Stuck on Sad: Why Traumatic Memories Stay With Us
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Sometimes finding our way down memory lane is a dreary and depressing ordeal. It can seem to some of us with more of a pessimistic mind that all we have are bad memories, and manic depressives like myself often feel stuck on sad. Is there a reason that these more traumatic memories seem to stick to us longer?
Traumatic events in our lives can be hard memories to shake, and scientists are not saying they understand why. Once again our friendly neighborhood laboratory rats have revealed new information to us humans to work with. For the first time in a recent study we now know the brain mechanism that translates unpleasant experiences into long-lasting memories!
The Hebbian Plasticity Hypothesis
65 years ago there was a hypothesis called Hebbian plasticity that the study is supporting with new data. The idea of Hebbian plasticity states that as a result of trauma, more neurons in the brain fire electrical impulses in unison and make stronger connections to each other than under normal situations. Thus the stronger connections create stronger memories. Thanks science.
What is especially exciting is that this new data is not only important for the advancement of researchers’ understanding of how Hebbian plasticity works, but these newest findings may in addition lead to innovative and exciting treatment opportunities to help patients forget horrible memories, such as those associated with post-traumatic stress disorder (PTSD).
People in the field of brain function like to say “neurons that fire together, wire together” which refers to the mind forming strong connections. So our traumatic memories stick with us so long because many are seared into our minds by a chemical reaction similar to our reaction to dopamine and drugs or alcohol.
Supposedly the idea is that Hebbian plasticity works when a brain region called the amygdala allows sensory stimuli to become associated with either rewarding or aversive outcomes, with results in producing emotional memories.
Studying the Science of Trauma
Researchers at New York University and Japan’s RIKEN Brain Science Institute published a study on December 8th, 2014 in the Proceedings of the National Academy of Sciences that further explained the data in detail, and since then there has been a lot of talk about the future.
Hebbian plasticity works when a brain region called the amygdala allows sensory stimuli to become associated with either rewarding or aversive outcomes, thus producing emotional memories. Joshua Johansen of RIKEN, one of the lead authors on the study said,
“These processes for triggering aversive memory storage may represent a general mechanism controlling memory formation that is shared across other learning systems in the brain.”
Previously Joseph LeDoux, director of NYU’s Emotional Brain Institute, led researchers who found evidence to back up the concept of Hebbian plasticity by using brain cells that had been removed from animals. The big difference is that the new study represents the first time the process was seen in a working brain with real memories.
Working with rats that were conditioned to associate an auditory tone with a mild electrical shock to their feet, the researchers used a new technique called optogenetics which allowed them to both control and track the path of electrical impulses in the rats’ amygdalas.
So by weakening or blocking the signaling among neurons, the memory that linked the sound with shock failed to form, the researchers say the study helps to prove the idea of Hebbian plasticity. As with some experiments though, there is always a shortcoming. The researchers also found that Hebbian plasticity cannot completely explain the process.
The scientists used lasers to directly stimulate neurons in the amygdala without actually delivering the shock, and found that the negative memory wasn’t formed, despite the strong neural activity. This implies that Hebbian mechanisms are important to form these kinds of memories, but alone do not make enough to form a memory. Meaning tiny molecules called neuromodulators seem to be required as well.
Thoughts of the Future
Lorenzo Diaz-Mataix, a postdoctoral at NYU who acted as another lead author on the report claimed,
“Our results not only show that we are able to artificially manipulate memory, but also that this manipulation is correlated with long-lasting changes in the brain. Basic findings like this one will potentially help to understand and treat many psychiatric conditions that share aberrant memory processing.”
Remembering scary events, such as an animal attack, clearly has advantages from an evolutionary perspective. But sometimes memories can be too painful. For people who have such memories, the new findings offer hope. Diaz-Mataix has even said that he believes this paper is instrumental in finding a way to be able to eliminate harmful memories such as those causing PTSD, or even reverse them!
“One possibility is that instead of tapping into ‘forgetting’ mechanisms, we try to reverse what happened during memory formation. Our findings in this paper are important in this regard and may enable novel approaches to enhance the forgetting or reversal of learning of aversive experiences.”
Some points here sound absolutely exciting and amazing! To think there is a developing science to wiping out memories. As much good as reversing memories may do, I can’t help but be skeptical at the same time, because I myself watch too many scifi movies. All I can think of is the flashy thing in “Men in Black” or the tragic unwinding of Jim Carrey in “Eternal Sunshine of a Spotless Mind”. Then they talk about manipulating memories and the theme music from “Inception” blares in my head and I start wondering how much of this is me being obnoxious.
Traumatic memories are the root of PTSD, and those same kind of memories are often found at the root of an a drug and/or alcohol addiction. Thanks to research and passionate recovery facilities, treatment for these kinds of afflictions are constantly growing and evolving. If you or someone you love is struggling with substance abuse or addiction, please call toll-free 1-800-777-9588