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Dr. David Brainard

Vision Research Thrives at UPenn

By Rebecca Salowe

Scheie Vision Winter 2015

An Ophthalmology Department is not complete without vision scientists.  Vision research drives progress in the field, leading to a better understanding of the eye and ocular diseases.  The innovative research of basic vision scientists allows ophthalmologists to offer state-of-the-art care to patients with severe eye disease and injury.  

At UPenn, vision researchers are led by David Brainard, PhD.  Dr. Brainard serves as the RRL Professor of Psychology and the Director of the Vision Research Center at UPenn.  The Vision Research Center administers the Core Grant from the National Eye Institute, which provides services to support all vision researchers at UPenn.  These researchers come from a variety of backgrounds.

“The Vision Research Center is made up of more than 50 investigators,” Dr. Brainard explained. “These investigators come from many different departments, ranging Ophthalmology, Psychology, Neuroscience, the Veterinary School, the Dental School, Bioengineering, and more.”   

Dr. Brainard’s research focuses specifically on vision and color image processing.  He works on several collaborations with Ophthalmology faculty, while also conducting his own research projects.  

One project, a collaboration with Geoffrey Aguirre in Neurology, has made extraordinary progress recently.  Drs. Brainard and Aguirre’s research centers around “melanopsin containing ganglion cells,” which are believed to be a new class of light-sensing cells.

“The basic cells that have long been known to sense light in the eye are the rods and the cones,” explained Dr. Brainard.  “It was discovered about 15 years ago that some of the retinal ganglion cells, which process the signals from rods and cones and send them to the brain, are also themselves capable of detecting light.  So this was a total shock to everyone – completely unknown and unsuspected.  There is one more class of light-sensing cells.”

However, the image produced by melanopsin containing ganglion cells is out of focus.  Thus the question arises: what is the purpose of these cells?

Researchers believe that these cells control our circadian clock and cause the familiar constriction of the pupil to bright light.  Using this logic, melanopsin may be involved in a number of disorders that involve sensing too much or too little light, such as seasonal affective disorder or migraine.

Drs. Brainard and Aguirre’s recent research succeeded in isolating and studying the properties of melanopsin, separate from cones cells – something that was previously not possible.  To accomplish this, the UPenn team developed a special class of visual stimuli: a flickering light that stimulates melanopsin but is invisible to cones, and a second flickering light that stimulates cones but is invisible to melanopsin.  Curiously, the light targeted at the short-wavelength sensing cones made the pupil enlarge, while the light targeted at melanopsin resulted in the familiar constriction of the pupil to increases in light.  Now that melanopsin and cone responses to light are teased apart, Dr. Brainard and colleagues can study what we “see” with melanopsin and how this affects light-related disorders. 

“Migraine will be our first target,” said Dr. Brainard.  “We think that melanopsin might normally control how strongly the cones send signals.   This is our working hypothesis.  Perhaps this isn’t working quite right and you get too much light response.  That may be why you want to be away from light when you have a migraine.”

Other conditions of interest include seasonal affective disorder, which involves receiving less light, and concussion.  In the future, Dr. Brainard hopes to expand findings on melanopsin to populations as a whole.  Discovering that certain populations have hyper- or hypo- activity of the melanopsin system would motivate studies of genetic variations that lead to these differences.

This study is just one example of how collaborations across departments lead to high-impact research.  

“No single faculty member can know everything,” said Dr. Brainard.  “Collaboration is a way that scientists have leveraged their specialized expertise in the areas where they couldn’t really venture by themselves.”

Dr. Brainard especially values his relationship with ophthalmologists at the Scheie Eye Institute.

“I can’t say that I distinguish between Scheie and the rest of campus,” he said.  “We have a little bit of physical distance to Scheie, but Dr. O’Brien is great about increasing the incidental contact.  She is hosting a Vision Scientist dinner at Scheie soon, for example.  This allows collaborations to develop in many ways, because you run into people in a slightly less formal setting and can chat about what you do.”

A prime example of a successful collaboration between Dr. Brainard and Ophthalmology faculty is his work on color in calibrated images.

“I work with Drs. Maureen Maguire, Richard Stone, Vatinee Bunya, Mina Massaro, and James Gee on a couple of different projects that involve using calibrated images to track progression of eye diseases and quantitatively evaluate the severity of disease,” Dr. Brainard explained.  “I got involved in this project because of the need to calibrate the images and make the colors reliable. For example, how red is it?  Having a computer program process the image, as opposed to human judgment, allows us to figure out the severity of the symptom.” 

Most recently, Dr. Brainard received a Research to Prevent Blindness Stein Innovation Award to support his collaboration with Dr. Jessica Morgan.  Dr. Morgan uses adaptive optics to measure very high-resolution images of the living eye.  She observes the structural changes that occur during disease progression and how these changes are (or are not) reversed during gene therapy.  Dr. Brainard will work with her to probe whether someone can see very fine spots, which helps the investigators understand how structural changes in the eye affect the ability to see.

Contact with ophthalmologists is very rewarding to Dr. Brainard.

“For basic scientists, who have structured their careers around obtaining knowledge that doesn’t have immediate applicability, it’s very satisfying to know you are helping people.”  

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