Society for Neuroscience Presents Lindsley Prize to Kiah Hardcastle and Christopher Zimmerman
WASHINGTON, D.C. — The Society for Neuroscience (SfN) will present the Donald B. Lindsley Prize to Kiah Hardcastle, PhD, and Christopher Zimmerman, PhD. Supported by an endowment from the Grass Foundation, the prize recognizes outstanding PhD theses in the area of general behavioral neuroscience. The $2,500 award was established in 1979 in honor of Donald B. Lindsley, an early trustee of the Grass Foundation. The award will be presented during SfN’s Awards Announcement Week 2020.
“SfN is excited to recognize two young, promising neuroscientists. Both Dr. Hardcastle and Dr. Zimmerman developed innovative ideas and rigorous methods of testing to move their respective fields forward with truly impressive thesis projects,” said SfN President Barry Everitt, PhD. “Dr. Hardcastle significantly advanced our understanding of how the brain supports navigation, while Dr. Zimmerman’s work transformed our knowledge of how the brain regulates thirst.”
Hardcastle completed her thesis work at Stanford University School of Medicine and used a combination of cutting-edge computational, theoretical, and experimental approaches to probe how the brain encodes navigation. Her rigorous research revealed how boundaries, rewards, and running speed can influence coding properties of neurons in the entorhinal cortex to support spatial representations.
During her thesis work, Hardcastle was very productive, beginning with publishing a paper in Neuron after her first-year research rotations. To mention just a few of her many projects, she demonstrated that grid cells — neurons in the entorhinal cortex that encode the distance an animal has traveled — are calibrated based on sensory input, a paradigm-shifting idea. Next, using machine learning algorithms, she was able to study responses in the vast majority of entorhinal neurons, many of which had never been classified. She found entorhinal neural responses are unexpectedly diverse and dynamic; representations are not fixed, as previously believed, but adapt based on the animal’s behavior or location of a reward. She also performed electrophysiology recordings on rats navigating different environments to show that entorhinal representations change depending on the navigational strategy used, unlike the fixed maps we use to navigate. Together, her work led to a new understanding of the diversity and flexibility with which the entorhinal cortex supports spatial navigation.
In his thesis work at the University of California San Francisco, Zimmerman used an impressive combination of molecular, physiological, and behavioral tools to redefine the neurobiology of thirst. His findings revealed the neural mechanisms behind every-day human experiences, such as the rapid satiation of thirst, the desire to drink during meals, and the unpleasantness of thirst.
Using his systematic and meticulous approach, Zimmerman discovered a new class of sensory signals that arise from the mouth, throat, and gut during ingestion and then converge in the brain to dynamically adjust the motivation to drink. He showed that thirst-promoting neurons in the subfornical organ, which were previously thought to exclusively detect slow changes in blood hydration levels, are also instantly modulated by the act of drinking or eating. This unexpected discovery revealed how drinking can quench thirst within seconds and how eating rapidly generates prandial thirst. He also paired optogenetics with operant conditioning to confirm a classic theory that hunger and thirst are aversive states and that animals eat and drink to reduce these unpleasant sensations. Additionally, Zimmerman revealed the existence of a sensory system in the gastrointestinal tract that helps regulate drinking behavior by rapidly communicating the osmolarity of ingested fluids to the brain’s thirst circuit. Taken together, his work has transformed our understanding of how the brain regulates thirst and drinking behavior and introduced experimental approaches that are now commonly used.
The Society for Neuroscience (SfN) is an organization of nearly 36,000 basic scientists and clinicians who study the brain and the nervous system.