Presentation Details
| Learning engages medial prefrontal cortex input to the olfactory system Zihao Zhang, Valentina Consuegra, Daniel W.Wesson. Department of Pharmacology and Therapeutics, Florida Chemical Senses Institute, University of Florida College of Medicine, Gainesville, FL, USA |
Abstract
Learning transforms neural representations of odors such that the same odor is perceived differently before versus after learning. While many olfactory regions and cell types exhibit learning-dependent changes in odor representations, the origin of the signals that drive these changes remains unresolved. Across sensory systems, the medial prefrontal cortex (mPFC) plays a central role in learning and executive control. Using AAV-based anatomical tracing, our laboratory previously identified the tubular striatum (TuS, also known as the olfactory tubercle) as a privileged recipient of mPFC output amongst all other olfactory cortices, receiving convergent input from the prelimbic, infralimbic, and orbitofrontal cortices. Additionally, the TuS receives dense dopaminergic input from the ventral tegmental area, a neuromodulatory system critical for synaptic plasticity and learning. We then hypothesized that learning recruits the mPFC→TuS pathway and that this recruitment is influenced by dopamine (DA). To test this hypothesis, we recorded changes in calcium activity from mPFC→TuS projection neurons using fiber photometry with GCaMP8f while mice performed a two-alternative forced-choice odor discrimination task. Early in learning, odor-evoked responses in the mPFC→TuS pathway were weak. In contrast, after learning, odor-evoked responses were robust and reliable. Preliminary recordings of DA dynamics in the TuS using GRAB-DA1h from separate mice performing the same task revealed large odor-evoked DA responses during early learning, and ongoing work is examining how DA signaling evolves with experience. Together, these findings support a role for prefrontal cortex input to the olfactory system in odor learning and suggest that DAergic signaling shapes learning-dependent engagement within this circuit.
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