Biology subjects

Dan, R.

Publications and source records attributed to Dan, R..

3 recordsLinked to original sources

bioRxiv2026

Glutamatergic and Redox Abnormalities in Major Depressive Disorder: Links to Childhood Maltreatment and Perceived Stress

Background: Childhood sexual abuse (CSA) increases the risk for major depressive disorder (MDD), yet the underlying neurobiological mechanisms remain poorly understood. We examined (1) associations of medial prefrontal cortex (mPFC) glutamatergic metabolites and redox balance with childhood maltreatment and MDD; and (2) whether these neurochemical measures predicted future perceived stress. Methods: Using proton and phosphorus 4T magnetic resonance spectroscopy, we quantified glutamate, glutamine, their sum (Glx), and the NAD/NADH ratio within the same mPFC voxel in 71 women across four groups: healthy controls (HC; n=27), current MDD without CSA (n=14), current MDD with CSA (n=14), and remitted MDD with CSA (n=16). Results: Glutamate and Glx levels were lower in both CSA-exposed groups (n=30) compared with HC (n=27), whereas women with MDD without CSA did not differ significantly from HC. Among CSA-exposed women, greater maltreatment severity was associated with lower glutamine, and greater maltreatment multiplicity with lower glutamate and Glx, specifically in women with current MDD. The association between depressive symptom severity and glutamine differed by CSA history. A significant interaction between baseline NAD/NADH ratio and clinical group predicted perceived stress at 6-month follow-up, adjusting for baseline perceived stress. Specifically, lower baseline NAD/NADH ratio predicted greater subsequent perceived stress in MDD without CSA, but not in the other clinical groups. Conclusions: Our findings suggest that mPFC glutamatergic metabolites and redox balance show distinct patterns of association with CSA history, depression status, and subsequent perceived stress, highlighting neurochemical heterogeneity in MDD and molecular markers of risk.

neuroscience↗

bioRxiv2022

Older age is associated with a shift from ventral to dorsal PCC in pathways connecting the DMN with visual and limbic areas and a directionality shift in pathways connecting the DMN with sensorimotor areas

Alterations in the default mode network (DMN) are known to associated with aging and with neurological and psychiatric diseases. We assessed age-dependent changes in interactions within the DMN and between the DMN with other brain areas, and correlations of these interactions with a battery of neuropsychological tests to formulate a macroscopic model of ageing. Using a novel multivariate analysis method, enabling determination of directed pathways, on resting-state functional MRI data from fifty young and thirty-one old healthy individuals, we identified directed intra- and inter-DMN directed pathways that differed between the groups and used their correlations with neuropsychological tests to infer their behavioral meaning. Pathways connecting the DMN with visual and limbic regions in old subjects engaged at BOLD low frequency and involved the dorsal PCC. In young subjects, they were at high frequency and involved the ventral PCC. Pathways combining the sensorimotor (SM) and the DMN, were efferent in young subjects (DMN SM). Most inter-DMN pathways in the old subjects, correlated with reduced speed and working memory and, were DMN efferent (DMN>). We suggest a macroscopic model of aging centered in the DMN. It suggests that the reduced sensorimotor efferent, probably brought about from reduced physical activity, and the increased need to control such activities by the mPFC, causes a higher dependency on external versus internal cues. This results in a shift from ventral to dorsal PCC of inter-DMN pathways. Consequently, the model combines physical activity with ageing.

neuroscience↗

bioRxiv2021

Emotional states as distinct configurations of functional brain networks

The conceptualization of emotional states as patterns of interactions between large-scale brain networks has recently gained support. Yet, few studies have directly examined the brains network structure during emotional experiences. Here, we investigated the brains functional network organization during experiences of sadness, amusement, and neutral states elicited by movies, in addition to a resting-state. We tested the effects of the experienced emotion on individual variability in the brains functional connectome. Next, for each state, we defined a community structure of the brain and quantified its segregation and integration. We found that sadness, relative to amusement, was associated with higher modular integration and increased connectivity of cognitive control networks: the salience and fronto-parietal networks. Moreover, in both the functional connectome and the emotional report, the similarity between individuals was dependent on the sex. Our results suggest that the experience of emotion is linked to a reconfiguration of whole-brain distributed, not emotion-specific, functional networks and that the brains topological structure carries information about the subjective emotional experience.

neuroscience↗