Neural basis of psychosis-related behaviour in the infection model of schizophrenia

Maternal infection during pregnancy is a notable risk factor for the offspring to develop severe neuropsychiatric disorders, including schizophrenia. One prevalent hypothesis suggests that infection-induced disruption of early prenatal brain development predisposes the organism for long-lasting structural and functional brain abnormalities, leading to the emergence of psychopathological behaviour in adulthood. The feasibility of this causal link has received considerable support from several experimental models established in both rats and mice. In this review, we provide an integrative summary of the long-term neuropathological consequences of prenatal exposure to infection and/or inflammation as identified in various experimental models of prenatal immune challenge. In addition, we highlight how abnormalities in distinct brain areas and neurotransmitter systems following prenatal immune activation may provide a neural basis for the emergence of specific forms of psychosis-related behaviour. Specifically, we suggest that prenatal infection-induced imbalances in the mesolimibic and mesocortical dopamine pathways may constitute critical neural mechanisms for disturbances in sensorimotor gating, abnormalities in selective associative learning and hypersensitivity to psychostimulant drugs. On the other hand, the emergence of working memory deficiency following prenatal immune challenge may be crucially linked to the concomitant disruption of GABAergic and glutamatergic functions in prefrontal cortical and hippocampal structures. Notably, many of the identified neuronal abnormalities are directly implicated in the neuropathology of schizophrenia. The findings from prenatal infection models of schizophrenia thus provide considerable experimental evidence for the assumption that prenatal exposure to infection and/or inflammation is a relevant environmental link to specific neuronal abnormalities underlying psychosis-related behaviour in humans.