Impaired visual processing in patients with insomnia disorder revealed by a dissociation in visual search

Effects of acupuncture at limb Acupoints-Guangming (GB37) on UDVA, CS, and EEG microstate in myopia

Introduction

Acupuncture is beneficial in improving visual function for myopi periocular acupoints Taiyang can improve contrast sensitivity (CS). In this study, we aim to further investigate the impact of acupuncture at the limbs acupoints-Guangming(GB37) acupoint on visual function, and the neural mechanism of acupuncture at the GB37 acupoint improving visual function through electroencephalography (EEG) microstate.

Methods

A total of 22 myopia were recruited. Uncorrected distance visual acuity (UDVA) and CS of myopic patients were tested before and after acupuncture, and EEG data were recorded throughout the entire acupuncture procedure.

Results

Our study found that compared with pre-acupuncture, the UDVA and CS of both eyes at each spatial frequency were improved; compared with the resting state of pre-acupuncture, the duration, occurrence and contribution of microstate A were significantly increased, while those of microstate D were decreased during the post-acupuncture state. The duration of microstate A was positively correlated with the CS. There was no correlation between UDVA and EEG microstates.

Discussion

Acupuncture at GB37 can improve the UDVA and CS in myopic patients, which may be related to microstate A.

Deciphering the impairment of perimenopausal insomnia on visual search from a neurocognitive processing perspective

STUDY OBJECTIVES

Perimenopausal insomnia (PMI) is associated with observable performance impairments in visual search tasks. This study examines how various cognitive processing stages contribute to search performance delays in PMI compared to healthy controls (HCs).

METHODS

We recruited 76 participants diagnosed with PMI and 63 HCs. Event-related potentials (ERPs) were recorded as participants engaged in a visual search task, reporting the orientation of a color popout target within an array of ellipses. We analyzed group differences in behavioral performance and ERP components across cognitive processing stages.

RESULTS

Compared to HCs, PMI patients exhibited behavioral response delays, although accuracy was not different between groups. Electrophysiological analyses revealed group differences across several ERP components. Firstly, the N1 component's amplitude increased bilaterally, suggesting enhanced visual sensory processing. Secondly, a slower and smaller N2pc indicated reduced attentional orienting. Thirdly, a decreased sustained posterior-contralateral negativity amplitude pointed to deficits in target discrimination. Fourthly, an increased amplitude of the stimulus-locked lateralized readiness potential (LRP), with unchanged latency, suggested heightened neural inputs for maintaining motor initiation speed. Fifthly, prolonged response-locked LRP latency indicated slower motor execution. Finally, these changes in ERP components, along with significant correlations between LRP components and insomnia symptoms, suggest potential neural biomarkers for PMI.

CONCLUSIONS

Our findings provide high-temporal-resolution insights into the neurocognitive disruptions associated with PMI, highlighting how sleep disturbances affect cognitive processing in visual tasks. These insights enhance our understanding of PMI and contribute to discussions on neural mechanisms driving behavioral performance in various conditions.

Resting-State EEG Reveals Abnormal Microstate Characteristics of Depression with Insomnia

Previous research revealed various aspects of resting-state EEG for depression and insomnia. However, the EEG characteristics of depressed subjects with insomnia are rarely studied, especially EEG microstates that capture the dynamic activities of the large-scale brain network. To fill these research gaps, the present study collected resting-state EEG data from 32 subclinical depression subjects with insomnia (SDI), 31 subclinical depression subjects without insomnia (SD), and 32 healthy controls (HCs). Four topographic maps were generated from clean EEG data after clustering and rearrangement. Temporal characteristics were obtained for statistical analysis, including cross-group variance analysis (ANOVA) and intra-group correlation analysis. In our study, the global clustering of all individuals in the EEG microstate analysis revealed the four previously discovered categories of microstates (A, B, C, and D). The occurrence of microstate B was lower in SDI than in SD and HC subjects. The correlation analysis showed that the total Pittsburgh Sleep Quality Index (PSQI) score negatively correlated with the occurrence of microstate C in SDI (r = - 0.415, p < 0.05). Conversely, there was a positive correlation between Self-rating Depression Scale (SDS) scores and the duration of microstate C in SD (r = 0.359, p < 0.05). These results indicate that microstates reflect altered large-scale brain network dynamics in subclinical populations. Abnormalities in the visual network corresponding to microstate B are an electrophysiological characteristic of subclinical individuals with symptoms of depressive insomnia. Further investigation is needed for microstate changes related to high arousal and emotional problems in people suffering from depression and insomnia.

Altered functional connectivity strength in chronic insomnia associated with gut microbiota composition and sleep efficiency

BACKGROUND

There is limited evidence on the link between gut microbiota (GM) and resting-state brain activity in patients with chronic insomnia (CI). This study aimed to explore the alterations in brain functional connectivity strength (FCS) in CI and the potential associations among altered FCS, GM composition, and neuropsychological performance indicators.

MATERIALS AND METHODS

Thirty CI patients and 34 age- and gender-matched healthy controls (HCs) were recruited. Each participant underwent resting-state functional magnetic resonance imaging (rs-fMRI) for the evaluation of brain FCS and was administered sleep-, mood-, and cognitive-related questionnaires for the evaluation of neuropsychological performance. Stool samples of CI patients were collected and subjected to 16S rDNA amplicon sequencing to assess the relative abundance (RA) of GM. Redundancy analysis or canonical correspondence analysis (RDA or CCA, respectively) was used to investigate the relationships between GM composition and neuropsychological performance indicators. Spearman correlation was further performed to analyze the associations among alterations in FCS, GM composition, and neuropsychological performance indicators.

RESULTS

The CI group showed a reduction in FCS in the left superior parietal gyrus (SPG) compared to the HC group. The correlation analysis showed that the FCS in the left SPG was correlated with sleep efficiency and some specific bacterial genera. The results of CCA and RDA showed that 38.21% (RDA) and 24.62% (CCA) of the GM composition variation could be interpreted by neuropsychological performance indicators. Furthermore, we found complex relationships between Alloprevotella, specific members of the family Lachnospiraceae, Faecalicoccus, and the FCS alteration, and neuropsychological performance indicators.

CONCLUSION

The brain FCS alteration of patients with CI was related to their GM composition and neuropsychological performance indicators, and there was also an association to some extent between the latter two, suggesting a specific interaction pattern among the three aspects: brain FCS alteration, GM composition, and neuropsychological performance indicators.

Objective Measures of Cognitive Performance in Sleep Disorder Research

Neurocognitive tests offer objective and reliable assessment of patients' status and progress. However, there is no consensus on how to use neurocognitive assessment in sleep disorder research. An effective use of neurocognitive assessment must be based on standardized practices and have a firm theoretic basis. The aim of this review is to offer an overview of how different tests have been used in the field, mapping each test onto a corresponding cognitive domain and propose how to move forward with a suggested cognitive battery of tests covering all major cognitive domains.

Impact of daytime sleepiness and insomnia on simple and complex cognitive task performances

OBJECTIVE

To examine the individual and combined effects of daytime sleepiness and insomnia disorder (ID) on measures of cognitive functioning.

DESIGN AND SETTING

This study was conducted at a medical center using a cross-sectional research design.

PARTICIPANTS

35 persons with ID (Mage = 40.6 years; 25 women) and 54 normal sleepers (NS; Mage = 31.5 years; 38 women).

METHODS AND MEASURES

Participants underwent two nights of home-based polysomnography (PSG) followed by daytime testing with a four-trial Multiple Sleep Latency Test (MSLT). Before each MSLT nap, they completed a computer-administered battery of reaction time tasks. Measures of response latencies and response accuracy were tabulated and used as dependent measures. The ID and NS groups were each subdivided into "alert" (eg, MSLT mean latency > 8 min) and "sleepy" (eg, MSLT mean latency ≤ 8 min) subgroups to identify hyperaroused persons with ID and allow for their comparisons with the other participant subgroups.

RESULTS

Multivariate analyses of variance showed a significant main effect for level of daytime sleepiness (F [1, 84] = 8.52, p = 0.0045) on simpler performance tasks and a significant main effect for presence vs. absence of ID (F [1,84] = 6.62, p = 0.012) on complex tasks. A lack of significant participant type x MSLT alertness level interactions in study analyses suggested those ID participants with presumed hyperaousal were not relatively more impaired than the other participant subgroups.

CONCLUSIONS

Daytime performance deficits on simple tasks seem most dependent on individuals' levels of daytime sleepiness, whereas performance deficits on more complex tasks appears related to the presence of ID. Therefore, it seems best to use complex performance measures both to document cognitive deficits among those with ID and to determine if insomnia treatments reduce such impairments.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02290405.

Tired and lack focus? Insomnia increases distractibility

Chronic insomnia is associated with subjective daytime cognitive dysfunction, but objective corroborative data are often lacking. In this study, we use Perceptual Load Theory to objectively assess distractibility in participants with insomnia ( N = 23) compared with age- and sex-matched controls ( N = 23). Following overnight supervised sleep observation, all participants completed a selective attention task which varied in the level of perceptual load and distractor congruency. The insomnia group was found to be more distracted than controls, whereas their selective attention mechanism appeared to be intact, with reduced distractor processing under high load for both groups. Insomnia symptom severity was positively correlated with participant distractibility. These findings suggest that there are insomnia-related daytime cognitive impairments that are likely to arise from compromised cognitive control rather than an ineffective selective attention mechanism. This task may be clinically useful in assessing daytime impairments, and potentially treatment response, in those with insomnia.

Primary insomnia patients' performances during simulated car following and urban driving in the afternoon

According to epidemiological studies, insomnia is associated with an increase in risk of traffic accidents. Recent investigations revealed that patients with insomnia had driving performance impairment under monotonous conditions. However, it is unclear whether other driving abilities may be impacted by insomnia, especially those needing more attentional resources than those involved in monotonous driving. Other findings revealed that impaired performances are more likely to occur with the increase of cognitive demands. However, such tests did not reflect difficulties in situations of everyday life expressed by patients with insomnia, such as driving in an urban environment with traffic and critical situations. Therefore, behaviour in situations encountered in everyday life has to be explored. The aim of the present study was to assess driving performances of patients with insomnia in daily routine tasks such as urban and car-following tests. For this purpose, 15 patients with insomnia and 16 good sleepers performed an urban test of driving with original risk scenarios and a car-following test during the middle afternoon. No significant behavioural difference between patients with insomnia and good sleepers has been found in both the urban test and the car-following test, showing that patients with insomnia have no impairment in behaviour implicated in daily contexts driving tasks of short period of time performed in the late afternoon. Although our results provide a first step towards knowledge of behavioural performance during daily routine driving tasks in patients with insomnia, future studies are needed using on-the-road driving tests and/or different population of patients with insomnia before generalisation.