Neuroengineering/Bioengineering Seminar: “Photovoltaic Restoration of Sight in Age-related Macular Degeneration” (Daniel Palanker)

Daniel Palanker, PhD

The Center for Neuroengineering and Therapeutics and the Department of Bioengineering present:

Speaker: Daniel Palanker, Ph.D.
Director of the Hansen Experimental Physics Laboratory and Professor of Ophthalmology
Stanford University

Date: Wednesday, November 18, 2020
Time: 1:00-2:00 PM EST
Zoom – check email for link or contact eprince@seas.upenn.edu

Title: “Photovoltaic Restoration of Sight in Age-related Macular Degeneration”

Abstract:

Retinal degenerative diseases lead to blindness due to loss of the “image capturing” photoreceptors, while neurons in the “image-processing” inner retinal layers are relatively well preserved. Information can be reintroduced into the visual system using electrical stimulation of the surviving inner retinal neurons. We developed a photovoltaic substitute of photoreceptors which convert light into pulsed electric current, stimulating the secondary retinal neurons. Visual information captured by a camera is projected onto the retina from augmented-reality glasses using pulsed near-infrared (~880nm) light. This design avoids the use of bulky electronics and wiring, thereby greatly reducing the surgical complexity. Optical activation of the photovoltaic pixels allows scaling the number of electrodes to thousands. In preclinical studies, we found that prosthetic vision with subretinal implants preserves many features of natural vision, including flicker fusion at high frequencies (>30 Hz), adaptation to static images, antagonistic center-surround organization and non-linear summation of subunits in receptive fields, providing high spatial resolution. Results of the clinical trial with our implants (PRIMA, Pixium Vision) having 100μm pixels, as well as preclinical measurements with 75 and 55μm pixels, confirm that spatial resolution of prosthetic vision can reach the pixel pitch. Remarkably, central prosthetic vision in AMD patients can be perceived simultaneously with peripheral natural vision. For broader acceptance of this technology by patients who lost central vision due to agerelated macular degeneration, visual acuity should exceed 20/100, which requires pixels smaller than 25μm. I will describe the fundamental limitations in electro-neural interfaces and 3-dimensional configurations which should enable such a high spatial resolution. Ease of implantation of these wireless arrays, combined with high resolution opens the door to highly functional restoration of sight.

Bio:

Daniel Palanker is a Professor of Ophthalmology and Director of the Hansen Experimental Physics Laboratory at Stanford University. He received MSc in Physics in 1984 from the State University of Armenia in Yerevan, and PhD in Applied Physics in 1994 from the Hebrew University of Jerusalem, Israel. Dr. Palanker studies interactions of electrical field with biological cells and tissues, and develops optical and electronic technologies for diagnostic, therapeutic, surgical and prosthetic applications, primarily in ophthalmology. In the range of optical frequencies, his studies include laser-tissue interactions with applications to ocular therapy and surgery, and interferometric imaging of neural signals. In the field of electro-neural interfaces, he is developing highresolution photovoltaic retinal prosthesis for restoration of sight and implants for electronic control of organs. Several of his developments are in clinical practice world-wide: Pulsed Electron Avalanche Knife (PEAK PlasmaBlade, Medtronic), Patterened Scanning Laser Photocoagulator (PASCAL, Topcon), Femtosecond Laser-assisted Cataract Surgery (Catalys, J&J), and Neural Stimulator for enhancement of tear secretion (TrueTear, Allergan). Photovoltaic retinal prosthesis for restoration of sight (PRIMA, Pixium Vision) is in clinical trials.

See the full list of upcoming Penn Bioengineering events here.

Penn Researchers Detect Brain Differences between Fast and Slow Learners

By Lauren Salig

These 12 object-number value pairs were taught to the participants, who had to properly learn the associations to succeed in value judgement tests. The researchers investigated the differences in their brain activity patterns to see why some were faster learners than others.

Why do some people naturally excel at learning instruments, languages or technology while others take longer to pick up new knowledge? Learning requires the brain to encode information, changing its neural “wiring” and creating networks between brain regions.

In a new study, researchers at the University of Pennsylvania’s School of Engineering and Applied Science and the Max Planck Institute for Dynamics and Self-Organization in Germany looked at how brain activation patterns might affect how long it takes for new information to really stick in the brain.

Earlier research has suggested that part of what might slow down learners is over-thinking. A 2015 study led by Danielle Bassett, Eduardo D. Glandt Faculty Fellow and associate professor in the Department of Bioengineering, showed a correlation between slow learning and cognitive control: the brain’s ability to regulate itself by activating the necessary networks and inhibiting unnecessary activity. In that study, when people unnecessarily engaged parts of the brain linked to cognitive control, they were more likely to take longer to learn a simple task.

But beyond what might make an individual learn more slowly, the researchers want to know what sort of geometric patterns of brain activity make for better learning.

Evelyn Tang and Danielle Bassett

Their new study was led by Bassett and Evelyn Tang, who was an Africk Family Postdoctoral Fellow in Bassett’s Complex Systems Lab before starting at the Max Planck Institute this fall. Sharon Thompson-Schill, Christopher H. Browne Distinguished Professor and chair of Psychology, also contributed to the study.

The study was published in the journal Nature Neuroscience.

Read the full story at the Penn Engineering Medium Blog.

Week in BioE: March 29, 2019

by Sophie Burkholder

New Studies in Mechanobiology Could Open Doors for Cellular Disease Treatment

When we think of treatments at the cellular level, we most often think of biochemical applications. But what if we began to consider more biomechanical-oriented approaches in the regulation of cellular life and death? Under a grant from the National Science Foundation (NSF),Worcester Polytechnic Institute’s (WPI) Head of the Department of Biomedical Engineering Kristen Billiar, Ph.D., performs research that looks at the way mechanical stimuli can affect and trigger programmed cell death.

Billiar, who received his M.S.E. and Ph.D. from Penn, began his research by first noticing the way that cells typically respond to the mechanical stimuli in their everyday environment, such as pressure or stretching, with behaviors like migration, proliferation, or contraction. He and his research team hope to find a way to eventually predict and control cellular responses to their environment, which they hope could open doors to more forms of treatment for disorders like heart disease or cancer, where cellular behavior is directly linked to the cause of the disease.

Self-Learning Algorithm Could Help Improve Robotic Leg Functionality

Obviously, one of the biggest challenges in the field of prosthetics is the extreme difficulty in creating a device that perfectly mimics whatever the device replaces for its user. Particularly with more complex designs that involve user-controlled motion for joints in the limbs or hands, the electrical circuits implemented are by no means a perfect replacement of the neural connections in the human body from brain to muscle. But recently at the University of Southern California Viterbi School of Engineering, a team of researchers led by Francisco J. Valero-Cuevas, Ph. D.,  developed an algorithm with the ability to learn new walking tasks and adapt to others without any additional programming.

The algorithm will hopefully help to speed the progress of robotic interactions with the world, and thus allow for more adaptive technology in prosthetics, that responds to and learns with their users. The algorithm Valero-Cuevas and his team created takes inspiration from the cognition involved with babies and toddlers as they slowly learn how to walk, first through random free play and then from pulling on relevant prior experience. In a prosthetic leg, the algorithm could help the device adjust to its user’s habits and gait preferences, more closely mimicking the behavior of an actual human leg.

Neurofeedback Can Improve Behavioral Performance in High-Stress Situations

We’re all familiar with the concept of being “in the zone,” or the feeling of extraordinary focus that we can sometimes have in situations of high-stress. But how can we understand this shift in mindset on a neuroengineering level? Using the principal of the Yerkes-Dodson law, which says that there is a state of brain arousal that is optimal for behavioral performance, a team of biomedical engineering researchers at Columbia University hope to find ways of applying neurofeedback to improving this performance in demanding high-stress tasks.

Led by Paul Sajda, Ph.D., who received his doctoral degree from Penn, the researchers used a brain-computer interface to collect electroencephalography (EEG) signals from users immersed in virtual reality aerial navigation tasks of varying difficulty levels. In doing so, they were able to make connections between stressful situations and brain activity as transmitted through the EEG data, adding to the understanding of how the Yerkes-Dodson law actually operates in the human body and eventually demonstrating that the use of neurofeedback reduced the neural state of arousal in patients. The hope is that neurofeedback may be used in the future to help treat emotional conditions like post-traumatic stress disorder (PTSD).

Ultrasound Stimulation Could Lead to New Treatments for Inflammatory Arthritis

Arthritis, an autoimmune disease that causes painful inflammation in the joints, is one of the more common diseases among older patients, with more than 3 million diagnosed cases in the United States every year. Though extreme measures like joint replacement surgery are one solution, most patients simply treat the pain with nonsteroidal anti-inflammatory drugs or the adoption of gentle exercise routines like yoga. Recently however, researchers at the University of Minnesota led by Daniel Zachs, M.S.E., in the Sensory Optimization and Neural Implant Coding Lab used ultrasound stimulation treatment as a way to reduce arthritic pain in mice. In collaboration with Medtronic, Zachs and his team found that this noninvasive ultrasound stimulation greatly decreased joint swelling in mice who received the treatment as opposed to those that did not. They hope that in the future, similar methods of noninvasive treatment will be able to be used for arthritic patients, who otherwise have to rely on surgical remedies for serious pain.

People and Places

Leadership and Inspiration: EDAB’s Blueprint for Engineering Student Life

To undergraduates at a large university, the administration can seem like a mysterious, all-powerful entity, creating policy that affects their lives but doesn’t always take into account the reality of their day-to-day experience. The Engineering Deans’ Advisory Board (EDAB) was designed to bridge that gap and give students a platform to communicate with key decision makers.

The 13-member board meets once per week for 60 to 90 minutes. The executive board, comprised of four members, also meets weekly to plan out action items and brainstorm. Throughout his interactions with the group, board president Jonathan Chen, (ENG ‘19, W ‘19), has found a real kinship with his fellow board members, who he says work hard and enjoy one another’s company in equal measure.

Bioengineering major Daphne Cheung (ENG’19) joined the board as a first-year student because she saw an opportunity to develop professional skills outside of the classroom. “For me, it was about trying to build a different kind of aptitude in areas such as project management, and learning how to work with different kinds of people, including students and faculty, and of course, the deans,” she says.

Read the full story on Penn Engineering’s Medium Blog. Media contact Evan Lerner.

Purdue University College of Engineering and Indiana University School of Medicine Team Up in New Engineering-Medicine Partnership

The Purdue University College of Engineering and the Indiana University School of Medicine recently announced a new Engineering-Medicine partnership, that seeks to formalize ongoing and future collaborations in research between the two schools. One highlight of the partnership is the establishment of a new M.D./M.S. degree program in biomedical engineering that will allow medical students at Indiana University to receive M.S.-level training in engineering technologies as they apply to clinical practice. The goal of this new level of collaboration is to further involve Purdue’s engineering program in the medical field, and to exhibit the benefits that developing an engineering mindset can have for medical students. The leadership of this new partnership includes