Date: Tuesday, April 15, 2025
Time: 2:00 pm – 3:00 pm
Location: Seminar Room 3310
 

Title: Respiration coordinates odor coding in the piriform cortex: toward a logic of cortical odor coding

Abstract:
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.