“To generate a single distinct sense of smell, the signals are probably integrated in the olfactory cortex,” Zou said.

Using a labeling technique that tracked the signal of single type of receptor, the group followed the signals of those receptors all the way to the brain.

Zou said the process of developing the mice used in the study and getting results was sometimes frustrating.

“We had so many problems that we thought about stopping many times,” he said. “But the results are wonderful.”

According to Reid, the study is important for understanding more about how smells are perceived and the work may eventually help in understanding other sensory systems.

“This is a first step in making a meaningful comparison between the olfactory system and other systems,” he said.

—Staff writer Jonathan H. Esensten can be reached at esensten@fas.harvard.edu.