Functionally defined regions may aid interpretation of striatal dopamine elevation in schizophrenia.

摘要

We read with interest the recent report by Nozaki et al. (2008) showing that presynaptic dopamine synthesis capacity is increased in the caudate nucleus of patients with schizophrenia. The authors suggest that the caudate may be more important than the putamen in the pathophysiology of schizophrenia due to its interconnections with limbic and cortical areas. This interpretation could be further evaluated if the authors apply functional rather than purely anatomical subdivisions of the striatum. Inputs to the striatum, from motor, associative and limbic cortices, are topographically organized along the dorsolateral to ventromedial gradient of the striatum, such that activity along this gradient may functionally relate to motor, cognitive and reward-associated processes (Haber et al., 2000). On the basis of differential cortical connectivity, the striatum can be divided into sensorimotor, associative and limbic 'functional subdivisions' for PET image analysis (Martinez et al., 2003). Several studies have recently highlighted the utility of the functional subdivision model in interpreting PET investigations of dopaminergic function (e.g. Lappin et al., 2008; Siessmeier et al., 2006).