brains, mind
Faudra que tu fasses travailler tes méninges.
You’ll have to put your thinking cap on.
— Alien³ (1992)
Creusez-vous les méninges.
Rack your brains.
— Get Out Your Handkerchiefs (1978)
Ils se creusent toujours les méninges.
They're always racking their brains.
— Memories of Murder (2003)
Si tu veux te fatiguer les méninges, va aux États-Unis.
If you want to exercise your brain, go to the United States.