Individual mice were implanted with an intraoral cannula28 (link) 3 days before c-Fos induction. On the day of experiments, mice were anaesthetized with urethane (1.6 mg/g) and the trachea was cannulated to aid breathing during oral stimulus presentation. Tastants were perfused into the mouth through the intraoral cannula for 1.5 hours at a rate of ~6 ml/hr. Mice were allowed to rest for 30 minutes and processed for immunostaining as previously described. The brains were sectioned coronally at 100 μm, and labeled with goat anti-c-Fos (Santa Cruz, sc-52-G) overnight; Alexa 488 donkey anti-goat or cy3 donkey anti-goat (Jackson immunoResearch) were used to visualize c-Fos expression. All images were taken using an Olympus FluoView 1000 confocal microscope.