Memory retrieval by activating hippocampus engram cells in the brain

Memories banished by Alzheimer’s can in theory be rescued by stimulating nerve cells to grow new connections, a study has shown.

The research, conducted in mice, raises the possibility of future treatments that reverse memory loss in early stages of the disease. Scientists used a technique called optogenetics, which uses light to activate cells tagged with a special photo-sensitive protein.

It was tested on mice with Alzheimer’s-like symptoms that quickly forgot the experience of receiving a mild electric shock to their feet. After tagged cells in their brains were stimulated with light, their memory returned and they displayed a fear response when placed in the chamber where the shock had been applied an hour earlier.

The optogenetic treatment helped the neurons re-grow small buds called dendritic spines, which form synaptic connections with other cells. Although the same technique cannot be used in humans, the research points the way to future memory-retrieving therapies, say the researchers.