Researchers from an institute of technology found a special gene in mice. It could help people forget painful memories. Many soldiers, crime victims and natural disaster survivors have memories that make them stressed. They have an illness called post-traumatic stress disorder (PTSD). Scientists will use their research to erase painful memories. They want to replace them with nice thoughts and feelings. This would help millions of people with PTSD.

Scientists did tests to make mice forget their fear. They put the mice into a cage and gave them electric shocks. The mice became afraid of the cage. They had "cage shock". The mice went into the cage again but with no electric shock. The mice no longer feared the cage. Their fear changed to good feelings. The scientists looked at the brains of the mice. They found a gene that erased old memories. They will now try to find this gene in human brains.