A Japanese translation of the Swedish Universities Scales of Personality.

Background: The Swedish Universities Scales of Personality (SSP) is a personality measurement tool with a short test battery of high psychometric quality, previously not availiable in Japanese. Methods: We translated the SSP into Japanese and administered it to 103 Japanese nationals. For 11 of the 13 SSP scales in the Japanese version of the SSP (SSP-J11), the Cronbach's alpha ranged from 0.50 to 0.82 with good internal scale reliability. Results: A principal factor analysis replicated the previous work by identifying the same three principal dimensions of Neuroticism, Aggression, and Extraversion factors. Conclusion: The resulting three-factor SSP-J11 shows acceptable reliability and should provide informative insights about personality traits in research and clinical practice in a Japanese context.

Directed causal effect with PCMCI in hyperscanning EEG time series.

Social activities are likely to cause effects or reactivity in the brains of the people involved in collaborative social situations. This study assesses a new method, Tigramite, for time domain analysis of directed causality between the prefrontal cortex (PFC) of persons in such situations. An experimental situation using hyperscanning EEG was applied while individuals led and followed each other in finger-tapping rhythms. This structured task has a long duration and a high likelihood of inter-brain causal reactions in the prefrontal cortices. Tigramite is a graph-based causal discovery method to identify directed causal relationships in observational time series. Tigramite was used to analyze directed causal connections within and between the PFC. Significantly directed causality within and between brains could be detected during the social interactions. This is the first empirical evidence the Tigramite can reveal inter- and intra-brain-directed causal effects in hyperscanning EEG time series. The findings are promising for further studies of causality in neural networks during social activities using Tigramite on EEG in the time domain.

An fMRI-study of leading and following using rhythmic tapping.

Leading and following is about synchronizing and joining actions in accordance with the differences that the leader and follower roles provide. The neural reactivity representing these roles was measured in an explorative fMRI-study, where two persons lead and followed each other in finger tapping using simple, individual, pre-learnt rhythms. All participants acted both as leader and follower. Neural reactivity for both lead and follow related to social awareness and adaptation distributed over the lateral STG, STS and TPJ. Reactivity for follow contrasted with lead mostly reflected sensorimotor and rhythmic processing in cerebellum IV, V, somatosensory cortex and SMA. During leading, as opposed to following, neural reactivity was observed in the insula and bilaterally in the superior temporal gyrus, pointing toward empathy, sharing of feelings, temporal coding and social engagement. Areas for continuous adaptation, in the posterior cerebellum and Rolandic operculum, were activated during both leading and following. This study indicated mutual adaptation of leader and follower during tapping and that the roles gave rise to largely similar neuronal reactivity. The differences between the roles indicated that leading was more socially focused and following had more motoric- and temporally related neural reactivity.