Altered insula-prefrontal functional connectivity correlates to decreased vigilant attention after total sleep deprivation

Altered hypothalamic functional connectivity after partial sleep deprivation in young and elderly adults

BACKGROUND

The hypothalamus plays a critical role in sleep-wake regulation and attention control. However, few studies explored the alterations of hypothalamic functional connectivity after sleep deprivation. The purpose of the study is to investigate the influence of partial sleep deprivation on hypothalamic functional connectivity in young and elderly adults and to determine whether age modulates the interactions between partial sleep deprivation and hypothalamic functional connectivity.

METHODS

Data for this study were collected as part of the Stockholm Sleepy Brain Project. Forty-one young adults (aged 20-30) and thirty-six elderly adults (aged 65-75) were finally recruited in the study. Participants underwent resting-state functional magnetic resonance imaging (rs-fMRI) scans following full sleep and partial sleep deprivation (3 h of sleep) in a crossover design. Seed-based functional connectivity analyses were performed for the bilateral hypothalamus using rs-fMRI data.

RESULTS

For young adults, partial sleep deprivation caused enhanced hypothalamic functional connectivity with the inferior frontal gyrus and precuneus. For elderly adults, reduced functional connectivity was observed between the hypothalamus and frontal, parietal, temporal, occipital regions, and cingulate gyrus following partial sleep deprivation. Further, a significant interactive effect between age and partial sleep deprivation on the hypothalamic functional connectivity was observed. Age-related abnormalities of hypothalamic functional connectivity were observed in frontoparietal regions, pallidum, rectus, and superior occipital gyrus.

CONCLUSION

Partial sleep deprivation led to increased hypothalamic functional connectivity in young adults, while decreased hypothalamic functional connectivity in elderly adults. Our results indicate that age modulates the influence of sleep deprivation on intrinsic brain functional connectivity.

Altering Temporal Dynamics of Sleepiness and Mood During Sleep Deprivation: Evidence from Resting-State EEG Microstates

Objective: Sleep deprivation negatively affects mood and sleepiness across subjective, objective, behavioral, and neuroimaging measures. However, the relationship between abnormal brain dynamics after sleep deprivation and mood or sleepiness impairments, from a temporal perspective, remains underexplored. Electroencephalogram microstate analysis offers a valuable approach for investigating the large-scale dynamics of brain networks. Methods: We implemented a strict sleep deprivation protocol with 71 participants, collecting resting-state electroencephalogram data, subjective sleepiness, objective alertness, and mood assessments after normal sleep and sleep deprivation (SD) conditions. Microstate time parameters were compared between sleep control (SC) and SD conditions. Additionally, we investigated how changes in these parameters correlated with subjective or objective measures of sleepiness and mood changes between SC and SD. Results: SD significantly decreased the mean duration and occurrence of microstate B while increasing those of microstate C. A decrease in microstate B occurrence significantly correlated with a higher Karolinska Sleepiness Scale score, whereas a reduction in microstate B duration indicated an increased response time on the Psychomotor Vigilance Performance. No significant associations were observed between microstate parameters and positive mood decline between SC and SD. Pearson correlation analysis was performed on the positive mood scores in both conditions. The findings demonstrated a significant positive relationship between positive mood scores and the mean duration of microstate B under SD conditions. Conclusions: Using a large SD dataset, this study demonstrated that subjective or objective sleepiness and positive mood were associated with decreased microstate B. These findings suggest that SD disrupts neural dynamics within the visual network.

Studying cognition impairment in patients with minimal hepatic encephalopathy through functional connectivity analysis: evidence from resting-state functional MRI

AIM

This study aimed to investigate functional connectivity (FC) alterations between the insula and other brain regions in minimal hepatic encephalopathy (MHE) patients and their association with cognitive deficits.

MATERIALS AND METHODS

The study included 23 MHE patients and 25 healthy control (HC) individuals. All participants underwent resting-state functional magnetic resonanceimaging (fMRI), neuropsychological testing, and cognitive scale assessments. FC analysis was performed to investigate the connectivity between the insula and the whole brain in the context of MHE. Pearson correlation analysis was conducted to assess the association between changes in FC and cognitive scale scores.

RESULTS

The HC and MHE groups showed significant differences in cognitive performance measures, such as the Number Connection Test-A (NCT-A), Digit symbol Test (DST), and Montreal Cognitive Assessment (MoCA) score (P < 0.01). The MHE group demonstrated elevated FC between the right insula and the right superior frontal gyrus, right middle frontal gyrus, and right precentral gyrus compared with the HC group. Furthermore, the left insula showed increased FC with the left middle frontal gyrus and the right middle frontal gyrus (P < 0.05, corrected). Notably, these changes in FC among MHE patients were significantly correlated with the MoCA score (P < 0.05, corrected).

CONCLUSION

This study emphasises the FC alterations between the insula and the prefrontal cortex in MHE patients, which have a close association with cognitive functions. FC could potentially serve as a biomarker for diagnosing and assessing the severity of cognitive impairments in MHE.

Effects of one night of sleep deprivation on whole brain intrinsic connectivity distribution using a graph theory neuroimaging approach

Neuroimaging studies have revealed disturbances in brain functional connectivity (FC) after one night of sleep deprivation (SD). These researches explored the alterations of FC using classical regions of interest (ROI)-based analysis or functional connectivity density. However, these methods need for a priori information about the selected ROIs and a specific correlation threshold to define a connection between two ROIs or voxels, which may bring inconsistent results. In the present study, we adopted a data-driven, whole brain voxel-based graph-theoretical approach, intrinsic connectivity distribution (ICD) analysis, to examine changes of brain connectivity after SD in 52 normal young subjects without any prior knowledge. The cross-hemisphere ICD (ch-ICD) analysis was also performed to discover the effect of SD on cerebral lateralization. We found that sleep-deprived subjects showed significant reduced ICD in default mode network (DMN) and limbic network, and increased ICD in sensorimotor network. Furthermore, after SD, the ICD in the right precuneus showed significant correlation with psychomotor vigilance test (PVT) performance following the stepwise regression analysis after Bonferroni correction (ICD = 0.43 - 0.62∗10 % fast reaction time + 0.31∗the standard deviation of reaction time, p = 0.0012). Follow-up seed-based FC analyses in the right precuneus revealed decreased FC to regions in DMN, visual network, ventral attentional network and frontal-parietal network. Nevertheless, no striking difference of ch-ICD was found following SD. In conclusion, these findings suggested that DMN, especially precuneus may be hubs of FC disturbances associated with vigilance after SD, and may provide new insights into the intervention for SD.

Effects of total sleep deprivation on functional connectivity of the anterior cingulate cortex: Insights from resting-state fMRI in healthy adult males

Inadequate sleep significantly impacts an individual's health by compromising inhibitory control and self-regulation abilities. This study employed resting-state functional magnetic resonance imaging (fMRI) to assess the functional connectivity between the anterior cingulate cortex (ACC) and the whole brain in 16 healthy adult males after 36 h of total sleep deprivation. Additionally, this study investigated alterations in individuals' inhibitory control functions and physiological mechanisms following sleep deprivation. The results showed a significant increase in functional connectivity between the ACC, the left angular gyrus, and the right hippocampus following 36 h of continuous sleep deprivation. Conversely, functional connectivity was notably decreased between the ACC and the right insular cortex, right paracingulate gyrus, and bilateral putamen. Furthermore, changes in ACC functional connectivity were significantly correlated with alterations in behavioral performance in the go/no-go task after sleep deprivation. This study contributes to understanding brain network mechanisms in the anterior cingulate gyrus after sleep deprivation. It clarifies the relationship between functional connectivity changes in the anterior cingulate gyrus and inhibitory control post-sleep deprivation.

Sleep deprivation alters utilization of negative feedback in risky decision-making

Background

Sleep loss has sometimes catastrophic effects on risky decision-making. However, it is unknown to what extent such deficits are exacerbated with increasing duration of sleep deprivation (SD) and whether sustained vigilant attention mediates this sleep deprivation-induced deficit.

Methods

The present study aimed to investigate the effect of 36 hours of SD on 37 male college students' arousal, emotion, vigilant attention, and risky decision-making, using the Psychomotor Vigilance Test, the Game of Dice Task, and scales assessing fatigue, sleep, and emotions.

Results

Compared to baseline, SD significantly increased sleepiness, fatigue, and negative emotions, decreased positive emotions and vigilant attention, and led to a shift toward risky decision-making, and these effects often appeared 15 or 20 hours after SD. Interestingly, participants' ability to employ positive feedback was maintained, whereas their performance to utilize negative feedback was impaired even after 8 hours of sleep deprivation. Meanwhile, vigilant attention acted as a mediator between SD and risky decision-making (z = -1.97, 95% [-6.00, -0.30]).

Discussion

These results suggest that sleep-deprived individuals are unable to use negative feedback to optimize their judgments, which may account for their poor decision-making under risk.

The shared neurobiological basis of developmental dyslexia and developmental stuttering: A meta-analysis of functional and structural MRI studies

Background

Developmental dyslexia (DD) and persistent developmental stuttering (PDS) are the most representative written and spoken language disorders, respectively, and both significantly hinder life success. Although widespread brain alterations are evident in both DD and PDS, it remains unclear to what extent these two language disorders share common neural substrates.

Methods

A systematic review and meta-analysis of task-based functional magnetic resonance imaging (fMRI) and voxel-based morphometry (VBM) studies of PDS and DD were conducted to explore the shared functional and anatomical alterations across these disorders.

Results

The results of fMRI studies indicated shared hypoactivation in the left inferior temporal gyrus and inferior parietal gyrus across PDS and DD compared to healthy controls. When examined separately for children and adults, we found that child participants exhibited reduced activation in the left inferior temporal gyrus, inferior parietal gyrus, precentral gyrus, middle temporal gyrus, and inferior frontal gyrus, possibly reflecting the universal causes of written and spoken language disorders. In contrast, adult participants exhibited hyperactivation in the right precentral gyrus and left cingulate motor cortex, possibly reflecting common compensatory mechanisms. Anatomically, the analysis of VBM studies revealed decreased gray matter volume in the left inferior frontal gyrus across DD and PDS, which was exclusively observed in children. Finally, meta-analytic connectivity modeling and brain-behavior correlation analyses were conducted to explore functional connectivity patterns and related cognitive functions of the brain regions commonly involved in DD and PDS.

Conclusions

This study identified concordances in brain abnormalities across DD and PDS, suggesting common neural substrates for written and spoken language disorders and providing new insights into the transdiagnostic neural signatures of language disorders.

Perceived stress and brain connectivity in subthreshold depression: Insights from eyes-closed and eyes-open states

Perceived stress is an acknowledged risk factor for subthreshold depression (StD), and fluctuations in perceived stress are thought to disrupt the harmony of brain networks essential for emotional and cognitive functioning. This study aimed to elucidate the relationship between eye-open (EO) and eye-closed (EC) states, perceived stress, and StD. We recruited 27 individuals with StD and 33 healthy controls, collecting resting state fMRI data under both EC and EO conditions. We combined intrinsic connectivity and seed-based functional connectivity analyses to construct the functional network and explore differences between EC and EO conditions. Graph theory analysis revealed weakened connectivity strength in the right superior frontal gyrus (SFG) and right median cingulate and paracingulate gyrus (MCC) among participants with StD, suggesting an important role for these regions in the stress-related emotions dysregulation. Notably, altered SFG connectivity was observed to significantly relate to perceived stress levels in StD, and the SFG connection emerges as a neural mediator potentially influencing the relationship between perceived stress and StD. These findings highlight the role of SFG and MCC in perceived stress and suggest that understanding EC and EO states in relation to these regions is important in the neurobiological framework of StD. This may offer valuable perspectives for early prevention and intervention strategies in mental health disorders.

The volume of gray matter mediates the relationship between glucolipid metabolism and neurocognition in first-episode, drug-naïve patients with schizophrenia

We aimed to examine the hypotheses that glucolipid metabolism is linked to neurocognition and gray matter volume (GMV) and that GMV mediates the association of glucolipid metabolism with neurocognition in first-episode, drug-naïve (FEDN) patients with schizophrenia. Parameters of glucolipid metabolism, neurocognition, and magnetic resonance imaging were assessed in 63 patients and 31 controls. Compared to controls, patients exhibited higher levels of fasting glucose, triglyceride, and insulin resistance index, lower levels of cholesterol and high-density lipoprotein cholesterol, poorer neurocognitive functions, and decreased GMV in the bilateral insula, left middle occipital gyrus, and left postcentral gyrus. In the patient group, triglyceride levels and the insulin resistance index exhibited a negative correlation with Rapid Visual Information Processing (RVP) mean latency, a measure of attention within the Cambridge Neurocognitive Test Automated Battery (CANTAB), while showing a positive association with GMV in the right insula. The mediation model revealed that triglyceride and insulin resistance index had a significant positive indirect (mediated) influence on RVP mean latency through GMV in the right insula. Glucolipid metabolism was linked to both neurocognitive functions and GMV in FEDN patients with schizophrenia, with the effect pattern differing from that observed in chronic schizophrenia or schizophrenia comorbid with metabolic syndrome. Moreover, glucolipid metabolism might indirectly contribute to neurocognitive deficits through the mediating role of GMV in these patients.

The Impact of Age-Related Hearing Loss on Working Memory among Older Individuals: An Event-Related Potential Study

Introduction

Age-related hearing loss (ARHL) may affect working memory (WM), which impacts problem-solving, decision-making, language comprehension, and learning. Limited research exists on how ARHL affects WM using N-back tasks, but studying this is crucial for understanding neural markers and associated cognitive processes. Our study explores the impact of ARHL on WM using behavioral and electrophysiological measures and how it correlates with speech-in-noise scores in older individuals with ARHL.

Method

The study involved two groups, each with 20 participants aged 60-80. Group 1 had individuals with mild to moderate sensorineural hearing loss, while Group 2 had age- and education-matched controls with normal or near-normal hearing. Participants underwent audiological assessments and completed cognitive tests, including simple reaction time and N-back tests. During the performance of cognitive tasks, a simultaneous electroencephalography was recorded. Data analysis included behavioral and event-related potentials, source estimation, and functional connectivity analysis.

Results

The study revealed significantly poor accuracy, longer reaction time, and smaller P300 amplitude among individuals with ARHL, even after controlling for general slowing. Individuals with ARHL experience compromised neural activity, particularly in the temporal and parietal regions, which are vital for cognition and WM. Furthermore, individuals with ARHL exhibited poor communication between the superior temporal gyrus and insulae regions among the brain regions mediating WM during the 1-back task. Also, the study found a strong correlation between hearing measures and WM outcomes.

Conclusion

The study findings suggest that individuals with ARHL have impaired WM compared to those with normal hearing. This indicates a potential link between ARHL and cognitive decline, which could significantly affect daily life and quality of life. The widely used WM test with simultaneous EEG recording and source estimation analysis would further validate the usefulness of the study in assessing WM in this population.

Effect of total sleep deprivation on effective EEG connectivity for young male in resting-state networks in different eye states

Background

Many studies have investigated the effect of total sleep deprivation (TSD) on resting-state functional networks, especially the default mode network (DMN) and sensorimotor network (SMN), using functional connectivity. While it is known that the activities of these networks differ based on eye state, it remains unclear how TSD affects them in different eye states. Therefore, we aimed to examine the effect of TSD on DMN and SMN in different eye states using effective functional connectivity via isolated effective coherence (iCoh) in exact low-resolution brain electromagnetic tomography (eLORETA).

Methods

Resting-state electroencephalogram (EEG) signals were collected from 24 male college students, and each participant completed a psychomotor vigilance task (PVT) while behavioral data were acquired. Each participant underwent 36-h TSD, and the data were acquired in two sleep-deprivation times (rested wakefulness, RW: 0 h; and TSD: 36 h) and two eye states (eyes closed, EC; and eyes open, EO). Changes in neural oscillations and effective connectivity were compared based on paired t-test.

Results

The behavioral results showed that PVT reaction time was significantly longer in TSD compared with that of RW. The EEG results showed that in the EO state, the activity of high-frequency bands in the DMN and SMN were enhanced compared to those of the EC state. Furthermore, when compared with the DMN and SMN of RW, in TSD, the activity of DMN was decreased, and SMN was increased. Moreover, the changed effective connectivity in the DMN and SMN after TSD was positively correlated with an increased PVT reaction time. In addition, the effective connectivity in the different network (EO-EC) of the SMN was reduced in the β band after TSD compared with that of RW.

Conclusion

These findings indicate that TSD impairs alertness and sensory information input in the SMN to a greater extent in an EO than in an EC state.

Total sleep deprivation impairs visual selective attention and triggers a compensatory effect: evidence from event-related potentials

Many studies have demonstrated the impairment of sustained attention due to total sleep deprivation (TSD). However, it remains unclear whether and how TSD affects the processing of visual selective attention. In the current study, 24 volunteers performed a visual search task before and after TSD over a period of 36 h while undergoing spontaneous electroencephalography. Paired-sample t-tests of behavioral performance revealed that, compared with baseline values, the participants showed lower accuracy and higher variance in response time in visual search tasks performed after TSD. Analysis of the event-related potentials (ERPs) showed that the mean amplitude of the N2-posterior-contralateral (N2pc) difference wave after TSD was less negative than that at baseline and the mean amplitude of P3 after TSD was more positive than that at baseline. Our findings suggest that TSD significantly attenuates attentional direction/orientation processing and triggers a compensatory effect in the parietal brain to partially offset the impairments. These findings provide new evidence and improve our understanding of the effects of sleep loss.

Relationships Among Short Self-Reported Sleep Duration, Cognitive Impairment, and Insular Functional Connectivity in Late-Life Depression

BACKGROUND

Both late-life depression (LLD) and short sleep duration increase the risk of cognitive impairment. Increased insular resting-state functional connectivity (FC) has been reported in individuals with short sleep duration and dementia.

OBJECTIVE

This study aimed to investigate whether short sleep duration is associated with impaired cognition and higher insular FC in patients with LLD.

METHODS

This case- control study recruited 186 patients with LLD and 83 normal controls (NC), and comprehensive psychometric assessments, sleep duration reports and resting-state functional MRI scans (81 LLD patients and 54 NC) were conducted.

RESULTS

Patients with LLD and short sleep duration (LLD-SS patients) exhibited more severe depressive symptoms and worse cognitive function than those with normal sleep duration (LLD-NS patients) and NC. LLD-SS patients exhibited higher FC between the bilateral insula and inferior frontal gyrus (IFG) pars triangularis than LLD-NS patients and NC, while LLD-NS patients exhibited lower FC than NC. Increased insular FC was correlated with short sleep duration, severe depressive symptoms, and slower information processing speeds. Furthermore, an additive effect was found between sleep duration and LLD on global cognition and insular FC.

CONCLUSION

LLD-SS patients exhibited impaired cognition and increased insular FC. Abnormal FC in LLD-SS patients may be a therapeutic target for neuromodulation to improve sleep and cognitive performance and thus decrease the risk of dementia.

Dissociable brainstem functional connectivity changes correlate with objective and subjective vigilance decline after total sleep deprivation in healthy male subjects

The maintenance of vigilance relies on the activation of the cerebral cortex by the arousal system centered on the brainstem. Previous studies have suggested that both objective and subjective vigilance are susceptible to sleep deprivation. This study aims to explore the alterations in brainstem arousal system functional connectivity (FC) and its involvement in these two types of vigilance decline following total sleep deprivation (TSD). Thirty-seven healthy male subjects underwent two counterbalanced resting-state fMRI scans, once in rested wakefulness (RW) and once after 36 h of TSD. The pontine tegmental area and caudal midbrain (PTA-cMidbrain), the core regions of the brainstem arousal system, were chosen as the seeds for FC analysis. The difference in PTA-cMidbrain FC between RW and TSD conditions was then investigated, as well as its associations with objective vigilance measured by psychomotor vigilance task (PVT) and subjective vigilance measured by Stanford Sleepiness Scale. The sleep-deprived subjects showed increased PTA-cMidbrain FC with the thalamus and cerebellum and decreased PTA-cMidbrain FC with the occipital, parietal, and sensorimotor regions. TSD-induced increases in PVT reaction time were negatively correlated with altered PTA-cMidbrain FC in the dorsolateral prefrontal cortex, extrastriate visual cortex, and precuneus. TSD-induced increases in subjective sleepiness were positively correlated with altered PTA-cMidbrain FC in default mode regions including the medial prefrontal cortex and precuneus. Our results suggest that different brainstem FC patterns underlie the objective and subjective vigilance declines induced by TSD.

Altered insular functional connectivity correlates to impaired vigilant attention after sleep deprivation: A resting-state functional magnetic resonance imaging study

Objectives

This study used resting-state functional magnetic resonance imaging (rs-fMRI) scans to assess the dominant effects of 36 h total sleep deprivation (TSD) on vigilant attention and changes in the resting-state network.

Materials and methods

Twenty-two healthy college students were enrolled in this study. Participants underwent two rs-fMRI scans, once in rested wakefulness (RW) and once after 36 h of TSD. We used psychomotor vigilance tasks (PVT) to measure vigilant attention. The region-of-interest to region-of-interest correlation was employed to analyze the relationship within the salience network (SN) and between other networks after 36 h of TSD. Furthermore, Pearson’s correlation analysis investigated the relationship between altered insular functional connectivity and PVT performance.

Results

After 36 h of TSD, participants showed significantly decreased vigilant attention. Additionally, TSD induced decreased functional connectivity between the visual and parietal regions, whereas, a significant increase was observed between the anterior cingulate cortex and insula. Moreover, changes in functional connectivity in the anterior cingulate cortex and insula showed a significant positive correlation with the response time to PVT.

Conclusion

Our results suggest that 36 h of TSD impaired vigilant visual attention, resulting in slower reaction times. The decrease in visual-parietal functional connectivity may be related to the decrease in the reception of information in the brain. Enhanced functional connectivity of the anterior cingulate cortex with the insula revealed that the brain network compensation occurs mainly in executive function.

Abnormal dynamic functional connectivity after sleep deprivation from temporal variability perspective

Sleep deprivation (SD) is very common in modern society and regarded as a potential causal mechanism of several clinical disorders. Previous neuroimaging studies have explored the neural mechanisms of SD using magnetic resonance imaging (MRI) from static (comparing two MRI sessions [one after SD and one after resting wakefulness]) and dynamic (using repeated MRI during one night of SD) perspectives. Recent SD researches have focused on the dynamic functional brain organization during the resting-state scan. Our present study adopted a novel metric (temporal variability), which has been successfully applied to many clinical diseases, to examine the dynamic functional connectivity after SD in 55 normal young subjects. We found that sleep-deprived subjects showed increased regional-level temporal variability in large-scale brain regions, and decreased regional-level temporal variability in several thalamus subregions. After SD, participants exhibited enhanced intra-network temporal variability in the default mode network (DMN) and increased inter-network temporal variability in numerous subnetwork pairs. Furthermore, we found that the inter-network temporal variability between visual network and DMN was negative related with the slowest 10% respond speed (β = -.42, p = 5.57 × 10^-4 ) of the psychomotor vigilance test after SD following the stepwise regression analysis. In conclusion, our findings suggested that sleep-deprived subjects showed abnormal dynamic brain functional configuration, which provides new insights into the neural underpinnings of SD and contributes to our understanding of the pathophysiology of clinical disorders.

Temporal fluctuations in vigilance and neural networks after sleep deprivation

Vigilance instability in the sleep-deprived state was deemed to result from the imbalance in thalamic-FPN-DMN circuits (FPN: frontoparietal network; DMN: default mode network), but the behavioural correlation of this neural hypothesis is still unclear. To address this issue, we applied dynamic functional connectivity (DFC) analysis on the task-based fMRI data and detected high arousal state (HAS) and low arousal state (LAS). Relative to HAS, LAS demonstrated higher positive connectivity within task-positive networks (TPN), attenuated TPN-DMN anti-correlation, and greater anti-correlation between cerebral and subcortico-cerebellar networks. Critically, DFC differences between HAS and LAS were correlated with the ongoing vigilance performance in the sleep-deprived state. The current findings confirmed a direct link between vigilance instability and DFC in the thalamic-FPN-DMN circuits. In particular, we postulated that the integration within task-related system and segregation between task-related system and the subcortico-cerebellar system might be the critical neural markers underlying vigilance instability in the sleep-deprived state.