Scientific

macneilage_main

Self-motion perception: interactions between visual, vestibular and motor signals

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Abstract: To reconstruct how the head is moving relative to the environment, the nervous system relies on a combination of visual and vestibular sensory information. Vestibular signals are driven by head movement whereas visual motion signals are driven by both head movement and eye movement relative to the head. Knowledge of eye movement, most likely based on motor efference, is therefore, necessary to allow for comparison and integration of visual cues with vestibular cues. Motor efference signals associated with head-on-body movement can also supplement sensory estimates of head movement. In this talk, I will present results of several psychophysical studies investigating interactions among these self-motion signals. Visual stimuli consist of optic flow patterns presented using either stereo monitors or head-mounted displays. Vestibular stimuli are presented by passively moving observers seated on either a motion platform or rotating chair. Oculomotor behavior is manipulated by varying movement of the fixation point between conditions. Participants judge their own movement or movement of the environment. Results suggest that motor signals play an important role in mediating visual-vestibular interactions. To relate these experimental results to natural behavior we have developed a system to track head and eye movement during everyday behavior, and we have begun characterizing typical visual, vestibular, and motor signals outside the lab. https://www.unr.edu/psychology/faculty/paul-macneilage

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Motion Perception in Central Field Loss

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  Abstract: Healthy peripheral retina is exquisitely sensitive to fast speeds. Individuals with central field loss (CFL) typically only have residual peripheral vision and studies suggest they become adept at using peripheral motion information, as in the case of vection (Tarita-Nistor et al. 2008). However, we showed that smooth pursuit in CFL is impaired across a range of speeds and visual acuity cannot explain this decrement in performance (Shanidze et al. 2016). Thus, the question remains whether this deficiency is due to oculomotor limitations, or a potential impairment of peripheral motion processing, as indicated by Eisenbarth et al. 2007. I will show data comparing the ability of CFL participants, age-matched controls and young controls to discriminate speed and direction of motion in a two spatial alternative forced-choice design. Our results indicate that age is a much stronger predictor of motion discrimination performance and suggest that CFL participants’ deficits in smooth pursuit are likely not due to motion perception deficits.

The NIH Study Study Section Review Process – a special Lunchtime talk

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Abstract: I will give a brief overview of the review process at the SPC study section at NEI. This will include review criteria including the blank critique form, instructions to reviewers on how to distribute scores, advice on giving the Overall Impact Score, the emphasis on scientific premise, scientific rigor. James Coughlan will provide his insight into the review process at BNVT. Bebe and the fellows who attended the NIH Grants training session last week will also be available for this Q&A session.

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Interocular suppression and selective visual attention in amblyopia

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Abstract Attention allows us to select the most important information while ignoring irrelevant information. One prominent role of attention is that visual attention operates through the facilitation of neural responses at the attended location and suppression of neural responses at the unattended location. This opens the possibility that amblyopic suppression may be a form of “attentional neglect” of visual input from the amblyopic eye to overcome “double vision” or “visual blur” due to strabismus or anisometropia. We speculate that a long-term “attentional neglect” of the visual input to the amblyopic eye may weaken attentional modulation in visual cortex. To test this hypothesis, we first measured attentional allocation and modulatory effects of spatial attention in the early visual cortex of human strabismic amblyopia using fMRI-informed EEG source imaging. Then, we related these findings to the psychophysical evidence of interocular suppression and the depth of amblyopia. In the latter part of the presentation, I will discuss the preliminary results from our ongoing studies.

mandu

(Computer) Vision without Sight: Finding, Reading, and Magnifying Text

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Abstract: Reading is a pervasive activity in our daily life. We read text printed on books and documents, shown on directional signs and advertisement, and displayed on computer and smartphone screens. People who are blind can read text using OCR on their smartphone; those with low vision may magnify onscreen content. But these tasks are not always easy. Reading a document with OCR requires taking a well-framed picture of it at an appropriate distance, something that is hard to do without visual feedback. Accessing “scene text” (e.g., a name tag or a directional sign) is even harder, as one needs to first figure out where the text might be. Screen magnification presents a different set of problems. One needs to manually control the center of magnification using the mouse or trackpad, all the while maintaining awareness of the current position in the document (the “page navigation problem”). In this talk, I will present a number of different projects in my lab addressing these problems. First, I will show how fast “text spotting” algorithms can be used to generate real-time feedback for blind users, indicating the presence of scene text in the camera’s field of view, or guiding the user to take a correctly framed picture of a document. I will then propose a simple gaze-contingent model for screen magnification control. Although our system currently uses an IR-based eye gaze tracker, we are planning to integrate it with an appearance-based tracker using data from the computer’s own camera. During the talk, I will present a number of experimental studies with blind and low vision participants, motivating and validating the proposed technology.   https://users.soe.ucsc.edu/~manduchi/  

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Attentive and subconscious mechanisms of smooth pursuit

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Abstract: Ocular smooth pursuit is fragile and therefore a sensitive biomarker of many neurological problems. But numerous disorders produce similar pursuit deficits rendering pursuit diagnosis non-specific. We think this problem arises because pursuit is almost exclusively tested with a small spot – a stimulus that compels foveation which is a function of the saccadic system. We hypothesize that when a spot is pursued, it not only invokes pursuit, it spontaneously and simultaneously activates the saccadic system. As a result, this not only causes catch-up saccades but also introduces sub-saccadic signals into pursuit. Furthermore, while pursuit is characterized as attentive, we think attention is conferred to pursuit by the saccadic system, and that pursuit is otherwise driven by a subconscious mechanism. Alternatively, many characteristics of pursuit result only from it sharing circuitry with the saccadic system. We have evidence that non-spot pursuit stimuli, or alternative saccade targets, reduces catch-up saccades, and change attention allocation during pursuit. Experiments test: if attentive saccade signals modulate pursuit, if subconscious pursuit can be disentangled from saccades, and if attention selects spot and non-spot pursuit goals. Pursuit, of non-spot stimuli, may reveal different patterns of neural deficits that allow more specific diagnoses.

Role of luminance contrast in depth perception from disparity

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Abstract: Binocular disparity is a precise depth cue yet in view of its derivation from binocular geometry. it is generally considered to be independent of luminance contrast. Our study, however, demonstrates a profound effect of luminance contrast on perceived depth from disparity. Such results cannot be explained by the existing disparity energy models because it would predict no effect of luminance contrast on depth perception. Instead, we conducted a multi-stage model that involves a contrast gain control mechanism followed by the disparity averaging to account for the luminance contrast effect on perceived depth from disparity.

fletcher

The Fourteenth Annual Meeting Low Vision Rehabilitation Study Group

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Announcing the Fourteenth Annual Meeting   Low Vision Rehabilitation Study Group     Purpose:  An informal gathering of clinicians/clinical researchers in low vision rehab   ·         discuss problem cases   ·         share techniques   ·         brainstorm ideas for new treatments or investigations   ·         enjoy collegiality Location:  San Francisco, California   ·         hosted by Don Fletcher, Ron Cole, Gus Colenbrander, and Tiffany Chan   ·         sponsored by Smith-Kettlewell Eye Research Institute (SKERI) and California Pacific Medical Center   ·         meeting is held at SKERI – 2318 Fillmore St., San Francisco, CA 94115   ·         rooms available at   o   Holiday Inn Golden Gate, Address: 1500 Van Ness Ave, San Francisco, CA 94109, Phone 🙁 415) 441-4000. Rates should be about $200 per night. Hotel is within walking distance of Smith-Kettlewell and has great views.   o   Kabuki Hotel, Address: 1625 Post St, San Francisco, CA 94115, Phone (415) 922-3200. Rates should be about $200 per night. An old favorite now remodeled – close to SKERI and good restaurants on Fillmore St.   o   Rodeway Inn – Civic Center, 860 Eddy Street, San Francisco CA 94109. Phone: (415)474-4374. Basic accommodation. Rate should be in the low $100s.   o   Uber from any of these hotels to the meeting for under $10   Dates:  Feb 1 and Feb 2, 2019   ·         Friday and Saturday – 3 hour morning and afternoon discussion groups   ·         fly in Thursday evening and out on Sunday   ·         stay longer if you like, San Francisco is a magnificent city   Who is invited? ·         anyone actively involved in vision rehabilitation   ·         NOT newcomers wanting to get started   o   (sorry – get your feet wet then join us) Registration Fee:  NONE (zero, no charge, $0.00 – what a deal!)   ·         you find your way here, cover your hotel and food – that’s the cost of it   ·         Contact Don Fletcher at floridafletch@msn.com to save a spot for Friday/Saturday   Attire and Attitude:  Informal   ·         Neckties, degrees, affiliations, and stuffiness must be checked at the door. Format:  Informal   ·         no invited speakers   ·         bring a case or technique to discuss   ·         no set agenda – we will divide the time between all comers   ·         if time allows we can discuss and solve all the problems facing the field   ·         divided into physician and therapist groups with some joint sessions Promise:  We won’t always agree but we’ll have a good time as a group that has a        common interest/passion.          

fletcher

The Fourteenth Annual Meeting Low Vision Rehabilitation Study Group

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  Announcing the Fourteenth Annual Meeting   Low Vision Rehabilitation Study Group     Purpose:  An informal gathering of clinicians/clinical researchers in low vision rehab   ·         discuss problem cases   ·         share techniques   ·         brainstorm ideas for new treatments or investigations   ·         enjoy collegiality   Location:  San Francisco, California   ·         hosted by Don Fletcher, Ron Cole, Gus Colenbrander, and Tiffany Chan   ·         sponsored by Smith-Kettlewell Eye Research Institute (SKERI) and California Pacific Medical Center   ·         meeting is held at SKERI – 2318 Fillmore St., San Francisco, CA 94115   ·         rooms available at   o   Holiday Inn Golden Gate, Address: 1500 Van Ness Ave, San Francisco, CA 94109, Phone 🙁 415) 441-4000. Rates should be about $200 per night. Hotel is within walking distance of Smith-Kettlewell and has great views.   o   Kabuki Hotel, Address: 1625 Post St, San Francisco, CA 94115, Phone (415) 922-3200. Rates should be about $200 per night. An old favorite now remodeled – close to SKERI and good restaurants on Fillmore St.   o   Rodeway Inn – Civic Center, 860 Eddy Street, San Francisco CA 94109. Phone: (415)474-4374. Basic accommodation. Rate should be in the low $100s.   o   Uber from any of these hotels to the meeting for under $10   Dates:  Feb 1 and Feb 2, 2019   ·         Friday and Saturday – 3 hour morning and afternoon discussion groups   ·         fly in Thursday evening and out on Sunday   ·         stay longer if you like, San Francisco is a magnificent city   Who is invited?   ·         anyone actively involved in vision rehabilitation   ·         NOT newcomers wanting to get started   o   (sorry – get your feet wet then join us)   Registration Fee:  NONE (zero, no charge, $0.00 – what a deal!)   ·         you find your way here, cover your hotel and food – that’s the cost of it   ·         Contact Don Fletcher at floridafletch@msn.com to save a spot for Friday/Saturday   Attire and Attitude:  Informal   ·         Neckties, degrees, affiliations, and stuffiness must be checked at the door.   Format:  Informal   ·         no invited speakers   ·         bring a case or technique to discuss   ·         no set agenda – we will divide the time between all comers   ·         if time allows we can discuss and solve all the problems facing the field   ·         divided into physician and therapist groups with some joint sessions   Promise:  We won’t always agree but we’ll have a good time as a group that has a        common interest/passion.          

dr

IRB Latest and Greatest

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Abstract:   This meeting will address a variety of topics near and dear to the Institutional Review Board. Items will range from reminders of guidelines and rules related to PIs communicating with the IRB re: research plans, as well as addressing some of the updated procedures coming from the NIH. This Brown Bag is intended for anyone at SKERI who has anything to do with human research subjects.   Please bring any questions, comments, and concerns to share with the group.