Date: Tuesday, April 15, 2025 Time: 2:00 pm – 3:00 pm Location: Seminar Room 3310Title: Respiration coordinates odor coding in the piriform cortex: toward a logic of cortical odor codingAbstract: Most animals rely on olfaction to locate food, attract mates, and avoid predators. Odor information is initially encoded in the olfactory bulb (OB) as sequences of activated glomeruli and then relayed to the piriform cortex (PCx), where distinct, distributed ensembles of neurons represent odors. However, the principles governing this transformation remain unclear. Here, using both odor- and optogenetically-evoked OB inputs, we show that PCx neurons are tuned to specific respiration phases, gated by their intrinsic phase preferences. While OB inputs exhibit weak, inhalation-biased phase tuning, PCx circuits refine this signal: feedforward inhibition sharpens tuning, and intracortical processing redistributes it across the sniff cycle. Our findings suggest that PCx neurons form distinct modules, each selective for a particular respiration phase. This coding strategy integrates dominant odor components from early OB inputs with more nuanced details arriving later, constructing a richer and more detailed odor representation. Furthermore, the neural circuit mechanisms for phase-to-rate coding in PCx provide a framework for understanding how temporal structure is processed across sensory and cognitive systems.Bio: Kevin Franks was born in South Africa in the 1970s, moved to Canada in his teens, and then to California for graduate school. He is not, however, a fascist or a billionaire. He earned his Ph.D. at UCSD with Terry Sejnowski, focusing on simulations of synaptic transmission. In his postdoc work, first with Jeffry Isaacson at UCSD, and then with Richard Axel and Steve Siegelbam at Columbia, he studied the synaptic organization of the piriform cortex. This work provided the foundation for his current research into the mechanisms underlying cortical coding. In 2013, he established his lab at Duke University, where he is now an Associate Professor. His research uses the mouse olfactory system to investigate the neural mechanisms underlying sensory perception and cortical computation.

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Title: Dual Pairs and Disconnected Reductive GroupsSpeaker: Marisa GaetzZoom Link: https://mit.zoom.us/j/99020638421

Speaker: Niven AchenjangTitle: The Average Size of 2-Selmer Groups of Elliptic Curves in Characteristic 2Zoom Link: https://mit.zoom.us/j/96646700269?pwd=ST8VE7YDozKVY3AMUBR7pw9dkMFoTo.1

"Getting the Picture" | Robby Akerlof (Warwick)

Speaker: Adel Djellouli (Harvard)Title: Shell buckling for programmable metafluidsAbstract:The pursuit of materials with enhanced functionality has led to the emergence of metamaterials—artificially engineered materials whose properties are determined by their structure rather than composition. Traditionally, the building blocks of metamaterials are arranged in fixed positions within a lattice structure. However, recent research has revealed the potential of mixing disconnected building blocks in a fluidic medium. Inspired by these recent advances, here we show that by mixing highly deformable spherical capsules into an incompressible fluid, we can realize a ‘metafluid’ with programmable compressibility, optical behaviour and viscosity. First, we experimentally and numerically demonstrate that the buckling of the shells endows the fluid with a highly nonlinear behaviour. Subsequently, we harness this behaviour to develop smart robotic systems, highly tunable logic gates and optical elements with switchable characteristics. Finally, we demonstrate that the collapse of the shells upon buckling leads to a large increase in the suspension viscosity in the laminar regime. As such, the proposed metafluid provides a promising platform for enhancing the functionality of existing fluidic devices by expanding the capabilities of the fluid itself.