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| DON TUCKER FINALIST: A Dopaminergic System Promoting Sniffing |
| Natalie L. Johnson1, Anamaria Cotelo1, Andy Chavez1, Minghong Ma2, Daniel W. Wesson1 1University of Florida, Gainesville, FL, United States 2University of Pennsylvania, Philadelphia , PA, United States |
Sniffing is a widely observed behavior reflecting motivational states. For example, rodents sniff when investigating odors, during social interactions, while foraging for food, and even in anticipation of a reinforcer in instrumental tasks. The brain systems mediating this conserved and adaptive behavior are unknown. Here we sought to link displays of sniffing with the dopaminergic (DAergic) system. We hypothesized that DA release in the tubular striatum (TuS, also known as the olfactory tubercle), a component of the ventral striatum receiving both midbrain DAergic input and olfactory sensory input, is integral to sniffing behavior. To first validate that VTA→TuS DAergic input is behaviorally relevant, we used an optical intracranial self-stimulation task and found that DA release into the TuS is reinforcing and supports approach behaviors. Next, using in vivo fiber photometry and whole-body plethysmography, we observed that phasic DA release in the TuS is tightly coupled to the display of individual sniff bouts, including both spontaneous and sensory-evoked bouts. Further, bidirectional causal manipulations revealed that while optical stimulation of DA release in the TuS triggers sniff bouts, pharmacological inhibition of DA1 and DA2, but not DA3 receptors, in the TuS reduced both the number and vigor of sniff bouts. Similar-sized effects were not observed in the nucleus accumbens. Together these results implicate DAergic actions within the TuS, a structure which receives dense olfactory input, in the orchestration of sniffing and uncover a system supporting this widely displayed motivated behavior. |