ABSTRACT
External reality is perceived by the sensory systems, which trigger the appropriate motor response. The process of plasticity transforms the signifiers linked to external reality. William James, the association between perception of external reality and somatic state has been the biological basis of emotion in the domain of consciousness. An internal reality is formed in this way, one that has logical sequences, other than those of external reality, by which signifiers are organized in scenarios corresponding to fantasies. The perceptions of internal reality are just as strong and striking as those of external reality. They provide fuel and are integrated on the same operational level so as to generate an action, a behavior. It is the distinctive function of psychoanalysis to decode this physiology of the unconscious by setting out from the signifiers that, in the unconscious, are associated with signifieds that no longer correspond to the signifieds of the code of external reality.
