The observation that visual hallucinations occur more frequently in those who are drowsy (even in the absence of frank sleep pathology) suggests that the reticular activating system plays a role in visual hallucinations, although the precise mechanism has not yet been established. Further, visual hallucinations are common in those with certain sleep disorders, and occur more frequently in those who are drowsy. Lesions of the brainstem have led to visual hallucinations (as in peduncular hallucinosis). 7įinally, due to its role in the maintenance of arousal, the reticular activating system has been implicated in the genesis of visual hallucinations. One study reported visual hallucinations in 10 of 13 healthy subjects blindfolded for a period of 5 days this finding lends strong support to the idea that the simple loss of normal visual input is sufficient to cause visual hallucinations.

6 Of note, visual hallucinations may be induced by prolonged visual deprivation. 5Ī multitude of lesions can cause this loss of input and inhibit other cognitive functions. It has been further suggested that deafferented neurons undergo specific biochemical and molecular changes that lead to an overall increase in excitability (similar to the denervation hypersensitivity seen in phantom limb syndrome experienced by amputees). 4 Normal inputs are thought to be under the control of inhibitory processes that are effectively removed by deafferentation. Lesions that cause deafferentation of the visual system may lead to cortical release phenomenon, including visual hallucinations.

3 These data are supported by both electroencephalographic (EEG) recordings and direct stimulation experiments. Irritation of the primary visual cortex (Brodmann's area 17) causes simple elementary visual hallucinations, while irritation of the visual association cortices (Brodmann's areas 18 and 19) causes more complex visual hallucinations. The first mechanism involves irritation (e.g., seizure activity) of cortical centers responsible for visual processing. Manford and Andermann 2 summarized 3 pathophysiologic mechanisms thought to account for complex visual hallucinations. To date, no single neural mechanism has explained all types of visual hallucinations however, the similarity of visual hallucinations that are associated with seemingly diverse conditions suggests a final common pathway. Visual hallucinations can be the result of all 3 processes, given the interplay among disturbances of brain anatomy, brain chemistry, prior experiences, and psychodynamic meaning. These have been summarized and categorized by Asaad and Shapiro 1: psychophysiologic (i.e., as a disturbance of brain structure), psychobiochemical (as a disturbance of neurotransmitters), and psychodynamic (as an emergence of the unconscious into consciousness). Religious topics of hallucinations and delusions change over time and relate to objective historical events and reflect changes in religiosity in society.Numerous hypotheses have been suggested to explain the genesis of visual hallucinations. The phenomenon of apocalyptic subjects in paranoid hallucinations and delusions increased after the Second World War. Evil dominates over good in productive symptoms in paranoid schizophrenia. The transfer of holiness from historical saints onto a subject was observed. There is a progressive decrease in the number of religious topics in paranoid schizophrenia. Whereas there was a clear diversity of religious-themed delusions, 'God', 'Christ', 'Mary', 'Satan/devil' and 'hell' all figured prominently across all reviewed years. Religious topics were demonstrated in 46.8% of the test population.

By reviewing the subject history and medical notes, information on the presence of religious hallucinations and/or delusions were collected and grouped. How the perception of religion has changed over time, especially in the context of mental illness, was the focal point of this long-term comparative study.Ī random selection of 100 case histories from the years 1932, 1952, 19 was selected. Religion has long been considered a major force in human life, regardless of economic, social or political affiliation. Different environmental factors are thought to be responsible for 15-20% of schizophrenia pathogenesis.

Daylight hallucination