Influence of Auditory and Haptic Stimulation in Visual Perception

While many studies have shown that visual information affects perception in the other modalities, little is known about how auditory and haptic information affect visual perception. In this study, we investigated how auditory, haptic, or auditory and haptic stimulation affects visual perception. We used a behavioral task based on the subjects observing the phenomenon of two identical visual objects moving toward each other, overlapping and then continuing their original motion. Subjects may perceive the objects as either streaming each other or bouncing and reversing their direction of motion. With only visual motion stimulus, subjects usually report the objects as streaming, whereas if a sound or flash is played when the objects touch each other, subjects report the objects as bouncing (Bounce-Inducing Effect). In this study, “auditory stimulation”, “haptic stimulation” or “haptic and auditory stimulation” were presented at various times relative to the visual overlap of objects. Our result shows the bouncing rate when haptic and auditory stimulation were presented were the highest. This result suggests that the Bounce-Inducing Effect is enhanced by simultaneous modality presentation to visual motion. In the future, a neuroscience approach (eg, TMS, fMRI) may be required to elucidate the brain mechanism in this study

メラノプシンを含む神経節細胞の瞳孔系への寄与 : 多原色光源による検討

従来, 人間の光受容器は赤緑青の3錐体と杆体だけであると考えられていたが, 最近, 新たに視物質メラノプシンを含む神経節細胞 (melanopsin-expressing retinal ganglion cell; mRGC) が発見された. mRGCは生体リズムを調節していると考えられている視交叉上核や瞳孔反射をつかさどっている視蓋前域などに投射していることが知られている. 本研究では, mRGCを他の光受容体と独立に刺激するための多原色光源装置を用いて, mRGC経路の信号が輝度経路や色経路の信号とともにどのように瞳孔反応経路に寄与しているかを調べた. 実験の結果は, 輝度信号とmRGC経路の信号は非線形に結合して瞳孔系に入力していることを示唆している. 一方, 色信号とmRGC経路の信号は, 独立に瞳孔システムに入力していることを示唆していることがわかった.A recent study has shown that retinal ganglion cells, which are intrinsically photosensitive in primates, contain the photopigment melanopsin and project to the pupillary control center in the pretectum. The aim of this study was to investigate how signals that are driven by the melanopsin-expressing retinal ganglion cells (mRGCs) and by the other visual photoreceptors are able to contribute to the pupillary control mechanism. To independently stimulate the mRGCs from the other photoreceptors, we designed and built a novel multi-primary stimulation system. With regard to the pupillary response, our results suggest that there is a weak interaction between the M-L color signals and the mRGC signals. However, we also found that there is a strong non-linear interaction between the M+L luminance signals and the mRGC signals

Contribution of human melanopsin retinal ganglion cells to steady-state pupil responses

The recent discovery of melanopsin-containing retinal ganglion cells (mRGCs) has led to a fundamental reassessment of non-image forming processing, such as circadian photoentrainment and the pupillary light reflex. In the conventional view of retinal physiology, rods and cones were assumed to be the only photoreceptors in the eye and were, therefore, considered responsible for non-image processing. However, signals from mRGCs contribute to this non-image forming processing along with cone-mediated luminance signals; although both signals contribute, it is unclear how these signals are summed. We designed and built a novel multi-primary stimulation system to stimulate mRGCs independently of other photoreceptors using a silent-substitution technique within a bright steady background. The system allows direct measurements of pupillary functions for mRGCs and cones. We observed a significant change in steady-state pupil diameter when we varied the excitation of mRGC alone, with no change in luminance and colour. Furthermore, the change in pupil diameter induced by mRGCs was larger than that induced by a variation in luminance alone: that is, for a bright steady background, the mRGC signals contribute to the pupillary pathway by a factor of three times more than the L- and M-cone signals