Dec 2018 – Bite Size Summit: Emerging technologies for gut-brain research

Speaker: Seongjun Park, Ph.D., Postdoctoral Associate in Dr. Polina Anikeeva’s Bioelectronics Group at Massachusetts Institute of Technology

Title: Bioelectronics for neural engineering

Summary: Dr. Seongjun Park received his Ph.D. in Electrical Engineering and Computer Science from MIT in Dr. Polinia Anikeeva’s lab in June of 2018. His doctoral research, which he has expanded upon in his post-doctoral work, has focused on flexible fiberoptics. In the brain, use of electrodes for long term stimulating and recording has been limited by the intense inflammatory response causing inflammatory cell infiltration and scarring. Dr. Park developed a novel flexible fiberoptic to improve the modulus mismatch between the brain and the electrode material. Using this device, he was able to use optogenetics to probe anxiety behavior associated with the circuit between the ventral hypothalamus and the basolateral amygdala. He also extended his work into the spinal cord. For success in the spinal cord, Dr. Park identified the need for a device that can stretch and deform; so, he engineering a stretchable fiber with excellent light transmission properties. Finally, Dr. Park has sought to further engineering his flexible fiberoptic by using a hydrogel coating. By coupling the hydrogel with the flexible fiberoptic, Dr. Park reduced strain between the device and the brain. Using this device, for the first time in the field, Dr. Park was able to record single unit spikes out to 6 months post-implantation. Dr. Park’s ambition is to be an independent investigator in bioengineering, with the goal of engineering devices to improve human health.

Speaker: David Hildebrand, Ph.D., Postdoctoral Associate in Dr. Winrich Freiwald’s Laboratory of Neural Systems at Rockefeller University

Title: High throughput TEM

Summary: Dr. David Hildebrand received his Ph.D. in Neuroscience from Harvard University in the Engert Laboratory. In his doctoral work, Dr. Hildebrand related anatomy, physiology, and behavior in the zebrafish nervous system. In particular, he used developed electron microscopy techniques to image the zebrafish brain at nanoresolution. Transmission electron microscopy is a fast, high signal to noise ratio, and inexpensive way to obtain high resolution images. However, the tissue processing is extremely challenging—nanometer thin samples must be placed by hand on a clear surface for imaging. Scanning transmission electron microscopy, however, can image with intact samples, but it sacrifices speed, resolution, and signal to noise ratio. Dr. Hildebrand merged the benefits of both systems by engineering a automated serial sections to tape transmission electron microscopy system. In his system, tissue is automatically sectioned and mounted to clear tape for transmission imaging. Using this system, he was able to obtain exquisite images of both the zebrafish brain as well as the mouse gastrointestinal tract.

Speaker: Ian Williamson, Ph.D., Postdoctoral Associate in Dr. Xiling Shen’s and Dr. John Rawls Laboratories at Duke University

Title: Nanofeeding human miniguts

Summary: Dr. Williamson received his Ph.D. in Biomedical Engineering from UNC/NCSU in the laboratory of Dr. Scott Magness. Early in his doctoral work, he was struck by how understudied the intestinal epithelium is. In particular, he was interested in how the microbiome interacts with the epithelial layer. He identified several techniques to better study the epithelial layer with the microbiome intact: culture with bacteria, microinjections of bacteria into organoids, or 2-D culture. Microinjection techniques were limited by the use of conventional technology, so Dr. Williamson developed a system for high throughout injection of fecal microbiome directly into the lumen of organoids. He identified that after injection into the lumen, the organoids live healthily in culture for up to 96 hours. During that time, the number of species in the microbiome increases with minor changes in species representation. Using this system, he further went on to demonstrate that organoids are able to reproducible metabolize fatty acids injected into their lumen. Dr. Williamson hopes to expand upon these techniques to study the gut epithelium in his post doctoral work at Duke University.

Speaker: Meg Younger, Ph.D., Kavli Fellow in Dr. Leslie Vosshall’s Laboratory of Neurogenetics and Behavior at Rockefeller University

Title: Processing human cues in the mosquito brain

Summary: Dr. Meg Younger received her Ph.D. from UCSF studying the homeostatic regulation of neurotransmitter release in the laboratory of Dr. Graeme Davis in 2013. Since joining Dr. Leslie Vosshall’s laboratory for her post-doctoral fellowship, Dr. Younger has focused on studying how mosquitos identify humans by sensory cues. Mosquitos integrate sensory information including body heat, human odor, and carbon dioxide emissions to find a blood meal. The human order code, however, remains unknown. Because mosquitos are not a model system, Dr. Younger began her research by developing a standard reference brain for mosquitoes (mosquitobrains.org). Using this, she identified 50 glomeruli for odor sensation; she targeted 3 specific glomeruli that synapse with sensory neurons from the maxillary palp. Using the CRISPR Q system and calcium imaging, she has been able to identify that the mosquito odorant is quite different that that of other model systems such as drosophila. Some sensory neurons express multiple odorant receptors to synapse on one glomeruli, while other sensory neurons express only one odorant receptor. And, one glomeruli may receive signals from multiple sensory neurons with different receptors. Using this work as a foundation, she hopes to uncover how mosquitos find humans.