Does stress motivate you, or does it defeat you? Researchers have identified a group of neurons in the brain that determine whether a mouse will learn to cope with stress or become depressed.
Previous work with brain imaging have shown that the medial prefrontal cortex region becomes hyperactive in depressed people.
A team led by Bo Li from Cold Spring Harbor Laboratory wanted to see if this increased activity actually causes depression, or if it’s just a byproduct of changes to neurons.
The researchers used a mouse model for depression known as “Learned helplessness.” That’s when random foot shocks are delivered to see how the mice respond: Some mice will keep trying to avoid the unpredictable jolts, while others just give up, sit in a corner, and don’t try to move away.
Having already marked specific neurons that respond to stress, the team discovered that brain cells in the mPFC become highly excited in “Depressed” mice; these same neurons are weakened in “Resilient” mice who aren’t deterred by the repeated stressful shocks.
Next, using chemical genetics, they engineered mice to mimic the neuronal conditions found in depressed mice, artificially enhancing their mPFC activity.
The team is now exploring how neurons in the mPFC become hyperactive in depressed mice.