Human orbitofrontal cortex signals decision outcomes to sensory cortex during behavioral adaptations

Multimodal investigations of structural and functional brain alterations in anorexia and bulimia nervosa and their relationships to psychopathology

BACKGROUND

Neurobiological understanding of eating disorders (EDs) is limited. This study presents the first comparative multi-modal magnetic resonance imaging (MRI) assessments of anorexia nervosa (AN) and bulimia nervosa (BN), uncovering neurobiological differences associated with these disorders.

METHODS

This female case-control study included 57 healthy controls (HC) and 130 participants with EDs (BN and AN subtypes). Structural and functional MRI assessed gray matter volume (GMV), cortical thickness (CT), and task-based activities related to reward processing, social-emotional functioning, and response inhibition. Whole-brain group differences were correlated to ED psychopathology.

RESULTS

Significant structural differences were observed in the ED group compared to HCs, including reduced GMV in the left lateral orbitofrontal cortex and lower CT in the left rostral middle frontal gyrus and precuneus, after adjusting for BMI. Specific structural alterations were only evident in AN subgroups. GMV reductions in the orbitofrontal cortex were linked to impulsivity, while lower CT in the frontal gyrus correlated with cognitive restraint in eating, suggesting these regions may play key roles in ED psychopathology. Functional MRI also revealed notable differences. During reward anticipation, participants with EDs exhibited deactivations in the cerebellum and right superior frontal gyrus, alongside reduced activation in the left lingual gyrus. These functional changes were associated with heightened neuroticism. Mediation analyses suggested that starvation-related GMV reductions in EDs disrupt reward-related brain function, increase neuroticism, and reinforce cognitive restraint, likely contributing to the persistence of ED symptoms.

CONCLUSIONS

These findings illuminate key neurobehavioral mechanisms underlying EDs, pointing to potential brain-based targets for developing specialized treatment.

A prefrontal thalamocortical readout for conflict-related executive dysfunction in schizophrenia

Executive dysfunction is a prominent feature of schizophrenia and may drive core symptoms. Dorsolateral prefrontal cortex (dlPFC) deficits have been linked to schizophrenia executive dysfunction, but mechanistic details critical for treatment development remain unclear. Here, capitalizing on recent animal circuit studies, we develop a task predicted to engage human dlPFC and its interactions with the mediodorsal thalamus (MD). We find that individuals with schizophrenia exhibit selective performance deficits when attention is guided by conflicting cues. Task performance correlates with lateralized MD-dlPFC functional connectivity, identifying a neural readout that predicts susceptibility to conflict during working memory in a larger independent schizophrenia cohort. In healthy subjects performing a probabilistic reversal task, this MD-dlPFC network predicts switching behavior. Overall, our three independent experiments introduce putative biomarkers for executive function in schizophrenia and highlight animal circuit studies as inspiration for the development of clinically relevant readouts.

Early attentional processing and cortical remapping strategies of tactile stimuli in adults with an early and late-onset visual impairment: A cross-sectional study

Neuroplastic changes appear in people with visual impairment (VI) and they show greater tactile abilities. Improvements in performance could be associated with the development of enhanced early attentional processes based on neuroplasticity. Currently, the various early attentional and cortical remapping strategies that are utilized by people with early (EB) and late-onset blindness (LB) remain unclear. Thus, more research is required to develop effective rehabilitation programs and substitution devices. Our objective was to explore the differences in spatial tactile brain processing in adults with EB, LB and a sighted control group (CG). In this cross-sectional study 27 participants with VI were categorized into EB (n = 14) and LB (n = 13) groups. They were then compared with a CG (n = 15). A vibrotactile device and event-related potentials (ERPs) were utilized while participants performed a spatial tactile line recognition task. The P100 latency and cortical areas of maximal activity were analyzed during the task. The three groups had no statistical differences in P100 latency (p>0.05). All subjects showed significant activation in the right superior frontal areas. Only individuals with VI activated the left superior frontal regions. In EB subjects, a higher activation was found in the mid-frontal and occipital areas. A higher activation of the mid-frontal, anterior cingulate cortex and orbitofrontal zones was observed in LB participants. Compared to the CG, LB individuals showed greater activity in the left orbitofrontal zone, while EB exhibited greater activity in the right superior parietal cortex. The EB had greater activity in the left orbitofrontal region compared to the LB. People with VI may not have faster early attentional processing. EB subjects activate the occipital lobe and right superior parietal cortex during tactile stimulation because of an early lack of visual stimuli and a multimodal information processing. In individuals with LB and EB the orbitofrontal area is activated, suggesting greater emotional processing.

Functional specialization of medial and lateral orbitofrontal cortex in inferential decision-making

Inferring prospective outcomes and updating behavior are prerequisites for making flexible decisions in the changing world. These abilities are highly associated with the functions of the orbitofrontal cortex (OFC) in humans and animals. The functional specialization of OFC subregions in decision-making has been established in animals. However, the understanding of how human OFC contributes to decision-making remains limited. Therefore, we studied this issue by examining the information representation and functional interactions of human OFC subregions during inference-based decision-making. We found that the medial OFC (mOFC) and lateral OFC (lOFC) collectively represented the inferred outcomes which, however, were context-general coding in the mOFC and context-specific in the lOFC. Furthermore, the mOFC-motor and lOFC-frontoparietal functional connectivity may indicate the motor execution of mOFC and the cognitive control of lOFC during behavioral updating. In conclusion, our findings support the dissociable functional roles of OFC subregions in decision-making.

Chronobioethics: Symphony of biological clocks observed by 7-day/24-hour ambulatory blood pressure monitoring and cardiovascular health

BACKGROUND

The high prevalence of desynchronized biological rhythms is becoming a primary public health concern. We assess complex and diverse inter-modulations among multi-frequency rhythms present in blood pressure (BP) and heart rate (HR).

SUBJECTS

and Methods: We performed 7-day/24-hour Ambulatory BP Monitoring in 220 (133 women) residents (23 to 74 years) of a rural Japanese town in Kochi Prefecture under everyday life conditions.

RESULTS

A symphony of biological clocks contributes to the preservation of a synchronized circadian system. (1) Citizens with an average 12.02-h period had fewer vascular variability disorders than those with shorter (11.37-h) or longer (12.88-h) periods (P<0.05), suggesting that the circasemidian rhythm is potentially important for human health. (2) An appropriate BP-HR coupling promoted healthier circadian profiles than a phase-advanced BP: lower 7-day nighttime SBP (106.8 vs. 112.9 mmHg, P=0.0469), deeper nocturnal SBP dip (20.5% vs. 16.8%, P=0.0101), and less frequent incidence of masked non-dipping (0.53 vs. 0.86, P=0.0378), identifying the night as an important time window.

CONCLUSION

Adaptation to irregular schedules in everyday life occurs unconsciously at night, probably initiated from the brain default mode network, in coordination with the biological clock system, including a reinforced about 12-hour clock, as "a biological clock-guided core integration system".

Changes in brain structure and function during early aging in patients with chronic low back pain

Objective

To explore the structural and functional changes in cognition-related brain regions in patients with chronic low back pain (CLBP) at earlier ages, and explore the impact of the interaction between CLBP and age on the brain.

Methods

Seventy-six patients with CLBP were recruited and divided into "younger" age group (20-29 years, YA), "middle" age group (30-39 years, MA), and "older" age group (40-49 years, OA). All patients underwent functional magnetic resonance imaging (fMRI) as well as clinical psychological and pain-related symptoms assessments.

Results

Structural analysis showed that patients in OA group had lower gray matter (GM) volumes in the orbitofrontal cortex (OFC) bilaterally and the right superior frontal gyrus (SFG) compared to YA group. The resting-state brain activity analysis showed that amplitude of low-frequency fluctuation (ALFF) values in the bilateral postcentral gyrus and left ventral medial prefrontal cortex (mPFC) were significantly different in the OA group. The functional connectivity (FC) in the right ventral dorsolateral prefrontal cortex (DLPFC) and the right insula was significantly decreased in the OA group compared to the YA and MA groups. Likewise, the FC in the left caudal parahippocampal gyrus (PHG) and left inferior parietal lobule (IPL) were significantly lower in the MA and OA groups compared to the YA group. In addition, both the structural properties and the FC values of these brain regions were significantly correlated with age.

Conclusion

This preliminary study concludes that CLBP affects the aging process. The synergistic effects of CLBP and aging accelerate the functional and structural decline of certain areas of the brain, which not only affects pain processing, but are also may be associated with cognitive declines.

Causal associations between gut microbiota and regional cortical structure: a Mendelian randomization study

Introduction

Observational studies have reported associations between gut microbiota composition and central nervous system diseases. However, the potential causal relationships and underlying mechanisms remain unclear. Here, we applied Mendelian randomization (MR) to investigate the causal effects of gut microbiota on cortical surface area (SA) and thickness (TH) in the brain.

Methods

We used genome-wide association study summary statistics of gut microbiota abundance in 18,340 individuals from the MiBioGen Consortium to identify genetic instruments for 196 gut microbial taxa. We then analyzed data from 56,761 individuals from the ENIGMA Consortium to examine associations of genetically predicted gut microbiota with alterations in cortical SA and TH globally and across 34 functional brain regions. Inverse-variance weighted analysis was used as the primary MR method, with MR Egger regression, MR-PRESSO, Cochran's Q test, and leave-one-out analysis to assess heterogeneity and pleiotropy.

Results

At the functional region level, genetically predicted higher abundance of class Mollicutes was associated with greater SA of the medial orbitofrontal cortex (β = 8.39 mm2, 95% CI: 3.08-13.70 mm2, p = 0.002), as was higher abundance of phylum Tenericutes (β = 8.39 mm2, 95% CI: 3.08-13.70 mm2, p = 0.002). Additionally, higher abundance of phylum Tenericutes was associated with greater SA of the lateral orbitofrontal cortex (β = 10.51 mm2, 95% CI: 3.24-17.79 mm2, p = 0.0046). No evidence of heterogeneity or pleiotropy was detected.

Conclusion

Specific gut microbiota may causally influence cortical structure in brain regions involved in neuropsychiatric disorders. The findings provide evidence for a gut-brain axis influencing cortical development, particularly in the orbitofrontal cortex during adolescence.

Modulation of prefrontal couplings by prior belief-related responses in ventromedial prefrontal cortex

Humans and other animals can maintain constant payoffs in an uncertain environment by steadily re-evaluating and flexibly adjusting current strategy, which largely depends on the interactions between the prefrontal cortex (PFC) and mediodorsal thalamus (MD). While the ventromedial PFC (vmPFC) represents the level of uncertainty (i.e., prior belief about external states), it remains unclear how the brain recruits the PFC-MD network to re-evaluate decision strategy based on the uncertainty. Here, we leverage non-linear dynamic causal modeling on fMRI data to test how prior belief-dependent activity in vmPFC gates the information flow in the PFC-MD network when individuals switch their decision strategy. We show that the prior belief-related responses in vmPFC had a modulatory influence on the connections from dorsolateral PFC (dlPFC) to both, lateral orbitofrontal (lOFC) and MD. Bayesian parameter averaging revealed that only the connection from the dlPFC to lOFC surpassed the significant threshold, which indicates that the weaker the prior belief, the less was the inhibitory influence of the vmPFC on the strength of effective connections from dlPFC to lOFC. These findings suggest that the vmPFC acts as a gatekeeper for the recruitment of processing resources to re-evaluate the decision strategy in situations of high uncertainty.