Volumetric alterations in the nucleus accumbens and caudate nucleus in bulimia nervosa: a structural magnetic resonance imaging study.

OBJECTIVE: Bulimia nervosa (BN) is an eating disorder characterized by recurrent episodes of binge eating and inappropriate compensatory behaviors (such as purging, fasting, or excessive exercise) to prevent weight gain. BN has been associated with deficits in inhibitory control processes. The basal ganglia specifically, the nucleus accumbens (NAc) and the caudate nucleus (CN) are part of the frontostriatal circuits involved in inhibitory control. The main goal of this study was to investigate the presence of morphological alterations in the NAc and the CN in a sample of patients diagnosed with BN. METHOD: Forty-one female participants, 21 diagnosed with BN and 20 healthy matched controls (HC), underwent a structural magnetic resonance imaging (MRI) acquisition and clinical assessment. The NAc and the CN were manually segmented using the software Slicer 3D. RESULTS: The results reveal a significant volumetric decrease in the CN and a preserved NAc volume in BN compared to the control group. DISCUSSION: These findings suggest a contributory role of the caudate nucleus part of the dorsal striatum in the psychopathology of BN.

Nodes of the default mode network implicated in the quality of empathic responses: A clinical perspective of the empathic response.

The ability to empathize with another person's inner experience is believed to be a central element of our social interactions. Previous research has focused on cognitive (e.g., theory of mind) and emotional (e.g., emotional contagion) empathy, and less on behavioral factors (i.e., the ability to respond empathically). Recent studies suggest that the Default Mode Network (DMN) mediates individual variability in distinct empathy-related behaviors. However, little is known about DMN activity during actual empathic responses, understood in this study as the ability to communicate our understanding of the others' experience back to them. This study used an empathy response paradigm with 28 participants (22-37 years old) to analyze the relationship between the quality of empathic responses to 14 empathy-eliciting vignettes and patterns of attenuation in the DMN. Overall, the results suggest that high levels of empathic response, are associated with sustained activation of the DMN when compared with lower levels of empathy. Our results demonstrate that the DMN becomes increasingly involved in empathy-related behavior, as our level of commitment to the other's experience increases. This study represents a first attempt to understand the relation between the capacity for responding in a supportive way to others' needs and the intra-individual variability of the pattern of the DMN attenuation. Here we underline the critical role that the DMN plays in high-level social cognitive processes and corroborate the DMN role in different psychiatric disorders associated with a lack of empathy.

Empathy by default: Correlates in the brain at rest.

BACKGROUND: Empathy, defined as the ability to access and respond to the inner world of another person, is a multidimensional construct involving cognitive, emotional and self-regulatory mechanisms. Neuroimaging studies report that empathy recruits brain regions which are part of the social cognition network. Among the different resting state networks, the Default Mode Network (DMN) may be of particular interest for the study of empathy since it has been implicated in social cognition tasks. METHOD: The current study compared the cognitive and emotional empathy scores, as measured by the Interpersonal Reactivity Index, with the patterns of activation within the DMN, through the neuroimaging methodology of resting-state functional magnetic resonance. RESULTS: Results suggest a significant positive correlation between cognitive empathy and activation of the bilateral superior medial frontal cortex nodes of the DMN. Contrastingly, a negative correlation was found between emotional empathy and the same brain region. CONCLUSIONS: Overall, this data highlights a critical role of the medial cortical regions of the DMN, specifically its anterior node, for both cognitive and emotional domains of the empathic process.

Metabolic concerns in aging HIV-infected persons: from serum lipid phenotype to fatty liver.

: Among HIV-infected persons, the assessment of nonalcoholic fatty liver disease (NAFLD) provides a window through which overall metabolic health can be evaluated. In this review, we summarize clinical data that support the roles of aging and metabolic dysregulation as factors contributing to fatty liver/NAFLD among HIV-infected persons.Age-related metabolic alterations include hepatic anatomic and functional changes, altered homeostasis of gastrointestinal microbiota and anthropometric changes (such as a shift of body fat depots from the subcutaneous to the visceral compartment) that are often associated with the development of insulin resistance and increased cardiovascular risk.Fatty changes in the liver occur not only with metabolic disruption but also with virus-induced injury. Chronic hepatitis C virus infection is commonly associated with fatty liver, and can be related to both hepatitis C virus genotype and host metabolic features. Similarly, HIV infection is associated with fatty liver as a result of multiple viral and host factors. Clearly, lipodystrophy, dysregulation of the gut-liver axis and HIV infection itself may each contribute simultaneously to NAFLD pathogenesis. Although lifestyle changes are the mainstay of treatment, to date no drug has specifically been approved for use in persons with NAFLD. Moreover, current guidelines provide no specific therapeutic recommendations for persons with NAFLD older than 65 years.Well-designed studies characterizing the epidemiology, pathogenesis, clinical outcomes and potential therapeutic interventions for liver disease and associated metabolic comorbidities in older HIV-infected patients are urgently needed.

Default mode network dissociation in depressive and anxiety states.

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.

Inferior frontal gyrus white matter abnormalities in obsessive-compulsive disorder.

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.

Differential activation of the default mode network in jet lagged individuals.

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.