In the 19th century, the psychologist Ernest Hilgard was interested in hypnosis. In his research, he discovered that consciousness levels shift during hypnosis and that cognitive functions are split while one part of the mind goes solo to carry out functions independently. Hilgard called this psychological state “divided consciousness.” Hypnotic responses in the brain are comparable to dissociative reactions and Hilgard theorized that hypnosis was a highly-controlled form of dissociation.
Brain imaging and neurobiological research explains that distinct areas of a posttraumatic person’s brain, such as the locus ceruleus, activate with triggering stimuli. The locus ceruleus is in the brainstem and is involved in the body’s response to stress. In this area, there is a high density of opioid receptors. When the brain senses danger, natural opioids are released en masse and normal opioid receptor binding is affected. In people with PTSD, this continues long after the end of the stressful event. What this does is reduce sensitivity to physical and emotional pain. It’s what happens in the brain during dissociation.
Opioids create a dissociative state where emotional responses are altered and pain is numbed. When scientists tested stress responses in already-stressed animals, they discovered that the animals became desensitized to stressors because endogenous opioid production automatically kicked into high gear. Scientists successfully reversed the numbing effect with the use of naloxone. Animals that are put under constant duress seem as if they are on an opioid like heroin. Scientists also observed animals reacting like addicts in withdrawal when an opioid blocker was used to disrupt the flow of natural endogenous opioids.
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