Bad memory? Delete it with a single dose

‘Emotions In Specific Parts Of Brain Can Be Edited’

Suppose scientists could erase certain memories by tinkering with a single substance in the brain. Could make you forget a chronic fear, a traumatic loss, even a bad habit.

Researchers in Brooklyn have recently accomplished comparable feats, with a single dose of an experimental drug delivered to areas of the brain critical for holding specific types of memory, like emotional associations, spatial knowledge or motor skills.

The drug blocks the activity of a substance that the brain apparently needs to retain much of its learned information. And if enhanced, the substance could help ward off dementias and other memory problems. So far, the research has been done only on animals. But scientists say this memory system is likely to work almost identically in people.

“If this molecule is as important as it appears to be, you can see the possible implications,” said Todd Sacktor, a 52-year-old neuroscientist who leads the team at the SUNY Downstate Medical Center, in Brooklyn, which demonstrated its effect on memory.

Research suggests, brain cells activated by an experience keep one another on biological speed-dial, like a group of people joined in common witness of some striking event. Call on one and word quickly goes out to the larger network of cells, each apparently adding some detail, sight, sound, smell. The brain appears to retain a memory by growing thicker, or more efficient, communication lines between these cells. In a 1999 paper, researchers listed 117 molecules that were somehow involved when one cell creates a lasting speed-dial connection with a neighbor, a process known as “long-term potentiation”.

Sacktor eventually landed up with a substance called PKMzeta. In a series of studies, Sacktor’s lab found that this molecule was present and activated in cells precisely when they were put on speed-dial by a neighboring neuron. In fact, the PKMzeta molecules appeared to herd themselves, like troops occupying a small peninsula, into precisely the fingerlike connections among brain cells that were strengthened. And they stayed there, indefinitely, like biological sentries.

Sacktor then tried to find out what, if anything, PKMzeta meant for living, breathing animals. His colleague, Andre Fenton, also of SUNY Downstate, who studies spatial memory in mice and rats, had already devised a clever way to teach animals strong memories for where things are located by teaching them to move around a small chamber to avoid a mild electric shock to their feet. Once the animals learn, they do not forget. Placed back in the chamber a day later, even a month later, they quickly remember how to avoid the shock and do so.

But when injected — directly into their brain — with a drug called ZIP that interferes with PKMzeta, they are back to square one, almost immediately.

Researchers led by Yadin Dudai at the Weizmann Institute of Science in Israel found that one dose of ZIP even made rats forget a strong disgust they had developed for a taste that had made them sick — three months earlier.