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| Poster #253 A Comparison of Cortical Taste Representations Arising from Free Licking and Intraoral Delivery |
| Martin Raymond, Jian-You Lin, Donald Katz Brandeis University, Waltham, MA, United States |
Historically, freely-moving electrophysiology and lickometers have been considered largely incompatible; artifacts introduced by lickometers prevent the tracking required for stimulus control. For ephys experiments, tastes have typically been delivered directly into the mouth of anesthetized animals or via intraoral cannula (IOC) in awake animals, despite the obvious limitations on naturalism involved in both cases. Recent techniques have made strides in reducing abstraction; photobeam lickometers are able to record licking without electrical artifact, and calcium imaging is indifferent to electrical noise, both of which have facilitated the investigation of cortical taste representations in active licking animals. Still, limitations remain–the temporal resolution of Calcium imaging is much lower than electrophysiology, and technical considerations have limited the use of photobeam lickometers to restrained animals, which limits their benefits. Much of this work is premised on the untested assumption that taste responses to licking are incomparable to responses to IOC delivery. In an attempt to reconcile these limitations and investigate the potential effects of route of ingestion on taste representations, we developed a paradigm using both IOC and a photobeam-based brief-access lickometer to deliver tastes to rats implanted with multielectrode arrays. This allows us to record gustatory cortical taste representations in freely moving, freely drinking animals with the full resolution of electrophysiology, and contrast that directly with IOC-evoked taste representations within subjects. With this design, we were able to test our hypothesis that route of administration will alter the taste response to an extent, but that the general structure of taste representations will remain largely the same. |