Harvard University - Department of Molecular & Cellular Biology

POSTDOC PROFILE: DAVID GIRE

by Sophie Blum

July 29th, 2014

David Gire paved his path-to-the-postdoc with collaboration and interdisciplinary inspiration. At Silver Creek High School in San Jose, CA, Gire’s AP Biology/Biotech teacher, Mark Okuda (soon to become a nationally recognized science educator), assembled donated equipment into a make-shift forensic lab where students prepared genetic evidence to present at mock trial. Inspired by the intellectual creativity sparked when disciplines (such as Law and Genetics) intersect, Gire double-majored in Philosophy and Neurobiology as an undergrad at the University of California, Berkeley and has been working on ways to constructively bridge disciplines ever since. At Berkeley his research on songbirds in Frederic Theunissen’s lab straddled the fields of Neuroanatomy and Electrophysiology: “We’d record in the songbirds and see what the neurons were doing and then we would look for anatomical connections between the neurons that would explain how the neurons were processing information.”

In the spirit of “Wanderjahr,” Gire headed to Italy after graduation to pursue his dual passions for art and science. Over a 7-month fellowship in Mathew Diamond’s lab at the International School for Advanced Studies in Trieste, Gire practiced human somatosensory psychophysics and learned computer programming, which has come in handy throughout his career. Outside of the lab, Gire endeavored to hunt down every Caravaggio painting in Rome. Caravaggio’s chiaroscuro style plays with light and perception with, Gire suspects, “some idea of human psychology and human psychophysics in mind.”

Although the stimulating combination of science and culture made Italy an attractive place to pursue further studies, Gire wanted to explore alternatives to the black box approach of human psychophysics. Rather than analyzing input and output, Gire was ready to open the box and directly observe the circuits inside. So he proceeded to graduate school at the University of Colorado at Denver School of Medicine (CU Denver), where he studied the olfactory system as a model for circuit processing with Nathan Schoppa. Here Gire focused on defining the neural circuit mechanisms that support information processing in the first olfactory relay in the brain, the olfactory bulb. Gire made precise recordings from multiple neurons at once in order to define how they are connected to each other and took advantage of the intact sensory nerve in olfactory bulb slices to examine how these connections process incoming sensory information.  Based on these studies, Gire and Schoppa redefined the path through which sensory information travels in the olfactory bulb.  A resulting publication, recognized by the Faculty of 1000, showed that the projection neurons of the olfactory bulb (mitral cells) are not driven directly by sensory input, but rather are activated by an excitatory class of interneurons. Shortly after beginning his doctorate, David broke his collarbone while playing hockey. The temporary lack of limb slowed lab work, but encouraged Gire to read papers and develop a strong academic background for his research. Meanwhile he applied for and won a predoctoral Ruth L. Kirchstein National Research Service Award (NRSA) from the NIDCD at the NIH.

Characteristic, perhaps, of Gire’s multi-disciplinary interests, he elected to do two short postdocs rather than one in order to maximize his exposure to diverse scholars and lenses of study. Because he hoped to apply for the time-sensitive NIH Pathway to Independence Award (K99/R00), he knew he would have to keep a strict career schedule. No sooner had he begun his first postdoc than he was making arrangements for his second.

First, Gire moved a few doors down the hall to Diego Restrepo’s lab at CU Denver to apply his newly minted expertise in circuitry to awake animals. In collaboration with Restrepo and Gidon Felsen, a CU Denver assistant professor of Physiology and Biophysics also conducting recordings in behaving animals, Gire applied for and earned a postdoctoral NRSA from the NIDCD.

While in the Restrepo lab, Gire combined careful behavioral analysis with electrophysiological recordings to examine how neural networks utilize the relative timing and synchrony of action potentials to encode sensory information during olfactory-based decision making. After two productive years in the Restropo lab and multiple attendant publications1, Gire headed east to join the Murthy lab, drawn by the MCB professor’s advanced imaging techniques, which approach the level of precision afforded by tissue slices, but in awake animals. Taking work-life balance quite literally, Gire located and leased an apartment precisely halfway between the Harvard Biolabs and the nearest hockey rink.

Murthy promptly facilitated another interdisciplinary partnership between Gire and former Harvard postdoc Agnese Seminara, a physicist with a focus on fluid dynamics. Gire’s current project entails an ongoing intercontinental collaboration with Seminara’s lab at the National Centre for Scientific Research (CNRS) in France. This research connects the neural circuit dynamics of the rodent olfactory system to the complex odor cues found in natural olfactory environments, where odors are distributed in chaotic, turbulent plumes.  Collaboration with Seminara has been particularly valuable in defining the spatiotemporal cues present in these plumes, while on the behavioral side of things Gire has developed novel olfactory-based tasks to examine how rodents extract information from odor plumes.  In one task, freely moving mice are trained to use odor plumes to navigate to the source of an odor where they receive a water reward.  This set of experiments has demonstrated that mice are highly adept at using airborne odor cues to find the source of an odor, even without visual feedback during tracking (all experiments are performed under far red light, which mice cannot see).  A second set of experiments utilizes multiphoton imaging to examine how specific components of the olfactory circuitry, such as feedback projections from the cortex, contribute to the ability of mice to sense the direction from which an odor plume travels.  Using state-of-the-art optical and electrophysiological techniques in the Murthy lab (such as multi-electrode recordings, optogenetics, and wireless telemetry), Gire can now observe olfactory neural circuits in action as they process complex odor cues and guide natural behaviors such as navigation. Among other things, Gire’s latest endeavors ask how the spatial cues present in natural plumes are processed by the circuitry of the olfactory cortex, as well as how cortical feedback operates during olfactory-guided behaviors.

Last summer the NIDCD granted Gire the hoped-for K99, which will support his transition to the University of Washington in Seattle next spring, where he has accepted a position as assistant professor of Psychology. Gire attributes his success in obtaining funding to the collaborative aspect of his projects. In addition to Venki Murthy, Gire’s current grant features three local mentors (MCB’s Nao Uchida, Rachel Wilson of HMS Neurobiology, and Ed Boyden at MIT) and a long-distance mentor, Peter Brunjes, an expert in olfactory circuitry at the University of Virginia. In Gire’s opinion, “What really strengthened the grant and allowed us to get the funding was that we’re working across disciplinary boundaries and also working with a lot of talented people.”

Not surprisingly, Murthy describes Gire as both an industrious and creative scientist and an invaluable social boon to the lab: “David is a great sounding board for the rest of us—he offers insightful comments on everyone’s projects, whether at lab meetings or on written documents. I will also note that he is a great conversationalist at late night bar gatherings at scientific meetings!”

As he starts his own lab next year, Gire will continue his investigations into the neural circuit mechanisms and behavioral strategies utilized to actively explore and interpret complex, natural olfactory environments. In order to most effectively monitor and manipulate neural circuits in behaving animals, Gire looks forward to collaborating with colleagues across the University, from engineers to ethologists.

Find out more at PubMed.

View Venkatesh Murthy's Faculty Profile