Early remission in multiple sclerosis is linked to altered coherence of the Cerebellar Network

Unstable functional brain states and reduced cerebro-cerebellar modularity in elderly individuals with subjective cognitive decline

The preclinical stage of Alzheimer's Disease (AD) holds great potential for intervention, therefore, it is crucial to elucidate the neural mechanisms underlying the progression of subjective cognitive decline (SCD). Previous studies have predominantly focused on the neural changes in the cerebrum associated with SCD, but have relatively neglected the cerebellum, and its functional relationship with the cerebrum. In the current study, we employed dynamic functional connectivity and large-scale brain network approaches to investigate the pathological characteristics of dynamic brain states and cerebro-cerebellar collaboration between SCD (n = 32) and the healthy elderly (n = 29) using resting-state fMRI. Two-way repeated measures ANOVA and permutation t-tests revealed significant group differences, with individuals with SCD exhibiting shorter state duration and more frequent transitions between states compared to the healthy elderly individuals. Additionally, individuals with SCD showed lower levels of intracerebellar functional connectivity, but higher levels of cerebellar-cerebral functional integration. Furthermore, the hub nodes of the functional networks in SCD shifted between the cerebellum and cerebrum across different brain states. These findings indicate that SCD exhibits greater state instability but may compensate for the negative effects of early disease by integrating cerebellar and cerebral networks, thereby maintaining cognitive performance. This study enhances our theoretical understanding of cerebellar-cerebral relationship changes in the early stages of AD and provides evidence for early interventions targeting the cerebellum.

Regional GABA levels modulate abnormal resting-state network functional connectivity and cognitive impairment in multiple sclerosis

More evidence shows that changes in functional connectivity with regard to brain networks and neurometabolite levels correlated to cognitive impairment in multiple sclerosis. However, the neurological basis underlying the relationship among neurometabolite levels, functional connectivity, and cognitive impairment remains unclear. For this purpose, we used a combination of magnetic resonance spectroscopy and resting-state functional magnetic resonance imaging to study gamma-aminobutyric acid and glutamate concentrations in the posterior cingulate cortex, medial prefrontal cortex and left hippocampus, and inter-network functional connectivity in 29 relapsing-remitting multiple sclerosis patients and 34 matched healthy controls. Neuropsychological tests were used to evaluate the cognitive function. We found that relapsing-remitting multiple sclerosis patients demonstrated significantly reduced gamma-aminobutyric acid and glutamate concentrations and aberrant functional connectivity involving cognitive-related networks compared to healthy controls, and both alterations were associated with specific cognition decline. Moreover, mediation analyses indicated that decremented hippocampus gamma-aminobutyric acid levels in relapsing-remitting multiple sclerosis patients mediated the association between inter-network functional connectivity in various components of default mode network and verbal memory deficits. In summary, our findings shed new lights on the essential function of GABAergic system abnormalities in regulating network dysconnectivity and functional connectivity in relapsing-remitting multiple sclerosis patients, suggesting potential novel approach to treatment.

Altered amygdalar emotion space in borderline personality disorder normalizes following dialectical behaviour therapy

BACKGROUND

Borderline personality disorder (BPD) is a mental health condition characterized by an inability to regulate emotions or accurately process the emotional states of others. Previous neuroimaging studies using classical univariate analyses have tied such emotion dysregulation to aberrant activity levels in the amygdala of patients with BPD. However, multivariate analyses have not yet been used to investigate how representational spaces of emotion information may be systematically altered in patients with BPD.

METHODS

Patients with BPD performed an emotional face matching task while undergoing MRI before and after a 10-week inpatient program of dialectical behavioural therapy. Representational similarity analysis (RSA) was applied to activity patterns (evoked by angry, fearful, neutral and surprised faces) in the amygdala and temporo-occipital fusiform gyrus of patients with BPD and in the amygdala of healthy controls.

RESULTS

We recruited 15 patients with BPD (8 females, 6 males, 1 transgender male) to participate in the study, and we obtained a neuroimaging data set for 25 healthy controls for a comparative analysis. The RSA of the amygdala revealed a negative bias in the underlying affective space (in that activity patterns evoked by angry, fearful and neutral faces were more similar to each other than to patterns evoked by surprised faces), which normalized after therapy. This bias-to-normalization effect was present neither in activity patterns of the temporo-occipital fusiform gyrus of patients nor in amygdalar activity patterns of healthy controls.

LIMITATIONS

Larger samples and additional questionnaires would help to better characterize the association between specific aspects of therapy and changes in the neural representational space.

CONCLUSION

Our findings suggest a more refined role for the amygdala in the pathological processing of perceived emotions and may provide new diagnostic and prognostic imaging-based markers of emotion dysregulation and personality disorders.Clinical trial registration: DRKS00019821, German Clinical Trials Register (Deutsches Register Klinischer Studien).