In several sensory systems, such as the visual system, parts of a sensory organ always pass information to the same regions in the brain. But the olfactory system appears to send information in a much less ordered way to the piriform cortex—the region of the brain that processes smells. Researchers now suggest that this apparently chaotic setup helps the brain better analyze smells. The results were published July 17 in The Journal of Comparative Neurology.
Researchers studied the spread and density of neurons in this brain region and their connections to the olfactory bulb, which transfers signals from the nose to the piriform. They found that each neuron in the bulb made connections with every neuron in the piriform.
“Every cell in the piriform is getting information from essentially every odor receptor there is,” coauthor Charles Stevens, a professor emeritus at the Salk Institute’s Molecular Neurobiology Laboratory, says in a statement. “There’s not one ‘coffee smell’ neuron but a whole bunch of coffee cell neurons all over the place.” The researchers propose that every smell activates multiple neurons, and that detection isn’t dependent on which neurons it lights up, but how robustness the signal is.
S. Srinivasan and C.F. Stevens, “The distributed circuit within the piriform cortex makes odor discrimination robust,” Journal of Comparative Neurology, doi:10.1002/cne.24492, 2018.