Central precuneus lesions are associated with impaired executive function

Oscillatory brain dynamics underlying affective face processing

Facial expressions are ubiquitous and highly reliable social cues. Decades of research has shown that affective faces undergo facilitated processing across a distributed brain network. However, few studies have examined the multispectral brain dynamics underlying affective face processing, which is surprising given the multiple brain regions and rapid temporal dynamics thought to be involved. Herein, we used magnetoencephalography to derive dynamic functional maps of angry, neutral, and happy face processing in healthy adults. We found stronger theta oscillations shortly after the onset of affective relative to neutral faces (0-250 ms), within distributed ventral visual and parietal cortices, and the anterior hippocampus. Early gamma oscillations (100-275 ms) were strongest for angry faces in the inferior parietal lobule, temporoparietal junction, and presupplementary motor cortex. Finally, beta oscillations (175-575 ms) were stronger for neutral relative to affective expressions in the middle occipital and fusiform cortex. These results are consistent with the literature in regard to the critical brain regions, and delineate a distributed network where multispectral oscillatory dynamics support affective face processing through the rapid merging of low-level visual inputs to interpret the emotional meaning of each facial expression.

Effects of a healthy diet based on seed-rich vegetables on the gut microbiota and intrinsic brain activity in perimenopausal women: A pilot study on cognitive improvement

Brain functional changes and gut microbiota dysbiosis have been observed in perimenopausal syndrome (PMS). We evaluated the effects of a plant-based daily diet enriched with Raphanus sativus L. (RSL, radish seed) on the gut microbiota composition, gastrointestinal symptoms, resting-state local spontaneous brain activity, and neuropsychology in perimenopausal women. For 12 weeks, the participants were instructed to adhere to a controlled, Raphanus sativus L.-rich plant-based diet (a mean RSL intake of 5 g/day). Two test days were organized: before and after the nutritional intervention. The fecal microbiota composition, gastrointestinal symptoms, resting-state brain function, and neuropsychology were assessed twice. A longitudinal single-arm study was conducted on 24 perimenopausal women. The Montreal Cognitive Assessment (MoCA) scores tended to improve in the visuospatial/executive function subitem and in the total score after the diet. The participants presented elevated amplitude of low-frequency fluctuation (ALFF) values in the left middle occipital gyrus, the left precentral gyrus, and the left middle cingulum gyrus. The abundances of the phyla Synergistetes and Verrucomicrobia were positively correlated with the ALFF values of the left middle occipital gyrus, left precentral gyrus, and left middle cingulum gyrus. These data suggest that specific gut microbes may modulate intrinsic brain activity and cognitive function in perimenopausal women. A plant-based RSL-rich diet has beneficial effects on the gut microbial composition and brain function of perimenopausal women.

Altered Brain Functional Connectivity and Topological Structural in Girls with Idiopathic Central Precocious Puberty: A Graph Theory Analysis Based on Resting-State fMRI

OBJECTIVES

This study aimed to investigate changes in brain functional connectivity (FC) and topological structure in girls with idiopathic central precocious puberty (ICPP) using complex network theory analysis.

METHODS

Resting-state fMRI data from 53 ICPP girls (ages 6-8) and 51 controls were analysed. Graph theory was used to construct whole-brain functional networks, identify topological differences, and assess the relationship between sex hormone levels and network properties in regions with group differences.

RESULTS

RS-FC analysis revealed reduced connectivity in cognitive and emotional regulation regions in the ICPP group (p < 0.05), but enhanced connectivity in emotional perception and self-regulation areas, such as the amygdala and insula (p < 0.05), suggesting a compensatory mechanism. Graph theory showed that ICPP girls' brain networks maintained small-world properties (γ > 1, λ ≈ 1, σ > 1). Local topological changes included decreased clustering and node efficiency in cognitive and emotional regulation regions, like the superior frontal gyrus and praecuneus (p < 0.05), while emotional regulation regions (amygdala, insula) showed increased clustering and node efficiency (p < 0.05), indicating compensation.

CONCLUSIONS

This study highlights compensatory mechanisms in emotional regulation that may offset impairments in cognitive regions, offering new insights into ICPP's neural mechanisms.

Advanced concentrative absorption meditation reorganizes functional connectivity gradients of the brain: 7T MRI and phenomenology case study of jhana meditation

There is growing scientific interest in advanced meditation, and particularly the Theravada Buddhist advanced concentrative absorption meditation known as jhana (ACAM-J). ACAM-J includes a series of eight consecutive meditative states, which are radically altered states of consciousness. The neuroscience of ACAM-J, specifically brain reorganization, remains underspecified in part due to the difficulty of finding and studying expert ACAM-J meditators and challenges related to laboratory investigation of ACAM-J. Using a nonlinear dimensionality reduction technique applied to human functional neuroimaging in an intensive case study, we investigated brain reorganization during ACAM-J. We applied linear mixed models and correlations to explore relations among brain reorganization and ACAM-J phenomenology. Results demonstrated that ACAM-J induces disruption of the hierarchical organization of the brain by shifting the gradients toward a more globally integrated rather than segregated state between sensory-related and higher-order cognitive regions. Additionally, ACAM-J induces a separation between sensory-related and attention modulation-related regions, resulting in greater differentiation in functional organization of these regions, consistent with phenomenological reports. This study highlights the need for further research into brain reorganization and health-related implications of both short-term and long-term practice of ACAM-J. Key points/highlights The neuroscience of advanced concentrative absorption meditation (ACAM) has the potential to improve our knowledge of well-being and altered states of consciousness but remains underexplored due to methodological challenges. We investigated functional reorganization of the brain during ACAM-J using gradient analysis and demonstrated that ACAM-J disrupts the hierarchical organization of the brain during meditation. Additionally, we demonstrated that ACAM-J increases differentiation between primary sensory areas and areas related to attention modulation.

Development and Training of Mindfulness and Its Relationship with Executive Function in Chinese Rural Upper-Grade Elementary School Students

The purpose of this study was to explore the development and relationship between mindfulness and executive function (EF) in students in grades 4-5 and investigate mindfulness training's impact on mindfulness and EF in grade 4 students in rural China. Study 1 measured mindfulness and EF in Chinese students in grades 4-5. Differences in the level of mindfulness among children in grade 4 (n = 159) and grade 5 (n = 187) in rural China were analyzed by multi-factor analysis of variance. Correlation and hierarchical multiple regression analyses were used to explore the relationship between mindfulness and EF in grade 4 (n = 103) and grade 5 (n = 124). Study 2 included 45 4th graders with a general mindfulness level, with 21 children in the experimental group receiving 12 mindfulness training lessons. The mindfulness and EF scores of individuals in the mindfulness and control groups were tested before and after the intervention. Study 1 showed that 4th graders had significantly lower mindfulness scores than 5th graders. EFs in grades 4-5 were significantly correlated with mindfulness. Study 2 revealed that mindfulness training significantly improved the experimental group's mindfulness and working memory. A non-significant improvement in inhibitory control and cognitive flexibility was observed. There was a significant difference in mindfulness in grades 4 and 5 of Chinese rural upper-grade elementary school. Children who perform well in mindfulness also perform well in EFs. Mindfulness training improved the mindfulness and working memory of 4th graders in rural China with a general mindfulness level.

Intersection of Brain Complexity, Functional Connectivity, and Neuropsychology: A Systematic Review

The definition of brain complexity is based on the principal property of the coexistence of a high degree of integration and differentiation within a single neural system. Despite the fruitful scope of emerging studies involving the applicability of brain complexity metrics, there is a notable scarcity of research focusing on the qualitative characteristics of conscious systems, which are recognized for their high complexity. These qualitative characteristics are expressed in complex cognitive processes, reflecting the interaction between distinct neuropsychological domains, such as attention, memory, language, and executive functions (EFs). Cognitive flexibility and inhibitory control, for instance, emerge from the dynamic integration of distributed neural networks, underscoring the interdependence between brain complexity and cognitive functioning. In light of this, the present study aimed to evaluate how studies addressing measures of functional connectivity and brain complexity, obtained through resting-state functional magnetic resonance imaging (rs-fMRI), relate to neuropsychological aspects. To achieve this, a systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and based on the PICO (Patient, Intervention, Comparison, Outcome) strategy. Studies were searched in PubMed, CAPES Periodicals, and Virtual Health Library databases to identify relevant studies published between 2019 and March 2024. Articles were included based on study type, sample characteristics, methodological aspects, and specific listed variables. Exclusion criteria encompassed theoretical studies, animal research, and studies involving children/adolescents, as well as those addressing psychiatric conditions, psychoactive substance use, intervention evaluations (e.g., transcranial magnetic stimulation), and disorders of consciousness, due to limitations in applying neuropsychological measures. Possible limitations include the exclusion of studies with specific populations and clinical conditions, which may limit the generalizability of findings to broader, more diverse groups. After applying the selection criteria, 30 articles were chosen and fully analyzed. The results allowed for the establishment of characteristics of the research landscape in this area, initially highlighting a greater number of studies focused on functional connectivity compared to those directed at brain complexity. Additionally, EFs were identified as the most frequently addressed neuropsychological domain in the studies, consistent with the most commonly used evaluative measures in the research: Trail Making Test (TMT), Symbol Digit Modalities Test (SDMT), and verbal fluency tasks. The findings suggest that this is an area of study still in its early stages of development, with notable gaps in the in-depth understanding of the relationships between neural network complexity metrics and neuropsychological functioning.

Trajectories of intrinsic connectivity one year post pediatric mild traumatic brain injury: Neural injury superimposed on neurodevelopment

The developing brain undergoes rapid changes throughout middle childhood and adolescence. The disambiguation of long-term changes in intrinsic activity following pediatric mild traumatic brain injury (pmTBI) from typical development can therefore only be ascertained in longitudinal studies with large sample size and at least three serial assessments. A comprehensive clinical battery and resting-state fMRI data were collected approximately 1-week (N = 263; 8-18 years old), 4-months (N = 192) and 1-year (N = 153) post-injury, with identical visits in a large cohort (N = 228) of age- and sex-matched healthy controls (HC). Results indicated persistent frontocerebellar and thalamic connectivity changes up to 1-year post-injury in pmTBI relative to controls (P's < .001), with similar longitudinal connectivity trajectories (i.e., typical neurodevelopment). Alterations in precuneal midline connectivity (p's < .05) and occupancy of a default mode/limbic dynamic brain state were present only up to 4-months (p's < .001) rather than 1-year (p's > .44) post-injury. However, absent group differences at 1-year post-injury may be explained as pseudo-normalization due to altered longitudinal connectivity trajectories in pmTBI associated with neurodevelopment. Persistent alterations of precuneal connectivity were also associated with lower executive function and long-term memory scores. In conclusion, pmTBI may result in chronic changes to both static and dynamic intrinsic connectivity which further interact with typical neurodevelopment. Longer follow-up studies may be needed to unravel this interaction.

The Case Series of Contralateral Interhemispheric Transfalcine Approach to Medial Parietooccipital Pathologies: Surgical Technique and Results

BACKGROUND AND OBJECTIVES

The medial parietooccipital and peritrigonal areas present challenges for neurosurgical procedures. Adjacency to the eloquent cortex-postcentral gyrus and cuneus, as well as crucial white matter tracts, such as optic radiation-makes the surgical approaches difficult. This study aims to describe the surgical technique and outcomes of treating lesions using the contralateral approach.

METHODS

This study is a retrospective analysis of 19 surgical cases treated in the Department of Neurosurgery and Neurooncology, Copernicus Memorial Hospital, in Łódź between April 2021 and May 2024.

RESULTS

Nineteen cases were treated with the contralateral posterior interhemispheric transfalcine transprecuneus approach. Six cases were vascular (all arteriovenous malformation) and 13 tumors (5 glioblastomas, 4 meningiomas, 4 metastasis, and 1 pilocytic astrocytoma). Twelve of them were in precuneus, 3 in the peritrigonal part of lateral ventricle, 2 in falx, and 2 in pulvinar. The mean surgery time was 4 hours 15 minutes ± 2 hours 21 minutes. The superior sagittal sinus was injured and managed using suture and hemostatic material in 2 cases. In 2 cases, a small anastomotic vein was sacrificed, and in none of cases, a venous infarction related to anastomotic veins was observed. A new neurologic deficit was present in 8 cases post-surgery improving after a few days. The mean hospitalization time was 11 ± 8.7 days.

CONCLUSION

The contralateral interhemispheric transfalcine approach is a valuable surgical technique for managing medial parietooccipital and peritrigonal lesions.

The association between precuneus cortex thickness and mild behavioral impairment in patients with mild stroke

The objective of this research was to examine the association between precuneus cortex thickness and mild behavioral impairment (MBI) in patients with mild stroke. Seventy-two patients were evaluated by high-resolution 3 T magnetic resonance and the mild behavioral impairment checklist (MBI-C). To determine the association between precuneus cortex thickness and MBI, we adjusted for demographics, vascular risk factors, and laboratory examination indicators in logistic regression analysis. In addition, we used mendelian randomization to further study the association through genetic databases. Of the 72 mild stroke patients in this study, 26 had MBI. We found a strong negative connection between precuneus cortex thickness and MBI after adjusting for any confounding variables. In patients with an initial mild stroke, the thinner the precuneus cortex, the higher the risk of MBI (OR: 0.02; 95% CI: 0.00-0.39; P < 0.05). Our study has uncovered a significant negative association between the thickness of the precuneus cortex and MBI. This finding provides a novel viewpoint for the radiological diagnosis of MBI, thereby augmenting the contribution of imaging to the diagnostic process of MBI and advancing the prediction of dementia. Specifically, in patients who have suffered mild stroke, a reduction in the cortical thickness of the precuneus has been pinpointed as crucial radiographic evidence of preclinical cognitive impairment. This insight could potentially facilitate earlier detection and intervention strategies for cognitive decline.

Exploring the links among brain iron accumulation, cognitive performance, and dietary intake in older adults: A longitudinal MRI study

This study evaluated longitudinal brain iron accumulation in older adults, its association with cognition, and the role of specific nutrients in mitigating iron accumulation. MRI-based, quantitative susceptibility mapping estimates of brain iron concentration were acquired from seventy-two healthy older adults (47 women, ages 60-86) at a baseline timepoint (TP1) and a follow-up timepoint (TP2) 2.5-3.0 years later. Dietary intake was evaluated at baseline using a validated questionnaire. Cognitive performance was assessed at TP2 using the uniform data set (Version 3) neuropsychological tests of episodic memory (MEM) and executive function (EF). Voxel-wise, linear mixed-effects models, adjusted for longitudinal gray matter volume alterations, age, and several non-dietary lifestyle factors revealed brain iron accumulation in multiple subcortical and cortical brain regions, which was negatively associated with both MEM and EF performance at T2. However, consumption of specific dietary nutrients at TP1 was associated with reduced brain iron accumulation. Our study provides a map of brain regions showing iron accumulation in older adults over a short 2.5-year follow-up and indicates that certain dietary nutrients may slow brain iron accumulation.

Frontal neurodegeneration associated with Frontal Assessment Battery in early Alzheimer's disease

BACKGROUND

The Frontal Assessment Battery (FAB) is widely used to assess executive dysfunction in patients with amnestic mild cognitive impairments due to Alzheimer's disease (aMCI-AD), but its neurobiological meaning is unclear. To elucidate this, we examined the relationship between the FAB score and three key imaging biomarkers: gray matter volume, amyloid-beta (Aβ) deposition, and glucose metabolism.

METHODS

Twenty Aβ- and tau-positive aMCI-AD patients and age-matched controls underwent structural magnetic resonance imaging and positron emission tomography with [11C]PiB and [18F]FDG. Voxel-based morphometry and statistical parametric mapping analyses were performed to elucidate the relationships between FAB scores and regional gray matter volume, [11C]PiB uptake for Aβ deposition, and [18F]FDG uptake for glucose metabolism.

RESULTS

FAB scores were significantly lower in aMCI-AD than in controls (p < 0.001). In aMCI-AD, FAB was significantly correlated with right inferior frontal gray matter volume and right medial and left middle frontal glucose metabolism (family-wise error p < 0.05). However, there was no correlation between Aβ deposition and FAB (family-wise error p < 0.05).

CONCLUSIONS

The decreased FAB score is linked more with frontal-lobe neurodegeneration than with Aβ pathology in aMCI-AD. The FAB could be an early marker for neurodegeneration related to frontal-lobe executive dysfunction.

Structural connectivity of the precuneus and its relation to resting-state networks

The precuneus is an association area in the posteromedial cortex (PMC) that is involved in high-order cognitive functions through integrating multi-modal information. Previous studies have shown that the precuneus is functionally heterogeneous and subdivided into several subfields organized by the anterior-posterior and ventral-dorsal axes. Further, the precuneus forms the structural core of brain connectivity as a rich-club hub and overlaps with the default mode network (DMN) as the functional core. This review summarizes recent research on the connectivity and cognitive functions of the precuneus. We then present our recent tractography-based studies of the precuneus and contextual these results here with respect to possible cognitive functions and resting-state networks.

Differences of regional homogeneity and cognitive function between psychotic depression and drug-naïve schizophrenia

BACKGROUND

Psychotic depression (PD) and schizophrenia (SCZ) share overlapping symptoms yet differ in etiology, progression, and treatment approaches. Differentiating these disorders through symptom-based diagnosis is challenging, emphasizing the need for a clearer understanding of their distinct cognitive and neural mechanisms.

AIM

This study aims to compare cognitive impairments and brain functional activities in PD and SCZ to pinpoint distinguishing characteristics of each disorder.

METHODS

We evaluated cognitive function in 42 PD and 30 SCZ patients using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and resting-state functional magnetic resonance imaging (rs-fMRI). Regional homogeneity (ReHo) values were derived from rs-fMRI data, and group differences in RBANS scores were analyzed. Additionally, Pearson correlation analysis was performed to assess the relationship between cognitive domains and brain functional metrics.

RESULTS

(1) The SCZ group showed significantly lower RBANS scores than the PD group across all cognitive domains, particularly in visuospatial/constructional ability and delayed memory (p < 0.05); (2) The SCZ group exhibited a significantly higher ReHo value in the left precuneus compared to the PD group (p < 0.05); (3) A negative correlation was observed between visuospatial construction, delayed memory scores, and the ReHo value of the left precuneus.

CONCLUSION

Cognitive impairment is more pronounced in SCZ than in PD, with marked deficits in visuospatial and memory domains. Enhanced left precuneus activity further differentiates SCZ from PD and correlates with cognitive impairments in both disorders, providing neuroimaging-based evidence to aid differential diagnosis and insights into cognitive dysfunction mechanisms, while also paving a clearer path for psychiatric research.

Local brain abnormalities in emotional disorders: Evidence from resting state fMRI studies

Emotional disorders inflict an enormous burden on society. Research on brain abnormalities implicated in emotional disorders has witnessed great progress over the past decades. Using cross-sectional and longitudinal designs, resting state functional magnetic resonance imaging (rs-fMRI) and its analytic approaches have been applied to characterize the local properties of patients with emotional disorders. Additionally, brain activity alterations of emotional disorders have shown frequency-specific. Despite the gains in understanding the roles of brain abnormalities in emotional disorders, the limitation of the small sample size needs to be highlighted. Lastly, we proposed that evidence from the positive psychology research stream presents it as a viable discipline, whose suggestions could be developed in future emotional disorders research. Such interdisciplinary research may produce novel treatments and intervention options. This article is categorized under: Psychology > Brain Function and Dysfunction.

Structural and functional connectivity in relation to executive functions in antipsychotic-naïve patients with first episode schizophrenia and levels of glutamatergic metabolites

Patients with schizophrenia exhibit structural and functional dysconnectivity but the relationship to the well-documented cognitive impairments is less clear. This study investigates associations between structural and functional connectivity and executive functions in antipsychotic-naïve patients experiencing schizophrenia. Sixty-four patients with schizophrenia and 95 matched controls underwent cognitive testing, diffusion weighted imaging and resting state functional magnetic resonance imaging. In the primary analyses, groupwise interactions between structural connectivity as measured by fixel-based analyses and executive functions were investigated using multivariate linear regression analyses. For significant structural connections, secondary analyses examined whether functional connectivity and associations with executive functions also differed for the two groups. In group comparisons, patients exhibited cognitive impairments across all executive functions compared to controls (p < 0.001), but no group difference were observed in the fixel-based measures. Primary analyses revealed a groupwise interaction between planning abilities and fixel-based measures in the left anterior thalamic radiation (p = 0.004), as well as interactions between cognitive flexibility and fixel-based measures in the isthmus of corpus callosum and cingulum (p = 0.049). Secondary analyses revealed increased functional connectivity between grey matter regions connected by the left anterior thalamic radiation (left thalamus with pars opercularis p = 0.018, and pars orbitalis p = 0.003) in patients compared to controls. Moreover, a groupwise interaction was observed between cognitive flexibility and functional connectivity between contralateral regions connected by the isthmus (precuneus p = 0.028, postcentral p = 0.012), all p-values corrected for multiple comparisons. We conclude that structural and functional connectivity appear to associate with executive functions differently in antipsychotic-naïve patients with schizophrenia compared to controls.

Multivariate mapping of low-resilient neurocognitive systems within and around low-grade gliomas

Accumulating evidence suggests that the brain exhibits a remarkable capacity for functional compensation in response to neurological damage, a resilience potential that is deeply rooted in the malleable features of its underlying anatomofunctional architecture. This propensity is particularly exemplified by diffuse low-grade glioma, a subtype of primary brain tumour. However, functional plasticity is not boundless, and surgical resections directed at structures with limited neuroplasticity can lead to incapacitating impairments. Yet, maximizing diffuse low-grade glioma resections offers substantial oncological benefits, especially when the resection extends beyond the tumour margins (i.e. supra-tumour or supratotal resection). In this context, the primary objective of this study was to identify which cerebral structures were associated with less favourable cognitive outcomes after surgery, while accounting for intra-tumour and supra-tumour features of the surgical resections. To achieve this objective, we leveraged a unique cohort of 400 patients with diffuse low-grade glioma who underwent surgery with awake cognitive mapping. Patients benefitted from a neuropsychological assessment consisting of 18 subtests administered before and 3 months after surgery. We analysed changes in performance and applied topography-focused and disconnection-focused multivariate lesion-symptom mapping using support vector regressions, in an attempt to capture resected cortico-subcortical structures less amenable to full cognitive compensation. The observed changes in performance were of a limited magnitude, suggesting an overall recovery (13 of 18 tasks recovered fully despite a mean resection extent of 92.4%). Nevertheless, lesion-symptom mapping analyses revealed that a lack of recovery in picture naming was linked to damage in the left inferior temporal gyrus and inferior longitudinal fasciculus. Likewise, for semantic fluency abilities, an association was established with damage to the left precuneus/posterior cingulate. For phonological fluency abilities, the left dorsomedial frontal cortex and the frontal aslant tract were implicated. Moreover, difficulties in spatial exploration were associated with injury to the right dorsomedial prefrontal cortex and its underlying connectivity. An exploratory analysis suggested that supra-tumour resections were associated with a less pronounced recovery following specific resection patterns, such as supra-tumour resections of the left uncinate fasciculus (picture naming), the left corticostriatal tract and the anterior corpus callosum (phonological fluency), the hippocampus and parahippocampus (episodic memory) and the right frontal-mesial areas (visuospatial exploration). Collectively, these patterns of results shed new light on both low-resilient neural systems and the prediction of cognitive recovery following glioma surgery. Furthermore, they indicate that supra-tumour resections were only occasionally less well tolerated from a cognitive viewpoint. In doing so, they have deep implications for surgical planning and rehabilitation strategies.

Aberrant auditory metabolite levels and topological properties are associated with cognitive decline in presbycusis patients

Presbycusis has been reported as related to cognitive decline, but its underlying neurophysiological mechanism is still unclear. This study aimed to investigate the relationship between metabolite levels, cognitive function, and node characteristics in presbycusis based on graph theory methods. Eighty-four elderly individuals with presbycusis and 63 age-matched normal hearing controls underwent magnetic resonance spectroscopy, functional magnetic resonance imaging scans, audiological assessment, and cognitive assessment. Compared with the normal hearing group, presbycusis patients exhibited reduced gamma-aminobutyric acid and glutamate levels in the auditory region, increased nodal characteristics in the temporal lobe and precuneus, as well as decreased nodal characteristics in the superior occipital gyrus and medial orbital. The right gamma-aminobutyric acid levels were negatively correlated with the degree centrality in the right precuneus and the executive function. Degree centrality in the right precuneus exhibited significant correlations with information processing speed and executive function, while degree centrality in the left medial orbital demonstrated a negative association with speech recognition ability. The degree centrality and node efficiency in the superior occipital gyrus exhibited a negative association with hearing loss and speech recognition ability, respectively. These observed changes indicate alterations in metabolite levels and reorganization patterns at the brain network level after auditory deprivation.

Cortical and subcortical functional connectivity and cognitive impairment in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease with cognitive as well as motor impairments. While much is known about the brain networks leading to motor impairments in PD, less is known about the brain networks contributing to cognitive impairments. Here, we leveraged resting-state functional magnetic resonance imaging (rs-fMRI) data from the Parkinson's Progression Marker Initiative (PPMI) to examine network dysfunction in PD patients with cognitive impairment. We focus on canonical cortical networks linked to cognition, including the salience network (SAL), frontoparietal network (FPN), and default mode network (DMN), as well as a subcortical basal ganglia network (BGN). We used the Montreal Cognitive Assessment (MoCA) as a continuous index of coarse cognitive function in PD. In 82 PD patients, we found that lower MoCA scores were linked with lower intra-network connectivity of the FPN. We also found that lower MoCA scores were linked with lower inter-network connectivity between the SAL and the BGN, the SAL and the DMN, as well as the FPN and the DMN. These data elucidate the relationship of cortical and subcortical functional connectivity with cognitive impairments in PD.

Uncovering the distinct macro-scale anatomy of dysexecutive and behavioural degenerative diseases

There is a longstanding ambiguity regarding the clinical diagnosis of dementia syndromes predominantly targeting executive functions versus behaviour and personality. This is due to an incomplete understanding of the macro-scale anatomy underlying these symptomatologies, a partial overlap in clinical features and the fact that both phenotypes can emerge from the same pathology and vice versa. We collected data from a patient cohort of which 52 had dysexecutive Alzheimer's disease, 30 had behavioural variant frontotemporal dementia (bvFTD), seven met clinical criteria for bvFTD but had Alzheimer's disease pathology (behavioural Alzheimer's disease) and 28 had amnestic Alzheimer's disease. We first assessed group-wise differences in clinical and cognitive features and patterns of fluorodeoxyglucose (FDG) PET hypometabolism. We then performed a spectral decomposition of covariance between FDG-PET images to yield latent patterns of relative hypometabolism unbiased by diagnostic classification, which are referred to as 'eigenbrains'. These eigenbrains were subsequently linked to clinical and cognitive data and meta-analytic topics from a large external database of neuroimaging studies reflecting a wide range of mental functions. Finally, we performed a data-driven exploratory linear discriminant analysis to perform eigenbrain-based multiclass diagnostic predictions. Dysexecutive Alzheimer's disease and bvFTD patients were the youngest at symptom onset, followed by behavioural Alzheimer's disease, then amnestic Alzheimer's disease. Dysexecutive Alzheimer's disease patients had worse cognitive performance on nearly all cognitive domains compared with other groups, except verbal fluency which was equally impaired in dysexecutive Alzheimer's disease and bvFTD. Hypometabolism was observed in heteromodal cortices in dysexecutive Alzheimer's disease, temporo-parietal areas in amnestic Alzheimer's disease and frontotemporal areas in bvFTD and behavioural Alzheimer's disease. The unbiased spectral decomposition analysis revealed that relative hypometabolism in heteromodal cortices was associated with worse dysexecutive symptomatology and a lower likelihood of presenting with behaviour/personality problems, whereas relative hypometabolism in frontotemporal areas was associated with a higher likelihood of presenting with behaviour/personality problems but did not correlate with most cognitive measures. The linear discriminant analysis yielded an accuracy of 82.1% in predicting diagnostic category and did not misclassify any dysexecutive Alzheimer's disease patient for behavioural Alzheimer's disease and vice versa. Our results strongly suggest a double dissociation in that distinct macro-scale underpinnings underlie predominant dysexecutive versus personality/behavioural symptomatology in dementia syndromes. This has important implications for the implementation of criteria to diagnose and distinguish these diseases and supports the use of data-driven techniques to inform the classification of neurodegenerative diseases.

Social Isolation, Brain Food Cue Processing, Eating Behaviors, and Mental Health Symptoms

Importance

Perceived social isolation is associated with negative health outcomes, including increased risk for altered eating behaviors, obesity, and psychological symptoms. However, the underlying neural mechanisms of these pathways are unknown.

Objective

To investigate the association of perceived social isolation with brain reactivity to food cues, altered eating behaviors, obesity, and mental health symptoms.

Design, Setting, and Participants

This cross-sectional, single-center study recruited healthy, premenopausal female participants from the Los Angeles, California, community from September 7, 2021, through February 27, 2023.

Exposure

Participants underwent functional magnetic resonance imaging while performing a food cue viewing task.

Main Outcomes and Measures

The main outcomes included brain reactivity to food cues, body composition, self-reported eating behaviors (food cravings, reward-based eating, food addiction, and maladaptive eating behaviors), and mental health symptoms (anxiety, depression, positive and negative affect, and psychological resilience).

Results

The study included 93 participants (mean [SD] age, 25.38 [7.07] years). Participants with higher perceived social isolation reported higher fat mass percentage, lower diet quality, increased maladaptive eating behaviors (cravings, reward-based eating, uncontrolled eating, and food addiction), and poor mental health (anxiety, depression, and psychological resilience). In whole-brain comparisons, the higher social isolation group showed altered brain reactivity to food cues in regions of the default mode, executive control, and visual attention networks. Isolation-related neural changes in response to sweet foods correlated with various altered eating behaviors and psychological symptoms. These altered brain responses mediated the connection between social isolation and maladaptive eating behaviors (β for indirect effect, 0.111; 95% CI, 0.013-0.210; P = .03), increased body fat composition (β, -0.141; 95% CI, -0.260 to -0.021; P = .02), and diminished positive affect (β, -0.089; 95% CI, -0.188 to 0.011; P = .09).

Conclusions and Relevance

These findings suggest that social isolation is associated with altered neural reactivity to food cues within specific brain regions responsible for processing internal appetite-related states and compromised executive control and attentional bias and motivation toward external food cues. These neural responses toward specific foods were associated with an increased risk for higher body fat composition, worsened maladaptive eating behaviors, and compromised mental health. These findings underscore the need for holistic mind-body-directed interventions that may mitigate the adverse health consequences of social isolation.

Regional differences in the link between water exchange rate across the blood-brain barrier and cognitive performance in normal aging

The blood-brain barrier (BBB) undergoes functional changes with aging which may contribute to cognitive decline. A novel, diffusion prepared arterial spin labeling-based MRI technique can measure the rate of water exchange across the BBB (kw) and may thus be sensitive to age-related alterations in water exchange at the BBB. However, studies investigating relationships between kw and cognition have reported different directions of association. Here, we begin to investigate the direction of associations between kw and cognition in different brain regions, and their possible underpinnings, by evaluating links between kw, cognitive performance, and MRI markers of cerebrovascular dysfunction and/or damage. Forty-seven healthy older adults (age range 61-84) underwent neuroimaging to obtain whole-brain measures of kw, cerebrovascular reactivity (CVR), and white matter hyperintensity (WMH) volumes. Additionally, participants completed uniform data set (Version 3) neuropsychological tests of executive function (EF) and episodic memory (MEM). Voxel-wise linear regressions were conducted to test associations between kw and cognitive performance, CVR, and WMH volumes. We found that kw in the frontoparietal brain regions was positively associated with cognitive performance but not with CVR or WMH volumes. Conversely, kw in the basal ganglia was negatively associated with cognitive performance and CVR and positively associated with regional, periventricular WMH volume. These regionally dependent associations may relate to different physiological underpinnings in the relationships between kw and cognition in neocortical versus subcortical brain regions in older adults.

The functional connectivity between right parahippocampal gyrus and precuneus underlying the association between reward sensitivity and procrastination

Procrastination has adverse effects on personal growth and social development. Behavior research has found reward sensitivity is positively correlated with procrastination. However, it remains unclear that the neural substrates underlie the relationship between reward sensitivity and procrastination. To address this issue, the present study used voxel-based morphometry (VBM) and resting-state functional connectivity (RSFC) analyses to investigate the neural substrates underlying the association with reward sensitivity and procrastination in two independent samples (N1 = 388, N2 = 330). In Sample 1, the behavioral result indicated reward sensitivity was positively correlated with procrastination. Moreover, the VBM analysis showed that reward sensitivity was positively associated with the gray matter volume (GMV) of the right parahippocampal gyrus. Furthermore, the RSFC result found reward sensitivity was negatively associated with the functional connectivity of the right parahippocampal gyrus-precuneus. Crucially, the mediation analysis revealed that functional connectivity of the right parahippocampal gyrus-precuneus mediated the relationship between reward sensitivity and procrastination. To verify the robustness of the results, confirmatory analysis was carried out in Sample 2. The results of Sample 1 (i.e., the behavioral, VBM, RSFC, and mediation results) can be verified in Sample 2. In brief, these findings suggested that the functional connectivity of the right parahippocampal gyrus-precuneus involved in reward impulsive control could modulate the relationship between reward sensitivity and procrastination, which is the first to reveal the neural underpinning of the association between reward sensitivity and procrastination.

White matter tracts and executive functions: a review of causal and correlation evidence

Executive functions are high-level cognitive processes involving abilities such as working memory/updating, set-shifting and inhibition. These complex cognitive functions are enabled by interactions among widely distributed cognitive networks, supported by white matter tracts. Executive impairment is frequent in neurological conditions affecting white matter; however, whether specific tracts are crucial for normal executive functions is unclear. We review causal and correlation evidence from studies that used direct electrical stimulation during awake surgery for gliomas, voxel-based and tract-based lesion-symptom mapping, and diffusion tensor imaging to explore associations between the integrity of white matter tracts and executive functions in healthy and impaired adults. The corpus callosum was consistently associated with all executive processes, notably its anterior segments. Both causal and correlation evidence showed prominent support of the superior longitudinal fasciculus to executive functions, notably to working memory. More specifically, strong evidence suggested that the second branch of the superior longitudinal fasciculus is crucial for all executive functions, especially for flexibility. Global results showed left lateralization for verbal tasks and right lateralization for executive tasks with visual demands. The frontal aslant tract potentially supports executive functions, however, additional evidence is needed to clarify whether its involvement in executive tasks goes beyond the control of language. Converging evidence indicates that a right-lateralized network of tracts connecting cortical and subcortical grey matter regions supports the performance of tasks assessing response inhibition, some suggesting a role for the right anterior thalamic radiation. Finally, correlation evidence suggests a role for the cingulum bundle in executive functions, especially in tasks assessing inhibition. We discuss these findings in light of current knowledge about the functional role of these tracts, descriptions of the brain networks supporting executive functions and clinical implications for individuals with brain tumours.

Associations Between Sleep Spindle Metrics, Age, Education and Executive Function in Young Adult and Middle-Aged Patients with Obstructive Sleep Apnea

Purpose

This study aimed to investigate the association between sleep spindle metrics and executive function in individuals with obstructive sleep apnea (OSA). Furthermore, we examined the association of age and education on executive function.

Patients and Methods

A total of 230 (40.90 ± 8.83 years, F/M = 45/185) participants were enrolled. Overnight electroencephalogram (C3-M2) recording detected sleep spindles by a novel U-Net-type neural network that integrates temporal information with time-frequency images. Sleep spindle metrics, including frequency (Hz), overall density (events/min), fast density (events/min), slow density (events/min), duration (sec) and amplitude (µV), were measured. Executive function was assessed using standardized neuropsychological tests. Associations between sleep spindle metrics, executive function, and demographic factors were analyzed using multivariate linear regression.

Results

In fully adjusted linear regression models, higher overall sleep spindle density (TMT-A, B=-1.279, p=0.009; TMT-B, B=-1.813, p=0.008), fast sleep spindle density (TMT-A, B=-1.542, p=0.048; TMT-B, B=-2.187, p=0.036) and slow sleep spindle density (TMT-A, B=-1.731, p=0.037; TMT-B, B=-2.449, p=0.034) were associated with better executive function. And the sleep spindle duration both during N2 sleep time (TMT-A, B=-13.932, p=0.027; TMT-B, B=-19.001, p=0.034) and N3 sleep time (TMT-B, B=-29.916, p=0.009; Stroop-incongruous, B=-21.303, p=0.035) was independently associated with better executive function in this population. Additionally, age and education were found to be highly associated with executive function.

Conclusion

Specific sleep spindle metrics, higher overall density, fast density and slow density during N2 sleep time, and longer duration during N2 and N3 sleep time, are independent and sensitive indicators of better executive function in young adult and middle-aged patients with OSA. Further research is needed to explore the underlying mechanisms and clinical implications of these findings.

Macroscale neurovascular coupling and functional integration in end-stage renal disease patients with cognitive impairment: A multimodal MRI study

End-stage renal disease (ESRD) is associated with vascular and neuronal dysfunction, causing neurovascular coupling (NVC) dysfunction, but how NVC dysfunction acts on the mechanism of cognitive impairment in ESRD patients from local to remote is still poorly understood. We recruited 48 ESRD patients and 35 demographically matched healthy controls to scan resting-state functional MRI and arterial spin labeling, then investigated the four types of NVC between amplitude of low-frequency fluctuation (ALFF), fractional ALFF, regional homogeneity, degree centrality, and cerebral blood perfusion (CBF), and associated functional networks. Our results indicated that ESRD patients showed NVC dysfunction in global gray matter and multiple brain regions due to the mismatch between CBF and neural activity, and associated disrupted functional connectivity (FC) within sensorimotor network (SMN), visual network (VN), default mode network (DMN), salience network (SN), and disrupted FC between them with limbic network (LN), while increased FC between SMN and DMN. Anemia may affect the NVC of middle occipital gyrus and precuneus, and increased pulse pressure may result in disrupted FC with SMN. The NVC dysfunction of the right precuneus, middle frontal gyrus, and parahippocampal gyrus and the FC between the right angular gyrus and the right anterior cingulate gyrus may reflect cognitive impairment in ESRD patients. Our study confirmed that ESRD patients may exist NVC dysfunction and disrupted functional integration in SMN, VN, DMN, SN and LN, serving as one of the mechanisms of cognitive impairment. Anemia and increased pulse pressure may be related risk factors.

A novel cognitive neurosurgery approach for supramaximal resection of non-dominant precuneal gliomas: a case report

Despite mounting evidence pointing to the contrary, classical neurosurgery presumes many cerebral regions are non-eloquent, and therefore, their excision is possible and safe. This is the case of the precuneus and posterior cingulate, two interacting hubs engaged during various cognitive functions, including reflective self-awareness; visuospatial and sensorimotor processing; and processing social cues. This inseparable duo ensures the cortico-subcortical connectivity that underlies these processes. An adult presenting a right precuneal low-grade glioma invading the posterior cingulum underwent awake craniotomy with direct electrical stimulation (DES). A supramaximal resection was achieved after locating the superior longitudinal fasciculus II. During surgery, we found sites of positive stimulation for line bisection and mentalizing tests that enabled the identification of surgical corridors and boundaries for lesion resection. When post-processing the intraoperative recordings, we further identified areas that positively responded to DES during the trail-making and mentalizing tests. In addition, a clear worsening of the patient's self-assessment ability was observed throughout the surgery. An awake cognitive neurosurgery approach allowed supramaximal resection by reaching the cortico-subcortical functional limits. The mapping of complex functions such as social cognition and self-awareness is key to preserving patients' postoperative cognitive health by maximizing the ability to resect the lesion and surrounding areas.

Causal evidence for the processing of bodily self in the anterior precuneus

To probe the causal importance of the human posteromedial cortex (PMC) in processing the sense of self, we studied a rare cohort of nine patients with electrodes implanted bilaterally in the precuneus, posterior cingulate, and retrosplenial regions with a combination of neuroimaging, intracranial recordings, and direct cortical stimulations. In all participants, the stimulation of specific sites within the anterior precuneus (aPCu) caused dissociative changes in physical and spatial domains. Using single-pulse electrical stimulations and neuroimaging, we present effective and resting-state connectivity of aPCu hot zone with the rest of the brain and show that they are located outside the boundaries of the default mode network (DMN) but connected reciprocally with it. We propose that the function of this subregion of the PMC is integral to a range of cognitive processes that require the self's physical point of reference, given its location within a spatial environment.