US scientists test on-off memory switch in rats

US scientists said Friday they have developed an on-off memory switch that helped laboratory rats remember a behavior that they had forgotten. The brain prosthesis marks the first time that researchers have been able to duplicate the brain's learning process, restoring memories that test rats were drugged to forget, and could offer hope for people with dementia. "Flip the switch on, and the rats remember. Flip it off, and the rats forget," said Theodore Berger of the University of Southern California's Viterbi School of Engineering's Department of Biomedical Engineering. Working with scientists from North Carolina's Wake Forest University Department of Physiology and Pharmacology, Berger's team focused on the hippocampus, the section of the brain where memories are made. The communication between two regions of the hippocampus results in a short-term memory being converted into a long-term memory. The team studied the signals sent between these subregions as rats learned a task that involved pressing a lever in order to get a reward. Through repetition, the rats learned the behavior as a long-term memory. When scientists drugged the rats to halt neuron signals between the two regions, the rats forgot the long-term memory. But when they implanted an electronic brain prosthetic that duplicated the signaling process between the subregions, the rats could remember again. In normal rats, "the device could actually strengthen the memory being generated internally in the brain and enhance the memory capability," said the study published in the Journal of Neural Engineering. The team hopes to test the device in monkeys next, in the hope it could one day help people who suffer from memory loss due to dementia, stroke or brain injury.