Taking two to tango:fMRI analysis of improvised joint action with physical contact

<div><p>Many forms of joint action involve physical coupling between the participants, such as when moving a sofa together or dancing a tango. We report the results of a novel two-person functional MRI study in which trained couple dancers engaged in bimanual contact with an experimenter standing next to the bore of the magnet, and in which the two alternated between being the leader and the follower of joint improvised movements. Leading showed a general pattern of self-orientation, being associated with brain areas involved in motor planning, navigation, sequencing, action monitoring, and error correction. In contrast, following showed a far more sensory, externally-oriented pattern, revealing areas involved in somatosensation, proprioception, motion tracking, social cognition, and outcome monitoring. We also had participants perform a “mutual” condition in which the movement patterns were pre-learned and the roles were symmetric, thereby minimizing any tendency toward either leading or following. The mutual condition showed greater activity in brain areas involved in mentalizing and social reward than did leading or following. Finally, the analysis of improvisation revealed the dual importance of motor-planning and working-memory areas. We discuss these results in terms of theories of both joint action and improvisation.</p></div

Synthesis, crystal structure and magnetic properties of Li_0.44Eu₃[B₃N₆]

Li0.44Eu3[B3N6] was synthesized from the metathesis reaction of Li-3[BN2] and EuCI3 at 850 degrees C. Li0.44EU3-[B3N6] crystallizes in the trigonal space group R (3) over barc (No. 167) with a=12.0225(2) angstrom, c=6.8556(2) angstrom and Z=6. In the crystal structure, isolated, planar cyclic [B3N6](9-) units are charge-balanced by the mixed-valence Eu3+/Eu2+ and Li+ cations. Li+ occupies partially (44%) the Wyckoff site 6b and is sandwiched between the [B3N6](9-) anions. Mossbauer spectroscopy results show the resonance lines of Eu2+ and Eu3+, respectively, indicating the heterogeneous mixed valency of the Eu atoms. X-Band ESR investigations between 5 and 300 K reveal an intense signal over the whole temperature range originating from Eu2+. Magnetic susceptibility measurements indicate a Curie-Weiss behavior with an experimental effective magnetic moment of (mu eff)=8.28 (mu B) per formula unit. (C) 2013 Elsevier Inc. All rights reserved