Recurrent circuitry is required to stabilize piriform cortex odor representations across brain states.

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Pattern completion, or the ability to retrieve stable neural activity patterns from noisy or partial cues, is a fundamental feature of memory. Theoretical studies indicate that recurrently connected auto-associative or discrete attractor networks can perform this process. Although pattern completion and attractor dynamics have been observed in various recurrent neural circuits, the role recurrent circuitry plays in implementing these processes remains unclear. In recordings from head-fixed mice, we found that odor responses in olfactory bulb degrade under ketamine/xylazine anesthesia while responses immediately downstream, in piriform cortex, remain robust. Recurrent connections are required to stabilize cortical odor representations across states. Moreover, piriform odor representations exhibit attractor dynamics, both within and across trials, and these are also abolished when recurrent circuitry is eliminated. Here, we present converging evidence that recurrently-connected piriform populations stabilize sensory representations in response to degraded inputs, consistent with an auto-associative function for piriform cortex supported by recurrent circuitry.





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Bolding, Kevin A, Shivathmihai Nagappan, Bao-Xia Han, Fan Wang and Kevin M Franks (2020). Recurrent circuitry is required to stabilize piriform cortex odor representations across brain states. eLife, 9. 10.7554/elife.53125 Retrieved from

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Fan Wang

Adjunct Professor in the Department of Neurobiology

My lab studies neural circuit basis of sensory perception. 
Specifically we are interested in determining neural circuits underlying (1) active touch sensation including tactile processing stream and motor control of touch sensors on the face; (2) pain sensation including both sensory-discriminative and affective aspects of pain; and (3) general anesthesia including the active pain-suppression process. We use a combination of genetic, viral, electrophysiology, and in vivo imaging (in free-moving animals) techniques to study these questions.


Kevin Michael Franks

Associate Professor of Neurobiology

We use the rodent olfactory system to study how the brain forms internal representations of the external world. We analyze small, functional neural circuits in the olfactory bulb and piriform cortex. We record and image odor-evoked responses in vivo, employ optogenetic circuit mapping in vitro, and use olfactory behavioral assays.

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