Re included in the stimuli set, and neural correlates of the imitation drive were assessed using post hoc multiple regression analyses. To determine the brain regions associated with imitation drive, the cortical areas inwhich the degree of activation was positively correlated with Urge score were determined. Finally, in addition to identifying areas that positively correlated with Urge, the neural networks underlying Urge and imitation performance were also assessed using a psychophysiological interaction (PPI) analysis to confirm functional connectivity between these two factors.Materials and methodsParticipantsForty-two healthy, right-handed participants with no psychiatric or neurological history were evaluated. The data from five participants were excluded from the final analyses due to excessive head motion (>2.5 mm; n ?2) or non-compliance with task instructions (two participants made mistakes on the rating, and one participant imitated all actions during the observation condition even though he understood the instructions). Thus, data from the remaining 37 participants (mean age 20.8 6 1.5 years; range 18?5 years; 23 males and 14 females) are reported. Handedness was evaluated using the Edinburgh Handedness Inventory (Oldfield, 1971). Informed consent was obtained from all participants prior to their participation. This study was approved by the Ethics Committee of Tohoku University Graduate School of Medicine.StimuliA total of 106 cyclic bimanual actions were identified as candidate actions for the stimuli. The cycle speed was the same for every action and maintained using a metronome (q ?96). Each action was repeated twice and the stimulus movie clip was 5 s in duration. We prepared 106 original movie clips as well as double-speed ��-Amatoxin supplier versions of the original clips using video editing software (Premiere Pro CS4, Adobe Systems, Inc., San Jose, CA, USA). Each movie was clipped to a 5-s duration; therefore, a total of 212 movie clips was prepared. Based on preliminary experiments, we selected 24 movie clips of different meaningless bimanual actions as visual stimuli for our fMRI analysis (Figure 1).Questionnaire construction and image selectionTo create a questionnaire for evaluating the degree of urge and NVP-AUY922 price explicit reasons to imitate, we first collected candidate descriptors. Twenty-three healthy participants (mean age 27.1 6 4.9 years; range 22?1 years; 10 males and 13 females) were asked to imagine situations in which they feel the urge to imitate. Then, factor analysis was performed to construct a questionnaire by determining dominant factors of the 24 descriptors (Supplementary Table S1). Ninety-six healthy participants (mean age 19.3 6 0.8 years; range 18?2 years; 48 males and 48 females) were shown 13 movie clips of meaningless bimanual actions. Participants rated each movie clip based on the 24 descriptors using a 7-point scale (0–totally disagree; 6–totally agree). After factor analysis, four factors were determined according to Kaiser’s criteria (Kaiser, 1960): urge to imitate (Urge), familiarity of the action (Familiarity), apparent difficulty to perform (Difficulty) and rhythmic action (Rhythm). To increase the stability of measurement, two items were selected that showed the largest loadings for Urge: Urge 1, I would like to respond to this person; Urge 2, My hands move almost automatically (or reflexively); Familiarity, I have seen this action many times; Difficulty, The action looks difficult to perform; and Rhythm, T.Re included in the stimuli set, and neural correlates of the imitation drive were assessed using post hoc multiple regression analyses. To determine the brain regions associated with imitation drive, the cortical areas inwhich the degree of activation was positively correlated with Urge score were determined. Finally, in addition to identifying areas that positively correlated with Urge, the neural networks underlying Urge and imitation performance were also assessed using a psychophysiological interaction (PPI) analysis to confirm functional connectivity between these two factors.Materials and methodsParticipantsForty-two healthy, right-handed participants with no psychiatric or neurological history were evaluated. The data from five participants were excluded from the final analyses due to excessive head motion (>2.5 mm; n ?2) or non-compliance with task instructions (two participants made mistakes on the rating, and one participant imitated all actions during the observation condition even though he understood the instructions). Thus, data from the remaining 37 participants (mean age 20.8 6 1.5 years; range 18?5 years; 23 males and 14 females) are reported. Handedness was evaluated using the Edinburgh Handedness Inventory (Oldfield, 1971). Informed consent was obtained from all participants prior to their participation. This study was approved by the Ethics Committee of Tohoku University Graduate School of Medicine.StimuliA total of 106 cyclic bimanual actions were identified as candidate actions for the stimuli. The cycle speed was the same for every action and maintained using a metronome (q ?96). Each action was repeated twice and the stimulus movie clip was 5 s in duration. We prepared 106 original movie clips as well as double-speed versions of the original clips using video editing software (Premiere Pro CS4, Adobe Systems, Inc., San Jose, CA, USA). Each movie was clipped to a 5-s duration; therefore, a total of 212 movie clips was prepared. Based on preliminary experiments, we selected 24 movie clips of different meaningless bimanual actions as visual stimuli for our fMRI analysis (Figure 1).Questionnaire construction and image selectionTo create a questionnaire for evaluating the degree of urge and explicit reasons to imitate, we first collected candidate descriptors. Twenty-three healthy participants (mean age 27.1 6 4.9 years; range 22?1 years; 10 males and 13 females) were asked to imagine situations in which they feel the urge to imitate. Then, factor analysis was performed to construct a questionnaire by determining dominant factors of the 24 descriptors (Supplementary Table S1). Ninety-six healthy participants (mean age 19.3 6 0.8 years; range 18?2 years; 48 males and 48 females) were shown 13 movie clips of meaningless bimanual actions. Participants rated each movie clip based on the 24 descriptors using a 7-point scale (0–totally disagree; 6–totally agree). After factor analysis, four factors were determined according to Kaiser’s criteria (Kaiser, 1960): urge to imitate (Urge), familiarity of the action (Familiarity), apparent difficulty to perform (Difficulty) and rhythmic action (Rhythm). To increase the stability of measurement, two items were selected that showed the largest loadings for Urge: Urge 1, I would like to respond to this person; Urge 2, My hands move almost automatically (or reflexively); Familiarity, I have seen this action many times; Difficulty, The action looks difficult to perform; and Rhythm, T.
