Associate Professor, Department of Biology
Ph.D. Stanford University
B.S. Stanford Univeristy
Research Interests: Function and development of neural circuits for visual processing
Overview: How do we make sense of the visual world around us? Our brain takes a pattern of photons hitting the retina and continually creates a coherent representation of what we see – detecting objects and landmarks rather than just perceiving an array of pixels. This image processing allows us to perform a range of visual tasks, such as recognizing a friend’s face, finding your way to the grocery store, and catching a frisbee. However, how these computational feats are achieved by the neural circuitry of the visual system is largely unknown. Furthermore, this circuitry is wired up by a range of cellular processes, such as arbor growth, synapse formation, and activity-dependent plasticity, and thus these developmental mechanisms effectively determine how we see the world.
Our research is focused on understanding how neural circuits perform the image processing that allows us to perform complex visual behaviors, and how these circuits are assembled during development. We use in vivo recording techniques, including high-density extracellular recording and two-photon imaging, along with molecular genetic tools to dissect neural circuits, such as cell-type specific markers, optogenetic activation and inactivation, tracing of neural pathways, and in vivo imaging of dendritic and synaptic structure. We have also implemented behavioral tasks for mice so we can perform quantitative pyschophysics to measure the animal’s perception, and we use theoretical models to understand general computational principles being instantiated by a neural circuit.
Dynamics of gaze control during prey capture in freely moving mice.
Elife. 2020 Jul 24;9:
Authors: Michaiel AM, Abe ETT, Niell CM
Many studies of visual processing are conducted in constrained conditions such as head- and gaze-fixation, and therefore less is known about how animals actively acquire visual information in natural contexts. To determine how mice target their gaze during natural behavior, we measured head and bilateral eye movements in mice performing prey capture, an ethological behavior that engages vision. We found that the majority of eye movements are compensatory for head movements, thereby serving to stabilize the visual scene. During movement, however, periods of stabilization are interspersed with non-compensatory saccades that abruptly shift gaze position. Notably, these saccades do not preferentially target the prey location. Rather, orienting movements are driven by the head, with the eyes following in coordination to sequentially stabilize and recenter the gaze. These findings relate eye movements in the mouse to other species, and provide a foundation for studying active vision during ethological behaviors in the mouse.
PMID: 32706335 [PubMed - as supplied by publisher]
Movement-Related Signals in Sensory Areas: Roles in Natural Behavior.
Trends Neurosci. 2020 Jun 22;:
Authors: Parker PRL, Brown MA, Smear MC, Niell CM
Recent studies have demonstrated prominent and widespread movement-related signals in the brain of head-fixed mice, even in primary sensory areas. However, it is still unknown what role these signals play in sensory processing. Why are these sensory areas 'contaminated' by movement signals? During natural behavior, animals actively acquire sensory information as they move through the environment and use this information to guide ongoing actions. In this context, movement-related signals could allow sensory systems to predict self-induced sensory changes and extract additional information about the environment. In this review we summarize recent findings on the presence of movement-related signals in sensory areas and discuss how their study, in the context of natural freely moving behaviors, could advance models of sensory processing.
PMID: 32580899 [PubMed - as supplied by publisher]