Purpose: Anhedonia has been proposed to be the result of a basic neurophysiologic dysfunction and a
vulnerability marker that precede and contribute to the liability of developing schizophrenia. We hypothesized that
anhedonia, as a construct reflecting the decreased capacity to experience pleasure, should be associated with
decreased positive hedonic affect trait. This study examined the relationship between anhedonia and positive hedonic
affect trait and searched for the brain regions which correlate with anhedonia in normal subjects. Materials and
Methods: Using 18F-FDG PET scan, we investigated the brain activity of twenty one subjects during resting state.
Questionnaires were administrated after the scan in order to assess the self-rated individual differences in
physical/social anhedonia and positive/negative affect traits. Results: Negative correlation between physical
anhedonia score and positive affect trait score was significant (Pearson coefficient=-0.440, p<0.05). The subjects'
physical and social anhedonia scores showed positive correlation with metabolic rates in the cerebellum and negative
correlation with metabolic rates in the inferior temporal gyrus and middle frontal gyrus. In addition, the positive
affect trait score positively correlated with various areas, most prominent with the inferior temporal gyrus.
Conclusion: These results suggest that neural substrates, such as the inferior temporal gyrus and prefrontal-cerebellar
circuit, which dysfunction has been proposed to be involved with the cognitive deficits of schizophrenia, may also
play a significant role in the liability of affective deficits like anhedonia.(Korean J Nucl Med 39(6):438-444, 2005)