Brain research bulletin
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Brain research bulletin · Sep 2005
Maintenance of upright standing posture during trunk rotation elicited by rapid and asymmetrical movements of the arms.
Nine healthy subjects standing upright, initiated small, medium and large (S, M and L conditions, respectively) forward movements of their right (Rt) arm together with backward movements of their left (Lt) arm. They also performed medium-size movements while holding a 3 kg dumbbell in each hand (D condition). Movements started with the arm hanging alongside the body and ended when the shoulder reached a desired orientation. ⋯ The trajectories of the center of foot pressure showed variations, initially toward the Rt side and then the Lt side which, respectively coincided with the initial and later phases of the trunk rotations and the muscle activation. The trunk muscles were generally coactivated between the Rt and Lt muscles, and the integrated EMGs increased with increasing the integrated torques. Our results showed that alternate rotations of the upper trunk, produced by rapid arm movements, were transmitted to the hip in part due to cocontraction of trunk muscles, and each pair of hip joint muscles contributed to the maintenance of the standing posture by stabilizing the hip joints against alternating trunk rotations.
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The neural system associated with face perception in the human brain was investigated using functional magnetic resonance imaging (fMRI). In contrast to many studies that focused on discreet face-responsive regions, the objective of the current study was to demonstrate that regardless of stimulus format, emotional valence, or task demands, face perception evokes activation in a distributed cortical network. Subjects viewed various stimuli (line drawings of unfamiliar faces and photographs of unfamiliar, famous, and emotional faces) and their phase scrambled versions. ⋯ This hemispheric asymmetry was manifested by larger and more significant clusters of activation and larger number of subjects who showed the effect. A region of interest analysis revealed that while all face stimuli evoked activation within all regions, viewing famous and emotional faces resulted in larger spatial extents of activation and higher amplitudes of the fMRI signal. These results indicate that a mere percept of a face is sufficient to localize activation within the distributed cortical network that mediates the visual analysis of facial identity and expression.
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Brain research bulletin · Sep 2005
Systemic administration of lipopolysaccharide and interleukin-1beta have different effects on memory consolidation.
Sickness behaviour is an adaptive response to infection that includes lethargy, anorexia and of direct relevance to this work, learning and memory impairments. It has been suggested that proinflammatory cytokines may disrupt learning and memory by interfering with memory consolidation [C. R. ⋯ Lipopolysaccharide-injected animals, but not interleukin-1beta-injected animals, exhibited less conditioned fear of context compared to saline-treated controls. All groups showed similar conditioned fear of tone. Our results suggest that systemic interleukin-1beta is not sufficient to disrupt memory consolidation, but rather, the synergistic actions of the proinflammatory cytokines released by lipopolysaccharide are required to disrupt memory consolidation.