Conversion Disorder: A disorder whose predominant feature is a loss or alteration in physical functioning that suggests a physical disorder but that is actually a direct expression of a psychological conflict or need.Freudian Theory: Philosophic formulations which are basic to psychoanalysis. Some of the conceptual theories developed were of the libido, repression, regression, transference, id, ego, superego, Oedipus Complex, etc.Abreaction: A process in psychotherapy in which the patient is "desensitized" to emotionally painful, often forgotten (repressed) memories by recalling and reacting to them in the "safety" of the treatment setting.Hysteria: Historical term for a chronic, but fluctuating, disorder beginning in early life and characterized by recurrent and multiple somatic complaints not apparently due to physical illness. This diagnosis is not used in contemporary practice.Malingering: Simulation of symptoms of illness or injury with intent to deceive in order to obtain a goal, e.g., a claim of physical illness to avoid jury duty.Neurology: A medical specialty concerned with the study of the structures, functions, and diseases of the nervous system.Dissociative Disorders: Sudden temporary alterations in the normally integrative functions of consciousness.Dyskinesias: Abnormal involuntary movements which primarily affect the extremities, trunk, or jaw that occur as a manifestation of an underlying disease process. Conditions which feature recurrent or persistent episodes of dyskinesia as a primary manifestation of disease may be referred to as dyskinesia syndromes (see MOVEMENT DISORDERS). Dyskinesias are also a relatively common manifestation of BASAL GANGLIA DISEASES.