Non-visual System Research Articles

AudioMove: Applying the Spatial Audio to Multi-Directional Limb Exercise Guidance

Guiding users with limb exercise can assist in muscle training or physical recovery. However, traditional vision-based methods often require multiple camera angles to help users understand the motions and require them to be within the range of the screen. Therefore, we propose a non-visual system that can guide users with multiple-directional limb motions utilizing spatial audio, AudioMove , with commercial-off-the-shelf (COTS) devices (i.e., smartphones and earphones). The proposed system addresses the challenge of conveying directional information encompassing multiple planes in real-time. We conduct a mixed-method user study to evaluate the effectiveness of the system with three methods combining motion data with spatial audio perception. Additionally, a user interface is built to collect users' comments. The results conclude that spatial audio guidance could create a natural, pervasive, and non-visual exercise training solution in daily life.

Light: An Extrinsic Factor Influencing Animal-based Research.

Light is an environmental factor that is extrinsic to animals themselves and that exerts a profound influence on the regulation of circadian, neurohormonal, metabolic, and neurobehavioral systems of all animals, including research animals. These widespread biologic effects of light are mediated by distinct photoreceptors-rods and cones that comprise the conventional visual system and melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) of the nonvisual system that interact with the rods and cones. The rods and cones of the visual system, along with the ipRGCs of the nonvisual system, are species distinct in terms of opsins and opsin concentrations and interact with one another to provide vision and regulate circadian rhythms of neurohormonal and neurobehavioral responses to light. Here, we review a brief history of lighting technologies, the nature of light and circadian rhythms, our present understanding of mammalian photoreception, and current industry practices and standards. We also consider the implications of light for vivarium measurement, production, and technological application and provide simple recommendations on artificial lighting for use by regulatory authorities, lighting manufacturers, designers, engineers, researchers, and research animal care staff that ensure best practices for optimizing animal health and well-being and, ultimately, improving scientific outcomes.

The Necessity for Multi-Spectral Simulations of the Indoor Non-Visual Luminous Environment: A Simplified Annual Approach

The difference between the functioning of the human non-visual and photopic systems has elicited the need for complex in situ measurements or time-consuming multi-spectral simulations to accurately predict the non-visual luminous content of the indoor environment. As such methodologies are time-consuming, the aim of the present study was to determine whether such complex methodologies are needed. The issue was studied through simulations of four cardinally oriented identical offices located in Ljubljana, Slovenia. Each was studied using orange, grey and blue walls. Diurnal luminous conditions were studied under clear, hazy and overcast skies on December, March and June 21st. The non-visual content was evaluated using novel metrics, the Autonomy of Circadian Potential and Circadian Autonomy, which assess temporal circadian luminous content. Diurnal results were used to construct climate-based spectral months to evaluate the monthly non-visual potential of the studied offices. Furthermore, simulations addressed the question of whether the requirements of the non-visual system might contradict the visual comfort of indoor environments. The results show that compliance with non-visual requirements for indoor spaces with spectrally neutral surfaces or those in shades of blue could be assessed using photopic methodologies. However, this is not true for spaces characterised by orange and red materials.

Design and Development of a Sustainable Environmentally Friendly and Human Centric Luminaire

Apart from the visual effects, light can also affect the human non-visual system, which includes a wide range of functions such as hormone secretion, alertness, mood etc. The non-image forming effects occur because light affects melanopsin, a photosensitive protein present in the receptive domain of retinal ganglion cells. These cells are responsible for generating nerve impulses that regulate the secretion of two hormones, cortisol and melatonin. Low-wavelength light at 460-480 nm inhibits melatonin secretion and activates brain activity. Aim of this paper is to create a sustainable and human centric luminaire suitable for office installations that will regulate the biological rhythm of the occupants and has the minimum environmental impact. The luminaire’s light source emits variable spectrum, with a collated colour temperature varying between 2700K and 6500K. For a 500K step of colour temperature values, the appropriate human centric lighting metrics are calculated: Equivalent Melanopic Lux, Melanopic Daylight Equivalent Illuminance, Circadian Stimulus. The development of the human centric luminaire considers not only the metrics of human centric lighting but energy efficiency and visual comfort as well. Conclusively, the proposed luminaire can provide a holistic approach to lighting design so as to integrate both visual and non-visual effects and produce sustainable and environmentally friendly lighting.

Visual system development and changes in hatching performance in hybrid grouper embryos under different light conditions

Light greatly impacts the performance of teleost embryos. In this study, the development of visual system and performance of Epinehelus moara × Epinephelus lanceolatus embryos under different light spectra (red, orange, green, blue and full spectrum) and dark conditions were assessed. The development of visual system was not completed during embryonic development, characterized by the absence of structural integrity in the retina, indicating the absence of visual photosensitivity. However, nonvisual system may play an important role in photosensitivity. Light conditions contributed significantly to embryo performance, including hatching rate, deformity rate and Wnt signaling pathway expression. There was no statistical difference in the oxygen consumption rate of embryos in different groups during heartbeat onset stage. Embryos in dark group had a significantly lower hatching rate than other groups. The hatching rate in full light spectrum group was significantly higher than red spectrum group, and no significant differences were observed among the other groups. The deformity rate of newly hatched larvae exposed to orange light was significantly lower than those under full spectrum and dark conditions. The mRNA expression level of frizzled2, dickkopf2, limb bud and heart homolog, and natural kermes dye inhibitor of Wnt signaling pathway 1 were detected. The results suggested that dark conditions could lead to the abnormal expression of the Wnt signaling pathway, characterized by significantly lower mRNA expression levels of these factors, which in turn may cause decreased hatchability. In order to increase the hatchability and performance of embryos, and reduce the deformity rate, orange light should be utilized and dark conditions should be avoided during the embryonic development of E. moara × E. lanceolatus.

Seasonal variation in neurohormones, mood and sleep in patients with primary open angle glaucoma – implications of the ipRGC-system

ABSTRACT Primary open angle glaucoma is associated with an increased risk of mood and sleep disorders. These adversities have been suggested to relate to a disrupted function of the intrinsically photosensitive retinal ganglion cells (ipRGCs). The ipRGCs are key components in the nonvisual photoreceptive system that mediates light effects on mood, sleep and circadian rhythm. We assessed the diurnal hormone levels, pupillary responses and mood and sleep under seasons with different photoperiods in 24 patients with glaucoma and 24 age- and sex-matched healthy controls to investigate responses to naturalistic seasonal changes in daylight. The patients had moderate-to-advanced glaucoma with substantial visual field defects and reductions in the ipRGC-mediated pupillary responses (p < .001). In winter, compared with summer, patients with glaucoma had higher daytime melatonin concentration (p < .001) and lower nighttime cortisol (p = .002). In winter, the daytime melatonin level was inversely correlated with the ipRGC-mediated pupillary responses in the control group (p = .04). In the control group, there were no significant changes in hormone levels between seasons or any correlations between neurohormone levels and the ipRGC-mediated responses. The two groups showed a similar response to season with lower depression scores in summer compared with winter. In between-group comparison, the nocturnal melatonin level (area under curve from 20:00 h to 08:00 h) in summer was lower in glaucoma compared with controls (p = .03). In winter, nocturnal cortisol (at 04:00 h) was lower (p = .004) and daytime cortisol (12:00 h and 16:00 h) was higher (p = .007) in glaucoma compared with controls. In conclusion, we found that patients with glaucoma displayed a seasonal variation in diurnal hormone levels that was not present in healthy controls. Such neurohormonal changes may contribute to the increased risk of mood and sleep disorders seen in patients with glaucoma.

Analysis of anomalous head posturing in patients with infantile nystagmus syndrome

To investigate anomalous head posturing in patients with INS. This was a prospective, cohort analysis of clinical and anomalous head posture (AHP) data in 34 patients with INS and an AHP. Particular outcome measures included measurement of AHP in three dimensions of pitch (anterior posterior flexion/extension), yaw (lateral rotation), and roll (lateral flexion) during best-corrected binocular acuity testing and during their subjective sense of straight. Patients were also queried as to their subjective sense of head posture in forced straight position and in their preferred AHP. The paired t test was used to determine significance in differences between measures. A total of 34 patients (19 males [56%]) 9-56years of age (mean, 16.5±6) were included. Associated systemic or ocular system deficits were present in 30 patients (88%). AHP during best-corrected visual acuity testing averaged 16.5°±8.20° (range, 10°-51°), which was significantly different from the mean voluntary "comfortable" position only in the pitch and roll directions (P<0.001). There was a significant noncongruous response during subjective response to head posturing with most sensing their head as "crooked" (76.5%) when manually straightened (P=0.001). The clinical AHP of patients with INS exists in all three spatial dimensions of pitch, yaw, and roll. Although the visual system may be causally related to the onset, amount, and direction of a compensatory AHP in patients with INS, its persistence over time or after surgical intervention is likely due to a combination of visual system (eg, nystagmus, strabismus) and nonvisual system (egocentric and musculo-skeletal) factors.

Task Analysis on Yoga Poses Toward a Wearable Sensor-based Learning System for Users with Visual Impairment

People with visual impairments may experience difficulties in learning new physical exercises due to a lack of visual feedback. Learning and practicing yoga is especially challenging for this population as yoga requires imitation-oriented learning. A typical yoga class requires students to observe and copy poses and movements as the instructor presents them, while maintaining postural balance during the practice. Without additional, nonvisual feedback, it can be difficult for students with visual impairments to understand whether they have accurately copied a pose – and if they have not, how to fix an inaccurate pose. Therefore, there is a need for an intelligent learning system that can capture a person’s physical posture and provide additional, nonvisual feedback to guide them into a correct pose. This study is a preliminary step toward the development of a wearable inertial sensor-based virtual learning system for people who are blind or have low vision. Using hierarchical task analysis, we developed a step-by-step conceptual model of yoga poses, which can be used in constructing an effective nonvisual feedback system. We also ranked sensor locations according to their importance by analyzing postural deviations in each pose compared to the reference starting pose.

Daytime Acute Non-Visual Alerting Response in Brain Activity Occurs as a Result of Short- and Long-Wavelengths of Light

Abstract. Very recent preliminary findings concerning the alerting capacities of light stimulus with long-wavelengths suggest the existence of neural pathways other than melatonin suppression that trigger the nonvisual response. Though the nonvisual effects of light during the daytime have not been investigated thoroughly, they are definitely worth investigating. The purpose of the present study is to enrich existing evidence by describing how quantitative electroencephalography (EEG) signal analysis can give insight into the measurement of the acute nonvisual response observed in brain states generated during daytime exposure to light (when melatonin secretion is negligible). EEG changes were assessed in 19 subjects during the daytime while being exposed to both short- (blue, 72 μW/cm2) and long-wavelength (red, 18 μW/cm2) radiation. We showed that artificial light stimulus as low as 40 lux decreases the synchronization in the upper theta, lower alpha, and upper alpha EEG activity spectrum. The direction of change was consistent with an increased level of alertness. We can conclude that EEG analysis is an indicator of the acute nonvisual response to daytime light. Surprisingly, the response was more spread over the scalp during exposure to red light than to blue light. According to our study, the response to long-wavelength stimulus that inhibits sleepiness, thereby inducing alertness, also takes place at the bright part of the 24-hr day when human beings are naturally predisposed to be exposed to a high level of sunlight: between 12 and 4 PM. The absorption spectrum of the nonvisual system seems to have different characteristics than was previously suspected: it is not dominated by the short-wavelengths, but involves long-wavelengths. Since we observed the predominance of the red-light alerting effect over the blue-light in this experiment, we conclude that more than one mechanism, beyond the melatonin pathway, must be involved.

Comparison of Four Control Methods for a Five-Choice Assistive Technology.

Severe motor impairments can affect the ability to communicate. The ability to see has a decisive influence on the augmentative and alternative communication (AAC) systems available to the user. To better understand the initial impressions users have of AAC systems we asked naïve healthy participants to compare two visual (a visual P300 brain-computer interface (BCI) and an eye-tracker) and two non-visual systems (an auditory and a tactile P300 BCI). Eleven healthy participants performed 20 selections in a five choice task with each system. The visual P300 BCI used face stimuli, the auditory P300 BCI used Japanese Hiragana syllables and the tactile P300 BCI used a stimulator on the small left finger, middle left finger, right thumb, middle right finger and small right finger. The eye-tracker required a dwell time of 3 s on the target for selection. We calculated accuracies and information-transfer rates (ITRs) for each control method using the selection time that yielded the highest ITR and an accuracy above 70% for each system. Accuracies of 88% were achieved with the visual P300 BCI (4.8 s selection time, 20.9 bits/min), of 70% with the auditory BCI (19.9 s, 3.3 bits/min), of 71% with the tactile BCI (18 s, 3.4 bits/min) and of 100% with the eye-tracker (5.1 s, 28.2 bits/min). Performance between eye-tracker and visual BCI correlated strongly, correlation between tactile and auditory BCI performance was lower. Our data showed no advantage for either non-visual system in terms of ITR but a lower correlation of performance which suggests that choosing the system which suits a particular user is of higher importance for non-visual systems than visual systems.

Evaluation of Indoor Daylight Parameters during Long–Term Observations in the Rooms Equipped with Intensive Coloured Surfaces

Examination, design and control of internal light conditions belong to important actual architectural issues. In most cases the reason is increasingly growing interest in non-visual response of human on the ambient light properties. Sick Building Syndrome (SBS) is assumed to be caused by complex of inappropriate indoor environment circumstances. Unsuitable light conditions are regarded to be one of them. This paper deals with comparison of internal light parameters such as photopic illuminance level EV, Spectral Power Distribution (SPD) and definition of peak wavelength value recorded in tested office rooms, which were scaled down to models for easier handling. Models are equipped with different selected colored wallpapers and flooring materials, whereby one model remains with all surfaces in neutral colors. The outputs of measured parameters are compared with each other and also with outdoor levels of the same light properties. There is also defined filtration efficacy of blue light component assumed to be most effective for controlling of non-visual sensoring system of human body. This observation may provide more complex overview on selection of internal surfaces colors in long-term occupied spaces, taking health and wellbeing into consideration.

The Effect of the Colour Selection for Internal Surfaces on Non-Visual Daylight Human Response

Nowadays lighting criterions for internal spaces can be widened; because there is need to not only stimulate properly the human visual system but also to entrain the non-visual system of users or inhabitants. Since the medical discoveries in the field of light influence of circadian system, a system that controls our daily body rhythms, gave us basic principles how it works, we can use advanced methods how to evaluate internal light climate in the buildings. We focused on the colours of wall finishes, which influence the spectral composition of the light that enters the eye of inhabitants in specified locations. A set of specified applied colors were compared to the neutrally coloured walls. Also the effect of external shading obstruction was examined in this study. This observation, based on the spectral examination of light conditions, may provide more complex overview on selection of internal surfaces colours in long-term occupied spaces, taking health and wellbeing into consideration.

New light for old eyes: comparing melanopsin-mediated non-visual benefits of blue-light and UV-blocking intraocular lenses

Background/aimsMelanopsin-expressing photosensitive retinal ganglion cells form a blue-light-sensitive non-visual system mediating diverse physiological effects including circadian entrainment and cognitive alertness. Reduced blue wavelength retinal illumination through cataract formation is thought...

Modelling ‘non-visual’ effects of daylighting in a residential environment

The importance of light not only as a therapeutic tool but as an essential element of healthy living has been highlighted by the recent discovery of a specialized photoreceptor in the eye responsible for synchronizing our internal circadian pacemaker. This pigment, melanopsin, differs from visual receptors in several characteristics, here simplified into a blue-shifted spectral sensitivity and a dose–response curve established from night-time studies. While a vast range of tools has been developed to simulate the amount of light in lux or lumens falling on a static, horizontal surface, corneal exposure estimates are needed for modelling the biological responses to light in space, which require a vertical sensor that can rotate and translate as a human eye does. This paper examines the effects of housing design upon the amount of daylight available for maintaining synchronization of the human circadian system considered in conjunction with human movement, using historic Boston row houses as a case study. Based on a series of simulations taking into account the two above-mentioned characteristics of the non-visual system, this paper proposes a preliminary workflow for suggestions regarding lighting restoration and opens new perspectives on future variables to include. This study found that even modest renovations like painting the space a lighter colour have a noticeable impact on the light received by a moving sensor. More aggressive design choices, such as not using the basement floor of the house for apartments, raise the amount and timing of light received to nearly the level of the best-case scenario.

A framework for predicting the non-visual effects of daylight – Part II: The simulation model

This paper describes a climate-based simulation framework devised to investigate the potential for the non-visual effects of daylight in buildings. It is part 2 of a study where the first paper focused on the formulation of the photobiological underpinnings of a threshold-based model configured for lighting simulation from the perspective of the human non-visual system (e.g. circadian response). This threshold-based model employs a static dose–response curve and instantaneous exposure of daylight at the eye to estimate the magnitude of the non-visual effect as a first step towards a simulation framework that would establish a link between light exposure at the eye in an architectural context and expected effects on the non-visual system. In addition to being highly sensitive to the timing and duration of light exposure, the non-visual system differs fundamentally from the visual system in its action spectrum. The photosensitivity of the retinal ganglion cells that communicate light exposure to the brain is known to be shifted to the blue with respect to the photopic sensitivity curve. Thus the spectral character of daylight also becomes a sensitive factor in the magnitude of the predicted non-visual effect. This is accounted for in the model by approximating ‘yellow’ sunlight, ‘grey’ skylight and ‘blue’ skylight to three distinct Commission Internationale de l'Eclairage (CIE) illuminant types, and then tracking their ‘circadian-lux’ weighted contributions in the summation of daylight received at the eye. A means to ‘condense’ non-visual effects into a synthesised graphical format for the year, split by periods of the day, is described in terms of how such a format could inform design decisions. The sensitivity of the simulation model’s predictions to prevailing climate and building orientation is demonstrated by comparing results from eight European locations.

Photochemical Properties of Mammalian Melanopsin

Melanopsin is the photoreceptor molecule of intrinsically photosensitive retinal ganglion cells, which serve as the input for various nonvisual behavior and physiological functions fundamental to organisms. The retina, therefore, possess a melanopsin-based nonvisual system in addition to the visual system based on the classical visual photoreceptor molecules. To elucidate the molecular properties of melanopsin, we have exogenously expressed mouse melanopsin in cultured cells. We were able to obtain large amounts of purified mouse melanopsin and conducted a comprehensive spectroscopic study of its photochemical properties. Melanopsin has an absorption maximum at 467 nm, and it converts to a meta intermediate having an absorption maximum at 476 nm. The melanopsin photoreaction is similar to that of squid rhodopsin, exhibiting bistability that results in a photosteady mixture of a resting state (melanopsin containing 11-cis-retinal) and an excited state (metamelanopsin containing all-trans-retinal) upon sustained irradiation. The absorption coefficient of melanopsin is 33000 ± 1000 M(-1) cm(-1), and its quantum yield of isomerization is 0.52; these values are also typical of invertebrate bistable pigments. Thus, the nonvisual system in the retina relies on a type of photoreceptor molecule different from that of the visual system. Additionally, we found a new state of melanopsin, containing 7-cis-retinal (extramelanopsin), which forms readily upon long-wavelength irradiation (yellow to red light) and photoconverts to metamelanopsin with short-wavelength (blue light) irradiation. Although it is unclear whether extramelanopsin would have any physiological role, it could potentially allow wavelength-dependent regulation of melanopsin functions.

No role for direct touch using the pectoral fins, as an information gathering strategy in a blind fish

Blind Mexican cave fish (Astyanax fasciatus) lack a functional visual system and have been shown to sense their environment using a technique called hydrodynamic imaging, whereby nearby objects are detected by sensing distortions in the flow field of water around the body using the mechanosensory lateral line. This species has also been noted to touch obstacles, mainly with the pectoral fins, apparently using this tactile information alongside hydrodynamic imaging to sense their surroundings. This study aimed to determine the relative contributions of hydrodynamic and tactile information during wall following behaviour in blind Mexican cave fish. A wall was custom built with a 'netted' region in its centre, which provided very similar tactile information to a solid tank wall, but was undetectable using hydrodynamic imaging. The fish swam significantly closer to and collided more frequently with the netted region of this wall than the solid regions, indicating that the fish did not perceive the netted region as a solid obstacle despite being able to feel it as such with their pectoral fins. We conclude that the touching of objects with the pectoral fins may be an artefact of the intrinsic link between pectoral fin extensions and tail beating whilst swimming, and does not function to gather information. During wall following, hydrodynamic information appears to be used strongly in preference to tactile information in this non-visual system.

Responses of the hypothalamic paraventricular neurons to light stimulation with different wavelengths in the rat

During exposure to light with different spectral compositions, the non-visual neural system in the brain gives rise to altered various physiological aspects that are not caused by the well-known primary visual pathway. This study has been designed to investigate non-visual information processing that affects the biological rhythms in humans by studying the properties of paraventricular neurons in Sprague-Dawley rats under urethane anesthesia. The responses of paraventricular nucleus neurons by stimulation with different wavelengths of light were recorded. It turned out that neural responses were most sensitive to 550 nm wavelength light. This result suggests that a non-visual system in the hypothalamus including the paraventricular nucleus responds to light stimuli to control biological rhythms or autonomic functions.

Pineal rhythms are synchronized to light–dark cycles in congenitally anophthalmic mutant rats

Genetically mutant anophthalmic rats lacking a complete visual system due to the absence of eyeballs and optic nerves up to the optic chiasma were used as a model to study photo-regulated physiological activities. The photoreception in these mutant rats was determined by measuring the neuroendocrine response of the pineal gland-melatonin levels in the serum, and synaptic ribbon complexes (SRCs) in the pinealocytes. These parameters were studied in both normal and anophthalmic rats maintained under light–dark (LD 12:12), continuous dark (DD) and light (LL) conditions. Both normal and mutant anophthalmic animals showed nocturnal increases in serum melatonin levels and in the number and diameter of SRC and their vesicles in the pinealocytes in LD. The daily rhythms persisted even upon transfer to DD both in normal and mutant rats, whereas in LL, the nocturnal elevation of both the parameters disappeared. These observations suggested that congenitally blind rats can perceive light. The studies of these parameters in both normal and mutant rats in reversed-LD conditions confirmed that pineal rhythms can be entrained by light–dark cycles in congenitally anophthalmic mutant rats through a nonvisual system for light perception.

Tonic retinal influences in primates.

A type of unit discharge, termed "luxotonic," has been found in the striate cortex of unanesthetized squirrel monkeys and macaques.6, 21 The firing frequency of these units shows relatively little adaptation, continues indefinitely (hours), and reflects the level of diffuse illumination of the eye. The more numerous "photergic" units discharge more rapidly in the light, whereas "scotergic" units fire fastest in the dark (or at luminance levels below threshold for cones). Luxotonic activity is abolished by anesthesia and has not been described for striate cortex of other species. Primates also display a profound alteration in the EEG of striate cortex following elimination of all retinal input.32 Since this change is far more drastic than that produced by blindness in other species, it is natural to inquire whether it is related to the loss of the normally prominent luxotonic activity. When the blind monkey sleeps, the bizarre EEG is replaced by patterns wholly normal in appearance,32 indicating that some nonvisual system has extensive access to striate cortex in this state.