Just don't let the rats escape. Scientists have developeda brain implant that restored lost memories and improved recollection in labrats. It's the first time cognitive function has been improved with a devicethat mimics neurons. The rats were implanted with an array of electrodes thatlinked two neighboring pieces of the hippocampus. The researchers then used adrug to shut down the implant, causing the rats to forget which lever to pullfor food. When they turned the array back on, the rats forgot about 40 percentof the time. And when they amplified the implant's signal, they forgot only 10percent of the time. “Turn the switch on, the animal has the memory; turn itoff and they don’t: that’s exactly how it worked,” says the lead author of thestudy.