Stress hormone takes effect while people retrieve and reconsolidate emotional memories.
The stress hormone cortisol strengthens memories of scary experiences. However, it is effective not only while the memory is being formed for the first time, but also later when people look back at an experience while the memory reconsolidates. This has been published by cognition psychologists from the Ruhr-Universität Bochum in the journal “Neuropsychopharmacology”. They suggest that the results might explain the persistence of strong emotional memories occurring in anxiety and Post-Traumatic Stress Disorder (PTSD).
Memories of emotional experiences usually fade over time
Strong memories of stressful experiences occur frequently, but they usually fade away over time. People suffering from anxiety or Post-Traumatic Stress Disorder, however, are affected by terrifying memories that haunt them again and again. It had been shown that the stress hormone cortisol has a strengthening impact on the consolidation of memories, i.e. the several-hour process in the course of which a memory is formed immediately after the experience.
Cortisol influences the reconsolidation of emotional memories
The researchers from Bochum have demonstrated that cortisol effects memories in humans also during the so-called reconsolidation, i.e. the consolidation of memories occurring after memory retrieval. The stress hormone can enhance this process. “The results may explain why certain undesirable memories don’t fade, for example in anxiety and PTSD sufferers,” says Dr Oliver Wolf. If a person remembering a terrifying event has a high stress hormone level, the memory of that specific event will be strongly reconsolidated after each retrieval.
On three consecutive days, the subjects took part in the study, carried out by Shira Meir Drexler, PhD student at the International Graduate School of Neuroscience in Bochum. On the first day, they learned an association between specific geometric shapes and an unpleasant electric shock. On the second day, some of the participants were given a cortisol pill, others a placebo. Subsequently, they were shown one of the geometric shapes associated with the electric shock. On the third day, the memory for the geometric shapes was tested. Participants who had taken cortisol remembered the fear-associated shape particularly well. This was evident in a heightened skin conductance, which is an established measure for emotional arousal.
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Funding: The study was financed by the DFG research group “Extinction Learning” (FOR 1581).
Source: Oliver T. Wolf – Ruhr-Universität Bochum Image Credit: Image is credited to Ben Mills and is in the public domain Original Research:Abstract for “Effects of Cortisol on Reconsolidation of Reactivated Fear Memories” by Shira Meir Drexler, Christian J Merz, Tanja C Hamacher-Dang, Martin Tegenthoff and Oliver T Wolf in Neuropsychopharmacology. Published online June 10 2015 doi:10.1038/npp.2015.160
Effects of Cortisol on Reconsolidation of Reactivated Fear Memories
The return of conditioned fear after successful extinction (eg, following exposure therapy) is a significant problem in the treatment of anxiety disorders and posttraumatic stress disorder (PTSD). Targeting the reconsolidation of fear memories may allow a more lasting effect as it intervenes with the original memory trace. Indeed, several pharmacological agents and behavioral interventions have been shown to alter (enhance, impair, or otherwise update) the reconsolidation of reactivated memories of different types. Cortisol is a stress hormone and a potent modulator of learning and memory, yet its effects on fear memory reconsolidation are unclear. To investigate whether cortisol intervenes with the reconsolidation of fear memories in healthy males and how specific this effect might be, we built a 3-day reconsolidation design with skin conductance response (SCR) as a measure of conditioned fear: Fear acquisition on day 1; reactivation/no-reactivation of one conditioned stimulus and pharmacological intervention on day 2; extinction learning followed by reinstatement and reinstatement test on day 3. The groups differed only in the experimental manipulation on day 2: Reactivation+Cortisol Group, Reactivation+Placebo Group, or No-reactivation+Cortisol Group. Our results revealed an enhancing effect of cortisol on reconsolidation of the reactivated memory. The effect was highly specific, strengthening only the memory of the reactivated conditioned stimulus and not the non-reactivated one. Our findings are in line with previous findings showing an enhancing effect of behavioral stress on the reconsolidation of other types of memories. These results have implications for the understanding and treatment of anxiety disorders and PTSD.
“Effects of Cortisol on Reconsolidation of Reactivated Fear Memories” by Shira Meir Drexler, Christian J Merz, Tanja C Hamacher-Dang, Martin Tegenthoff and Oliver T Wolf in Neuropsychopharmacology. Published online June 10 2015 doi:10.1038/npp.2015.160
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