Schizophrenia: Pathogenesis and Symptoms

Increased dopaminergic transmission in mesolimbic projection

-> Dopaminergic neurons here project into the limbic system, responsible for behaviors and emotions.

-> Abnormal dopamine transmission here is thought to cause the Positive Symptoms of Schizophrenia:

 • Delusions (Fixed, false beliefs out of keeping with cultural background)

 • Hallucinations (Sensations without stimuli; usually auditory in schizophrenia)

 • Speech disorganization or senselessness (Tangentiality, derailment, word salads)

 • Grossly disorganized motor behavior including catatonia (unresponsive to environment) 



Decr dopaminergic transmission in mesocortical projection

-> Dopaminergic neurons here project into the cerebral cortex (i.e. frontal lobes), responsible for thinking, decision-making, language production, and mood)

-> Abnormal dopamine transmission here is thought to cause Negative Symptoms of Schizophrenia:

 • Diminished emotional expression

 • affective flattening

 • alogia

 • avolition

 • diminution of thoughts

 • asociality



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