We are all troubled by certain memories. A schoolyard bully. A heart-wrenching breakup. The loss of a loved one. But if you could forget parts of your past, would you really want to? What would that mean for who you are?
Such questions are the stuff of science fiction—but not for long. In the last few years, there has been a huge body of work on the neural mechanisms of fear memories, writes University of Michigan neuroscientist Stephen Maren in a recent review in Neuron. "There is now considerable evidence that they can be erased."
New techniques, from behavioral conditioning to interrupting memory consolidation at a molecular level, push the science of memory erasure closer to reality—and straight into a thicket of ethical uncertainty.
"Therapy doesn't bother people, even if that also changes the contours of memory," says Adam Kolber, a bioethics researcher at Brooklyn College. "But once we introduce drugs, it makes people uncomfortable."
We are what we have experienced. But intrusive memories—of painful experiences, for example, or phantom limbs—can keep us from becoming the people we want to be.
For those with post-traumatic stress disorder, who constantly relive terrible experiences, the question is not whether it's ethical to adjust memories, but whether it's fair to get in the way of a pill that might outdo years of therapy. "We think it's bad not to treat people's physical wounds," Kolber observes. "Shouldn't we also do our best to treat people's emotional wounds?"
Scientists have already developed drugs that can delete memories in rats, but figuring out how to target them is "the holy grail," says Maren. "We don't want to just erase the day in your life when this thing happened."
Even taking the emotional sting out of traumatic memories has its risks. Remorse keeps behavior in check. Without it, people could do terrible things without any fear of crippling regret. And the pain of violence is part of what motivates victims to prosecute assailants. —Ian Chant
How to Forget
The beta-blocker, commonly used to combat high blood pressure and stage fright, seems to weaken the link between the facts of a memory and its emotional impact by blocking adrenaline and other substances that ignite the fear response.
Zeta Inhibitor Peptide
ZIP inhibits PKM Zeta, an enzyme that, research suggests, maintains and strengthens long-term memories by reinforcing synaptic connections. Rats injected with ZIP stumble right into shock-rigged obstacles they had previously learned to avoid.
A genetically disarmed herpes virus seems to effectively infiltrate and cripple neural networks that hold fear memories. But a human application is still far-fetched: Scientists would need to identify in advance where certain memories are stored.