Drugs with hallucinotic effects facilitate the occurrence of "internal" pictures independent of external perceptions which are described phenomenologically as hallucinations. This theory is based on the fact that hallucinogenic drugs intensify the electrical potentials which are evoked by optic stimulation in the visual area, while an intracortical impulse propagation is inhibited. 2. A change in emotion either caused by situation or by exogenous or endogenous factors facilitates the development of hallucinations, especially if emotions dominate to such a degree that rational control of reality is being suppressed. Since hallucinogenic drugs exert their effects not only on the sensory system but also on brain structures which influence directly or indirectly emotional functions, hallucinations might also be evoked via this mechanism. 3. Brain stem has-apart from its importance in emotional processes-a filter effect and a controlling function of sensoric stimuli originating in the periphery.

1500 BCE in the Ebers Papyrus. A hallucination is defined as a sensory perception in the absence of external stimuli. Hallucinations are different from In psychopathology, psychosis ( ) is the inability to distinguish what is or is not real. Examples of psychotic symptoms are delusions, hallucinations, and disorganized or incoherent thoughts or speech. Psychosis is a description of a person's state or symptoms, rather than a specific mental illness, and it is not related to the personality construct of psychopathy. Common causes of chronic psycho In 1888, Swiss psychiatrist Gottlieb Burckhardt performed the first medically sanctioned psychosurgery in which the cerebral cortex was excised. Although some patients showed improvement of symptoms and became more subdued, one patient died and several developed aphasia or seizure disorders. Burckhardt would go on to publish his clinical outcomes in a scholarly paper. This procedure was met with criticism from the medical community and his academic and surgical endeavors were largely ignored. In the late 1930s, Egas Moniz conceived the leucotomy (AKA prefrontal lobotomy) in which the fibers connecting the frontal lobes to the rest of the brain were severed. Moniz's primary inspiration stemmed from a demonstration by neuroscientists John Fulton and Carlyle's 1935 experiment in which two chimpanzees were given leucotomies and pre- and post-surgical behavior was compared. Prior to the leucotomy, the chimps engaged in typical behavior including throwing feces and fighting. After the procedure, both chimps were pacified and less violent. During the Q&A, Moniz asked if such a procedure could be extended to human subjects, a question that Fulton admitted was quite startling. Moniz would go on to extend the controversial practice to humans with various psychotic disorders, an endeavor for which he received a Nobel Prize in 1949. Between the late 1930s and early 1970s, the leucotomy was a widely accepted practice, often performed in non-sterile environments such as small outpatient clinics and patient homes. Psychosurgery remained standard practice until the discovery of antipsychotic pharmacology in the 1950s. The first clinical trial of antipsychotics (also commonly known as neuroleptics) for the treatment of psychosis took place in 1952. Chlorpromazine (brand name: Thorazine) passed clinical trials and became the first antipsychotic medication approved for the treatment of both acute and chronic psychosis. Although the mechanism of action was not discovered until 1963, the administration of chlorpromazine marked the advent of the dopamine antagonist, or first generation antipsychotic. While clinical trials showed a high response rate for both acute psychosis and…

as “subjective sensory images” which arise without the aid of external stimuli , and illusions as the false interpretation of external objects, but he