Prefrontal cognitive systems in schizophrenia: towards human genetic brain mechanisms.

Schizophrenia has complex genetic heritability. It is also genetically heterogeneous. To the extent that genes are associated with symptom constellations in schizophrenia, they do so by affecting the development and function of neural systems that mediate the expression of such diverse behavioral, cognitive and perceptual phenomena. The genetic mechanisms of human brain dysfunction remain to be well understood. "Imaging genetics" is an emerging field that attempts to integrate the basic biology of putative disease mechanisms with physiological correlates from the live human brain. Here, we review recent imaging genetics work on prefrontal brain systems associated with working memory and executive function - heritable traits relevant to schizophrenia. Starting with genetic variation in dopaminergic systems (e.g., COMT), we examined the modulation of prefrontal brain networks during active cognitive processing; there is also evidence that variation in the expression of dopamine-related downstream intra-cellular signaling molecules (e.g., AKT1) are implicated. Moreover, these genetic variants evidence epistasis on neuroimaging measures, lending further support to the conceptualization that non-additive combinations of multiple genes modulate active human cognitive brain mechanisms. The imaging genetics platform therefore could extend understanding of genetic mechanisms of human cognitive brain processes relevant to neuropsychiatric disease.