**This seminar will take place virtually via Zoom.**
This month's speakers:
Sumin Jang, PhD, (Wichterle lab): "Investigating species-specific timescales of neurogenesis"
The timescales of neurogenesis are disproportionately protracted in human relative to other mammals, allowing for a greater number of neurons to be generated during development. To investigate the mechanisms underlying this difference in timescale, we compared human and mouse motor neuron differentiation by combining single-cell gene expression profiling and in-vitro differentiation of pluripotent stem cells toward a motor neuron fate. By comparing mouse and human cells undergoing motor neuron differentiation, we identify increased and precocious canonical Wnt signaling as a potential factor that leads to the disproportionate protraction of human neurogenic timescales.
Chris Rodgers, PhD (Bruno lab): "The sensorimotor strategies and neuronal representations of whisker-based shape recognition in mice"
Humans and other animals can identify objects by active touch, requiring the coordination of exploratory motion and tactile sensation. The brain must integrate these exploratory motor actions with the resulting tactile signals in order to form a holistic representation of object identity. In this study we developed a shape discrimination task for head-fixed mice that challenged them to discriminate concave from convex objects. In collaboration with Ramon Nogueira and Stefano Fusi at the Theory Center, we used classifier analysis to reveal that mice compared the number of contacts across whiskers in order to discriminate shape. We recorded populations of neurons in the barrel cortex, which processes whisker input, to identify how it encoded the sensorimotor variables that mice use to recognize shape. We found widespread coding of touch, whisker motion, and task-related signals. The formatting of the touch signals was task-specific and well-suited for the decoding of shape identity. We suggest that a similar computation of comparing across multiple sensors may underlie object recognition in other brain areas and species.