Lasers reactivate 'lost' memories in mice with Alzheimer's

Forgotten memories have been reawakened in mice with Alzheimer's disease, suggesting that the condition may not actually destroy our memories, but instead impair our ability to recall them. It has long been assumed that Alzheimer's disease completely erases memories. The condition involves clumps of proteins known as amyloid plaques and tau tangles accumulating in the brain, where they are thought to destroy the neurons that store our memories. But experiments by Christine Denny at Columbia University and her colleagues suggest that memories may not be wiped by Alzheimer's disease, but instead become harder to access. What's more, these memories can be reawakened by artificially activating the neurons they are stored in. The finding could be revolutionary, says Ralph Martins at Edith Cowan University in Australia.