Traumatic events can do more than hinder an individual at the moment of the event; they can carry on throughout one’s life as emotional memories, repeating and intensifying the trauma itself. This recurring trauma can be debilitating, causing some people to develop an anxiety disorder. This past November, Sinai Health System Department of Medicine and Department of Psychiatry co-sponsored a talk by Dr. Daniela Schiller, Associate Professor of Psychiatry and Neuroscience at the Icahn School of Medicine at Mount Sinai in New York. Dr. Schiller has dedicated her research to exploring how the traumatic emotional nature of memories can be modified in humans.
Humans are naturally wired to have a fight or flight response, an instinct that served us well in the wild. We’ve evolved to be good at predicting danger, but how do we change this process in the brain to accommodate our changing environment? We need fear to survive
Dr. Schiller’s work examines the possibility of modifying an original memory in such a way that an individual keeps the memory, but loses the fear that comes with it. So how do we modify an original memory? We have to first look at how memories are formed.
Memories can be fleeting if they do not have the time to concretely form. This is why those who have experienced a car accident or other type of trauma often do not recall the time before and after it. “The brain doesn’t have a chance to form the memory. It’s not that you forget it, it merely was never there,” says Dr. Schiller. When a memory is formed correctly, it is taken from short-term memory and it becomes a stable long-term memory for later retrieval, this is called consolidation. When a memory is retrieved, it has to go through consolidation again and retrace its path within the brain, a process called reconsolidation.
Some pharmaceuticals have been shown to block this reconsolidation by targeting the proteins needed in the neural synapses (information that flows from one neuron to another). Although safe in animals, these drugs have proven to be too toxic for use in humans. The search for the right compound continues.
In the absence of a safe drug that can block reconsolidation and thus modify an emotional memory, Dr. Schiller’s research takes a different approach. In an experiment, Dr. Schiller trained individuals to fear a certain colored square, associating it with a shock. Given this training, the next day this group was exposed to the colored square alone, which now induced a fearful reaction. She then presented the colored square several times without the fear-inducing information (i.e. the shock). This process is called extinction. Dr. Schiller found that time is key; those who saw the squares unaccompanied by a shock within ten minutes no longer feared the square. However, those who saw the squares unaccompanied by a shock a few hours after the initial presentation of squares with shocks still feared it. It has to be the moment of reconsolidation that this extinction occurs. Dr. Schiller has found the reversal of the fear to last for a minimum of a year.
Dr. Schiller’s method takes advantage of the fact that with an ever-changing environment we need to update our emotional responses consistently to align with new and current information. Similar methods could potentially be used to help those with anxiety disorders, including post-traumatic stress disorder, phobias or addiction.