Results showed characteristic changes in regional cerebral blood flow (r CBF) when hypnotised with or without suggestions. (1999) concluded that the changes in r CBF reflect different emotional reactions (i.e.
of high/low unpleasantness) to pain perception in hypnotic consciousness.
Also, hypnotic suggestions can alter neural activity, most notably in pain and colour perception. To define pain, researchers therefore measured brain activity and found characteristic neural activity patterns commonly referred to as “pain matrix” (Peyron et al., 2000).
Several studies used positron emission tomography (PET) to determine cerebral structures under pain, both in normal conditions and under hypnosis.
There are other models and other explanations and this is by no means exhaustive.
Recent functional neuroimaging studies show that brain activity varies when a task is performed in a waking state and again under hypnosis.
Here are some of the well-known definitions given by popular authors from the field of hypnosis; “Hypnosis is an altered state of awareness in which the individual withdraws his peripheral awareness and concentrates all attention on a focal goal…
is related to the ability to concentrate in an attentive, responsive manner, even to the point of dissociation” (Spiegel, 1972).
“Hypnosis typically involves an introduction to the procedure during which the subject is told that suggestions for imaginative experiences will be presented.(Irving Kirsch 1994) “The term hypnosis´ is used to denote an interaction between two people (or one person and a group) in which one of them, the hypnotist, by means of verbal communication, encourages the other, the subject or subjects, to focus their attention away from their immediate realities and concerns and on inner experiences such as thoughts feelings and imagery.The hypnotist further attempts to create alterations in the subjects´ sensations, perceptions an, feelings, thoughts and behaviour by directing them to imagine various events or situations that, were they to occur in reality, would evoke the intended changes” (Heap & Aravind 2002) If you’d like to examine and understand in more depth the issues related to definitions of hypnosis, then a paper entitled ‘Definitions of Hypnosis and Hypnotizability and Their Relation to Suggestion and Suggestibility’ (Kirsch et al, 2011) is available.The hypnotic induction is an extended initial suggestion for using one´s imagination, and may contain further elaborations of the introduction.A hypnotic procedure is used to encourage and evaluate responses to suggestions.
When using hypnosis, one person (the subject) is guided by another (the hypnotist) to respond to suggestions for changes in subjective experience, alterations in perception, sensation, emotion, thought or behavior.