Meissner-Bernard, C. et al. Curr. Biol. 29, 367–380 (2019)

New research from Brown University pinpoints the piriform cortex as the region of the brain responsible for olfactory fear memories. The researchers conditioned mice to associate a specific odor with a small shock, from which the animals learned to flee. They then watched the activation of c-Fos-tagged neurons in the piriform cortex, an area near the olfactory bulb suspected to be the location of olfactory memory processing. A subset of neurons in the piriform cortex was activated by the negative odor, but not by other unconditioned scents.

The researchers then turned those neurons off and on. When the neurons were inactivated during memory recall tests with the negative odor, the mice stayed put, suggesting the fearful memory was impaired. When the neurons were activated without the negative odor, the mice attempted to flee.