Memories need to be stable from a functional perspective. If the environment doesn’t change, why would a related memory trace be altered or erased? The only reason for a memory to be altered is if the environment is found to have changed.
Scientists at the University of Amsterdam (UvA) have discovered that fear responses can be erased by making people learn something new whilst retrieving their fear memories. The researchers, whose work has been published in the journal Science, found that whereas patients who are treated with conventional cognitive behavioural therapy (CBT) often regain their fears, fear responses did not return to participants who underwent this new technique in the laboratory.
Professor Merel Kindt
In order to test whether or not participants had learned anything new, the team employed a strategy of prediction error; a situation in which a subject’s anticipation of what is going to happen is incongruous with what takes place in actuality. After using conditioning to create fear anticipation and responses, the scientists combined learning with the beta blocker propranolol to erase those fear responses. Even when they tried to reintroduce these responses, the researchers found that the fears did not return.
In an interview with ScienceOmega.com, lead researcher Professor Merel Kindt explained how this new strategy could eventually be used to help patients with conditions such as anxiety and post-traumatic stress disorder (PTSD)…
How does the technique that you have developed differ from today’s CBT?
Traditional exposure therapy and some other forms of CBT make use of extinction learning. The idea is that the new memory formed through this technique regulates and inhibits the original fear memory, thereby reducing the previously learned fear response.
In contrast, we set out to weaken the underlying fear memory. We engineered a situation in which there was something to be learned. Using prediction error, we created a mismatch between what participants were anticipating and what actually happened. When they learned that their environment was in some way different to what they had been expecting, their fear memory was destabilised. This is an important factor because if the memory trace is not destabilised, there can be no break in synthesis. In turn, the propranolol prevents this break from being repaired and the fear response does not return.
Do you understand why learning is so important to the eradication of fear responses? How are the two processes connected?
Think about the function of memory. We learn a lot of things and our ability to retrieve these pieces of information is really helpful. If we were not able to do this, we would have to constantly relearn what we learned previously. Memories need to be stable from a functional perspective. If the environment doesn’t change, why would a related memory trace be altered or erased? The only reason for a memory to be altered is if the environment is found to have changed.
So the memory relates to something that you believe to be true, and by learning that things are different, your fear response is modified…
Yes. People usually talk about memory in terms of easily recallable declarative memory: facts or knowledge. However, the largest proportion of human memory expresses itself through behaviour, performance, fear, etc. This is what is meant by emotional, or fear, memory. It is important to note that our technique only erases fear responses, i.e. components of fear memory.
In our last paper, we manipulated the different conditions and we demonstrated that when nothing has been learned, the propranolol does not erase the fear response. However, in participants who had learned a fear the day before, and who had retrieved their fear memory whilst engaging in new learning, the propranolol that was administered after memory retrieval erased this fear response a day later. Of course, this situation is largely artificial. Essentially, we have conducted an experimental study to show the conditions necessary to erase a previously learned fear response.
What are the next steps for your research?
The next step is to test this procedure in patients with anxiety disorders. We are in the process of designing two studies: one for patients suffering from PTSD and another for a group with panic disorder. We are now at the experimental phase whereby we search for the optimal procedure and run randomised controlled trials (RCTs) to see whether this technique remains effective in patients. Of course, we cannot yet say with any certainty whether or not this will be the case. After all, our laboratory investigations have been conducted on healthy participants. One can only assume that the fear responses of real patients will be much stronger and more complex than the artificial responses that we manufactured in the laboratory.
Even so, the results that we have so far obtained from lab tests are much stronger and more convincing than those related to extinction learning, and extinction learning is the current experimental model used in CBT. For this reason, we are quite confident that our technique will prove to be effective.