title: Resting state low-frequency fluctuations in prefrontal cortex reflect degrees of harm avoidance and novelty seeking: an exploratory NIRS study.
abstract: Harm avoidance (HA) and novelty seeking (NS) are temperament dimensions defined by Temperament and Character Inventory (TCI), respectively, reflecting a heritable bias for intense response to aversive stimuli or for excitement in response to novel stimuli. High HA is regarded as a risk factor for major depressive disorder and anxiety disorder. In contrast, higher NS is linked to increased risk for substance abuse and pathological gambling disorder. A growing body of evidence suggests that patients with these disorders show abnormality in the power of slow oscillations of resting-state brain activity. It is particularly interesting that previous studies have demonstrated that resting state activities in medial prefrontal cortex (MPFC) are associated with HA or NS scores, although the relation between the power of resting state slow oscillations and these temperament dimensions remains poorly elucidated. This preliminary study investigated the biological bases of these temperament traits by particularly addressing the resting state low-frequency fluctuations in MPFC. Regional hemodynamic changes in channels covering MPFC during 5-min resting states were measured from 22 healthy participants using near-infrared spectroscopy (NIRS). These data were used for correlation analyses. Results show that the power of slow oscillations during resting state around the dorsal part of MPFC is negatively correlated with the HA score. In contrast, NS was positively correlated with the power of resting state slow oscillations around the ventral part of MPFC. These results suggest that the powers of slow oscillation at rest in dorsal or ventral MPFC, respectively, reflect the degrees of HA and NS. This exploratory study therefore uncovers novel neural bases of HA and NS. We discuss a neural mechanism underlying aversion-related and reward-related processing based on results obtained from this study.
authors.affiliation: Department of Psychology, Graduate School of Education, Hiroshima University Hiroshima, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakao
authors.affiliation: Department of Psychiatry and Neurosciences, Institute of Biomedical and Health Sciences, Hiroshima University Hiroshima, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Faculty of Medicine, Hiroshima University Hiroshima, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Shimizu
authors.affiliation: Faculty of Medicine, Hiroshima University Hiroshima, Japan.
authors.forename: Machiko
authors.initials: M
authors.lastname: Morita
authors.affiliation: Department of Psychology, Faculty of Psychology, Otemon Gakuin University Osaka, Japan.
authors.forename: Shinpei
authors.initials: S
authors.lastname: Yoshimura
authors.affiliation: Institute of Mental Health Research, University of Ottawa Ottawa, ON, Canada.
authors.forename: Georg
authors.initials: G
authors.lastname: Northoff
authors.affiliation: Department of Psychiatry and Neurosciences, Institute of Biomedical and Health Sciences, Hiroshima University Hiroshima, Japan ; Department of Neuropsychiatry, Kochi University Kochi, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Morinobu
authors.affiliation: Department of Psychiatry and Neurosciences, Institute of Biomedical and Health Sciences, Hiroshima University Hiroshima, Japan.
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Okamoto
authors.affiliation: Department of Psychiatry and Neurosciences, Institute of Biomedical and Health Sciences, Hiroshima University Hiroshima, Japan.
authors.forename: Shigeto
authors.initials: S
authors.lastname: Yamawaki
keywords: aversion; harm avoidance; low-frequency fluctuations; medial prefrontal cortex (MPFC); novelty seeking; personality; resting state; reward