DESCRIPTION (provided by applicant): We like to think of taste as working relatively simply-a sweet taste is recognized as sweet by virtue of activating certain cells on the tongue, and that information is used to drive neurons that cause us to eat more of whatever food is in our mouths. The truth, however, is much more interesting: a taste hits the tongue, and complex circuits in the brain go into action, passing food-related information back and forth as the system as a whole decides whether the morsel is palatable enough to swallow. My lab studies this process by recording from multiple parts of the taste system while active rats are sampling various tastes. Our work allows us to observe this decision-making process in action, as taste cortex reports, in turn, that a taste is on the tongue, that the taste is (say) sugar, and that it the rat) currently likes the taste; this last step appears to be one arrived at suddenly, in a moment o insight-the food rolls around in the rat's mouth for 0.5-1.5 seconds, and then the decision is made. The research that we're currently proposing will study this process. First, we will do a direct, rigorous evaluation of whether the appearance of palatability- related information in cortical neurons actually predicts the behavioral decision in single trials, and testing whether loss of cortical function perturbs the decision process; in a complementary experiment, we will test whether cortical function changes appropriately when one decision is made easier. Finally, we will look at where that information in cortex comes from, by recording from cortex while temporarily silencing other brain areas and pathways proposed to be involved in taste decisions. As a whole, this research project has the potential to completely change the way we think about taste, and to usher in new thinking about perception in general-thinking that makes a great deal more biological sense, given the complexity of brain circuitry.