Takehiko Bando

Target spatial frequency determines the response to conflicting defocus- and convergence-driven accommodative stimuli

Asthenopia, or visual fatigue, is a frequent complaint from observers of stereoscopic three-dimensional displays. It has been proposed that asthenopia is a consequence of anomalous oculomotor responses generated by conflict between accommodative and convergence stimuli. The hypothesis was examined by measuring accommodation and convergence continuously with a Shin-Nippon SRW5000 infrared autorefractor and a limbus tracking device. Subjects viewed a high contrast Maltese Cross target at three levels of Gaussian filter target blur under conditions of relatively low- and high-conflict between accommodation and convergence stimuli, the latter inducing the sensation of stereopsis. Under the low-conflict conditions accommodation was stable, but convergence-driven accommodation was dominant when the target was extremely blurred. Under the high-conflict conditions the role of convergence-driven accommodation increased systematically with the degree of target blur. It is proposed that defocus-driven accommodation becomes weak when the target comprises low spatial frequency components. Large accommodative overshoots to step stimuli that are not blurred or only mildly blurred were consistently observed and are attributed to the initial accommodative response being convergence-driven. Whereas the possibility that high-conflict conditions are a cause of asthenopia has been previously reported, this is the first evidence that they specifically affect accommodative responses while viewing stereoscopic displays.

disjunctive eye movement evoked by microstimulation in an extrastriate cortical area of the cat

Slow disjunctive eye movement similar to ocular convergence was evoked by microstimulation in parts of the lateral suprasylvian area (LSA) in alert cats. A tungsten-in-glass microelectrode was used for stimulation, and eye movement was monitored using the magnetic search coil method. The velocity-versus-amplitude relationship of disjunctive eye movement evoked by microstimulation was comparable to that of ocular convergence evoked by presenting a visual target. It is suggested that the LSA plays a role in controlling convergence eye movement.

Visual fatigue caused by stereoscopic images and the search for the requirement to prevent them: A review

Abstract Recent literatures related to the evaluations of visual fatigue induced by stereoscopic images (VFSI) are reviewed with the short introduction of cortical mechanisms related to early visual processing, vergence eye movement and lens accommodation. Based on this knowledge, the requirements to prevent visual fatigue and discomfort induced by viewing stereoscopic images were sought. Firstly, the careful alignment in the right/left eye images is required for the stereoscopic vision without discomfort. Secondly, the conflict between the demands for vergence eye movement and lens accommodation in the near response should be avoided, by using modest binocular disparity. Thirdly, the frequency of changes in binocular disparity should be restricted. Finally, the appropriate viewing distance is also recommended to avoid visual fatigue.

Cortical neurons in and around the Clare-Bishop area related with lens accommodation in the cat

Single-unit discharges in the cat Clare-Bishop area were correlated with spontaneous accommodation responses. No appreciable change was found in accommodation responses evoked by stimulating the Clare-Bishop area, when cerebellar outflow was blocked reversibly by cooling the superior cerebellar peduncle. It is suggested, therefore, that the Clare-Bishop area plays an important role in the lens accommodation system through a pathway independent from that of the cerebellum.

Pupillary constriction evoked from the posterior medial lateral suprasylvian (PMLS) area in cats.

Pupillary constriction was evoked by systematic stimulation using a microelectrode in the upper medial bank of the middle suprasylvian sulcus in the parieto-occipital cortex of the cat. The pupillo-constrictor area corresponded to the rostral and middle parts of the posterior medial lateral suprasylvian (PMLS) area. This pupillo-constrictor area extended by 2-3 mm along the middle suprasylvian sulcus. It is suggested that this pupillo-constrictor area overlaps or lies in close proximity of a part of the region in PMLS area related to lens accommodation, in which unit activity temporally related to lens accommodation was recorded and from which lens accommodation was evoked by electric stimulation.

Blink rate variability in patients with panic disorder: New trial using audiovisual stimulation

Several lines of evidence have implicated central dopaminergic pathways in the modulation of spontaneous blink rate (BR). Furthermore, previous studies have indicated a relationship between spontaneous BR and anxiety and/or depression. However, to our knowledge, there is no report on the examination of BR in a group of patients with panic disorder (PD). During the conditions of rest and with audiovisual stimulation, exposed to a video of imaginary experiences, such as driving a motor vehicle or diving into the sea, BR was examined in 11 male patients with PD and compared with the BR of 16 age‐matched normal controls. The BR was significantly higher in PD patients relative to normal controls under both conditions. In particular, the PD group had a higher BR score during the sea scene as relaxation compared with the normal controls. In conclusion, although the sample size was small the present preliminary study, these findings suggest that BR may have potential for application in the assessment of anxiety state, which is consistent with previous studies.

Functional roles of the lateral suprasylvian cortex in ocular near response in the cat

The lateral suprasylvian (LS) area, an extrastriate visual area in the cat, has been suggested to play an important role in processing motion in 3-dimensional visual space. In addition, the LS area is related to all three components of the ocular near response, i.e. lens accommodation, pupillary constriction, and ocular convergence: microstimulation in this area evoked these intra- and extraocular movements, and neuronal discharges associated with these movements were also found. Anatomical pathways, direct and indirect, from this area to premotor nuclei in the brainstem are known to exist. The present paper reviews studies useful for assessing the functional roles played by the LS area in triggering and modulating component movements in the ocular near response.

Pupillary light reflex in panic disorder. A trial using audiovisual stimulation.

Abstract.BackgroundAlthough many previous studies reported abnormalities of autonomic function in patients with panic disorder (PD), almost all targets in those studies primarily focused on cardiovascular autonomic functions. In the present study, we determined whether PD patients exhibited abnormalities in the pupillary autonomic nervous system (ANS).MethodsBefore and after audiovisual stimulation (AS), which induced mental stress through exposure to video images of high stress experiences, such as driving motor vehicles, the pupillary light reflex (PLR) was measured by infrared pupillometer in 13 remitted PD patients and twenty age– and gender–matched normal controls (NC).ResultsBefore and after AS, there were no significant differences in initial pupillary diameters in dark conditions (D1), pupillary diameters at maximum constriction (D2) or constriction ratios (CR: (D1-D2)/D1) between PD and NC subjects. However, the CR ratio (CR before/CR after) was significantly higher in the PD group than in the NC.ConclusionsThese findings suggest that even remitted PD patients may have a dysfunctional PLR regulation with experimental stressors such as AS.

Chapter 21: Lens accommodation-related and pupil-related units in the lateral suprasylvian area in cats

Publisher Summary This chapter discusses lens accommodation-related and pupil-related unit activities in anesthetized cats. Nineteen of 146 units in posteromedial lateral suprasylvian (PMLS) discharged in synchrony with lens accommodation, papillary constriction or pupillary dilation. Lens accommodation, pupillary constriction or pupillary dilation were synchronized only occasionally with each other in this chapter, which was conducted under anesthesia and without any visual stimulation. The good correlation between these variables supports the notion that lateral suprasylvian area (LSA) contributes to the central nervous control of these intraocular muscular movements. The activities of most of these units also discharged in prominent synchrony with only one of these three intraocular muscular movements. The close parallelism of unit activities and effects of microstimulation favors the notion that LSA plays an important role in controlling intraocular muscular movements such as accompany lens accommodation and papillary constriction.

A pilot study on pupillary and cardiovascular changes induced by stereoscopic video movies.

BackgroundTaking advantage of developed image technology, it is expected that image presentation would be utilized to promote health in the field of medical care and public health. To accumulate knowledge on biomedical effects induced by image presentation, an essential prerequisite for these purposes, studies on autonomic responses in more than one physiological system would be necessary. In this study, changes in parameters of the pupillary light reflex and cardiovascular reflex evoked by motion pictures were examined, which would be utilized to evaluate the effects of images, and to avoid side effects.MethodsThree stereoscopic video movies with different properties were field-sequentially rear-projected through two LCD projectors on an 80-inch screen. Seven healthy young subjects watched movies in a dark room. Pupillary parameters were measured before and after presentation of movies by an infrared pupillometer. ECG and radial blood pressure were continuously monitored. The maximum cross-correlation coefficient between heart rate and blood pressure, ρmax, was used as an index to evaluate changes in the cardiovascular reflex.ResultsParameters of pupillary and cardiovascular reflexes changed differently after subjects watched three different video movies. Amplitudes of the pupillary light reflex, CR, increased when subjects watched two CG movies (movies A and D), while they did not change after watching a movie with the real scenery (movie R). The ρmax was significantly larger after presentation of the movie D. Scores of the questionnaire for subjective evaluation of physical condition increased after presentation of all movies, but their relationship with changes in CR and ρmax was different in three movies. Possible causes of these biomedical differences are discussed.ConclusionThe autonomic responses were effective to monitor biomedical effects induced by image presentation. Further accumulation of data on multiple autonomic functions would contribute to develop the tools which evaluate the effects of image presentation to select applicable procedures and to avoid side effects in the medical care and rehabilitation.