Visual Hallucinations: Another Argument for Brain Equals Behavior

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Visual Hallucinations: Another Argument for Brain Equals Behavior A hallucination is defined as a sensory perception in the absence of an externally generated stimulus (4). They are different from illusions in that in an illusion an external object actually exists and is perceived, but is misinterpreted by the individual (4). Main forms of hallucinations are be visual, auditory, and olfactory, but since we have been discussing vision and interpretation of reality lately this paper will focus only on those that are visual. And I will attempt through the examination of two different types of visual hallucinations - release hallucinations and those experienced by schizophrenics - to make an argument for brain equals behavior. Much work has been done to find the exact cause of hallucinations and what is going on in the brain when they occur. Some progress has been made. Charles Bonnet syndrome is the onset of hallucinations in psychologically healthy individuals who have recently become blind or seeing impaired. These are called release hallucinations because it is thought that they are 'released' or instigated by the, "removal of normal visual afferent impute to association cortex"(5). Experiments involving direct stimulation of the temporal lobe, and fMRI's taken during hallucinations have indicated that - at least for complex hallucinations - the cause may be that corresponding visual areas in the brain are activated in the absence of inhibition due to visual input. In other words, this is an example of the chicken with its head cut off - apparently normal visual input to areas of the brain responsible for interpreting different things may be the only thing that keeps us from experiencing hallucinations of this kind (5). A... ... middle of paper ... ...2000,Perception, mental imagery, and reality discriminations. . . http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T1H-41WT8B9-3T8&_user=400777&_coverDate=12%2F14%2F2000&_alid=13627922&_rdoc=2&_fmt=summary&_orig=search&_cdi=4891&_sort=d&_st=0&_acct=C000018819&_version=1&_urlVersion=0&_userid=400777&md5=e8154e0eeeaca16570434a033eabb45d 3)The Anatomy of Conscious Vision http://serendip.brynmawr.edu/bb/neuro/neuro01/web2/Nature%20Neuroscience 4)Introduction to Psychopathology http://www.uams.edu/department_of_psychiatry/syllabus/Psypath/Intpsyp1.htm 5)Survey of Opthalmology http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TCC-42M796G-2&_user=400777&_coverDate=04%2F30%2F2001&_alid=13655655&_rdoc=1&_fmt=full&_orig=search&_cdi=5167&_sort=d&_st=0&_acct=C000018819&_version=1&_urlVersion=0&_userid=400777&md5=0407c705527195206627a86a140e6c93

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