A morbidly obese man who was undergoing treatment with deep brain electrical stimulation experienced a surprising boost in his memory. Deep brain stimulation devices are comparable to a "pacemaker" for the brain and are used to treat Parkinson's disease, depression, and other disorders. When the physicians at the Toronto Western Hospital first stimulated the electrodes in the patient's brain, he experienced deja vu and was then overwhelmed with incredibly vivid memories from decades before. He subsequently performed much better on memory tests when the stimulator was switched on. From the BBC News:
(After the deja vu, he) had a sudden perception of being in a park with friends.Link to BBC News, Link to paper abstract in Annals of Neurology, Link to more coverage in The Independent
He felt younger, thought he was around 20-years-old, and his girlfriend of the time was there. He was an observer, and saw the scene in colour.
As the intensity of the stimulation increased, details in the scene became more vivid.
Following surgery, the patient recovered for two months. But later when the electrodes were stimulated for a second time, he experienced a similar effect...
The results suggest it might be possible to use deep brain stimulation directly to boost memory.
"We hopefully have found a circuit in the brain which can be modulated by stimulation, and which might provide benefit to patients with memory disorders," said Professor (Andres) Lozano.