@misc{oai:repo.qst.go.jp:00069626,
 author = {Nagai, Yuji and Obayashi, Shigeru and Ito, Hiroshi and Suhara, Tetsuya and 永井 裕司 and 大林 茂 and 伊藤 浩 and 須原 哲也},
 month = {Nov},
 note = {It is well known that dopaminergic system plays a crucial role in cognitive functions including working memory as well as reward processing and emotion in human and monkeys. Also, schizophrenia may result from the aberrant dopaminergic system in that in vivo PET studies in patients with schizophrenia showed the changes in dopamine (DA) receptors, suggesting the alteration of the system in neurotransmitter level. However, it is true that there are different distributions of DA receptors in different brain regions. So far, it remains unknown to the extent what the normal or aberrant distribution differences of the DA receptors in the brain may result in functional specializations in normal subjects and their symptoms in the patients. Accordingly, it is essential to understand in vivo brain distribution of DA receptors globally referring to the functional specialization. On the contrary, monkeys have not only brains comparable with human in a cytoarchitectonical and neurochemical terms, but also can learn relatively complicated and abstract behavioral tasks where the trained monkeys can be compared with human. Especially, monkeys can be characterized by the accessibility to some invasive manipulation into their brain directly. However, monkey PET studies have been almost always conducted in an anesthetized condition, which would profoundly affect their brain functions as well as PET signals. Furthermore, the distribution differences of DA receptors in the monkey extra-striatal regions were not confirmed yet. Now, we used 7 male rhesus monkeys to establish the database of extra-striatal DA D1 and D2 receptor distributions in the brain of normal and awake monkeys using PET with [11C]SCH23390 and [11C]FLB 457, respectively. Eighteen regions of interest were placed on 12 cortical areas, 5 subcortical areas, and the cerebellum, referring to the corresponding MRI coregistered with PET. DA receptor availabilities were quantified as binding potential by simplified reference tissue model. PET results revealed that some brain regions responsible for cognitive function or showing pathological findings in schizophrenia, such as dorsolateral prefrontal cortex, anterior cingulate cortex, thalamus, amygdala, and hippocampus, have relatively reliable and higher levels of D1 and D2 receptor availability beyond 0.3 and 0.8, respectively. These findings were almost consistent with those from normal human subjects. Our results suggest that monkey PET data could be useful for facilitating the understanding of the causal relation between distribution differences of the DA receptors and functional specializations in normal subjects or symptoms in the patients., 38th Annual Meeting of Society for Neuroscience},
 title = {The distribution differences of extra-striatal dopamine receptors in the awale monkey brains using in vivo PET},
 year = {2008}
}