Regions of the frontal cortex project to the caudate or putamen in segregated, parallel neuronal pathways. Within the basal ganglia, these projections arc propagated to related

downstream structures, including specific thalamic nuclei, and then project, back to the discrete frontal cortex regions. Since the basal ganglia have a diversity of neurotransmitters and modulators, and are richly innervated by diverse brain structures, there is ample opportunity within these pathways to capture significant regional influence and to subsequently modulate frontal cortical function. Any abnormality in the dopaminergic dynamics,83 Inhibitors,research,lifescience,medical the balance of neurotransmitter function in the basal ganglia,76 or the influence of the thalamus65 could alter frontal cortical function through these pathways. Neurodevelopmental factors The idea that schizophrenia is a neurodevelopmental illness, whose pathology is already set at birth Inhibitors,research,lifescience,medical and only expresses itself as psychosis later, has become popular. This formulation of illness onset explains the influence of pre- or perinatal events and the evidence of premorbid cognitive predictors of illness onset. Nonetheless, the course of schizophrenia does not. conform to that of a traditional neurodevelopmental illness, like

mental retardation, whose symptoms Inhibitors,research,lifescience,medical appear at birth. However, it has Inhibitors,research,lifescience,medical been argued that the neural apparatus subserving schizophrenia does not mature until late teens, and cannot fully express its dysfunction before this. Another caveat is that there is actually scant biological evidence to support the neurodevelopmental formulation.

Also, it. is not. the case that all forms of schizophrenia need to be based on the same etiology, even if they involve the same pathophysiology. Hence, neurodevelopmental aspects may be important in some, but not all, forms of schizophrenia. Inhibitors,research,lifescience,medical Limbic cortex Experimental modalities beyond brain imaging have advanced our understanding of the pathophysiology of schizophrenia. These include postmortem tissue studies and animal, whatever model experiments. Findings from postmortem brain studies in schizophrenia are reviewed in this issue by Harrison et al.85 From the substantial body of postmortem work reviewed, several learn more guiding formulations emerge: (i) the limbic system has been consistently identified as affected in schizophrenia; and (ii) although the examination of postmortem transmitter systems has been skewed toward the monoamines and dopamine in particular, it. is clear that many chemical systems are affected in schizophrenia.76 In accounting for a demonstrated abnormality, separating cause and effect of the psychotic condition is always critical and, at present, a matter of hypothesis.