Distinguished Science in Medicine Lecture
Thurs., April 26, 2018
Faces: a neural Rosetta stone
Objects constitute the fundamental currency of the brain: they are things that we perceive, remember, and think about. One of the most important objects for a primate is a face. Research on the macaque face patch system in recent years has given us a remarkable window into the detailed processes underlying object recognition. I will discuss recent findings from our lab elucidating the code for facial identity used by cells in face patches. I will then discuss how this code is used by downstream areas, as well as how the brain computes what constitutes an object in the first place.
Professor of Biology
California Institute of Technology
location: T-747, HSB
host: Stan Froehner
New Cortex. Who dis(inhibition)?
Brent Doiron, PhD
Department of Mathematics
University of Pittsburgh
host: Adrienne Fairhall
New Cortex. Who dis(inhibition)?
It is now clear that the inhibitory circuitry within cortical networks is very complex, with multiple cell types interacting with one another and pyramidal neurons in complicated and cell specific ways. The theoretical community has been slow to adapt to this new circuit reality, and much of our results are obtained from analysis of simpler recurrent excitatory-inhibitory circuits. Two often cited functional roles of inhibition is to: 1) stabilize the dynamics of recurrently coupled excitatory networks, and 2) enact gain control of excitatory neuron responses to a driving stimulus. In classic excitatory-inhibitory networks mechanisms that place the network in a high gain state necessarily flirt with network instability. We analyze how recurrent networks of pyramidal neurons (PN), parvalbumin-expressing (PV), somatostatin-expressing (SOM), and vasoactive intestinal polypeptide-expressing (VIP) interneurons compartmentalize stability and gain control through distinct inhibitory and disinhibitory pathways. This permits a disassociation of stability and gain control in the circuit. We further show how PC to SOM connections can be crucial in state dependent gain amplification with a simultaneous decrease of shared variability (noise correlations). In sum, by expanding the complexity of inhibitory architecture cortical circuits can navigate distinct functional roles of inhibition through a “division of labor” with the inhibitory circuit. This imparts a robustness to the functional operations of the circuit that is absent in the often fine-tuned reduced excitatory-inhibitory framework.
Simvastatin: unexpected or logical therapy for muscular dystrophy?
Nicholas P Whitehead, Ph.D.
University of Washington
host: Stanley C. Froehner
Learning and Relearning Movement
Human motor learning depends on a suite of brain mechanisms that are driven by different signals and operate on timescales ranging from minutes to years. Understanding these processes requires identifying how new movement patterns are normally acquired, retained, and generalized, as well as the effects of distinct brain lesions. The lecture focuses on normal and abnormal motor learning and how we can use this information to improve rehabilitation for individuals with neurological damage
Amy Bastian, Ph.D.
Professor of Neuroscience
Johns Hopkins University
Host: John Tuthill