Mendelsohn et al.’s study is important because it demonstrates that hypnotic suggestions influence brain activity, not just behavior and experience. Hypnotic effects are real! This fact has been demonstrated clearly in earlier work, for instance, by psychologist David Oakley (University College London) and colleagues, who compared brain activation of genuinely hypnotized people given suggestions for leg paralysis with brain activation of people simply asked to fake hypnosis and paralysis.

The next major development came from behavioural psychology in American university research. Clark L. Hull (1884–1952), an eminent American psychologist, published the first major compilation of laboratory studies on hypnosis, Hypnosis & Suggestibility (1933), in which he proved that hypnosis and sleep had nothing in common. Hull published many quantitative findings from hypnosis and suggestion experiments and encouraged research by mainstream psychologists. Hull's behavioural psychology interpretation of hypnosis, emphasising conditioned reflexes, rivalled the Freudian psycho-dynamic interpretation which emphasised unconscious transference.
Hypnosis has been used as a pain relieving technique during dental surgery and related pain management regimens as well. Researchers like Jerjes and his team have reported that hypnosis can help even those patients who have acute to severe orodental pain.[135] Additionally, Meyerson and Uziel have suggested that hypnotic methods have been found to be highly fruitful for alleviating anxiety in patients suffering from severe dental phobia.[136]

But for the comparison between PHA and functional amnesia to be most meaningful, we need to know that they share underlying processes. One way to test this is to identify the brain activity patterns associated with PHA. In a groundbreaking study published in Neuron, neuroscientist Avi Mendelsohn and colleagues at the Weizmann Institute in Israel did just that using functional magnetic resonance imaging (fMRI). They carefully selected 25 people to participate in their experiment. Although all were susceptible to hypnosis, earlier testing had shown that half could respond to a PHA suggestion (labelled “the PHA group”) and half could not (the “non-PHA group”). In the Study session of their experiment, participants watched a 45-minute movie. One week later, in the Test session, participants returned to the laboratory and were hypnotized while they lay within the fMRI scanner. During hypnosis, people in both the PHA and non-PHA groups received a suggestion to forget the movie until they heard a specific cancellation cue.
At first, Freud was an enthusiastic proponent of hypnotherapy. He "initially hypnotised patients and pressed on their foreheads to help them concentrate while attempting to recover (supposedly) repressed memories",[61] and he soon began to emphasise hypnotic regression and ab reaction (catharsis) as therapeutic methods. He wrote a favorable encyclopedia article on hypnotism, translated one of Bernheim's works into German, and published an influential series of case studies with his colleague Joseph Breuer entitled Studies on Hysteria (1895). This became the founding text of the subsequent tradition known as "hypno-analysis" or "regression hypnotherapy".
Surgery/Anesthesiology (In unusual circumstances, hypnosis has been used as the sole anesthetic for surgery, including the removal of the gall bladder, amputation, cesarean section, and hysterectomy. Reasons for using hypnosis as the sole anesthetic may include: situations where chemical anesthesia is contraindicated because of allergies or hyper-sensitivities; when organic problems increase the risk of using chemoanesthesia; and in some conditions where it is ideal for the patient to be able to respond to questions or directives from the surgeon);
Many of the clucking chicken images are the result of hypnosis’s forefather, Franz Anton Mesmer (1734-1815). Mesmer believed that there was an invisible force, a cosmic energy, that could be harnessed by one person to influence another person’s behavior. While his theory was wrong, the techniques he used were effective. These techniques were picked up on and developed over the coming years for therapeutic and medical purposes. Sigmund Freud, for instance, used hypnosis techniques. In the mid-1900s, hypnotherapy as we know it evolved. Milton Erickson (1901-1980) pioneered “indirect hypnosis,” during which therapists work with individual patients to shift their perceptions of themselves and their issues.
Some hypnotists view suggestion as a form of communication that is directed primarily to the subject's conscious mind,[40] whereas others view it as a means of communicating with the "unconscious" or "subconscious" mind.[40][41] These concepts were introduced into hypnotism at the end of the 19th century by Sigmund Freud and Pierre Janet. Sigmund Freud's psychoanalytic theory describes conscious thoughts as being at the surface of the mind and unconscious processes as being deeper in the mind.[42] Braid, Bernheim, and other Victorian pioneers of hypnotism did not refer to the unconscious mind but saw hypnotic suggestions as being addressed to the subject's conscious mind. Indeed, Braid actually defines hypnotism as focused (conscious) attention upon a dominant idea (or suggestion). Different views regarding the nature of the mind have led to different conceptions of suggestion. Hypnotists who believe that responses are mediated primarily by an "unconscious mind", like Milton Erickson, make use of indirect suggestions such as metaphors or stories whose intended meaning may be concealed from the subject's conscious mind. The concept of subliminal suggestion depends upon this view of the mind. By contrast, hypnotists who believe that responses to suggestion are primarily mediated by the conscious mind, such as Theodore Barber and Nicholas Spanos, have tended to make more use of direct verbal suggestions and instructions.[citation needed]
Hypnosis is not a psychotherapeutic treatment or a form of psychotherapy, but rather a tool or procedure that helps facilitate various types of therapies and medical or psychological treatments. Only trained health care providers certified in clinical hypnosis can decide, with their patient, if hypnosis should be used along with other treatments. As with psychotherapy, the length of hypnosis treatment varies, depending on the complexity of the problem.