If moments are fleeting, then memories are permanent. When we share our most powerful memories, they grow with time rather than fade — giving us the ability to celebrate friends and family members long after they have passed.

But we all have some memories we'd rather forget. Could it be possible to edit our memories? It sounds like something out of science fiction, but imagine if memory could be tuned in such a way that good memories were enhanced for those suffering from dementia, or bad memories were wiped away for those with post-traumatic stress disorder (PTSD).

Although emotion that is activated by a memory may not be felt as intensely as the actual experience, the recall can be enjoyable or painful nonetheless. Emotional memory adds credibility to the notion that thoughts can trigger emotion just as the activation of emotion can create cognition.

Brain mechanisms underlying memory are not well understood, but most scientists believe the region of the brain most involved in emotional memory is the amygdala. Acetylcholine is delivered to the amygdala by cholinergic neurons that reside in the base of the brain. These same neurons appear to be affected early in cognitive decline.

Previous research has suggested that cholinergic input to the amygdala appears to strengthen emotional memories. Now, new research published in the journal Neuron points to a possible breakthrough, which could lead to new, drug-free ways to treat PTSD.

According to Lorna Role, Ph.D., professor and chair of the Department of Neurobiology and Behavior and co-director of the Neurosciences Institute at Stony Brook Medicine, memories of emotionally charged experiences whether positive or negative are particularly strong. The goal of this research was to determine the mechanisms underlying the strengthening of memory.

Role and colleagues used a fear-based memory model in mice to test the underlying mechanism of memory, because fear is a strong and emotionally charged experience.The model is a newer research method optogenetics (or optogenetic regulation) which uses light to control cells in living tissue to stimulate specific populations of cholinergic neurons during the experiments.

There were two interesting and surprising findings: First, when they increased acetylcholine release in the amygdala during the formation of a traumatic memory, it greatly strengthened memory and made the memory last more than twice as long as normal. When they decreased acetylcholine signaling in the amygdala during a traumatic experience, one that normally produces a fear response, they could actually wipe out memory. Second, the researchers essentially created fearless mice by manipulating acetylcholine circuits in the brain.

However, there is a challenge in researching cholinergic neurons because they are intermingled with other types of neurons and are few in number compared to other types of neurons in the brain. Because acetylcholine is a natural signaling mechanism and seemingly essential for memory, additional research will center on nonpharmacologic ways to manipulate or fine-tune memory.

Hopefully, independent of drug administration, researchers will find ways to affect the strength of specific memories and diminish the bad ones.