An old saying tells us not to dwell on an unpleasant event. A new clinical study suggests the saying has both psychological and neurological support for its validity. Along with his advisors, Thomas Ågren – a doctoral candidate in psychology at Uppsala University in Sweden – has shown that it is possible to erase newly formed emotional memories from the human brain.
There are two forms (at least) of memory, short-term and long-term. Short-term memory keeps a very small amount of information, about the seven digits of a telephone number, at your fingertips for a brief period – typically less than a minute. Long-term memory, on the other hand, seems to store nearly unlimited amounts of information for years or decades.
A long-term memory of an experience, however, is not formed immediately upon the fading of the experience from short-term memory. The information is slowly consolidated into long-term (potentially lifelong) storage over time. This is why some drugs or experiences (such as a concussion) are associated with a period of amnesia – their effects stop the consolidation process cold, so the memory is lost.
When we remember an experience, the memory of that experience briefly becomes unstable, then is restabilized by consolidation of the remembered event. In effect, we don't actually remember the original event, but rather a memory of a memory of a memory of the original event. By disrupting the reconsolidation process that follows re-remembering, we can change the content of memory.