The resting state brain networks, particularly the Default Mode Network (DMN), have been found to be altered in several psychopathological conditions such as depression and anxiety. In this study we hypothesized that cortical areas of the DMN, particularly the anterior regions--medial prefrontal cortex and anterior cingulate cortex--would show an increased functional connectivity associated with both anxiety and depression. Twenty-four healthy participants were assessed using Hamilton Depression and Anxiety Rating Scales and completed a resting-state functional magnetic resonance imaging scan. Multiple regression was performed in order to identify which areas of the DMN were associated with anxiety and depression scores. We found that the functional connectivity of the anterior portions of DMN, involved in self-referential and emotional processes, was positively correlated with anxiety and depression scores, whereas posterior areas of the DMN, involved in episodic memory and perceptual processing were negatively correlated with anxiety and depression scores. The dissociation between anterior and posterior cortical midline regions, raises the possibility of a functional specialization within the DMN in terms of self-referential tasks and contributes to the understanding of the cognitive and affective alterations in depressive and anxiety states.

These findings suggest a contributory role of the caudate nucleus part of the dorsal striatum in the psychopathology of BN.

The aim of the present study is to explore obsessive-compulsive disorder (OCD)-related abnormalities in white matter connectivity in OCD for a core region associated with inhibitory control [i.e. inferior frontal gyrus (IFG)]. Fifteen patients with OCD (11 men) and 15 healthy controls (nine men) underwent diffusion tensor imaging scanning to study four diffusivity indexes of white matter integrity [fractional anisotropy, mean diffusivity (MD), axial diffusivity and radial diffusivity (RD)]. The results showed that persons with OCD manifested significantly lower fractional anisotropy levels in the bilateral IFG as well as its parcellations in the pars opercularis, pars triangularis, and pars orbitalis. Significantly higher levels of MD, RD were evident for the OCD group in the IFG as a whole as well as in the bilateral subregions of the pars triangularis and pars opercularis (for MD and RD), the right side of the pars orbitalis (for RD), and the left side of the pars triangularis and right side pars opercularis (for axial diffusivity). Overall, the results suggest significant alterations in structural connectivity, probably associated with myelination and axonal abnormalities in the IFG of OCD patients.

Long-term exposure to transmeridian flights has been shown to impact cognitive functioning. Nevertheless, the immediate effects of jet lag in the activation of specific brain networks have not been investigated. We analyzed the impact of short-term jet lag on the activation of the default mode network (DMN). A group of individuals who were on a transmeridian flight and a control group went through a functional magnetic resonance imaging acquisition. Statistical analysis was performed to test for differences in the DMN activation between groups. Participants from the jet lag group presented decreased activation in the anterior nodes of the DMN, specifically in bilateral medial prefrontal and anterior cingulate cortex. No areas of increased activation were observed for the jet lag group. These results may be suggestive of a negative impact of jet lag on important cognitive functions such as introspection, emotional regulation and decision making in a few days after individuals arrive at their destination.

Introduction:The default mode network (DMN) is one of the best known resting state networks, which are active when the brain is “at rest” and the individual is not focused on any external demand. The DMN comprises areas of the posterior cingulate cortex (PCC) and adjacent precuneus; the medial prefrontal cortex (MPFC); medial, lateral and inferior parietal cortex and medial temporal cortex. DMN abnormalities have been found in several psychiatry disorders (Broyd et al., 2009) including depression and anxiety where increases in its connectivity namely on the MPFC have been reported (Greicius et al., 2007).Objectives:The goal of this study was to investigate the relationship between the DMN activation at rest and both anxiety and depressive symptoms.Methods:Twenty-five participants completed the Hamilton Anxiety and Depression Rating Scales and were submitted to a functional magnetic resonance imaging task-free acquisition in which they were instructed to close their eyes and to think about nothing particular. Independent component analysis was used to extract the DMN maps of each subject and statistical analysis were performed in SPM.Results:Depression scores correlated positively with the activation of the orbitofrontal gyrus and middle frontal gyrus and negatively with the occipital gyrus, fusiform gyrus, PCC and precuneus. Anxiety scores correlated positively with the activation of the MFPC and ACC and negatively with parietal and temporal areas.Conclusions:These results provide some support for the role of the DMN particularly its anterior nodes for the ruminative aspects that are common in depressive and anxious individuals.