Biology subjects

Merglen, A.

Publications and source records attributed to Merglen, A..

3 recordsLinked to original sources

bioRxiv2026

Mapping sex-specific hormone-metabolite coupling in the adolescent brain: a longitudinal whole-brain spectroscopic imaging study

Adolescence is marked by coordinated endocrine and brain maturation, yet how blood circulating steroid hormones relate to neurochemical change in the brain remains largely unknown. We combined longitudinal data from a novel fast whole-brain, high-resolution three-dimensional proton magnetic resonance spectroscopic imaging technique with repeated measurements of sexual hormones and adrenal steroids in the serum of 42 healthy adolescents (13-15 years; 24 females) totalizing 100 scan-visits. Longitudinal voxel-wise models separated within-individual changes from stable between-individual differences and controlled the false discovery rate across whole-brain tests. In the whole sample, increasing age was associated with higher N-acetylaspartate plus N-acetylaspartylglutamate within individuals, whereas age was positively associated with higher glutamate plus glutamine between individuals. We then observed a hormone-metabolite coupling that differed by sex and steroids. In males, within-individual increases in testosterone tracked frontal increases in glutamate plus glutamine and disseminated increases in total N-acetylaspartate. In females, higher mean estradiol between individuals was associated with higher frontal choline-containing compounds. Within-individual changes in cortisone were associated with myo-inositol and choline-containing compounds in a widespread sex-interaction effect, with positive coupling in males and negative in females. The cortisone/cortisol ratio showed a similar sex-interaction for choline-containing compounds. These findings reveal spatially distributed, sex-dependent links between steroid maturation and adolescent brain neurochemical composition and underscore the importance of differentiating within- and between-individual associations. These observational data extend predominantly structural descriptions of pubertal brain development by identifying distinct coupling of gonadal hormones with neuronal-metabolic markers and glucocorticoid interconversion with glia-weighted metabolites.

neuroscience↗

bioRxiv2026

Sex differences in brain metabolism assessed with whole-brain magnetic resonance spectroscopic imaging

Sex differences in brain disorders span age at onset, symptom profiles, disease course and treatment response, and may partly reflect underlying differences in cellular metabolism. Indeed, in vivo evidence of sex-related neurometabolic variation remains sparse, with heterogenous and conflicting findings. Using fast high-resolution whole-brain three-dimensional magnetic resonance spectroscopic imaging, we mapped five brain metabolites in three independent cohorts of healthy participants (total n = 114). In a discovery sample of adolescents scanned at 3 Tesla (3T) (n = 61), males showed higher total N-acetylaspartate (tNAA) across widespread gray matter regions. Regional analyses further revealed opposing sex patterns with a complementary higher total creatine (tCr) observed in females, motivating examination of their ratio as an integrative metabolic index. The tNAA/tCr ratio was consistently higher in males in the discovery sample and this finding was replicated across two independent young-adult samples (3T, n = 26; 7T, n = 27), with a widespread gray and white matter distribution. This tNAA/tCr ratio may link neuronal mitochondrial metabolism with cellular energy buffering, positioning it as a potential index of bioenergetic balance relevant for conditions showing both sex differences and altered neurometabolism, notably multiple sclerosis, Alzheimer disease, and psychosis. Together, these findings reveal a reproducible, distributed metabolic sexual dimorphism in the human brain, and underscore the importance of accounting for sex-specific neurometabolic profiles in studies of brain health and disease.

neuroscience↗

bioRxiv2024

Mindfulness training impacts brain network dynamics linked to stress response in young adolescents.

Mindfulness-based interventions (MBI) may lead to lower levels of psychological distress, including depression, anxiety, and stress in adolescents. Past research has advanced the discovery of neural architecture recruited by MBI. However, the brain mechanisms through which mindfulness exerts more resilient responses to social stressors in teens remain unclear. Here, we examined how MBI modulates changes in brain network dynamics following social stress with different affective valence (i.e., neutral, negative, and positive). For this aim, we carried out a longitudinal randomized controlled trial in which non-clinical adolescents underwent MBI for 8 weeks. They completed a psychosocial stress task before and following MBI. Functional magnetic resonance imaging (fMRI) and self-reported measurements of psychological distress were collected in both measurement points (i.e., "pre" and "post" MBI). We computed co-activation patterns on fMRI data to characterize dynamic functional connectivity within whole-brain networks. The results depicted how MBI modulates transient co-activation changes in dorsal medial regions of the brain default network (DN) following the experience of stress. However, these brain changes were not specific to the affective valence of stressful stimuli. The relationship between the DN dynamics and the measurements of psychological distress was mediated by MBI. Globally, our findings support a model in which MBI causally mediate brain-behavior interactions related to psychosocial stress in adolescents.

neuroscience↗