Frequency-dependent oscillatory neural profiles during imitation.

Imitation is a complex process that includes higher-order cognitive and motor function. This process requires an observation-execution matching system that transforms an observed action into an identical movement. Although the low-gamma band is thought to reflect higher cognitive processes, no studies have focused on it. Here, we used magnetoencephalography (MEG) to examine the neural oscillatory changes including the low-gamma band during imitation. Twelve healthy, right-handed participants performed a finger task consisting of four conditions (imitation, execution, observation, and rest). During the imitation and execution conditions, significant event-related desynchronizations (ERDs) were observed at the left frontal, central, and parietal MEG sensors in the alpha, beta, and low-gamma bands. Functional connectivity analysis at the sensor level revealed an imitation-related connectivity between a group of frontal sensors and a group of parietal sensors in the low-gamma band. Furthermore, source reconstruction with synthetic aperture magnetometry showed significant ERDs in the low-gamma band in the left sensorimotor area and the middle frontal gyrus (MFG) during the imitation condition when compared with the other three conditions. Our results suggest that the oscillatory neural activities of the low-gamma band at the sensorimotor area and MFG play an important role in the observation-execution matching system related to imitation.

Hydroxylated polychlorinated biphenyls (OH-PCBs): recent advances in wildlife contamination study.

The exposure of wildlife and human population to environmental hazardous contaminants has been of global concern for over several decades. More recently, focus has been directed towards potential toxicological effects such as the endocrine disrupting function of xenobiotics. The hydroxylated metabolites of PCBs (OH-PCBs) should be pointed out as these compounds. OH-PCBs have emerged as important classes of environmental contaminants in wildlife and humans because of their ability to bind with the thyroxin transport protein, transthyretin (TTR), and their interaction with thyroid hormone receptors. However, data on their occurrence in wildlife and their behavior in the matrices of environment are limited. Topics include the formation of OH-PCBs, their physicochemical properties (octanol-water partition coefficient, Kow), analytical procedures and contamination status in wildlife. The guidance for improving the study of OH-PCB contamination is also briefly mentioned.