incoherent, idle thoughts "at the top of the brain"

Eggcorn of rack one's brain.

(idiomatic) To struggle to think or remember something.

(medicine) A traumatic injury to the brain caused by an external force.

(dated) attention deficit hyperactivity disorder

plural of traumatic brain injury

(surgery) A neurosurgical procedure involving the implantation of a medical device called a neurostimulator which sends electrical impulses, through implanted electrodes, to specific parts of the brain for the treatment of movement and affective disorders

The return of people who emigrated from a country during the process of brain drain.

(UK, dated, figuratively) to think hard and try to remember something.

plural of reverse brain drain