The brain has a remarkable capacity for keeping track of our past experiences. But detailed memories can sometimes seem more a curse than a blessing. This is especially true for those who've suffered significant losses or other traumas. Thus, while the holiday season is meant to be a joyous time, for many it merely provides salient reminders of these debilitating experiences.
Fortunately, researchers are discovering that memories may be far less durable than previously thought. Indeed research on "erasing" traumatic memories is quickly moving from the realm of science fiction to scientifically backed reality.
That each of us may be able to exert some control over what gets in and what then stays in long-term memory arises from our growing understanding of how the brain represents and stores information related to our conscious life experiences.
Which details of an event get consolidated into this "episodic" memory is largely determined by what we are focused on and processes that reinforce associations between these initially fragile representations of the event. This is done through oscillating patterns of neural activity led by such brain regions as the hippocampus. The resulting memory traces become increasingly stable and distributed throughout the brain's outer cortex.
A growing body of research has shown that the impact of a painful memory can be significantly reduced by interfering with this consolidation process shortly after a traumatic event. The aim is not to block or erase all memory of the event, but only the problematic details.
The hypertension drug propranolol, for example, blocks certain neurotransmitter receptors in the emotion-intensive amygdala. By administering propranolol within six hours of a traumatic event, researchers have shown it to selectively disrupt consolidation of the terror that would otherwise be associated with the event. Individuals can later think back on the event without experiencing a high level of emotional and physiological distress.
A team of British researchers has found a far less intrusive (and much more enjoyable) method of preventing troublesome flashbacks in the video game Tetris. It seems the mental gymnastics required to correctly rotate geometric shapes into position as they drop down the screen requires a considerable amount of visual-spatial processing power.
So much so that when played within four hours of viewing a traumatic film, too few neural resources were leftover to properly consolidate the film's visual details. The result was a long-lasting reduction in unwanted traumatic images popping into the minds of the Tetris players compared with those who played a different video game with very few visual-spatial demands.
In addition to methods that block the formation of traumatic memories, researchers have also discovered how to alter records of painful events that have already been well-established in long-term memory.
The key to this discovery arises through recent evidence that, upon retrieval, previously consolidated memories return again to a fragile, malleable state that must undergo a reconsolidation process to regain stability. And information available during a time period of approximately 10 minutes can be incorporated into the active memory trace. The impact of a painful memory can also be modulated during this reconsolidation period.
Recent studies of altering traumatic memories through reconsolidation have used both drug-based interventions and tasks without drugs. Benefits lasting beyond a year have been observed after individuals retrieved a previously problematic memory cue and then relearned its perceptual details in the absence of any potential threat.
All of us are shaped by life's experiences. How we react and reflect on these experiences may be critical in determining their continuing impact. If you have a troubling memory, it may help to focus on any non-emotional details whenever the event replays in your mind. And a few rounds of Tetris can't hurt.
Mark Fenske, co-author of The Winner's Brain: 8 Strategies Great Minds Use to Achieve Success, is an associate professor in neuroscience at the University of Guelph.