Researches in California have created a proof-of-concept method to erase memories in mice using flashes of light. From Science Daily:
Optogenetics, pioneered by Karl Diesseroth at Stanford University, is a new technique for manipulating and studying nerve cells using light. The techniques of optogenetics are rapidly becoming the standard method for investigating brain function.
Kazumasa Tanaka, Brian Wiltgen and colleagues at UC Davis applied the technique to test a long-standing idea about memory retrieval. For about 40 years, Wiltgen said, neuroscientists have theorized that retrieving episodic memories — memories about specific places and events — involves coordinated activity between the cerebral cortex and the hippocampus, a small structure deep in the brain.
The scientists used genetically modified mice with nerve cells that glow florescent green and have a protein that can allow the cells to be turned on or off with pulses of light. By mapping the brain response of mice to specific events, Tanaka and Wiltgen were able to target memories for deletion. Fiber optic cables were inserted into the mouse brains and the memories were turned off with flashes of light.
In the future, it may be possible to create a similar memory deletion treatment for humans via gene therapy or through the use of pharmaceuticals. There are a number of “photodynamic therapy” drugs already in trials that have demonstrated the ability to bind to brain tumor cells and respond to light.