es of schizophrenia in three phases, which makes up what is called Cognitive Dysmetria. According to Andreasen et al., schizophrenia was initially diagnosed as a brain disease, which was supported primarily through the use of neuroimaging techniques such as computerized tomography (CT). This neuroimaging technique consistently showed that patients had diffused nonspecific abnormalities such as prominent sulci or ventricular enlargement. The next phase that Andreasen et al. (1998) discusses drew on traditions of neurology and neuropsychology. These traditional methods attempted to localize the anatomic abnormalities and relate specific manifestations of the illness to specific brain regions. Some specific relationships that were hypothesized and partially verified include the prefrontal cortex and negative symptoms, the temporal lobes and auditory hallucinations, and the planum temporale and thought disorder. The third phase, which is fairly recent, draws on traditions of cognitive psychology, models of distributed parallel processing, and the study of neural circuitry. The emphasis of this phase is an attempt to understand schizophrenia as an abnormality in fundamental cognitive processes and distributed circuits. This phase shifts the development of the Integrative Theory of Schizophrenia. The integrative approach has several advantages: It attempts to explain the diversity of schizophrenic symptoms with a single theory or mechanism. It applies a top-down approach that permits the testing of abnormalities in multiple related regions, rather than a piecemeal bottom-up approach, which examines a single region and a single symptom at a time. It is also consistent with most current thinking in neuroscience, which maps circuits and assumes distributed parallel processing. The major disadvantage of the integrative approach is that it can quickly become quite complex and lead to multinodal models that are difficult to test in a si...
