Brain has emotional sense
Poignant memories held in regions for sight, sound and smell
For some people, the smell of an apple pie might spark a warm childhood memory. For others, a loud sound may bring back strong battlefield images. New research in rats may help explain these connections by suggesting that emotional memories like these are stored in parts of the brain linked to sight, sound and smell.
Scientists have long known that emotionally charged memories tend to be stronger than neutral ones. But researchers haven’t been able to pinpoint where in the brain those memories are stored in the long term.
In the new study, published in the Aug. 6 Science, researchers trained rats to associate sounds, smells and sights with electric shocks. After a month, the researchers damaged an auditory, visual or olfactory part of the brain, called a secondary sensory cortex, in some of the rats. The damage appeared to make the animals lose memories linked to the damaged sense; they no longer froze in their tracks at the sounds, smells, or sights they had previously learned to fear.
Each sense, including sound, smell and vision, has a primary and a secondary sensory cortex area in the brain. The primary cortex sends sensory information to the secondary cortex, which then connects to emotional and memory areas of the brain.
“I think it’s a groundbreaking paper,” says neuroscientist Alcino Silva of the University of California, Los Angeles. “It’s the first time that I know of that someone was able to connect the sensory cortices to a remote memory, and that’s quite significant.”