||The neural and molecular mechanisms associated with unreality feeling.
横川, 啓太 ,
伊藤, 岳人 ,
須原, 哲也山田, 真希子
[Background] Experience of unreality toward the external world is a characteristic of depersonalization disorder. Although depersonalization symptoms are observed in various psychiatric disorders, the underlying neural and molecular mechanisms are not well understood. The current study employed a multimodal neuroimaging strategy to explore the relationship between unreality-related neural activity, assessed using fMRI and striatal D2 receptor availability, assessed using [11C]raclopride PET with 14 healthy male subjects (23.4 ± 4.3 years old ). [Methods] Subjects rated how much visual objects looked real/unreal using a visual analog scale in the chromatic adaptation task inside an fMRI scanner. Stimuli are composed of 3 saturation levels: high, medium, low. We compared brain activities of medium chromatic object followed by high versus low. The task was performed four blocks (25 trials / brock). For evaluation of striatal D2 receptors, a bolus of 228.4 ± 8.1 MBq of [11C]raclopride with high specific radioactivity (158.4 ± 53.5 GBq/umol) was injected. Dynamic scans were performed for 60 minutes for [11C]raclopride immediately after the injection. [Results and conclusion] We observed a significant relationship wherein greater striatal D2 receptor availability was associated with greater unreality-related activities in occipital and dorsolateral prefrontal regions. Our results indicate that unreality feeling is strongly associated with an interrelationship between fronto-occipital activities and striatal dopaminergic neurotransmission.