There are people who are difficult or impossible to hypnotize. Many have thought this was because of their personality but this may not be true. ScienceDaily has an item (here) on the paper by Hieft and others, Functional Brain Basis of Hypnotizability in Archives of General Psychiatry.
The researchers examined 12 highly hypnotizable and 12 people with low hypnotizability with various scans, looking at three networks: the default network, the executive-control network and the salience network.
The findings, Spiegel said, were clear: Both groups had an active default-mode network, but highly hypnotizable participants showed greater co-activation between components of the executive-control network and the salience network. More specifically, in the brains of the highly hypnotizable group the left dorsolateral prefrontal cortex, an executive-control region of the brain, appeared to be activated in tandem with the dorsal anterior cingulate cortex, which is part of the salience network and plays a role in focusing of attention. By contrast, there was little functional connectivity between these two areas of the brain in those with low hypnotizability. Spiegel said he was pleased that he and his team found something so clear. “The brain is complicated, people are complicated, and it was surprising we were able to get such a clear signature,” he explained.
Hypnotizability is not due to personality variables but on cognitive style rooted in neural traits. Future work will look at how the networks interact under actual hypnosis.