The positive symptoms of schizophrenia

The positive symptoms of schizophrenia are thought to be caused by an excess of dopamine within the pathway of the brain that projects from the ventral tegmental area in the brainstem to the nucleus accumbens in the ventral striatum.^{[Owen et al., 2016; Stahl, 2013]} This dopamine pathway of the brain is known as the ‘mesolimbic’ dopamine pathway.^{[Stahl, 2013]} Hence, the ‘dopamine hypothesis’ of schizophrenia can perhaps more accurately be described as ‘the mesolimbic dopamine hypothesis of positive symptoms of schizophrenia’.^{[Stahl, 2013]}

References:
Owen MJ, Sawa A, Mortensen PB. Schizophrenia. Lancet 2016; 388 (10039): 86–97. Stahl SM.

Stahl’s Essential Psychopharmacology.
Neuroscientific Basis and Practical Applications. Fourth Edition. © Cambridge University Press, 2013.