Neural correlates of working memory performance in primary insomnia

Reduced prefrontal activation during cognitive control under emotional interference in chronic insomnia disorder

This study investigated the altered neural activation underlying cognitive control under emotional and sleep-related interference conditions and its role in subjective sleep disturbance in patients with chronic insomnia disorder. In total, 48 patients with chronic insomnia disorder, and 48 age-, sex- and body mass index-matched controls were included in this study. They completed self-reported questionnaires to assess subjective sleep and emotional distress. A sleep diary was used to evaluate subjective sleep parameters. All participants performed the emotional Stroop task (three blocks each of negative emotional, sleep-related, and neutral words) during functional magnetic resonance imaging assessments. We compared brain activation during the emotional Stroop task between the two groups. We also analysed the correlations between altered neural activation and sleep variables. Less neural activation was detected in the right anterior prefrontal cortex of patients with chronic insomnia disorder than in controls when performing the emotional Stroop task with negative emotional words. The decrease in neural activation was negatively correlated with scores on Pittsburgh Sleep Quality Index, Insomnia Severity Index, and Dysfunctional Beliefs and Attitudes about Sleep Scale. In contrast, they were positively correlated with subjective total sleep time and sleep efficiency as reported in sleep diaries. A decrease in right anterior prefrontal cortex activity under the negative emotional words condition of the emotional Stroop task in patients with chronic insomnia disorder suggests a failure of top-down inhibition of negative emotional stimuli. This failure induces disinhibition of cognitive hyperarousal, manifested as rumination or intrusive worries, and potentially causing subjective sleep disturbances.

Sleep-aiding music therapy for insomnia: Exploring EEG functional connectivity of sleep-related attentional bias

STUDY OBJECTIVES

This study aimed to investigate the relationship between sleep-aiding music and sleep-related attentional bias based on electroencephalography (EEG) functional connectivity (FC) in patients with insomnia disorder (ID), to evaluate the effectiveness of music in aiding sleep.

METHOD

This study included 30 participants, comprising 15 patients with ID and 15 healthy controls (HCs). Six types of music were selected for sleep aid, and a dot-probe task based on sleep-related attentional bias was utilized to collect behavioral and EEG data. Vigilance bias and disengagement bias were measured using reaction time and EEG FC. Differences in sleep-related attentional bias before and after the intervention of music were explored to evaluate the sleep-aiding effects and identify EEG biomarkers.

RESULTS

Compared with HCs, patients with ID showed decreased sleep-related attentional bias of EEG FC between occipital-central and temporal-frontal lobes. Among the six types of music, International Standard Sleep Aid and Lullaby had a greater impact on decreasing vigilance bias in the ID group. Additionally, the International Standard Sleep Aid and Nature Sound were more effective in decreasing disengagement bias in the ID group. This study also examined the resting-state EEG FC of patients with ID before and after the intervention of music. The results showed that the FC in the temporal, frontal, and occipital lobes significantly differed before and after the intervention of music, especially with the use of International Standard Sleep Aid, Lullaby, and Alpha Sound Wave. However, it is worth noting that these three types of music showed no similarities in EEG FC, in contrast to the result of sleep-related attentional bias of EEG FC.

CONCLUSION

This study found that the sleep-related attentional bias of EEG FC has more distinct characteristics when compared to resting-state EEG FC. The results suggest that the sleep-related attentional bias of EEG FC could be a potential biomarker for assessing the sleep-aiding effect of music interventions. International Standard Sleep Aid was the most effective for patients with ID among six types of sleep-aiding music. These findings could facilitate the development of personalized therapies for patients with ID.

CLINICAL TRIALS REGISTRATION

Chinese Clinical Trial Register, http://www.chictr.org.cn, ID: ChiCTR2400081608.

Self-control enhances vigilance performance in temporally irregular tasks: an fNIRS frontoparietal investigation

The present study investigated whether trait self-control impacted operators' behavior and associated neural resource strategies during a temporally irregular vigilance task. Functional near-infrared spectroscopy (fNIRS) readings of oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (HbR) from 29 participants were recorded fromthe prefrontal and parietal cortices. Self-control was associated with better perceptual sensitivity (A') in the task with the irregular event schedule. A left-lateralized effect of HbO2 was found for temporal irregularity within the dorsomedial prefrontal cortex, in accordance with functional transcranial doppler (fTCD) studies. Self-control increased HbR (decreasing activation) at right superior parietal lobule (rSPL; supporting vigilance utilization) and right inferior parietal lobule (rIPL; supporting resource reallocation). However, only rSPL was associated with the vigilance decrement-where decreases in activation led to better perceptual sensitivity in the temporally irregular task. Additionally, short stress-state measures suggest decreases in task engagement in individuals with higher self-control in the irregular task. The authors suggest a trait-state-brain-behavior relationship for self-control during difficult vigilance tasks. Implications for the study include steps toward rectifying the resource utilization vs. allocation debate in vigilance-as well as validating HbO2 and HbR as effective constructs for predicting operators' mental resources through fNIRS.

Insomnia-related brain functional correlates in first-episode drug-naïve major depressive disorder revealed by resting-state fMRI

Introduction

Insomnia is a common comorbidity symptom in major depressive disorder (MDD) patients. Abnormal brain activities have been observed in both MDD and insomnia patients, however, the central pathological mechanisms underlying the co-occurrence of insomnia in MDD patients are still unclear. This study aimed to explore the differences of spontaneous brain activity between MDD patients with and without insomnia, as well as patients with different level of insomnia.

Methods

A total of 88 first-episode drug-naïve MDD patients including 44 with insomnia (22 with high insomnia and 22 with low insomnia) and 44 without insomnia, as well as 44 healthy controls (HC), were enrolled in this study. The level of depression and insomnia were evaluated by HAMD-17, adjusted HAMD-17 and its sleep disturbance subscale in all subjects. Resting-state functional and structural magnetic resonance imaging data were acquired from all participants and then were preprocessed by the software of DPASF. Regional homogeneity (ReHo) values of brain regions were calculated by the software of REST and were compared. Finally, receiver operating characteristic (ROC) curves were conducted to determine the values of abnormal brain regions for identifying MDD patients with insomnia and evaluating the severity of insomnia.

Results

Analysis of variance showed that there were significant differences in ReHo values in the left middle frontal gyrus, left pallidum, right superior frontal gyrus, right medial superior frontal gyrus and right rectus gyrus among three groups. Compared with HC, MDD patients with insomnia showed increased ReHo values in the medial superior frontal gyrus, middle frontal gyrus, triangular inferior frontal gyrus, calcarine fissure and right medial superior frontal gyrus, medial orbital superior frontal gyrus, as well as decreased ReHo values in the left middle occipital gyrus, pallidum and right superior temporal gyrus, inferior temporal gyrus, middle cingulate gyrus, hippocampus, putamen. MDD patients without insomnia demonstrated increased ReHo values in the left middle frontal gyrus, orbital middle frontal gyrus, anterior cingulate gyrus and right triangular inferior frontal gyrus, as well as decreased ReHo values in the left rectus gyrus, postcentral gyrus and right rectus gyrus, fusiform gyrus, pallidum. In addition, MDD patients with insomnia had decreased ReHo values in the left insula when compared to those without insomnia. Moreover, MDD patients with high insomnia exhibited increased ReHo values in the right middle temporal gyrus, and decreased ReHo values in the left orbital superior frontal gyrus, lingual gyrus, right inferior parietal gyrus and postcentral gyrus compared to those with low insomnia. ROC analysis demonstrated that impaired brain region might be helpful for identifying MDD patients with insomnia and evaluating the severity of insomnia.

Conclusion

These findings suggested that MDD patients with insomnia had wider abnormalities of brain activities in the prefrontal-limbic circuits including increased activities in the prefrontal cortex, which might be the compensatory mechanism underlying insomnia in MDD. In addition, decreased activity of left insula might be associated with the occurrence of insomnia in MDD patients and decreased activities of the frontal-parietal network might cause more serious insomnia related to MDD.

The abnormalities of brain function in females with primary insomnia: a resting-state functional magnetic resonance imaging study

Background

The neuropathologic mechanism of primary insomnia (PI) of females remains unclear. This study aims to investigate the features of amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) in females with PI using functional magnetic resonance imaging (fMRI), and then explore the abnormalities of functional connectivity (FC).

Materials and methods

A total of 39 female PI patients and 31 female healthy controls (HC) were enrolled in the study. The sleep condition was assessed using the Pittsburgh Sleep Quality Index (PSQI), and Insomnia Severity Index (ISI), and their depressive symptom was evaluated using the Hamilton Depression Scale (HAMD-24). The rs-fMRI was once conducted for every subject. ReHo, ALFF, and ROI-based FC were used to analyze the changes of brain function.

Results

ALFF values were increased in the Cerebelum_4_5_L, as well as decreased ALFF in the bilateral Frontal_Sup_Medial (SFGmed), Angular_L (ANG.L), Parietal_Inf_R (IPL.R), SupraMarginal_R (SMG.R), and Postcentral_R (PoCG.R). ReHo values were increased in the Temporal_Pole_Mid_R (TPOsup.R), as well as decreased ReHo in the Insula_R (INS.R), Frontal_Inf_Oper_R (ORBinf.R), Putamen_R (PUT.R), Rolandic_Oper_R (ROL.R), bilateral Cingulum_Post (PCG), bilateral Frontal_Sup_Medial (SFGmed), bilateral anterior cingulate and paracingulate gyri (ACG), and the bilateral precuneus (PCUN). Across the entire brain, there was a decline in the FC between Angular_R and Frontal_Sup_Medial_L.

Conclusion

Alterations in brain regions of female patients with PI involved multiple functional networks, including the default mode network, the salience network, the central executive network, and the limbic network. Reduced coordination between functional networks may be an important mechanism for insomnia and may lead to reduced cognitive function and decision-making ability.

Towards the neurobiology of insomnia: A systematic review of neuroimaging studies

Insomnia disorder signifies a major public health concern. The development of neuroimaging techniques has permitted to investigate brain mechanisms at a structural and functional level. The present systematic review aims at shedding light on functional, structural, and metabolic substrates of insomnia disorder by integrating the available published neuroimaging data. The databases PubMed, PsycARTICLES, PsycINFO, CINAHL and Web of Science were searched for case-control studies comparing neuroimaging data from insomnia patients and healthy controls. 85 articles were judged as eligible. For every observed finding of each study, the effect size was calculated from standardised mean differences, statistic parameters and figures, showing a marked heterogeneity that precluded a comprehensive quantitative analysis. From a qualitative point of view, considering the findings of significant group differences in the reported regions across the articles, this review highlights the major involvement of the anterior cingulate cortex, thalamus, insula, precuneus and middle frontal gyrus, thus supporting some central themes in the debate on the neurobiology of and offering interesting insights into the psychophysiology of sleep in this disorder.

Neural mechanisms of working memory dysfunction in patients with chronic insomnia disorder

OBJECTIVE

This study aimed to investigate the neural mechanisms underlying working memory impairment in patients with chronic insomnia disorder (CID) using event-related potentials (ERP) and resting-state functional connectivity (rsFC) approaches.

METHODS

Participants, including CID patients and healthy controls (HCs), completed clinical scales and underwent electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). EEG analysis compared reaction times, P3 amplitudes, event-related spectral perturbations (ERSP), and inter-trial phase synchronisation (ITPS) between CID patients and HCs. Subsequently, frontal regions (i.e., the Superior Frontal Gyrus [SFG] and Middle Frontal Gyrus [MFG]) corresponding to the EEG were selected as seeds for rsFC analysis. Correlation analyses were conducted to further investigate the relationship between functional connectivity abnormalities in brain regions and clinical symptom severity and P3 amplitude in CID patients.

RESULTS

Compared to HCs, CID patients exhibited slower reaction times across all working memory conditions, with the deficits becoming more pronounced as memory load increased. ERP analysis revealed increased P3 amplitude, theta wave power, and reduced inter-trial synchrony in CID patients. rsFC analysis showed decreased connectivity of SFG-posterior cingulated cortex (PCC), SFG-MFG, and MFG-frontal pole (FP), and increased connectivity of MFG- Middle Temporal Gyrus (MTG)in CID patients. Importantly, a significant correlation was found between the rsFC of SFG-MTG and P3 amplitude during 1-back.

CONCLUSION

This study confirms deficits in working memory capacity in patients with CID, specifically in the neural mechanisms of cognitive processing that vary depending on the level of cognitive load. Alterations in connectivity patterns within and between the frontal and temporal regions may be the neural basis of the cognitive impairment.

Hyperarousal in insomnia disorder: Current evidence and potential mechanisms

Insomnia disorder is among the most frequent mental disorders, making research on its aetiology and pathophysiology particularly important. A unifying element of many aetiological and pathophysiological models is that they support or even centre on the role of some form of hyperarousal. In this theoretical review, we aim to summarise the current evidence on hyperarousal in insomnia. Hyperarousal is discussed as a state of relatively increased arousal in physiological, cortical and cognitive-emotional domains. Regarding physiological hyperarousal, there is no conclusive evidence for the involvement of autonomous variables such as heart rate and heart rate variability, whereas recent evidence points to a pathophysiological role of neuroendocrine variables. In addition, current literature supports a central involvement of cortical arousal, that is, high-frequency electroencephalographic activity. An increasingly important focus in the literature is on the role of other microstructural sleep parameters, especially the existence of microarousals during sleep. Beyond that, a broad range of evidence exists supporting the role of cognitive-emotional hyperarousal in the form of insomnia-related thought and worries, and their concomitant emotional symptoms. Besides being a state marker of insomnia, hyperarousal is considered crucial for the predisposition to insomnia and for the development of comorbid mental disorders. Thus, beyond presenting evidence from cross-sectional studies on markers of hyperarousal in insomnia, hypotheses about the mechanisms of hyperarousal are presented. Nevertheless, longitudinal studies are needed to further elucidate the mechanism of hyperarousal throughout the course of the disorder, and future studies should also focus on similarities and differences in hyperarousal across different diagnostic entities.

Neuroimaging in insomnia: Review and reconsiderations

Over the last decades, neuroimaging has become a substantial component of insomnia research. While theoretical underpinnings of different studies vary just like methodological choices and the experimental design, it is suggested that major features of insomnia disorder rely on the impaired function, structure, metabolism and connectivity of brain areas involved in sleep generation, emotion regulation, self-processing/-awareness and attentional orientation. However, neuroimaging research on insomnia often suffers from small sample sizes, heterogeneous methodology and a lack of replicability. With respect to these issues, the field needs to address the questions: (1a) how sufficiently large sample sizes can be accumulated within a reasonable economic framework; (1b) how effect sizes in insomnia-related paradigms can be amplified; (2a) how a higher degree of standardisation and transparency in methodology can be provided; and (2b) how an adequate amount of flexibility/complexity in study design can be maintained. On condition that methodological consistency and a certain degree of adaptability are given, pooled data/large cohort analyses can be considered to be one way to answer these questions. Regarding experimental single-centre trials, it might be helpful to focus on insomnia-related transdiagnostic concepts. In doing so, expectable effect sizes (in between-subjects designs) can be increased by: (a) comparing groups that are truly distinct regarding the variables examined in a concept-specific paradigm; and (b) facilitated, intensified and precise elicitation of a target symptom.

Mechanisms of cognitive behavioural therapy for insomnia

Although much is known now about behavioural, cognitive and physiological consequences of insomnia, little is known about changes after cognitive behavioural therapy for insomnia on these particular factors. We here report baseline findings on each of these factors in insomnia, after which we address findings on their changes after cognitive behavioural therapy. Sleep restriction remains the strongest determinant of insomnia treatment success. Cognitive interventions addressing dysfunctional beliefs and attitudes about sleep, sleep-related selective attention, worry and rumination further drive effectiveness of cognitive behavioural therapy for insomnia. Future studies should focus on physiological changes after cognitive behavioural therapy for insomnia, such as changes in hyperarousal and brain activity, as literature on these changes is sparse. We introduce a detailed clinical research agenda on how to address this topic.

The potential of biomarkers for diagnosing insomnia: Consensus statement of the WFSBP Task Force on Sleep Disorders

OBJECTIVES

Thus far, the diagnosis of insomnia is based on purely clinical criteria. Although a broad range of altered physiological parameters has been identified in insomniacs, the evidence to establish their diagnostic usefulness is very limited. Purpose of this WFSBP Task Force consensus paper is to systematically evaluate a series of biomarkers as potential diagnostic tools for insomnia.

METHODS

A newly created grading system was used for assessing the validity of various measurements in establishing the diagnosis of insomnia; these measurements originated from relevant studies selected and reviewed by experts.

RESULTS

The measurements with the highest diagnostic performance were those derived from psychometric instruments. Biological measurements which emerged as potentially useful diagnostic instruments were polysomnography-derived cyclic alternating pattern, actigraphy, and BDNF levels, followed by heart rate around sleep onset, deficient melatonin rhythm, and certain neuroimaging patterns (mainly for the activity of frontal and pre-frontal cortex, hippocampus and basal ganglia); yet, these findings need replication, as well as establishment of commonly accepted methodology and diagnostic cut-off points. Routine polysomnography, EEG spectral analysis, heart rate variability, skin conductance, thermoregulation, oxygen consumption, HPA axis, and inflammation indices were not shown to be of satisfactory diagnostic value.

CONCLUSIONS

Apart from psychometric instruments which are confirmed to be the gold standard in diagnosing insomnia, six biomarkers emerge as being potentially useful for this purpose.

[Changes of brain network in patients with insomnia following radiotherapy for cervical cancer and their correlation with IT-TMS treatment efficacy: a graph-theory analysis]

OBJECTIVE

To analyze the changes of brain small-world and node function network properties in patients with insomnia following radiotherapy for cervical cancer based on graph theory analysis and explore the correlation between functional networks and the clinical efficacy of individual-target transcranial magnetic stimulation (IT-TMS) for treatment of insomnia.

METHODS

The resting state functional magnetic resonance imaging (rs-fMRI) data were collected from 30 patients with insomnia following radiotherapy for cervical cancer and 30 matched healthy individuals. All the patients received accelerated intelligent neuromodulation TMS therapy. Using graph theory analysis and GRETNA software, the functional connectivity matrices were constructed and the attribute features were extracted. The scores on the Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), Self-Rating Anxiety Scale (SAS), and Self-Rating Depression Scale (SDS) of the participants were collected before and after IT-TMS, and the correlation between improvement in insomnia and the functional network was investigated.

RESULTS

The two groups matched for age, gender, and education level (P>0.05) showed significant differences in PSQI, ISI, SAS and SDS scores (P<0.05). Both groups showed attributes of the small-world network. Compared with the healthy individuals, the patients showed significantly decreased σ, EI, Cp and Lp (P<0.05) and increased Eg (P<0.05) at baseline, which, along with insomnia symptoms, were all improved after IT-TMS treatment. The patients showed reduced functional connections of the node network at follow-up compared with the baseline, and the low functional connectivity between the right insula and left superior frontal gyrus was correlated with the improvement of ISI scores.

CONCLUSION

The patients with insomnia following radiotherapy for cervical cancer have impaired information integration ability of the brain network, IT-TMS can significantly improve insomnia symptoms by reducing the hyperconnectivity between the default mode network and the salience network.

Distracted driving behavior in patients with insomnia

Insomnia is one of the most common sleep disorders and is characterized by a subjective perception of difficulty falling asleep. Drivers with insomnia are vulnerable to distraction and exhibit higher levels of risk while driving. This study investigated the effect of two sources of in-vehicle distractions on the driving performance of drivers with insomnia and good sleepers by analyzing different driving behavior measures. Twenty-one drivers with insomnia and twenty-one healthy volunteers were recruited to complete simulated driving dual tasks. The primary task required the participants to perform: (a) a lane-keeping task, and (b) a lane-change task. The secondary task required the participants to deal with: (a) baseline (non-task), (b) internal distraction task, and (c) external distraction task. The internal distraction task required participants to complete quantitative reasoning tasks, while the external distraction task was a 0-back test. The relationship between distracted driving ability and cognitive function was also investigated. The results demonstrate that for lane-keeping tasks, drivers with insomnia had significantly higher standard deviations (SD) for speed, throttle position, acceleration, and lateral position than healthy drivers under internal distraction, but the driving performance did not differ significantly between groups under internal distraction or baseline. In the lane-change task, drivers with insomnia had higher SDs for steering wheel angle, steer angular velocity, lateral acceleration, and lateral speed than healthy drivers under external distraction. Moreover, external distraction impaired driving behavior in the healthy group, while internal distraction impaired driving ability in both groups. Healthy drivers with cognitive impairment displayed impaired lane-keeping abilities under internal distractions and impaired lane-changing abilities under external distractions. Driving performance in the insomnia group was not significantly associated with cognitive function. The results demonstrate that insomnia and distraction impair driving ability, and driver performance is affected differently by the distraction source (internal or external). The driving ability of healthy drivers with decreased cognition was impaired, but not that of insomniacs.The findings of this study provide new insights for preventing and estimating the potential influence of distracted driving behavior in individuals with insomnia.

Prefrontal Cortex Hemodynamics and Functional Connectivity Changes during Performance Working Memory Tasks in Older Adults with Sleep Disorders

Objective: Older adults with sleep disorders (SDs) show impaired working memory abilities, and working memory processes are closely related to the prefrontal cortex (PFC). However, the neural mechanism of working memory impairment in older adults with SD remains unclear. This study aimed to investigate changes in PFC function among older adults with SD when carrying out the N-back task by functional near-infrared spectroscopy (fNIRS). Method: A total of 37 older adults with SDs were enrolled in this study and matched with 37 healthy older adults by gender, age, and years of education. Changes in PFC function were observed by fNIRS when carrying out the N-back task. Results: The accuracy on the 0-back and 2-back tasks in the SD group was significantly lower than that in the healthy controls (HC) group. The oxygenated hemoglobin (oxy-Hb) concentration of channel 8 which located in the dorsolateral prefrontal cortex (DLPFC) was significantly reduced in the SD group during the 2-back task, and the channel-to-channel connectivity between the PFC subregions was significantly decreased. Conclusions: These results suggest that patients with sleep disorders have a weak performance of working memory; indeed, the activation and functional connectivity in the prefrontal subregions were reduced in this study. This may provide new evidence for working memory impairment and brain function changes in elderly SDs.

TAG-ME again: A serious game for measuring working memory

BrainTagger (demo version: researcher-demo.braintagger.com) is a suite of Target Acquisition Games for Measurement and Evaluation (TAG-ME). Here we introduce TAG-ME Again, a serious game modeled after the well-established N-Back task, to assess working memory ability across three difficulty levels corresponding to 1-, 2-, and 3-back conditions. We also report on two experiments aimed at assessing convergent validity with the N-Back task. Experiment 1 examined correlations with N-Back task performance in a sample of adults (n = 31, 18-54 years old) across three measures: reaction time; accuracy; a combined RT/accuracy metric. Significant correlations between game and task were found, with the strongest relationship being for the most difficult version of the task (3-Back). In Experiment 2 (n = 66 university students, 18-22 years old), we minimized differences between the task and the game by equating stimulus-response mappings and spatial processing demands. Significant correlations were found between game and task for both the 2-Back and 3-Back levels. We conclude that TAG-ME Again is a gamified task that has convergent validity with the N-Back Task.

Altered functional connectivity of anterior cingulate cortex in chronic insomnia: A resting-state fMRI study

The aim of our present study was to explore the connectivity pattern change between the anterior cingulate cortex (ACC) and the voxels from the whole brain in chronic insomnia (CI). With region of interest (ROI)-based functional connectivity, a two-sample t-test was performed on individual FC correlation maps from two groups based on the resting-state fMRI data acquired from 57 CI patients and 46 healthy controls (GRF correction, voxel-level P < 0.001 and cluster-level P < 0.001). A correlation analysis was performed to evaluate the relationship between the clinical features and the abnormal FC. Compared to the healthy controls, the CI patients show increased connectivity between the ACC and the right middle frontal gyrus, with decreased connectivity between the ACC and the bilateral precuneus gyrus. Correlation analysis indicated that the decreased connectivity showed positive correlations with Self-Rating Anxiety Scale (SAS) scores. Our study shows the alterations of CI patients in the level of functional integration and may indicate the dysfunction of communication within brain regions of the default mode network (DMN). These changes and their correlation with negative emotions may provide additional evidence to understand the possible neural mechanisms of CI.

Neuroimaging Correlates of Cognitive Behavioral Therapy for Insomnia (CBT-I): A Systematic Literature Review

Cognitive behavioral therapy for insomnia (CBT-I) is the gold-standard non-pharmacological treatment for insomnia, a complex disorder that comprises psychological, behavioral, and physiological components. This systematic literature review aimed to evaluate a growing body of exploratory studies that have examined CBT-I treatment effects using neuroimaging assessment. Nine studies met current review selection criteria, of which six studies compared insomnia groups with good sleepers, waitlist, and/or control groups. CBT-I administration varied in treatment length and duration across the studies, as did neuroimaging assessment, which included task-based and resting-state functional magnetic resonance imaging (fMRI), and structural magnetic resonance imaging (MRI). Functional connectivity abnormalities were observed in participants, including reduced engagement in task-related brain regions and apparent difficulties in regulating default mode brain areas that appeared to reverse following CBT-I treatment. Taken together, the neuroimaging results complement behavioral measures of treatment efficacy, indicating support for the effectiveness of CBT-I treatment in the recovery of brain function and structure.

The evolving role of quantitative actigraphy in clinical sleep medicine

Actigraphy has a consolidated role in Insomnia and Circadian Rhythm Sleep-Wake Disorders (CRSWD) and recent studies have highlighted the use of actigraphy for narcolepsy and REM sleep behaviour disorder (RBD). This review aims at summarising the results of studies published over the last decade regarding the use of actigraphy. Thirty-five studies proved eligible, and results were analysed separately for insomnia, narcolepsy and RBD. Actigraphy showed to consistently differentiate insomnia patients from healthy controls. Furthermore, the application of advanced analytical techniques has been shown to provide both unique insights into the physiology of insomnia and sleep misperception and to improve the specificity of actigraphy in detecting wakefulness within sleep periods. Regarding narcolepsy, several studies showed that actigraphy can detect peculiar sleep/wake disruption and the effects of pharmacological treatments. Finally, although the number of studies in RBD patients is still limited, the available evidence indicates a reduced amplitude of the activity pattern, sleep-wake rhythm dysregulation and daytime sleepiness. Therefore, the potential use of these markers as predictors of phenoconversion should be further explored. In conclusion, quantitative actigraphy presents a renewed interest when considering the possibility of using actigraphy in clinical sleep medicine to diagnose, monitor, and follow sleep disorders other than CRSWD.

Diagnostic identification of chronic insomnia using ALFF and FC features of resting-state functional MRI and logistic regression approach

This study investigated whether the amplitude of low-frequency fluctuation (ALFF) and functional connectivity (FC) features could be used as potentially neurological markers to identify chronic insomnia (CI) using resting-state functional MRI and machine learning method logistic regression (LR). This study included 49 CI patients and 47 healthy controls (HC). Voxel-wise features, including the amplitude of low-frequency fluctuations (ALFF) and functional connectivity (FC), were extracted from resting-state functional magnetic resonance brain images. Then, we divided the data into two independent cohorts for training (44 CI patients and 42 HC patients), and independent validation (5 CI patients and 5 HC patients) by using logistic regression. The model was evaluated using 20 rounds of fivefold cross‑validation for training. In particular, a two-sample t-test (GRF corrected, p-voxel < 0.001, p-cluster < 0.05) was used for feature selection during the model training. Finally, single‑shot testing of the final model was performed on the independent validation cohort. A correlation analysis (Bonferroni correction, p < 0.05/4) was also conducted to determine whether the features contributing to the prediction were correlated with clinical characteristics, including the Insomnia Severity Index (ISI), Pittsburgh sleep quality index (PSQI), self-rating anxiety scale (SAS), and self-rating depression scale (SDS). Results showed that resting-state features had a discrimination accuracy of 86.40%, with a sensitivity of 93.00% and specificity of 79.80%. The area under the curve (AUC) was 0.89 (all [Formula: see text]< 0.001). The ALFF and FC features showed significant differences between the CI patients and HC. The regions contributing to the prediction mainly included the anterior cingulate, prefrontal cortex, orbital part of the frontal lobe, angular gyrus, cingulate gyrus, praecuneus, parietal lobe, temporal gyrus, superior temporal gyrus, and middle temporal gyrus. Furthermore, some specific functional connectivity among related regions was positively correlated with the ISI, and also negatively related to the SDS in correlation analysis. Our current study suggested that ALFF and FC in the regions contributing to diagnostic identification might serve as potential neuromarkers for CI.

Identification of discriminative neuroimaging markers for patients on hemodialysis with insomnia: a fractional amplitude of low frequency fluctuation-based machine learning analysis

BACKGROUND AND OBJECTIVE

Insomnia is one of the common problems encountered in the hemodialysis (HD) population, but the mechanisms remain unclear. we aimed to (1) detect the spontaneous brain activity pattern in HD patients with insomnia (HDWI) by using fractional fractional amplitude of low frequency fluctuation (fALFF) method and (2) further identify brain regions showing altered fALFF as neural markers to discriminate HDWI patients from those on hemodialysis but without insomnia (HDWoI) and healthy controls (HCs).

METHOD

We compared fALFF differences among HDWI subjects (28), HDWoI subjects (28) and HCs (28), and extracted altered fALFF features for the subsequent discriminative analysis. Then, we constructed a support vector machine (SVM) classifier to identify distinct neuroimaging markers for HDWI.

RESULTS

Compared with HCs, both HDWI and HDWoI patients exhibited significantly decreased fALFF in the bilateral calcarine (CAL), right middle occipital gyrus (MOG), left precentral gyrus (PreCG), bilateral postcentral gyrus (PoCG) and bilateral temporal middle gyrus (TMG), whereas increased fALFF in the bilateral cerebellum and right insula. Conversely, increased fALFF in the bilateral CAL/right MOG and decreased fALFF in the right cerebellum was observed in HDWI patients when compared with HDWoI patients. Moreover, the SVM classification achieved a good performance [accuracy = 82.14%, area under the curve (AUC) = 0.8202], and the consensus brain regions with the highest contributions to classification were located in the right MOG and right cerebellum.

CONCLUSION

Our result highlights that HDWI patients had abnormal neural activities in the right MOG and right cerebellum, which might be potential neural markers for distinguishing HDWI patients from non-insomniacs, providing further support for the pathological mechanism of HDWI.

Functional connectivity correlates of attentional networks in insomnia disorder: A pilot study

Insomnia disorder has been associated with poor executive functioning. Functional imaging studies of executive functioning in insomnia are scarce and inconclusive. Because the Attentional Network Test relies on well-defined cortical networks and sensitively distinguishes different aspects of executive function, it might reveal brain functional alterations in relatively small samples of patients. The current pilot study assessed functional connectivity during the Attentional Network Test performed using magnetic resonance imaging in 12 participants with insomnia and 13 self-defined good sleepers. ANCOVAs were used to evaluate group differences in performance and functional connectivity in the regions of interest representing the attentional networks (i.e. alerting, orienting and executive control) at p < 0.05, uncorrected. During the orienting part, participants with insomnia showed weaker connectivity of the precentral gyrus with the superior parietal lobe (false discovery rate-corrected), while they showed stronger connectivity between premotor and visual regions. Individual differences in connectivity between premotor and visual regions correlated inversely with reaction time. Reaction times suggested more efficient executive control in participants with insomnia compared with good sleepers. During the executive control part, participants with insomnia showed stronger connectivity of thalamic parts of the arousal circuit with the middle frontal and the occipital gyri. Conversely, connectivity between the inferior and superior frontal gyri was weaker. Participants with insomnia seem to recruit more cortical resources in visuo-motor regions to orient attention than good sleepers do, and seem to have enhanced executive control that relates to stronger connectivity of arousal-related thalamic areas. This latter result should be treated with caution and requires confirmation.

Fatigue performance in patients with chronic insomnia

Insomnia is associated with fatigue and poor driving performance, thus increasing the risk of traffic accidents. This study aimed to evaluate the effect of fatigue on driving in patients with chronic insomnia in a free-flow traffic scenario and car-following scenario, and to investigate the relationships between driving performance, cognitive function, and insomnia. The Trail Making Test (TMT), Stroop Color and Word Test (SCWT), Symbol Digit Modalities Test (SDMT), and Digit Span Test (DST) of 15 participants with mild-to-moderate chronic insomnia and 16 healthy participants were assessed. During the fatigue driving task, drivers completed simulated driving tasks under free-flow traffic and car-following scenarios. The mean speed (MS), mean acceleration (MA), mean lateral position (MLP), and standard deviation of lateral position (SDLP) were measured to assess driving performance. During fatigued tasks, the MA and MLP in the free-driving scenario were higher than those in the car-following scenario (P < 0.01), the SDLP was higher in the insomnia group than in the healthy group (P = 0.02), and the interaction effect was significantly different for MLP between the groups (P = 0.03). MS was negatively correlated with TMT score, SDMT score, and DST score, and positively correlated with time to complete TMT, errors in SCWT, and time to complete SCWT. SDLP was negatively correlated with DST score and positively correlated with time to complete SCWT. Furthermore, the insomnia group had poorer lateral vehicle control ability than the healthy group. The insomnia group had a more impaired driving performance in the free-driving scenario than in the car-following scenario. Drivers with impaired cognitive function exhibited impaired driving performance.

The moderating effect of prefrontal response to sleep-related stimuli on the association between depression and sleep disturbance in insomnia disorder

We investigated differences in brain activity in response to sleep-related pictures between chronic insomnia disorder (CID) patients and good sleepers (GS), and examined whether brain activity moderated the relationship between depressive symptoms and sleep disturbance in CID patients and GS. This study included 43 patients diagnosed with CID, based on the International Classification of Sleep Disorders-3, and 42 GS. The participants kept a sleep diary, underwent nocturnal polysomnography to measure sleep parameters, and completed self-report questionnaires to assess sleep and psychiatric symptoms. They underwent functional magnetic resonance imaging (fMRI) to examine differences in brain activity in response to sleep-related pictures compared to neutral pictures. A moderated moderation analysis was performed to investigate the moderating role of brain responses to sleep-related pictures in the association between depressive symptoms and sleep disturbance. Compared to GS, the brain responses to sleep-related stimuli were significantly lower in CID patients in the right lateral prefrontal cortex (LPFC) and dorsomedial prefrontal cortex (DMPFC). More severe depressive symptoms were significantly associated with longer sleep latency only when LPFC activity was low in CID patients, but not in GS. LPFC hypoactivity in response to sleep-related stimuli in CID patients could moderate the relationship between depression and sleep disturbance.

The associations of insomnia symptoms with daytime behavior and cognitive functioning in children with attention-deficit/hyperactivity disorder

STUDY OBJECTIVES

The current study aimed to examine the association of insomnia symptoms with daytime behavior and cognitive functioning in children with attention-deficit/hyperactivity disorder (ADHD).

METHODS

Thirty-six children with ADHD and insomnia symptoms, 27 children with ADHD without insomnia symptoms, and 21 age-matched healthy controls were recruited in this study (age range: 6-12 years, 70% male). They were assessed by parent-report questionnaires on insomnia symptoms (Children's Sleep Habits Questionnaire) and ADHD symptoms (Strengths and Weaknesses of ADHD Symptoms and Normal Behavior Scale [SWAN]), and completed a battery of cognitive tests including the Continuous Performance Test (CPT) for sustained attention, Letter-digit test for processing speed, Digit Span forward test and N-back task for working memory, Tower of London (TOL) test for planning skills and Bergs Card Sorting Test (BCST) for set-shifting ability.

RESULTS

Children with ADHD and insomnia symptoms had the highest scores on SWAN total and inattention and hyperactivity subscales, followed by children with ADHD without insomnia and healthy controls (all P < .05). After controlling for potential confounders, children with ADHD and insomnia symptoms showed poorer performance on the CPT and Letter-digit test as compared with children with ADHD without insomnia and healthy controls (all P < .05).

CONCLUSIONS

Insomnia symptoms are associated with more severe ADHD symptoms and cognitive impairments in children with ADHD, especially deficits in sustained attention and processing speed. Future longitudinal studies are needed to explore the long-term impacts of insomnia symptoms and the effects of sleep-focused intervention on cognitive functioning in children with ADHD.

CITATION

Li X, Shea KSC, Chiu WV, et al. The associations of insomnia symptoms with daytime behavior and cognitive functioning in children with attention-deficit/hyperactivity disorder. J Clin Sleep Med. 2022;18(8):2029-2039.

Transcutaneous Auricular Vagus Nerve Stimulation Modulates the Prefrontal Cortex in Chronic Insomnia Patients: fMRI Study in the First Session

Objectives

Transcutaneous auricular vagus nerve stimulation (taVNS) has been reported to be effective for chronic insomnia (CI). However, the appropriate population for taVNS to treat insomnia is unclear.

Methods

Total twenty-four patients with CI and eighteen health controls (HC) were recruited. Rest-state functional magnetic resonance imaging (Rs-fMRI) was performed before and after 30 min' taVNS at baseline. The activated and deactivated brain regions were revealed by different voxel-based analyses, then the seed-voxel functional connectivity analysis was calculated. In the CI group, 30 min of taVNS were applied twice daily for 4 weeks. Pittsburgh Sleep Quality Index (PSQI) and Flinders Fatigue Scale (FFS) were also assessed before and after 4 weeks of treatment in the CI group. The HC group did not receive any treatment. The correlations were estimated between the clinical scales' score and the brain changes.

Results

The scores of PSQI (p < 0.01) and FFS (p < 0.05) decreased after 4 weeks in the CI group. Compared to the HC group, the first taVNS session up-regulated left dorsolateral prefrontal cortex (dlPFC) and decreased the functional connectivity (FCs) between dlPFC and bilateral medial prefrontal cortex in the CI group. The CI groups' baseline voxel wised fMRI value in the dlPFC were negatively correlated to the PSQI and the FFS score after 4 weeks treatment.

Conclusions

It manifests that taVNS has a modulatory effect on the prefrontal cortex in patients with CI. The initial state of dlPFC may predict the efficacy for taVNS on CI.

Improved Functional Organization in Patients With Primary Insomnia After Individually-Targeted Transcranial Magnetic Stimulation

Primary insomnia (PI) is among the most prevalent sleep-related disorders and has a far-reaching impact on daytime functioning. Repetitive transcranial magnetic stimulation (rTMS) has drawn attention because of its effectiveness and safety. The purpose of the current study was to detect changes in the topological organization of whole-brain functional networks and to determine their associations with the clinical treatment effects of rTMS. Resting-state functional magnetic resonance imaging (rsfMRI) data from 32 patients with PI were collected and compared with findings from 32 age- and gender-matched healthy controls (HCs). The patients were treated with Stanford accelerated intelligent neuromodulation therapy, which is a recently validated neuroscience-informed accelerated intermittent theta-burst stimulation protocol. Graph theoretical analysis was used to construct functional connectivity matrices and to extract the attribute features of small-world networks in insomnia. Scores on the Insomnia Severity Index (ISI), Pittsburgh Sleep Quality Index, Self-Rating Anxiety Scale, Self-Rating Depression Scale, and the associations between these clinical characteristics and functional metrics, were the primary outcomes. At baseline, the patients with PI showed inefficient small-world property and aberrant functional segregation and functional integration compared with the HCs. These properties showed renormalization after individualized rTMS treatment. Furthermore, low functional connectivity between the right insula and left medial frontal gyrus correlated with improvement in ISI scores. We highlight functional network dysfunctions in PI patients and provide evidence into the pathophysiological mechanisms involved and the possible mode of action of rTMS.

Neural alterations in working memory of mild-moderate TBI: An fMRI study in Malaysia

Working memory (WM) encompasses crucial cognitive processes or abilities to retain and manipulate temporary information for immediate execution of complex cognitive tasks in daily functioning such as reasoning and decision-making. The WM of individuals sustaining traumatic brain injury (TBI) was commonly compromised, especially in the domain of WM. The current study investigated the brain responses of WM in a group of participants with mild-moderate TBI compared to their healthy counterparts employing functional magnetic resonance imaging. All consented participants (healthy: n = 26 and TBI: n = 15) performed two variations of the n-back WM task with four load conditions (0-, 1-, 2-, and 3-back). The respective within-group effects showed a right hemisphere-dominance activation and slower reaction in performance for the TBI group. Random-effects analysis revealed activation difference between the two groups in the right occipital lobe in the guided n-back with cues, and in the bilateral occipital lobe, superior parietal region, and cingulate cortices in the n-back without cues. The left middle frontal gyrus was implicated in the load-dependent processing of WM in both groups. Further group analysis identified that the notable activation changes in the frontal gyri and anterior cingulate cortex are according to low and high loads. Though relatively smaller in scale, this study was eminent as it clarified the neural alterations in WM in the mild-moderate TBI group compared to healthy controls. It confirmed the robustness of the phenomenon in TBI with the reproducibility of the results in a heterogeneous non-Western sample.

Distinct alterations of functional connectivity of the basal forebrain subregions in insomnia disorder

BACKGROUND

Cholinergic basal forebrain (BF) plays an important role in sleep-wake regulation and is implicated in cortical arousal and activation. However, less is known currently regarding the abnormal BF-related neuronal circuit in human patients with insomnia disorder (ID). In this study, we aimed to explore alterations of functional connectivity (FC) in subregions of the BF and the relationships between FC alterations and sleep and mood measures in ID.

MATERIALS AND METHODS

One hundred and two ID patients and ninety-six healthy controls (HC) were included in this study. Each subject underwent both resting-state fMRI and high-resolution anatomical scanning. All participants completed the sleep and mood questionnaires in ID patients. Voxel-based resting-state FC in each BF subregion (Ch_123 and Ch_4) were computed. For the voxel-wise FC differences between groups, a two-sample t-test was performed on the individual maps in a voxel-by-voxel manner. To examine linear relationships with sleep and mood measures, Pearson correlations were calculated between FC alterations and sleep and mood measures, respectively.

RESULTS

The ID group showed significantly decreased FC between the medial superior frontal gyrus and Ch_123 compared to HC. However, increased FC between the midbrain and Ch_4 was found in ID based on the voxel-wise analysis. The correlation analysis only revealed that the altered FC between the midbrain with Ch_4 was significantly negatively correlated with the self-rating anxiety scale.

CONCLUSION

Our findings of decreased FC between Ch_123 and medial superior frontal gyrus and increased FC between midbrain and Ch4 suggest distinct roles of subregions of BF underlying the neurobiology of ID.

Sleep Treatments in Disorders of Consciousness: A Systematic Review

Sleep disorders are among the main comorbidities in patients with a Disorder of Consciousness (DOC). Given the key role of sleep in neural and cognitive functioning, detecting and treating sleep disorders in DOCs might be an effective therapeutic strategy to boost consciousness recovery and levels of awareness. To date, no systematic reviews have been conducted that explore the effect of sleep treatments in DOCs; thus, we systematically reviewed the existing studies on both pharmacological and non-pharmacological treatments for sleep disorders in DOCs. Among 2267 assessed articles, only 7 were included in the systematic review. The studies focused on two sleep disorder categories (sleep-related breathing disorders and circadian rhythm dysregulation) treated with both pharmacological (Modafinil and Intrathecal Baclofen) and non-pharmacological (positive airway pressure, bright light stimulation, and central thalamic deep brain stimulation) interventions. Although the limited number of studies and their heterogeneity do not allow generalized conclusions, all the studies highlighted the effectiveness of treatments on both sleep disorders and levels of awareness. For this reason, clinical and diagnostic evaluations able to detect sleep disorders in DOC patients should be adopted in the clinical routine for the purpose of intervening promptly with the most appropriate treatment.

Functional connectivity changes in insomnia disorder: A systematic review

Insomnia (ID) is the most common sleep disorder; however pathogenetic mechanisms underlying ID symptoms are not fully understood. Adopting a multifactorial view and considering ID a condition that involves interregional neuronal coordination would be useful to understand the ID pathophysiology. Functional connectivity (FC) may help to shed light on functional processes and neural correlates underlying ID symptoms. Despite a growing number of studies assessing FC anomalies, insight into ID pathophysiology is still fragmentary. This systematic review aims to search empirical evidence regarding FC changes in ID during resting-state. Thirty-one studies involving 1052 ID participants met the inclusion criteria for this review. Results suggested several associations between ID symptoms and impaired intra- and inter-hemispheric interactions of principal resting-state networks. Overall, evidence supported the hypothesis that a disrupted organization of the brain functional connectome characterizes ID, resulting in a decline in sleep, cognition, emotion, and memory. However, the wide methodological heterogeneity between reviewed studies and limitations in terms of study protocols and statistical approaches raised from this systematic review, makes it difficult to provide a univocal framework of ID pathophysiology. Future researches in this field should lead towards shared and rigorous search designs to ensure solid research evidence in the ID pathophysiology.

Understanding insomnia as systemic disease

Sleep plays a critical role in homeostasis of the body and mind. Insomnia is a disease that causes disturbances in the initiation and maintenance of sleep. Insomnia is known to affect not only the sleep process itself but also an individual’s cognitive function and emotional regulation during the daytime. It increases the risk of various neuropsychiatric diseases such as depression, anxiety disorder, and dementia. Although it might appear that insomnia only affects the nervous system, it is also a systemic disease that affects several aspects of the body, such as the cardiovascular, endocrine, and immune systems; therefore, it increases the risk of various diseases such as hypertension, diabetes mellitus, and infection. Insomnia has a wide range of effects on our bodies because sleep is a complex and active process. However, a high proportion of patients with insomnia do not seek treatment, which results in high direct and indirect costs. This is attributed to the disregard of many of the negative effects of insomnia. Therefore, we expect that understanding insomnia as a systemic disease will provide an opportunity to understand the condition better and help prevent secondary impairment due to insomnia.

Relationship between circadian rhythm and brain cognitive functions

Circadian rhythms are considered a masterstroke of natural selection, which gradually increase the adaptability of species to the Earth's rotation. Importantly, the nervous system plays a key role in allowing organisms to maintain circadian rhythmicity. Circadian rhythms affect multiple aspects of cognitive functions (mainly via arousal), particularly those needed for effort-intensive cognitive tasks, which require considerable top-down executive control. These include inhibitory control, working memory, task switching, and psychomotor vigilance. This mini review highlights the recent advances in cognitive functioning in the optical and multimodal neuroimaging fields; it discusses the processing of brain cognitive functions during the circadian rhythm phase and the effects of the circadian rhythm on the cognitive component of the brain and the brain circuit supporting cognition.

Multitask fMRI and machine learning approach improve prediction of differential brain activity pattern in patients with insomnia disorder

We investigated the differential spatial covariance pattern of blood oxygen level-dependent (BOLD) responses to single-task and multitask functional magnetic resonance imaging (fMRI) between patients with psychophysiological insomnia (PI) and healthy controls (HCs), and evaluated features generated by principal component analysis (PCA) for discrimination of PI from HC, compared to features generated from BOLD responses to single-task fMRI using machine learning methods. In 19 patients with PI and 21 HCs, the mean beta value for each region of interest (ROIbval) was calculated with three contrast images (i.e., sleep-related picture, sleep-related sound, and Stroop stimuli). We performed discrimination analysis and compared with features generated from BOLD responses to single-task fMRI. We applied support vector machine analysis with a least absolute shrinkage and selection operator to evaluate five performance metrics: accuracy, recall, precision, specificity, and F2. Principal component features showed the best classification performance in all aspects of metrics compared to BOLD response to single-task fMRI. Bilateral inferior frontal gyrus (orbital), right calcarine cortex, right lingual gyrus, left inferior occipital gyrus, and left inferior temporal gyrus were identified as the most salient areas by feature selection. Our approach showed better performance in discriminating patients with PI from HCs, compared to single-task fMRI.

Sleep deprivation and compensatory cognitive effort on a visual information processing task

STUDY OBJECTIVES

Total sleep deprivation (TSD) is often associated with worse performance on tasks of attention and working memory, but some studies show no performance changes. One possibility is that greater compensatory cognitive effort is put forth to achieve similar results after TSD. We aimed to better understand the relationship between TSD, cognitive engagement, and performance outcomes following TSD.

METHODS

Twenty healthy adults completed cognitive testing following a night of normal sleep and again after ~55 hours of TSD. Participants detected target letters in low (3-item) and high (10-item) load visual letter displays on the span of apprehension task with concurrent pupillometry, a measure of cognitive effort.

RESULTS

We found significantly poorer detection accuracy and marginally longer response times following TSD across both arrays. In both arrays, significantly greater preparatory pupillary responses were found just prior to array onset. There was also a significant session by array interaction for pupillary responses, such that significantly greater dilation was found for the 3-letter array after TSD, while a nonsignificant decline in dilation was found following the 10-letter array after TSD.

CONCLUSIONS

These results suggest a complex relationship between attentional control and cognitive resource allocation following TSD. Sleep-deprived individuals may allocate more compensatory cognitive effort to easier tasks but choose to disengage from more challenging cognitive tasks that have little perceived reward or probability of success to preserve diminishing cognitive resources. More work is needed to better delineate the underlying neurological systems involved in these processing load-dependent attentional control mechanisms after TSD.

Brain reactivity to humorous films is affected by insomnia

STUDY OBJECTIVES

Emotional reactivity to negative stimuli has been investigated in insomnia, but little is known about emotional reactivity to positive stimuli and its neural representation.

METHODS

We used 3T fMRI to determine neural reactivity during the presentation of standardized short, 10-40-s, humorous films in insomnia patients (n=20, 18 females, aged 27.7 +/- 8.6 years) and age-matched individuals without insomnia (n=20, 19 females, aged 26.7 +/- 7.0 years), and assessed humour ratings through a visual analogue scale (VAS). Seed-based functional connectivity was analysed for left and right amygdala networks: group-level mixed-effects analysis (FLAME; FSL) was used to compare amygdala connectivity maps between groups.

RESULTS

fMRI seed-based analysis of the amygdala revealed stronger neural reactivity in insomnia patients than in controls in several brain network clusters within the reward brain network, without humour rating differences between groups (p = 0.6). For left amygdala connectivity, cluster maxima were in the left caudate (Z=3.88), left putamen (Z=3.79) and left anterior cingulate gyrus (Z=4.11), while for right amygdala connectivity, cluster maxima were in the left caudate (Z=4.05), right insula (Z=3.83) and left anterior cingulate gyrus (Z=4.29). Cluster maxima of the right amygdala network were correlated with hyperarousal scores in insomnia patients only.

CONCLUSIONS

Presentation of humorous films leads to increased brain activity in the neural reward network for insomnia patients compared to controls, related to hyperarousal features in insomnia patients, in the absence of humor rating group differences. These novel findings may benefit insomnia treatment interventions.

White matter microstructural abnormalities in primary insomnia: A systematic review of diffusion tensor imaging studies

Primary insomnia (PI), the most common sleep disorder, is primarily characterized by difficulties in initiating and maintaining sleep and deficits in daytime functioning. Study of white matter (WM) connections of the brain might provide valuable information regarding the underlying neural mechanism of PI. Diffusion tensor imaging (DTI) provides non-invasive access to the microstructural and network properties of brain WM, and thus, a great opportunity to quantitatively and sensitively study the human brain. The current literature of PI does not provide a consistent explanation of the etiology and pathology of the disorder; thus, we searched PubMed, EMBASE, and SCOPUS for DTI studies that compared WM integrity or network organization between PI patients and healthy controls to integrate all existing literature as an insight for further studies, and, hopefully, effective prevention and management of the disorder. English peer-reviewed full-text publications that investigated the diffusion indices of PI patients or those with insomnia symptoms compared with a group of healthy controls were included. We included 11 studies and extracted the data for qualitative synthesis. Except for one study, all studies were rated as high-quality, based on quality assessment. In aggregation, a total of 541 patients with PI and 679 healthy controls were included in this study. Our review of DTI studies suggests that WM disruptions in PI are better characterized in the context of neural networks. Frontostriatal, frontothalamic, and corticocortiscal networks, as well as the limbic system, seem to be the main neural networks with microstructural and network alterations in patients with PI. To illustrate, different parts of corona radiate and internal capsule within the corticosubcortical networks and superior longitudinal fasciculus within the corticocortical networks showed altered microstructural properties in PI patients. In view of the fact that the findings from individual studies are heterogeneous, it is difficult to derive consistent findings from the results, and the divergence of the findings must not be disregarded. Thus, this study is a starting point for future studies, and its implications for etiology and pathogenesis of insomnia should be regarded cautiously.

Relation of Decreased Functional Connectivity Between Left Thalamus and Left Inferior Frontal Gyrus to Emotion Changes Following Acute Sleep Deprivation

Objective: The thalamus is a key node for sleep-wake pathway gate switching during acute sleep deprivation (ASD), and studies have shown that it plays a certain role in emotion changes. However, there are no studies on the association between the thalamus and emotion changes in ASD. In this study, we used resting-state functional magnetic resonance imaging (R-fMRI) to explore whether changes in the functional connections between the thalamus and other brain regions are related to emotion changes and further explored the function of the thalamus under total ASD conditions.

Method: Thirty healthy, right-handed adult men underwent emotional assessment according to the Profile of Mood States Scale and R-fMRI scans before and after ASD. The correlations between changes in functional connectivity between the thalamus and other brain regions and emotion changes were then studied.

Results: Positive emotions and psychomotor performance were reduced, and negative emotions were increased following ASD. The functional connections between the left thalamus and left middle temporal gyrus, left inferior frontal gyrus, right thalamus, right inferior temporal gyrus, left middle temporal pole gyrus, right calcarine, left cuneus, left rectus and left medial superior frontal gyrus were significantly altered. Decreased functional connectivity between left thalamus and left inferior frontal gyrus related to emotion changes following ASD.

Conclusion: This study finds that functional changes in the thalamus are associated with emotion changes during ASD, suggesting that the left thalamus probably plays an essential role in emotion changes under ASD conditions.

Dysfunctional beliefs and attitudes about sleep are associated with regional homogeneity of left inferior occidental gyrus in primary insomnia patients: a preliminary resting state functional magnetic resonance imaging study

BACKGROUND

The neural mechanisms of sleep beliefs and attitudes in primary insomnia (PI) patients at resting state remain unclear. The aim of this study was to investigate the features of regional homogeneity (ReHo) in PI using resting-state functional magnetic resonance imaging (rsfMRI).

METHODS

Thirty-two PI patients and 34 normal controls (NC) underwent rsfMRI using a 3 T scanner at Tongde Hospital of Zhejiang Province. Participants were assessed with the Dysfunctional Beliefs and Attitudes about Sleep scale (DBAS-16) and Pittsburgh Sleep Quality Index (PSQI). Statistical analyses were performed to determine the regions in which ReHo differed between the two groups. Correlation analyses were performed between the ReHo index of each of these regions and DBAS-16 in PI patients.

RESULTS

PI patients showed increased ReHo values in the right superior frontal gyrus, and decreased ReHo values in the left cerebellar gyrus, left inferior occipital gyrus (IOG) and left amygdala compared with those of NC. ReHo values in the left IOG were negatively correlated with total DBAS-16 scores, and scores for "consequences of insomnia" and"worry/helplessness about sleep"in PI patients.

CONCLUSIONS

These results suggest that ReHo alterations in the left IOG may play an important role in the dysfunctional beliefs and attitudes about sleep in PI.

The effect of sleep medications on prospective and retrospective memory: a population-based study

Sleep medications, especially benzodiazepines, are known to cause motor and cognitive impairments as side-effects from their use. However, an evaluation of the effects of sleep medications in general on prospective and retrospective memory remains to be seen. Thus, the effects of the different types of sleep medicines were assessed using the total score and the 8 subscales of the Prospective and Retrospective Memory Questionnaire (PRMQ) in a representative sample from the Municipality of São Paulo. The effects of each type of medication on these same parameters were evaluated afterwards. Each analysis was performed controlling for different covariates to observe their degree of interference on the observed results. Impairment due to use of sleep aid medication was observed in 6 of the 8 subscales, as well in the overall score of the PRMQ when compared to non-users. Prospective subscales were particularly affected, even when controlling for highly interfering covariates such as depression and anxiety, and objective sleep variables related to sleep architecture and wakefulness in the night. Few effects were detected between the various types of medication even when controlling for covariates, suggesting that a sample with higher power is necessary to conduct a more detailed analysis. Using pharmacological aids to improve sleep may impair prospective and (to some extent) retrospective memory. Therefore, the relationship between sleep impairment, memory deficits and medication use must be considered by physicians.

Attention Performance Correlated With White Matter Structural Brain Networks in Shift Work Disorder

Neuroimaging studies have revealed that shift work disorder (SWD) affected the functional connectivity in specific brain regions and networks. However, topological disruptions in the structural connectivity of the white matter (WM) networks associated with attention function remain poorly understood. In the current study, we recruited 33 patients with SWD and 29 matched healthy subjects. The attention network test (ANT) was employed to investigate the efficiency of alerting, orienting, and executive control networks. The diffusion tensor imaging (DTI) tractography was used to construct the WM structural networks. The graph theory analysis was applied to detect the alterations of topological properties of structural networks. Our results showed lower alerting effect and higher executive effect for patients with SWD. Using the link-based analysis, 15 altered connectivity matrices (lower fiber numbers) were found between the two groups. Meanwhile, the graph theoretical analysis showed that the global efficiency and characteristic path length within SWD patients declined in contrast with the healthy controls. Furthermore, a significantly negative correlation was found between the executive effect and global network efficiency. Our findings provide the new insights into the fundamental architecture of interregional structural connectivity underlying attention deficits in SWD, which may be a potential biomarker for SWD.

Altered long- and short-range functional connectivity density associated with poor sleep quality in patients with chronic insomnia disorder: A resting-state fMRI study

INTRODUCTION

Previous neuroimaging studies have suggested that brain functional impairment and hyperarousal occur during the daytime among patients with chronic insomnia disorder (CID); however, alterations to the brain's intrinsic functional architecture and their association with sleep quality have not yet been documented.

METHODS

In this study, our aim was to investigate the insomnia-related alterations to the intrinsic connectome in patients with CID (n = 27) at resting state, with a data-driven approach based on graph theory assessment and functional connectivity density (FCD), which can be interpreted as short-range (intraregional) or long-range (interregional) mapping.

RESULTS

Compared with healthy controls with good sleep, CID patients showed significantly decreased long-range FCD in the dorsolateral prefrontal cortices and the putamen. These patients also showed decreased short-range FCD in their multimodal-processing regions, executive control network, and supplementary motor-related areas. Furthermore, several regions showed increased short-range FCD in patients with CID, implying hyper-homogeneity of local activity.

CONCLUSIONS

Together, these findings suggest that insufficient sleep during chronic insomnia widely affects cortical functional activities, including disrupted FCD and increased short-range FCD, which is associated with poor sleep quality.

Brain mechanisms of insomnia: new perspectives on causes and consequences

While insomnia is the second most common mental disorder, progress in our understanding of underlying neurobiological mechanisms has been limited. The present review addresses the definition and prevalence of insomnia and explores its subjective and objective characteristics across the 24-hour day. Subsequently, the review extensively addresses how the vulnerability to develop insomnia is affected by genetic variants, early life stress, major life events, and brain structure and function. Further supported by the clear mental health risks conveyed by insomnia, the integrated findings suggest that the vulnerability to develop insomnia could rather be found in brain circuits regulating emotion and arousal than in circuits involved in circadian and homeostatic sleep regulation. Finally, a testable model is presented. The model proposes that in people with a vulnerability to develop insomnia, the locus coeruleus is more sensitive to-or receives more input from-the salience network and related circuits, even during rapid eye movement sleep, when it should normally be sound asleep. This vulnerability may ignite a downward spiral of insufficient overnight adaptation to distress, resulting in accumulating hyperarousal, which, in turn, impedes restful sleep and moreover increases the risk of other mental health adversity. Sensitized brain circuits are likely to be subjectively experienced as "sleeping with one eye open". The proposed model opens up the possibility for novel intervention studies and animal studies, thus accelerating the ignition of a neuroscience of insomnia, which is direly needed for better treatment.

Succeeding in deactivating: associations of hair zinc levels with functional and structural neural mechanisms

Zinc is a biologically essential element and involved in a wide range of cellular processes. Here, we investigated the associations of zinc levels in hair with brain activity during the n-back working memory task using functional magnetic resonance imaging, fractional anisotropy (FA) of diffusion tensor imaging, and cognitive differences in a study cohort of 924 healthy young adults. Our findings showed that greater hair zinc levels were associated with lower brain activity during working memory in extensive areas in the default mode network (i.e., greater task-induced deactivation) as well as greater FA in white matter areas near the hippocampus and posterior limbs of the internal capsule. These findings advance previous non-neuroimaging findings of zinc's associations with excitability, excitability-associated disorders, and myelination.

Acoustic slow wave sleep enhancement via a novel, automated device improves executive function in middle-aged men

STUDY OBJECTIVES

As slow-wave activity (SWA) is critical for cognition, SWA-enhancing technologies provide an exciting opportunity to improve cognitive function. We focus on improving cognitive function beyond sleep-dependent memory consolidation, using an automated device, and in middle-aged adults, who have depleted SWA yet a critical need for maximal cognitive capacity in work environments.

METHODS

Twenty-four healthy adult males aged 35-48 years participated in a randomized, double-blind, cross-over study. Participants wore an automated acoustic stimulation device that monitored real-time sleep EEG. Following an adaptation night, participants were exposed to either acoustic tones delivered on the up phase of the slow-wave (STIM) or inaudible "tones" during equivalent periods of stimulation (SHAM). An executive function test battery was administered after the experimental night.

RESULTS

STIM resulted in an increase in delta (0.5-4 Hz) activity across the full-night spectra, with enhancement being maximal at 1 Hz. SWA was higher for STIM relative to SHAM. Although no group differences were observed in any cognitive outcomes, due to large individual differences in SWA enhancement, higher SWA responders showed significantly improved verbal fluency and working memory compared with nonresponders. Significant positive associations were found between SWA enhancement and improvement in these executive function outcomes.

CONCLUSIONS

Our study suggests that (1) an automated acoustic device enhances SWA; (2) SWA enhancement improves executive function; (3) SWA enhancement in middle-aged men may be an important therapeutic target for enhancing cognitive function; and (4) there is a need to examine interindividual responses to acoustic stimulation and its effect on subsequent cognitive function.

CLINICAL TRIAL REGISTRATION

This study has been registered with the Australian New Zealand Clinical Trials Registry. "The efficacy of acoustic tones in slow-wave sleep enhancement and cognitive function in healthy adult males". https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=371548&isReview=true.

REGISTRATION

ACTRN12617000399392.

Affect and Arousal in Insomnia: Through a Lens of Neuroimaging Studies

PURPOSE OF REVIEW

Previous research has struggled with identifying clear-cut, objective counterparts to subjective distress in insomnia. Approaching this discrepancy with a focus on hyperarousal and dysfunctional affective processes, studies examining brain structures and neural networks involved in affect and arousal are reviewed and conclusions for an updated understanding of insomnia are drawn.

RECENT FINDINGS

Recent studies found that amygdala reactivity, morphometry and adaptation in insomnia are altered, indicating that processing of negative stimuli is intensified and more lasting. Also, patients with insomnia show aberrant connectivity in the default mode network (DMN) and the salience network (SN), which is associated with subjective sleep disturbances, hyperarousal, maladaptive emotion regulation and disturbed integration of emotional states. The limbic circuit is assumed to play a crucial role in enhanced recall of negative experiences. There is reason to consider insomnia as a disorder of affect and arousal. Dysregulation of the limbic circuit might perpetuate impaired connectivity in the DMN and the SN. However, the interplay between the networks is yet to be researched.

Functional Connectivity Abnormalities of Brain Regions With Structural Deficits in Primary Insomnia Patients

OBJECTIVES

The present study examined the abnormal resting state functional connections (RSFCs) in structural deficit brain regions of primary insomnia (PI) patients.

METHODS

Thirty-three PI patients and 38 well-matched healthy controls participated in our study. We used voxel-based morphometry and RSFC to study functional connectivity abnormalities of brain regions with structural deficits in PI patients.

RESULTS

PI patients showed decreased gray matter (GM) volume in the left dorsolateral prefrontal cortex, left orbitofrontal cortex (OFC), bilateral middle frontal gyrus (MFC), right inferior frontal gyrus (IFG), and left inferior temporal gyrus. Gray matter volume in the right MFC negatively correlated with Self-Rating Scale of Sleep (SRSS) scores, and GM volume in the right IFG negatively correlated with SRSS and Insomnia Severity Index (ISI) scores. Therefore, the right MFC and right IFG were selected as regions of interest for RSFC analysis. PI patients had weakened RSFC between the right inferior parietal gyrus (IPC) and the right MFC compared to the healthy controls and between the left OFC and right IFG. The RSFC between the right MFC and right IPC negatively correlated with SRSS scores. The RSFC between the right IFG and left OFC negatively correlated with SRSS, ISI, SAS, and SDS scores.

CONCLUSIONS

The present study found structural changes in the right MFC and right IFG accompanied by RSFC changes. This finding may provide novel insights into the neural mechanisms of PI via combining structural and functional modality information.

Effects of insomnia symptoms and objective short sleep duration on memory performance in youths

Sleep quantity and quality are both important for optimal development and functioning during youth. Yet few studies have examined the effects of insomnia symptoms and objective short sleep duration on memory performance among adolescents and young adults. One-hundred and ninety participants (female: 61.6%) aged from 12 to 24 years completed this study. All participants underwent a clinical interview, a 7-day actigraphic assessment, a battery of self-report questionnaires and cognitive tests to assess working memory and episodic memory. Insomnia symptoms were defined as a score ≥ 9 on the Insomnia Severity Index, and objective short sleep duration was defined as average total sleep time less than 7 hr for those aged 12-17 years, and 6 hr for those aged 18 years and above as assessed by actigraphy. Insomnia symptoms were significantly associated with worse self-perceived memory (p < .05) and poorer performance on the digit span task (p < .01), but not the dual N-back task and verbal learning task. There was no significant difference in any of the memory measures between participants with objective short sleep duration and their counterparts. No interaction effect was found between insomnia and short sleep duration on any of the objective memory outcomes. Insomnia symptoms, but not objective short sleep duration, were associated with poorer subjective memory and objective working memory performance in youths. Further studies are needed to investigate the underlying mechanisms linking insomnia and memory impairments, and to delineate the long-term impacts of insomnia on other aspects of neurocognitive functioning in youth.

Onset of regular cannabis use and young adult insomnia: an analysis of shared genetic liability

STUDY OBJECTIVES

Estimate the genetic and environmental influences on the relationship between onset of regular cannabis use and young adult insomnia.

METHODS

In a population-based twin cohort of 1882 twins (56% female, mean age = 22.99, SD = 2.97) we explored the genetic/environmental etiology of the relationship between onset of regular cannabis use and insomnia-related outcomes via multivariate twin models.

RESULTS

Controlling for sex, current depression symptoms, and prior diagnosis of an anxiety or depression disorder, adult twins who reported early onset for regular cannabis use (age 17 or younger) were more likely to have insomnia (β = 0.07, p = 0.024) and insomnia with short sleep on weekdays (β = 0.08, p = 0.003) as young adults. We found significant genetic contributions for the onset of regular cannabis use (a2 = 76%, p < 0.001), insomnia (a2 = 44%, p < 0.001), and insomnia with short sleep on weekdays (a2 = 37%, p < 0.001). We found significant genetic correlations between onset of regular use and both insomnia (rA = 0.20, p = 0.047) and insomnia with short sleep on weekdays (rA = 0.25, p = 0.008) but no significant environmental associations between these traits.

CONCLUSIONS

We found common genetic liabilities for early onset of regular cannabis use and insomnia, implying pleiotropic influences of genes on both traits.