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The multisensory integration of odors and tastes (i.e. flavor) is an essential factor guiding food choices. The perception of flavor relies upon a network of brain regions to integrate and process odor and taste signals. One critical node in this network is the interaction between the sensory cortices for smell (piriform cortex) and taste (gustatory cortex). We combine multi-wire electrophysiology and optogenetics in behaving rats to investigate the circuit mechanisms underlying the cortical representation of flavors.

A simplified schematic of the gustatory (blue) and olfactory (red) pathways. When a food is sampled, tastes (blue dots) dissolve in the saliva activating taste-receptors in the tongue and odors (red dots) travel retronasally from the mouth to activate olfactory receptors in nose. Taste signals from the tongue first travel to the brainstem, then thalamus, before reaching the gustatory cortex (GC). Odor signals from the olfactory bulb (OB) travel first to the anterior piriform cortex (aPC) and then to the posterior piriform cortex (pPC). The cortico-cortical interactions between the cortices  for smell and taste are thought to be critical for the perception of flavor

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Stocke and Samuelsen, J Neurosci Methods. 2021

Combining optogenetic tools with behaving electrophysiology is a powerful approach for investigating the neural mechanisms underlying behavior. Recently, we designed a drivable optrode for chronic recordings in behaving rats (top left). Using a virus to drive the expression of channelrhodopsin-2 (ChR2) in the anterior piriform cortex, we used the drivable optrode to record consistent light-evoked modulation of neural activity in the gustatory cortex during the photo-activation of the axonal projections from anterior piriform cortex in behaving rats (top right). We use tools like these to investigate the circuit and network mechanisms underlying the multisensory integration of smell and taste and consummatory choice.

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