Finally, the neural underpinnings of PHA will be even clearer when we incorporate its most important aspect in imaging studies—the dissociation between implicit and explicit memory. In PHA (and in functional amnesia) the person is unable to explicitly recall certain information, yet we see evidence of this material on implicit measures. For instance, a participant given PHA may fail to recall the word “doctor,” learned earlier, but will have no trouble completing the word fragment “d _ _ t _ r”. Mendelsohn et al. did not assess implicit memory. Rather, they tested recognition, which in a sense confounds explicit and implicit memory. We’d like to compare brain scans of a PHA group trying to explicitly recall the movie (they should show reduced activation, as above) with brain scans of the same group completing an implicit memory measure of the movie (they should show normal activation). This would be tricky to do—implicit measures of complex material such as movies and autobiographical memories are hard to find or construct. But it would contribute to a more complete neural picture of the processes involved in these fascinating forms of forgetting. 
Pierre Janet (1859–1947) reported studies on a hypnotic subject in 1882. Charcot subsequently appointed him director of the psychological laboratory at the Salpêtrière in 1889, after Janet had completed his PhD, which dealt with psychological automatism. In 1898, Janet was appointed psychology lecturer at the Sorbonne, and in 1902 he became chair of experimental and comparative psychology at the Collège de France.[60] Janet reconciled elements of his views with those of Bernheim and his followers, developing his own sophisticated hypnotic psychotherapy based upon the concept of psychological dissociation, which, at the turn of the century, rivalled Freud's attempt to provide a more comprehensive theory of psychotherapy.

It’s important to remember that depression, along with severe and chronic mental illnesses such as bipolar disorder and schizophrenia, also affect a person’s physical health. Depression is more than just feeling sad or having negative thoughts. It’s a condition where the chemicals in your brain are imbalanced. Hypnotherapy is a complementary therapy, and it shouldn’t be the only therapy a person uses to enhance their mental health.

In 1974, Theodore X. Barber and his colleagues published a review of the research which argued, following the earlier social psychology of Theodore R. Sarbin, that hypnotism was better understood not as a "special state" but as the result of normal psychological variables, such as active imagination, expectation, appropriate attitudes, and motivation.[16] Barber introduced the term "cognitive-behavioral" to describe the nonstate theory of hypnotism, and discussed its application to behavior therapy.
An approach loosely based on information theory uses a brain-as-computer model. In adaptive systems, feedback increases the signal-to-noise ratio, which may converge towards a steady state. Increasing the signal-to-noise ratio enables messages to be more clearly received. The hypnotist's object is to use techniques to reduce interference and increase the receptability of specific messages (suggestions).[182]
Look for a hypnotherapist who is a member of the American Society of Clinical Hypnosis (ASCH) or the Society for Clinical and Experimental Hypnosis. To be a member of either of these organizations, a hypnotherapist must have a doctorate level degree in medicine, dentistry, or psychology, or a master’s degree in nursing, social work, psychology, or marital/family therapy plus a specific number of hours of approved training in hypnotherapy. In some cases, accredited, doctoral-level practitioners of alternative health care, such traditional Chinese medicine, may also be approved for membership. Of course, in addition to looking at qualifications, you should also find a hypnotherapist with whom you feel confident and comfortable in a therapeutic relationship.