At this point in time, the diagnosis of “schizophrenia” today is made on the basis of subjective data, which are based on the observation of the patient and the study of his experiences – that is, at the phenomenological level.
Brain studies after the death of patients show that schizophrenia can have various neuropathological processes. But the new methods used in the practice of neuroimaging are not yet effective enough to identify such a pathology in this disorder. When using them, both functional and morphological changes in the brain are not recorded .
Some functional neuroimaging methods allow identifying specific changes in the frontostriatal and frontolimbic areas of the brain in schizophrenia. Moreover, these changes were detected both at the onset of the disease and during manifestation during the first episode of psychosis.
Neuronal dysfunction is at the core of cognitive impairment in schizophrenia.
Dysfunction of the prefrontal cortex in schizophrenia
Many of the symptoms of schizophrenia are associated with damage to various areas of the prefrontal cortex. For example, impairment of working memory and other test scores are associated with insufficient activity in the dorsolateral prefrontal cortex.
Functional neuroimaging in schizophrenia, confirming a decrease in the activity of the prefrontal dorsolateral locus, which is confirmed by special tests ( Perlstein with et al ., 2003).
Numerous studies indicate an increase in activity in the dorsolateral prefrontal cortex of the brain in patients with schizophrenia. When performing complex tests, such as split ring tones that require some effort, these changes become more pronounced. With simple tests, there is an increase in the activity of the dorsolateral prefrontal cortex of the brain, and when performing complex tests, the activity of this department decreases if patients with schizophrenia do not perform these tests. ( Callicot with et al ., 2003).
A decrease in the activity of the dorsolateral prefrontal cortex leads to an executive response deficit in patients with schizophrenia. A deficiency in selecting the appropriate responses to the feeling of success, with the concomitant rewards associated with the ventral and the orbitofrontal prefrontal cortex ( Chemerinski with et al ., 2002).
Reduced prefrontal activity is associated with the reduction of response to stimuli that increase motivation, as tonsils suppressed neural networks which are projected on the prefrontal region ( Paradiso with et al ., 2003).
Strengthening the motivational aspect when choosing an answer is associated with the lower or orbitofrontal region, which play a role in the process of choosing one or another solution to problems associated with tests for inappropriate behavior.
In healthy individuals, the interaction between the dorsolateral and ventral and prefrontal cortex provides a balance between choice-based test responses and motivation to inhibit inappropriate responses. And in patients with schizophrenia, this interaction is destroyed.
In schizophrenic patients, the interaction between the inferior and dorsal foci of the prefrontal region influences pathological activity in the anterior cingulate region, which is also involved in monitoring responses.
These data suggest that prefrontal cortex dysfunction is observed in schizophrenia, leading to clinical and cognitive symptoms.
Dysfunction of the temporal cortex
The decreased activity of the temporal cortex in schizophrenia has been identified by many scientists. It is set as using functional neuroimaging , so and electrophysiological studies, as well as in the process of auditory tests of selective attention.
A progressive deficit in the activity of the temporal cortex has been identified in schizophrenia by many researchers. Functional neuroimaging and electrophysiological studies also revealed pathological foci. The results of the studies revealed a decrease in the connections between the frontal and temporal cortex of the brain, which was associated with the results of the auditory test.
Functional limbic cortex deficiency and midbrain pathology
The limbic system of the brain is represented by an area of the cortex on the medial side of both hemispheres of the brain, and includes the amygdala and hippocampus. The limbic system is involved in the cognitive process, and is also associated with taste, eating behavior, aggression, expression of emotions, and sexual behavior.
In patients with schizophrenia, the content of dopamine in the limbic system is increased, especially in the left amygdala of the brain.
An increase in dopamine receptors has also been found in schizophrenic patients in the optic hillock. Based on these data, we can say that diagnostic methods based on the phenomenological level will soon become a thing of the past.