Researchers were able to "incept" memories into mice, which could help explain the phenomenon of remembering something that never happened.
In a previous study, researchers detected a "single memory in the brain, genetically tagged the brain cells housing that memory with a light-sensitive protein, and flickered pulses of light to 'turn on' the memory at any given moment," a Riken press release reported.
A new test manipulated that memory and created one that had never actually happened.
Memories are stored in neuron structures called engram-bearing cells, the process can be compared to Legos.
"When we recall a sequence of events, our brains reconstruct the past from these bricks of data, but the very act of accessing a memory modifies and distorts it. When you add in the influence of external sources, it's not surprising that memory can be notoriously unreliable, yet inaccurate memories can have dire consequences," the researchers said in the statement.
Over 250 people in the U.S. have almost been convicted of crimes due to faulty eyewitness testimony, but were saved by DNA evidence.
"Human studies utilizing behavioral and fMRI (functional magnetic resonance imaging) techniques have not been able to delineate the hippocampal subregions and circuits responsible for generating false memories," study author Susumu Tonegawa, Picower Professor of Biology and Neuroscience and director of the RIKEN-MIT Center for Neural Circuit Genetics, said. "Our experiments provide the first animal model in which false and genuine memories can be investigated at the memory engram level."
In order to manipulate the memories, scientists modified engram-bearing cells in the hippocampus (the part of the brain known for storing and creating memories).
The researchers programmed the mice's brain cells to respond to pulses of light. They then moved them to a new environment and pulsed light into their brains in order to recreate the memory.
"They then gave the animals mild foot shocks, creating a negative association between the light-reactivated memory of Box A and the foot shocks, which mice find highly aversive. When the animals were placed back in Box A-the safe environment in which nothing averse had ever happened-the researchers found that the animals now displayed heightened fear responses. In addition, after placing the animals in yet another new environment while shining light on the hippocampal cells that had been artificially associated with fear, the researchers found they could reactivate the false fear memory at will," the press release stated.
Steve Ramirez, a graduate student in the Tonegawa lab, hopes the findings will help bring light to the severity of false witness in the courtroom.
