Scientific

Abstract – The brain is the most incredible computational machine imaginable, with trillions of synaptic connections. How are connections wired up in development? Wiring happens sequentially first by forming a basic scaffold of connectivity according to genetic blueprints that define strict molecular guidance cues. Then the exact details of each circuit emerge by pruning and sculpting synapses from the immature pattern of connections. The decision-making process that determines which synaptic connections remain and which are pruned is also genetically specified and requires neural function. Even before birth, the brain generates its own internal neural activity to jump-start the sculpting process. After birth sensory systems mature and experience of the external world takes over to influence brain wiring during developmental critical periods. Neural activity and sensory experience regulate expression of sets of genes including several previously thought to act only in the immune system. These activity-regulated genes- including Major Histocompatibility Class I family members and Paired immunoglobulin-like receptor B- are required in neurons for pruning and sculpting synapses during development. Unexpectedly PirB signaling may also contribute to excessive synapse pruning in Alzheimer’s disease and PirB blockade can restore visual function in a mouse model of Amblyopia. Thus, the baby’s brain is not a miniature version of the adult, but rather is a dynamically changing structure in which neural activity and experience ultimately select and stabilize essential details of neural circuitry that make each of us different from one another. https://profiles.stanford.edu/carla-shatz

Abstract -The psychophysical and oculomotor literatures have long proposed that stereoscopic vision is served by multiple underlying subsystems. The subsystems are usually construed in terms of dichotomies, e.g patent vs qualitative, local vs global, first-order vs second-order, transient vs sustained, absolute vs relative, etc. Whether these multiple sub-systems are all independent is a matter of debate and moreover, there is very little known about their neural basis. Here I will describe recent work in which we attempt to unify two of the more prominent dichotomies — one spatial — absolute vs relative disparity and the other temporal — transient vs sustained. In a series of high-density EEG experiments using dynamic random dot stereograms that alternate between a flat plane and a stereo grating at 2 Hz, we find that odd harmonic components of the response reflect relative disparity extraction and that even harmonic components reflect absolute disparity extraction. Moreover, the odd harmonics reflect a sustained temporal mechanism, while the even harmonics reflect a transient mechanism. Taken together our results indicate that relative disparities are processed by sustained mechanisms while absolute disparity processing is transient in nature. https://profiles.stanford.edu/anthony-norcia

Abstract – Social use of gaze has long been a subject of interest in research on Autism Spectrum Disorder. However, a substantial body of work suggests that vision differences in ASD extend beyond social contexts to basic oculomotor control and visual information processing. Vision differences are observed clinically in ASD, but rarely addressed in early intervention for a number of reasons, leading to downstream consequences for motor skills and general ability. In this colloquium, we will discuss the potential mechanisms underlying visual system differences in ASD, their functional consequences, and potential avenues for assessment and intervention. https://www.kines.umich.edu/directory/haylie-miller

Abstract – Whenever we tilt our head towards the shoulder our eyes partially compensate by rotating around the line of sight in the opposite direction. This combination of head tilt and torsional eye movements results in a tilted retinal image, while we nevertheless perceive the world as still and upright. I will present the development of a new method to measure torsional eye movements reliably, which has enabled us to study the relationship between torsion and perception in the lab and the effects of vestibular loss in the clinic. I will show how stimulating the temporo-parietal cortex can alter perception of upright without affecting torsional eye movements, confirming the role of this area in the multisensory process maintaining upright perception. I will also present how patients can reweight different sensory inputs after acute vestibular loss and how measuring torsion helps us understand the effect of strong magnetic fields on the vestibular system. https://vision.berkeley.edu/posts/welcome-dr-jorge-otero-milan https://optometry.berkeley.edu/people/jorge-otero-millan-phd/

Abstract: The human visual system evolved in an environment with many statistical regularities. Binocular vision is adapted to these regularities such that depth perception and binocular eye movements are more precise, faster, and performed with more comfort in environments that are consistent with the regularities. We measured the statistics of eye movements and binocular disparities in natural and VR-gaming environments and found that they are quite different from one another. Fixation direction and distance are more restricted in VR. In addition, fixation distance is farther in VR. The pattern of binocular disparity across the visual field is less regular in VR and does not conform to a prominent property of naturally occurring disparities. The disparity pattern makes it more likely to experience double vision in VR-gaming environments. We determined from our fixation statistics the optimal screen distance to minimize discomfort due to the vergence-accommodation conflict. https://vision.berkeley.edu/people/avigael-aizenman/

Abstract – Conducting experimental research in the field of mobile accessibility and assistive technologies is difficult due to the low dimension of the representative population. To address this issue, a possible approach is remote collection and analysis of usage data through publicly available mobile applications. This method is useful for performing large scale experimental evaluations and acquiring knowledge of the target population and their behavior. The acquired knowledge can be used to advance future research and to improve the mobile applications themselves. https://sites.google.com/view/sergiomascetti/home.