Brain cells combine place and taste to make food maps

Sometimes a really good meal can make an evening unforgettable. A new study of rats, published online February 18 in the Journal of Neuroscience, may help explain why. 

A select group of nerve cells in rats’ brains holds information about both flavors and places, becoming active when the right taste hits the tongue when the rat is in a certain location. These double-duty cells could help animals overlay food locations onto their mental maps.

Researchers implanted electrodes into the hippocampus, an area of the brain that is heavily involved in both memory formation and mapping. The rats then wandered around an enclosure, allowing researchers to identify “place cells” that become active only when the rat wandered into a certain spot. At the same time, researchers occasionally delivered one of four flavors (sweet, salty, bitter and plain water) via an implanted tube directly onto the wandering rats’ tongues.

Some of the active place cells also responded to one or more flavors, but only when the rat was in the right spot within its enclosure. When the rat moved away from a place cell’s preferred spot, that cell no longer responded to the flavor, the researchers found. A mental map of the best spots for tasting something good would come in handy for an animal that needs to find its next meal.