New preprint on prolonged taste modulation
We’ve posted a new preprint on bioRxiv! In this study, we investigated how taste cues elicit prolonged modulation of feeding responses. The project was led by Dr. Devineni’s former technician at Columbia, Julia Deere (now a PhD student at Rockefeller).
Most taste studies have focused on the immediate effects of taste, like how sweet taste makes you want to eat something or bitter taste makes you want to spit it out. How taste modulates future behavior hasn’t been as well-studied. Mostly it’s been studied in the context of associative learning: for example, presenting sugar along with a bitter taste makes an animal less likely to eat the sugar in the future.
We studied how one taste can modulate the response to a different taste even when they don’t overlap in time. We found that a brief taste of sugar makes flies want to eat stuff they aren’t normally excited about, and vice versa for the taste of bitter. Since taste cues signal local food quality, this prolonged modulation could enable an animal to integrate taste information over time as it explores an environment, adjusting its likelihood of feeding based on recent history.
Prolonged taste modulation can be elicited by brief optogenetic activation of taste neurons, so it’s not just due to residual tastant on the fly - the brain must store a memory of each taste after it disappears. But this doesn’t rely on canonical memory circuits in the fly, namely the mushroom body. Also, downstream neurons that acutely regulate feeding responses don’t necessarily elicit prolonged modulation of the same response. So the sugar and bitter pathways each seem to diverge into different downstream circuits that regulate the same behavior in different contexts.
We’re still investigating the circuit mechanisms, like how the taste memory is stored (is it a specific “memory” or a general internal state?) and where the modulation occurs (is it at the same site as other types of modulation?).
If you might be interested in studying these types of questions, learn more about joining the lab here! We are actively seeking new people to follow up on this project and other questions related to taste processing.
