Stimulating these areas could one day lead to new treatments for pain, anxiety, and more.
While many people associate hypnosis with questionable stage tricks, some doctors argue that it has true medical value.
"Hypnosis is the oldest Western form of psychotherapy, but it's been tarred with the brush of dangling watches and purple capes," senior author David Spiegel, professor and associate chair of psychiatry and behavioral sciences at Stanford University, said in a press release. "In fact, it's a very powerful means of changing the way we use our minds to control perception and our bodies."
The team of Stanford researchers set out to gain a better understanding of how the brain is affected during a hypnotic trance, publishing their results in the journal Cerebral Cortex.
Only about 10 percent of the general population is considered to be “highly hypnotizable,” so the researchers started out by screening 545 healthy participants to see who could more readily enter a hypnotic state.
They found 36 participants who consistently scored high on the tests of hypnotizability, and 21 control subjects who scored on the extreme low end of the scale.
"It was important to have the people who aren't able to be hypnotized as controls," said Spiegel. "Otherwise, you might see things happening in the brains of those being hypnotized but you wouldn't be sure whether it was associated with hypnosis or not."
All 57 participants underwent MRI brain scans during four conditions: resting, recalling a memory, and two different hypnosis sessions.
Through their observations, the team discovered three hallmarks of the brain in a hypnotic state — these changes were only found in the highly hypnotizable sample as they underwent hypnosis.
First, there was a decrease in brain activity in an area called the dorsal anterior cingulate, which is involved in cognition and motor control. "In hypnosis, you're so absorbed that you're not worrying about anything else," Spiegel explained.
Second, there was an increase in connectivity between the dorsolateral prefrontal cortex and the insula, and this constitutes a brain-body connection that helps the brain process and control what’s happening in the body, the researchers explain.
Lastly, the team saw a decrease in connectivity between the dorsolateral prefrontal cortex and the default mode network, which likely indicates a disconnect between an individual’s actions and his or her awareness of those actions.
"Now that we know which brain regions are involved, we may be able to use this knowledge to alter someone's capacity to be hypnotized or the effectiveness of hypnosis for problems like pain control," said Spiegel.
Interestingly, among patients who can be easily hypnotized, hypnosis has shown to be effective in a number of therapeutic endeavors: easing anxieties or phobias, treating smoking addictions, reducing chronic pain and the pain of childbirth, and more.
A 2009 study found that hypnosis reduced procedure-related pain in adolescents and children, and a 2007 review looked into the evidence of how hypnosis affects those with PTSD, finding that “hypnosis can be a useful adjunctive procedure in the treatment of posttraumatic conditions.”
Going forward, "We're certainly interested in the idea that you can change people's ability to be hypnotized by stimulating specific areas of the brain," said Spiegel.
If future research in this area is promising, then a treatment combining hypnosis and brain stimulation could improve the effects of hypnosis — even among those who aren’t as readily hypnotized — and potentially go on to replace addictive painkillers and anti-anxiety drugs.
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