Enhanced reactivity and delayed recovery of sensorimotor cortex in the novelty seeking personality.
BACKGROUND
The novelty seeking (NS) personality trait is hypothesized to be associated with high cortical reactivity, poor inhibitory control and/or varied dopaminergic neurotransmission in the basal ganglia. After somatosensory stimulation, electrical oscillations in alpha and beta bands generated in the sensorimotor cortex show a short duration decrease (event-related desynchronization) and a subsequent increase (event-related synchronization) that is thought to reflect cortical activation and the inhibitory/recovery process, respectively. These oscillatory changes are also believed to be affected by the status of the basal ganglia and by dopaminergic functions. In the present study, we investigated the association between the NS personality trait and somatosensory oscillatory changes after median nerve stimulation assessed by magnetoencephalography.


METHODS
From 48 healthy subjects, we selected 14 high scorers and 14 age- and sex-matched low scorers on the NS dimension of the Temperament and Character Inventory. Magnetic fields were recorded while subjects received electrical stimulation of either the right or left median nerve with equal probability and with a randomized interstimulus interval. Frequency analysis was performed on the alpha and beta bands.


RESULTS
Compared with the low NS group, the high NS group showed larger magnitude of beta event-related desynchronization and larger latencies of the alpha and beta event-related synchronization.


CONCLUSIONS
These results suggest that individuals with high degrees of the NS trait have greater reactivity and delayed recovery of the sensorimotor cortex in response to simple somatosensory stimulation. This may be significant for the understanding of their exploratory and impulsive behavior.
Shishida
Kazuhiro
K
Department of Psychiatry and Neurosciences, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan.
Hashizume
Akira
A
Onoda
Keiichi
K
Okamoto
Yasumasa
Y
Yamawaki
Shigeto
S
D000328:Adult; D000513:Alpha Rhythm; D000704:Analysis of Variance; D001611:Beta Rhythm; D001931:Brain Mapping; D003344:Cortical Synchronization; D004558:Electric Stimulation / Q000379:methods; D005071:Evoked Potentials / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D015225:Magnetoencephalography / Q000379:methods; D008297:Male; D008475:Median Nerve / Q000502:physiology / Q000528:radiation effects; D009044:Motor Cortex / Q000502:physiology*; D010551:Personality / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology*; D013997:Time Factors