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Reading the neural code in behaving animals, ~1000 neurons at a time

Abstract: A longstanding challenge in neuroscience is to understand how populations of individual neurons and glia contribute to animal behavior and brain disease. Addressing this challenge has been difficult partly due to lack of appropriate brain imaging technology for visualizing cellular properties in awake behaving animals. I will describe a miniaturized, integrated fluorescence microscope for imaging cellular dynamics in the brains of freely behaving mice. The microscope also allows time-lapse imaging, for watching how individual cells' coding properties evolve over weeks. By using the integrated microscope to perform calcium-imaging in behaving mice as they repeatedly explored a familiar environment, we tracked the place fields of thousands of CA1 hippocampal neurons over weeks. Rewarded spatial locations were represented by a disproportionally greater number of place cells than non-rewarded locations. Spatial coding was also highly dynamic, for on each day the neural representation of this environment involved a unique subset of neurons. Yet, the cells within the ~15–25% overlap between any two of these subsets retained the same place fields, and though this overlap was also dynamic it sufficed to preserve a stable and accurate ensemble representation of space across weeks. This study in CA1 illustrates the types of time-lapse studies on reward, memory, ensemble neural dynamics, and coding that will now be possible in multiple brain regions of behaving rodents. Ongoing brain areas under study include amygdala, basal ganglia and multiple others.
Speaker: Mark Schnitzer - Stanford University
Speaker Bio: Professor Mark J. Schnitzer is a faculty member in the Biology and the Applied Physics Departments of Stanford University. He is also an Investigator of the Howard Hughes Medical Institute. Dr. Schnitzer's lab innovates and uses novel optical brain imaging technologies in the pursuit of understanding how large ensembles of how cells control behavior. He recently served on the NIH Advisory Committee for the BRAIN Initiative. Over the last 7 years, the Schnitzer lab has invented several technologies, including tiny microscopes that are only 1-3 grams in mass and small enough to be mounted on the head of a freely moving adult mouse. This technology won The Scientist’s Top Innovation of 2013, is now commercially available from Inscopix Inc., and is presently used by about 65 neuroscience labs in the USA, Europe and Asia. Dr. Schnitzer's lab is using micro-optic techniques extensively for research on the fundamental cellular basis for various aspects of cognition and reward processing. He currently serves on the NIH BRAIN Multi-Council Working Group.
Poster Link: Poster