Scientific

 Multisensory integration is essential for postural control and enabling safe navigation. The vestibular system plays a crucial role in these processes, contributing to functions important for maintaining one’s autonomy, such as balance, oculomotor control and spatial orientation. Healthy aging is accompanied by a decline in many perceptual, cognitive, and motor abilities, however, potentially leading to a loss of autonomy and increased health risks, most notably falls. Age-related macular degeneration (AMD), the leading cause of irreversible visual impairment in older adults in industrialized countries, adds another layer of complexity to these age-related changes. Binocular AMD results in central visual field loss, forcing individuals to adopt eccentric viewing strategies and develop  preferred retinal loci (PRLs) in the peripheral retina. This adaptation calls for significant oculomotor and eye-head coordination changes that would require a recalibration with the vestibular system in particular. The interplay of visual impairment, altered oculomotor function, and age-related sensorimotor deficits likely contributes to the balance and mobility difficulties reported in this population, though the mechanisms are poorly understood. For instance, how does the combined loss of central vision and associated oculomotor changes affect visual sampling during motion, space representation, and the integration of visual and body-based signals necessary for accurate perception and adaptive movements? Little is known about whether and how older individuals with AMD adapt to a peripheral PRL in the context of spatial orientation and postural control.In this talk, I will present relevant work from the literature and my studies in healthy aging and central field loss. I will then introduce an R01 proposal evolving from this research, which examines the recalibration of different sensorimotor systems to a PRL in individuals with AMD. The proposal focuses on three key areas: 1) head stabilization and the exploitation of residual vision, 2) gaze-direction induced illusions in spatial orientation perception, and 3) postural adaptation to eccentrically-viewed optic flow stimuli.  This research aims to bridge our knowledge gap in multisensory integration for balance, mobility, and fall risk in AMD. Ultimately, the goal is to inform the development of appropriate interventions, aids, and rehabilitation strategies for this population.

Digital drawing has historically been a significant challenge for blind individuals, with previous solutions requiring extensive imagination and technical skills. However, the Coughlan lab has been developing a groundbreaking “what you hear is what you get” drawing tool, revolutionizing this field. This innovative tool, powered by Audiom, enables blind users to create and edit complex shapes, maps, and art through auditory feedback. Users navigate a canvas using arrow keys, dropping points to form shapes and lines, which are then audibly represented, allowing for an intuitive and accessible drawing experience. Additionally, the tool supports the addition of sounds to objects, enhancing the creative process. This advancement not only facilitates artistic expression among the blind community but also offers educational applications, such as geometry assignments. With the ability to instantly share or export creations, this shape editor represents a significant leap forward in making digital drawing accessible to blind individuals.  Smith-Kettlewell Eye Research Institute is Listening to the Future of Navigation – Meet Engineer, Brandon Biggs (blindabilities.com)

I will present a system based on an iPhone app developed in the Coughlan Lab. This system is a novel “Point-and-Tap” interface that enables people who are blind or visually impaired (BVI) to easily acquire multiple levels of information about tactile graphics and 3D models. The interface uses an iPhone’s depth and color cameras to track the user’s hands while they interact with a model. To get basic information about a feature of interest on the model read aloud, the user points to the feature with their index finger. For additional information, the user lifts their index finger and taps the feature again. This process can be repeated multiple times to access additional levels of information. No audio labels are triggered unless the user makes a pointing gesture, which allows the user to explore the model freely with one or both hands. In addition, multiple taps can be issued in rapid succession to skip through to the desired information (an utterance in progress is halted whenever the fingertip is lifted off the feature), which is much faster than having to listen to all levels of information being played aloud in succession to reach the desired level. Experiments with BVI participants demonstrate that the approach is practical, easy to learn, and effective.

Movement is ubiquitous in everyday life, and accounting for our physical position as we move through the world is a constant process. Over the lifespan, experience in estimating one’s position accumulates, and the nervous system’s representation of this prior experience is thought to inform current perception of spatial orientation. Broadly, spatial orientation perception is a multimodal sensory process. The nervous system rapidly monitors, interprets, and integrates sensory information from various sources in an efficient, statistically optimal manner to estimate an organism’s position in its environment. In humans, key information in this process comes from the visual and vestibular systems, which use head-based sense organs. While statistics of natural visual and vestibular stimuli have been characterized, unconstrained head movement and position, which may drive correlated dynamics across these head-based senses in the real world, have not. Furthermore, head-based sensory cues essential to human spatial orientation perception, like estimation of one’s head orientation relative to gravity and heading (the direction of linear-velocity in a head-based coordinate system), have not been robustly measured in unconstrained, natural behaviors. Measurement of these head-based sensory cues in naturalistic settings, even if incomplete, will likely comprise a portion of the behaviors that make up ones’ total prior experience, and the quantitative characteristics of these behaviors may explain previously observed patterns of bias in verticality and heading perception.  In this brown bag, I will discuss methods of motion tracking in and out of the lab, my previous work to characterize natural statistics of head orientation and heading over 50 hours of human activity using these methods, work to use these natural statistics to constrain Bayesian models of sensory processing, and future research and applications that might leverage these data and approaches. Christian Sinnott | Smith-Kettlewell (ski.org)