Scientists Erase Memories in Rat Brains

A yellow line indicates the track of a rat demonstrating spatial memory on a rotating disc. The animal avoids the stationary sector where it had been shocked the previous day. Inhibition of the persistent kinase that maintains long-term potentiation at hippocampal synapses erases the stored memory. The instability of long-term memory is suggested by the Salvador Dali painting, The Disintegration of the Persistence of Memory. The background shows Golgi-stained hippocampal neurons by Lorente de Nó. CREDIT: Science

Scientists have for the first time erased long-term memories in rats and also directly seen how the brain is changed by learning.

The research points to potential human benefits.

These findings could prove key "to understanding how memories can be augmented, for example in diseases that affect memory, like Alzheimer's," said neuroscientist Mark Bear at the Picower Institute for Learning and Memory at MIT.

The research could also help treat pain that does not go away, "like neuropathic pain, where people have a moderately severe injury, typically to the hands or feet, and instead of going away in a couple of hours just perpetuates," neurologist and molecular biologist Todd Sacktor at the State University of New York Downstate Medical Center in Brooklyn said in a phone interview.

The investigators separately examined the hippocampus, a structure critical for memory. Three decades ago, scientists discovered the existence of persistent increases in the strength of the connections, or synapses, linking brain cells in the hippocampus. This mechanism is largely believed to help in memory formation.

Remarkably, however, until now there was no evidence confirming a link between learning and this synaptic strengthening. One major problem was that these changes in the hippocampus during learning are few and far between.

"It was getting fairly embarrassing to the field that it had yet to be directly observed," Bear told LiveScience.