Dr. Gilles Michaux – Workshop 2009

Placebo – Relief Beyond Belief
Dr. Gilles Michaux, Psychobiology, Uni. of Luxembourg

Although pain has traditionally been discussed in the framework of sensory physiology and psychology of perception, it is fundamentally different from all other sensory systems. In addition to a sensory component related to information about the location, the duration and the intensity of the noxious stimulus, pain is almost always characterized by an emotional-motivational component (i.e. suffering), which drives us to avoid or to stop it. The cognitive-evaluative component is concerned with the appraisal of the current pain by retrieving comparable situations from memory stores.  Within the brain, these components have been claimed to rely on distinct neural substrates, which are however closely interconnected. Two further elements to be discussed are the autonomic component (e.g. blood pressure, heart and respiration rate), which is closely related to the emotional and the motor component (withdrawal reflexes, facial expression etc.). The described multidimensionality points out that physiological and psychological mechanisms have to be considered concomitantly for the assessment and modification of pain.

Taking into account the different dimensions of pain processing, the second part of the talk will be devoted to the presentation of psychophysiological aspects of pain modulation. The placebo effect and its dependence on sensorimotor factors like associative learning and motivational factors like treatment expectations and the desire for pain relief will be discussed. Another interesting and related issue in this field is the modification of pain by hypnosis (i.e. hypnotic anesthesia), with its ability to independently modulate perceptual (‘hurting’) and emotional (‘suffering’) aspects of the pain experience. Both phenomena will be analyzed within a neurobiological and psychosocial framework with regard to their potential to disentangle pain perception and affect.