Animals constantly modify their behavior through experience. Flexible behavior is key to our ability to adapt to the ever-changing environment. My laboratory is interested in studying the activity of neuronal ensembles in behaving animals, and how it changes with learning.
We have recently set up a paradigm where mice learn to associate sensory information (two different odors) to motor outputs (lick vs no-lick) under head-fixation. We combined this with two-photon calcium imaging, which can monitor the activity of a microcircuit of many tens of neurons simultaneously from a small area of the brain. Imaging the motor cortex during the learning of this task revealed neurons with diverse task-related response types. Intriguingly, different response types were spatially intermingled; even immediately adjacent neurons often had very different response types. As the mouse learned the task under the microscope, the activity coupling of neurons with similar response types specifically increased, even though they are intermingled with neurons with dissimilar response types. This suggests that intermingled subnetworks of functionally-related neurons form in a learning-related way, an observation that became possible with our cutting-edge technique combining imaging and behavior.
We are working to extend this study. How plastic are neuronal microcircuits during other forms of learning? How plastic are they in other parts of the brain? What are the cellular and molecular mechanisms of the microcircuit plasticity? Are the observed activity and plasticity required for learning? How does the activity of identified individual neurons change over days to weeks? We are asking these questions, combining a variety of techniques including in vivo two-photon imaging, optogenetics, electrophysiology, genetics and behavior.
Figure 1: In vivo two-photon calcium imaging from head-fixed mice during learning
Figure 2: A snapshot of calcium imaging
Dr. Komiyama was a Postdoc at Janelia Farm, Howard Hughes Medical Institute, received his Phd in Neurosciences at Stanford University (2006) and his BA in Biochemistry at University of Tokyo (2001). His Honors include: Helen Hay Whitney Foundation Postdoctoral Fellowship, Harold M. Weintraub Graduate Student Award, Japan-Stanford Association Graduate Fellowship, Stanford Graduate Fellowship, Pew Scholars Program, Packard Fellowship and Sloan Research Fellowship. Dr. Komiyama is a NYSCF-Robertson Investigator.