported. A software program, developed from Microsoft Office Excel®, was used to semiautomatically analyze the RWA ratio extracted from PSG to compare with manual viewing measurement analysis. In addition, a quantitative muscle tonus study was carried out to evaluate the effect of medication on RBD patients. Using this new software program, we were able to analyze RWA on the same cases in approximately 15 min as compared with 60 min in the manual viewing measurement analysis. This software program can not only quantify RWA easily but also identify RWA waves for either phasic or tonic bursts. We consider that this software program will support physicians and scientists in their future research on RBD. We are planning to offer this software program for free to physicians and scientists.

Effect of Reading a Book on a Tablet Computer on Cerebral Blood Flow in the Prefrontal Cortex

OBJECTIVES By measuring cerebral blood flow in the prefrontal cortex, we aimed to determine how reading a book on a tablet computer affects sleep. METHODS Seven students (7 men age range, 21-32 years) participated in this study. In a controlled illuminance environment, the subjects read a novel in printed form or on a tablet computer from any distance. As the subjects were reading, the cerebral blood flow in their prefrontal cortex was measured by near-infrared spectroscopy. The study protocol was as follows. 1) Subjects mentally counted a sequence of numbers for 30 s as a pretest to standardized thinking and then 2) read the novel for 10 min, using the printed book or tablet computer. In step 2), the use of the book or tablet computer was in a random sequence. Subjects rested between the two tasks. RESULTS Significantly increased brain activity (increase in regional cerebral blood flow) was observed following reading a novel on a tablet computer compared with that after reading a printed book. Furthermore, the region around Brocas area was more active when reading on a tablet computer than when reading a printed book. CONCLUSIONS Considering the results of this study and previous studies on physiological characteristics during nonrapid eye movement sleep, we concluded that reading a book on a tablet computer before the onset of sleep leads to the potential inhibition of sound sleep through mechanisms other than the suppression of melatonin secretion.

Nonlinear Analysis of Electrogastrograms During Acute Exercise Loads

A percutaneous electrogastrogram (EGG) is a simple and low-restraint way to measure the electrical activity of the gastrointestinal tract. An electrogastrogram examination is a noninvasive method of evaluating gastrointestinal motility and autonomic nervous system activity. However, EGGs are not as widely used in clinical settings as electrocardiograms (ECGs) or electroencephalographs (EEGs) because an EGG can be impacted by electrical activity from the myocardium and the diaphragm (due to respiration), and there is no method to relate the functions of the stomach to the data obtained. This paper examines the effect of exercise on gastric electrical activity using two exercise intensities to confirm the basic biological response of an EGG. It was found that, after high-intensity exercising, the spectrum density at the normal frequency band of the stomach (2.4-3.7 cpm) decreased, which may indicate a decline in gastric activity taking place during exercise. Moreover, after high-intensity exercise, translation error increased significantly. Exercise intensity is thought to affect the electrical activity of not only the gastrointestinal tract, but also of other organs.

Evaluation of Cerebral Blood Flow While Viewing 3D Video Clips

The technology provides an enhanced visual experience with realistic scene portrayal, but is known to cause motion sickness when stereoscopic video clips of rotating or blurred images are viewed. Viewers complain of symptoms such as eye fatigue, nausea, and dizziness. The underlying cause of these symptoms has not been identified; therefore, an investigation to determine the mechanism for the motion sickness is necessary. Previous stabilometry studies have reported that 3D sickness is induced by a peripheral viewing of stereoscopic video clips as opposed to the visual pursuit. In this study, the author investigated the influence of 3D recognition on brain activity. Functional near-infrared imaging (fNIRS) was used to determine if either peripheral viewing or visual pursuit changes brain activity. Stabilograms and eye movement were simultaneously recorded while the subject viewed video clips to confirm that the actual visual recognition method in use corresponded to our instructions. Using the fNIRS technique, cerebral blood flow was measured while the subject viewed stereoscopic video clips with and without a background. Following a preliminary test with the subject’s eyes closed (baseline), changes in the concentration of oxygenated hemoglobin were measured. This test was performed for 70 s, with and without backgrounds, while the subject peripherally viewed a moving sphere. Compared to the baseline test, the concentration of oxygenated hemoglobin in the occipital lobe increased significantly during a viewing for both background cases. The result is consistent with both visual recognition methods. Furthermore, for both background cases, the concentration in the upper occipital lobe significantly increased during peripheral viewing versus visual pursuit. Peripheral viewing might enhance the activity in the dorsal stream, which could serve as an indication to the mechanism causing 3D sickness.

Temporal Evolution in Potential Functions While Peripheral Viewing Video Clips with/without Backgrounds

In daily life, stereoscopic image technology, such as 3D TV and movies, has become used in various places. Images, not limited to stereoscopic images, may exhibit unfavorable biological effects depending on the viewing and physical conditions, age, and individual differences. In our previous study, an increase was indicated in the sway values that were observed while/after peripheral viewing a stereoscopic video clip. Backgrounds are considered to affect our balance function. We examine the effect of the exposure to stereoscopic video clips without the background on our equilibrium function paper, and fifteen healthy young males voluntarily participated in the present study. Their stabilograms were recorded during monocular vision or binocular parallax vision using semipermeable smart glasses, where the subjects maintained the Romberg posture in stabilometry. We also measured the body sway with the subjects’ eyes closed 0–3 min after the exposure to the video clips. We herein compare the temporal averaged potential functions to control the standing posture during the exposure to 2D/3D video clips with those after the exposure.