title: Memory and frontal lobe functions; possible relations with dopamine D2 receptors in the hippocampus.
abstract: Cerebral cortical regions are thought to be important for cognitive functions such as memory and executive function. Although the functional associations between dopamine D2 receptors and motor and cognitive functions have been extensively examined in the striatum using positron emission tomography (PET), the role of dopamine D2 receptors in extrastriatal regions has been unexplored. We aimed to investigate the relationship between dopamine D2 receptors in extrastriatal regions and the performance of a broad spectrum of cognitive functions including memory, language, attention, and executive function in healthy subjects. Extrastriatal dopamine D2 receptors were measured in 25 male subjects using PET with [(11)C]FLB457. After the PET scans, a battery of neuropsychological tests was administered to all subjects. We found that the binding potential (BP) of [(11)C]FLB457 in the hippocampus was positively correlated with memory function. Furthermore, BP of [(11)C]FLB457 in the hippocampus, but not in the prefrontal cortex, was associated with frontal lobe functions such as executive function and verbal fluency. Our findings suggest that dopamine D2 receptors in the hippocampus might affect the local hippocampal function, but also brain functions outside the hippocampus such as the prefrontal cortex.
authors.affiliation: Molecular Imaging Center, Department of Molecular Neuroimaging, National Institute of Radiological Sciences, 4-9-1 Anagawa, Chiba 263-8555, Japan.
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Takahashi
authors.forename: Motoichiro
authors.initials: M
authors.lastname: Kato
authors.forename: Mika
authors.initials: M
authors.lastname: Hayashi
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Okubo
authors.forename: Akihiro
authors.initials: A
authors.lastname: Takano
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ito
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Suhara
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000502:physiology; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000502:physiology*; D006624:Hippocampus / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D007858:Learning / Q000502:physiology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008568:Memory / Q000502:physiology*; D008570:Memory, Short-Term / Q000502:physiology; D049268:Positron-Emission Tomography / Q000379:methods; D017397:Prefrontal Cortex / Q000000981:diagnostic imaging / Q000502:physiology; D017448:Receptors, Dopamine D2 / Q000502:physiology*; D012016:Reference Values; D013060:Speech
chemical_list: D017448:Receptors, Dopamine D2