A study published in the August issue of the journal Nature showed that the brain’s own endocannabinoids could be involved in helping to learn past painful memories.
Researchers at the Max Planck Institute of Psychiatry in Munich, Germany, studied genetically modified mice that had no CB1 cannabinoid receptor, along with mice who were given a CB1 receptor antagonist (which blocks the receptors).
Both types of mice were trained to associate a musical tone with an electric shock, as were normal mice. When the tone was no longer accompanied with a shock, the normal mice soon stopped reacting in fear, but the mice who had no access to their natural endocannabinoids took far longer to re-adapt.
Researchers also found that when the normal mice were gradually forgetting the learned response to the shock, the area of the brain central to storing memory and fear (the amygdala) was flooded with endocannabinoids.