BackgroundThe electroencephalogram (EEG) reflects the electrical activity in the brain on the surface of scalp. A major challenge in this field is the localization of sources in the brain responsible for eliciting the EEG signal measured at the scalp. In order to estimate the location of these sources, one must correctly model the sources, i.e., dipoles, as well as the volume conductor in which the resulting currents flow. In this study, we investigate the effects of dipole depth and orientation on source localization with varying sets of simulated random noise in 4 realistic head models.MethodsDipole simulations were performed using realistic head models and using the boundary element method (BEM). In all, 92 dipole locations placed in temporal and parietal regions of the head with varying depth and orientation were investigated along with 6 different levels of simulated random noise. Localization errors due to dipole depth, orientation and noise were investigated.ResultsThe results indicate that there are no significant differences in localization error due tangential and radial dipoles. With high levels of simulated Gaussian noise, localization errors are depth-dependant. For low levels of added noise, errors are similar for both deep and superficial sources.ConclusionIt was found that if the signal-to-noise ratio is above a certain threshold, localization errors in realistic head models are, on average the same for deep and superficial sources. As the noise increases, localization errors increase, particularly for deep sources.

Cytosolic choline appears to be involved in the pathophysiology of early-onset MDD, likely secondary to corticosteroid-neuroendocrine-driven changes.

Children (N = 404), 7 to 12 years old, were given the Children's Depression Inventory, the State-Trait Anxiety Inventory for Children, and the Piers-Harris Self-Concept Scale. First-born children scored significantly lower on depression than second-, third-, fourth-born, and youngest children. First borns showed significantly less trait anxiety than third-born children. First-born children also showed significantly higher levels of self-esteem than second-born and youngest children. Girls in this study showed significantly more trait anxiety than boys.

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