Functional connectivity within and between intrinsic brain networks correlates with trait mind wandering

Dysfunction of large-scale brain networks underlying cognitive impairments in shift work disorder

It has been demonstrated that shift work can affect cognitive functions. Several neuroimaging studies have revealed altered brain function and structure for patients with shift work disorder (SWD). However, knowledge on the dysfunction of large-scale brain networks underlying cognitive impairments in shift work disorder is limited. This study aims to identify altered functional networks associated with cognitive declines in shift work disorder, and to assess their potential diagnostic value. Thirty-four patients with shift work disorder and 36 healthy controls (HCs) were recruited to perform the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and resting-state functional scans. After surface-based preprocessing, we calculated within- and between-network functional connectivity (FC) using the Dosenbach atlas. Moreover, correlation analysis was done between altered functional connectivity of large-scale brain networks and scores of cognitive assessments in patients with shift work disorder. Finally, we established a classification model to provide features for patients with shift work disorder concerning the disrupted large-scale networks. Compared with healthy controls, increased functional connectivity within-networks across the seven brain networks, and between-networks involving ventral attention network (VAN)-subcortical network (SCN), SCN-frontoparietal network (FPN), and somatosensory network (SMN)-SCN were observed in shift work disorder. Decreased functional connectivity between brain networks was found in shift work disorder compared with healthy controls, including visual network (VN)-FPN, VN-default mode network (DMN), SMN-DMN, dorsal attention network (DAN)-DMN, VAN-DMN, and FPN-DMN. Furthermore, the altered functional connectivity of large-scale brain networks was significantly correlated with scores of immediate memory, visuospatial, and delayed memory in patients with shift work disorder, respectively. Abnormal functional connectivity of large-scale brain networks may play critical roles in cognitive dysfunction in shift work disorder. Our findings provide new evidence to interpret the underlying neural mechanisms of cognitive impairments in shift work disorder.

Conscious but not thinking-Mind-blanks during visuomotor tracking: An fMRI study of endogenous attention lapses

Attention lapses (ALs) are complete lapses of responsiveness in which performance is briefly but completely disrupted and during which, as opposed to microsleeps, the eyes remain open. Although the phenomenon of ALs has been investigated by behavioural and physiological means, the underlying cause of an AL has largely remained elusive. This study aimed to investigate the underlying physiological substrates of behaviourally identified endogenous ALs during a continuous visuomotor task, primarily to answer the question: Were the ALs during this task due to extreme mind-wandering or mind-blanks? The data from two studies were combined, resulting in data from 40 healthy non-sleep-deprived subjects (20M/20F; mean age 27.1 years, 20-45). Only 17 of the 40 subjects were used in the analysis due to a need for a minimum of two ALs per subject. Subjects performed a random 2-D continuous visuomotor tracking task for 50 and 20 min in Studies 1 and 2, respectively. Tracking performance, eye-video, and functional magnetic resonance imaging (fMRI) were recorded simultaneously. A human expert visually inspected the tracking performance and eye-video recordings to identify and categorise lapses of responsiveness as microsleeps or ALs. Changes in neural activity during 85 ALs (17 subjects) relative to responsive tracking were estimated by whole-brain voxel-wise fMRI and by haemodynamic response (HR) analysis in regions of interest (ROIs) from seven key networks to reveal the neural signature of ALs. Changes in functional connectivity (FC) within and between the key ROIs were also estimated. Networks explored were the default mode network, dorsal attention network, frontoparietal network, sensorimotor network, salience network, visual network, and working memory network. Voxel-wise analysis revealed a significant increase in blood-oxygen-level-dependent activity in the overlapping dorsal anterior cingulate cortex and supplementary motor area region but no significant decreases in activity; the increased activity is considered to represent a recovery-of-responsiveness process following an AL. This increased activity was also seen in the HR of the corresponding ROI. Importantly, HR analysis revealed no trend of increased activity in the posterior cingulate of the default mode network, which has been repeatedly demonstrated to be a strong biomarker of mind-wandering. FC analysis showed decoupling of external attention, which supports the involuntary nature of ALs, in addition to the neural recovery processes. Other findings were a decrease in HR in the frontoparietal network before the onset of ALs, and a decrease in FC between default mode network and working memory network. These findings converge to our conclusion that the ALs observed during our task were involuntary mind-blanks. This is further supported behaviourally by the short duration of the ALs (mean 1.7 s), which is considered too brief to be instances of extreme mind-wandering. This is the first study to demonstrate that at least the majority of complete losses of responsiveness on a continuous visuomotor task are, if not due to microsleeps, due to involuntary mind-blanks.

Creative tempo: Spatiotemporal dynamics of the default mode network in improvisational musicians

The intrinsic dynamics of human brain activity display a recurring pattern of anti-correlated activity between the default mode network (DMN), associated with internal processing and mentation, and task positive regions, associated with externally directed attention. In human functional magnetic resonance imaging (fMRI) data, this anti-correlated pattern is detectable on the infraslow timescale (<0.1 Hz) as a quasi-periodic pattern (QPP). While the DMN is implicated in creativity and musicality in traditional time-averaged functional connectivity studies, no one has yet explored how creative training may alter dynamic spatiotemporal patterns involving the DMN such as QPPs. In the present study, we compare the outputs of two QPP detection approaches, sliding window algorithm and complex principal components analysis (cPCA). We apply both methods to an existing dataset of musicians captured with resting state fMRI, grouped as either classical, improvisational, or minimally trained non-musicians. The original time-averaged functional connectivity (FC) analysis of this dataset used improvisation as a proxy for creative thinking and found that the DMN and visual networks (VIS) display higher connectivity in improvisational musicians. We expand upon this dataset's original study and find that QPP analysis detects convergent results at the group level with both methods. In improvisational musicians, dynamic functional correlation in the group-averaged QPP was found to be increased between the DMN-VIS and DMN-FPN for both the QPP algorithm and complex principal components analysis (cPCA) methods. Additionally, we found an unexpected increase in FC in the group-averaged QPP between the dorsal attention network and amygdala in improvisational musicians; this result was not reported in the original seed-based study of this dataset. The current study represents a novel application of two dynamic FC detection methods with results that replicate and expand upon previous seed-based FC findings. The results show the robustness of both the QPP phenomenon and its detection methods. This study also demonstrates the value of dynamic FC methods in reproducing seed-based findings and their promise in detecting group-wise or individual differences that may be missed by traditional seed-based resting state fMRI studies.

Recent advances in the neuroscience of spontaneous and off-task thought: implications for mental health

People spend a remarkable 30-50% of awake life thinking about something other than what they are currently doing. These experiences of being "off-task" can be described as spontaneous thought when mental dynamics are relatively flexible. Here we review recent neuroscience developments in this area and consider implications for mental wellbeing and illness. We provide updated overviews of the roles of the default mode network and large-scale network dynamics, and we discuss emerging candidate mechanisms involving hippocampal memory (sharp-wave ripples, replay) and neuromodulatory (noradrenergic and serotonergic) systems. We explore how distinct brain states can be associated with or give rise to adaptive and maladaptive forms of thought linked to distinguishable mental health outcomes. We conclude by outlining new directions in the neuroscience of spontaneous and off-task thought that may clarify mechanisms, lead to personalized biomarkers, and facilitate therapy developments toward the goals of better understanding and improving mental health.

Altered Functional Connectivity of Large-Scale Brain Networks in Psychogenic Erectile Dysfunction Associated with Cognitive Impairments

Purpose

Several studies have demonstrated that psychogenic erectile dysfunction (pED) patients potentially suffer from cognitive dysfunction. Despite that previous neuroimaging studies have reported abnormal functional connections of brain areas associated with cognitive function in pED, the underlying mechanisms of cognitive dysfunction in pED remain elusive. This study aims to investigate the underlying mechanisms of cognitive dysfunction by analyzing large-scale brain networks.

Patients and Methods

A total of 30 patients with pED and 30 matched healthy controls (HCs) were recruited in this study and scanned by resting-state functional magnetic resonance imaging. The Dosenbach Atlas was used to define large-scale networks across the brain. The resting-state functional connectivity (FC) within and between large-scale brain networks was calculated to compare pED patients with HCs. The relationship among cognitive performances and altered FC of large-scale brain networks was further explored in pED patients.

Results

Our results showed that the decreased FC within visual network, and between visual network and default mode network, visual network and frontoparietal network, and ventral attention and default mode network were found in pED patients. Furthermore, there was a positive correlation between immediate memory score and FC within visual network. The visuospatial score was negatively correlated with decreased FC between ventral attention network and default mode network.

Conclusion

Taken together, our findings revealed the relationship between cognitive impairments and altered FC between large-scale brain networks in pED patients, providing the new evidence about the neural mechanisms of cognitive dysfunction in pED patients.

Aberrant connectivity in the right amygdala and right middle temporal gyrus before and after a suicide attempt: Examining markers of suicide risk

Functional neuroimaging has the potential to help identify those at risk for self-injurious thoughts and behaviors, as well as inform neurobiological mechanisms that contribute to suicide. Based on whole-brain patterns of functional connectivity, our previous work identified right amygdala and right middle temporal gyrus (MTG) connectivity patterns that differentiated Veterans with a history of a suicide attempt (SA) from a Veteran control group. In this study, we aimed to replicate and extend our previous findings by examining whether this aberrant connectivity was present prior to and after a SA. In a trauma-exposed Veteran sample (92 % male, mean age = 34), we characterized if the right amygdala and right MTG connectivity differed between a psychiatric control sample (n = 56) and an independent sample of Veterans with a history of SA (n = 17), using fMRI data before and after the SA. Right MTG and amygdala connectivity differed between Veterans with and without a history of SA (replication), while MTG connectivity also distinguished Veterans prior to engaging in a SA (extension). In a second study, neither MTG or amygdala connectivity differed between those with current suicidal ideation (n = 27) relative to matched psychiatric controls (n = 27). These results indicate a potential stable marker of suicide risk (right MTG connectivity) as well as a potential marker of acute risk of or recent SA (right amygdala connectivity) that are independent of current ideation.

The interaction between random and systematic visual stimulation and infraslow quasiperiodic spatiotemporal patterns of whole brain activity

One prominent feature of the infraslow BOLD signal during rest or task is quasi-periodic spatiotemporal pattern (QPP) of signal changes that involves an alternation of activity in key functional networks and propagation of activity across brain areas, and that is known to tie to the infraslow neural activity involved in attention and arousal fluctuations. This ongoing whole-brain pattern of activity might potentially modify the response to incoming stimuli or be modified itself by the induced neural activity. To investigate this, we presented checkerboard sequences flashing at 6Hz to subjects. This is a salient visual stimulus that is known to produce a strong response in visual processing regions. Two different visual stimulation sequences were employed, a systematic stimulation sequence in which the visual stimulus appeared every 20.3 secs and a random stimulation sequence in which the visual stimulus occurred randomly every 14~62.3 secs. Three central observations emerged. First, the two different stimulation conditions affect the QPP waveform in different aspects, i.e., systematic stimulation has greater effects on its phase and random stimulation has greater effects on its magnitude. Second, the QPP was more frequent in the systematic condition with significantly shorter intervals between consecutive QPPs compared to the random condition. Third, the BOLD signal response to the visual stimulus across both conditions was swamped by the QPP at the stimulus onset. These results provide novel insights into the relationship between intrinsic patterns and stimulated brain activity.

Evaluating brain spectral and connectivity differences between silent mind-wandering and trance states

Trance is an altered state of consciousness characterized by alterations in cognition. In general, trance states induce mental silence (i.e., cognitive thought reduction), and mental silence can induce trance states. Conversely, mind-wandering is the mind's propensity to stray its attention away from the task at hand and toward content irrelevant to the current moment, and its main component is inner speech. Building on the previous literature on mental silence and trance states and incorporating inverse source reconstruction advances, the study's objectives were to evaluate differences between trance and mind-wandering states using: (1) electroencephalography (EEG) power spectra at the electrode level, (2) power spectra at the area level (source reconstructed signal), and (3) EEG functional connectivity between these areas (i.e., how they interact). The relationship between subjective trance depths ratings and whole-brain connectivity during trance was also evaluated. Spectral analyses revealed increased delta and theta power in the frontal region and increased gamma in the centro-parietal region during mind-wandering, whereas trance showed increased beta and gamma power in the frontal region. Power spectra at the area level and pairwise comparisons of the connectivity between these areas demonstrated no significant difference between the two states. However, subjective trance depth ratings were inversely correlated with whole-brain connectivity in all frequency bands (i.e., deeper trance is associated with less large-scale connectivity). Trance allows one to enter mentally silent states and explore their neurophenomenological processes. Limitations and future directions are discussed.

The interaction between random and systematic visual stimulation and infraslow quasiperiodic spatiotemporal patterns of whole brain activity

One prominent feature of the infraslow BOLD signal during rest or task is quasi-periodic spatiotemporal pattern (QPP) of signal changes that involves an alternation of activity in key functional networks and propagation of activity across brain areas, and that is known to tie to the infraslow neural activity involved in attention and arousal fluctuations. This ongoing whole-brain pattern of activity might potentially modify the response to incoming stimuli or be modified itself by the induced neural activity. To investigate this, we presented checkerboard sequences flashing at 6Hz to subjects. This is a salient visual stimulus that is known to produce a strong response in visual processing regions. Two different visual stimulation sequences were employed, a systematic stimulation sequence in which the visual stimulus appeared every 20.3 secs and a random stimulation sequence in which the visual stimulus occurred randomly every 14∼62.3 secs. Three central observations emerged. First, the two different stimulation conditions affect the QPP waveform in different aspects, i.e., systematic stimulation has greater effects on its phase and random stimulation has greater effects on its magnitude. Second, the QPP was more frequent in the systematic condition with significantly shorter intervals between consecutive QPPs compared to the random condition. Third, the BOLD signal response to the visual stimulus across both conditions was swamped by the QPP at the stimulus onset. These results provide novel insights into the relationship between intrinsic patterns and stimulated brain activity.

EEG complexity during mind wandering: A multiscale entropy investigation

Our attention often drifts away from the ongoing task to task-unrelated thoughts, a phenomenon commonly referred to as mind wandering. Ample studies dedicated to delineating its electrophysiological correlates have revealed distinct event-related potentials (ERP) and spectral patterns associated with mind wandering. It remains less clear whether the complexity of the electroencephalography (EEG) changes when our minds wander, a metric that captures the predictability of the time series at varying timescales. Accordingly, this study investigated whether mind wandering impacts EEG signal complexity. We further explored whether such effects differ across timescales, and change in a context-dependent manner as indexed by global and local levels of processing. To address this, we recorded participants' EEG while they completed Navon's global and local processing task and occasionally reported whether they were on-task or mind wandering throughout the task. We found that brain signal complexity as indexed by multiscale entropy decreased at medium timescales in centro-parietal regions and increased at coarse timescales in anterior and posterior regions during mind wandering, as compared to the on-task state, for global processing. Moreover, global processing showed increased complexity at fine to medium timescales compared to local processing. Finally, behavioral performance revealed a context-dependent effect in accuracy measures, with mind wandering showing lower accuracy compared to the on-task state only during the local condition. Taken together, these results indicate that changes in brain signal complexity across timescales may be an important feature of mind wandering.

Beyond mind wandering: Performance variability and neural activity during off-task thought and other attention lapses

To study the characteristics of attention lapses, a metronome response task and experience sampling were employed while recording fMRI data. Thought prompts queried several attention states (on-task, task-related interference, off-task, inattention). Off-task thoughts were probed on whether they arose in a spontaneous or constrained (i.e., directed) manner. Increased fMRI activation was observed in the default mode network during off-task thought and in subregions of the anterior cingulate cortex and inferior frontal gyrus during inattention. Activation also increased in the left hippocampus during constrained thoughts. Functional connectivity increased between the left superior temporal sulcus and right temporoparietal junction for constrained compared to spontaneous thoughts. Overall, behavioral results indicated a monotonic increase in performance variability from on-task to inattention. However, subtle but consistent differences were observed between self-reported attention state and performance. Results are discussed from perspectives of mind wandering frameworks, the function of brain networks, and the role of engagement in off-task thought.

Amplitudes of resting-state functional networks - investigation into their correlates and biophysical properties

Resting-state fMRI studies have shown that multiple functional networks, which consist of distributed brain regions that share synchronised spontaneous activity, co-exist in the brain. As these resting-state networks (RSNs) have been thought to reflect the brain's intrinsic functional organization, intersubject variability in the networks' spontaneous fluctuations may be associated with individuals' clinical, physiological, cognitive, and genetic traits. Here, we investigated resting-state fMRI data along with extensive clinical, lifestyle, and genetic data collected from 37,842 UK Biobank participants, with the object of elucidating intersubject variability in the fluctuation amplitudes of RSNs. Functional properties of the RSN amplitudes were first examined by analyzing correlations with the well-established between-network functional connectivity. It was found that a network amplitude is highly correlated with the mean strength of the functional connectivity that the network has with the other networks. Intersubject clustering analysis showed the amplitudes are most strongly correlated with age, cardiovascular factors, body composition, blood cell counts, lung function, and sex, with some differences in the correlation strengths between sensory and cognitive RSNs. Genome-wide association studies (GWASs) of RSN amplitudes identified several significant genetic variants reported in previous GWASs for their implications in sleep duration. We provide insight into key factors determining RSN amplitudes and demonstrate that intersubject variability of the amplitudes primarily originates from differences in temporal synchrony between functionally linked brain regions, rather than differences in the magnitude of raw voxelwise BOLD signal changes. This finding additionally revealed intriguing differences between sensory and cognitive RSNs with respect to sex effects on temporal synchrony and provided evidence suggesting that synchronous coactivations of functionally linked brain regions, and magnitudes of BOLD signal changes, may be related to different genetic mechanisms. These results underscore that intersubject variability of the amplitudes in health and disease need to be interpreted largely as a measure of the sum of within-network temporal synchrony and amplitudes of BOLD signals, with a dominant contribution from the former.

Evidence from "big data" for the default-mode hypothesis of ADHD: a mega-analysis of multiple large samples

We sought to identify resting-state characteristics related to attention deficit/hyperactivity disorder, both as a categorical diagnosis and as a trait feature, using large-scale samples which were processed according to a standardized pipeline. In categorical analyses, we considered 1301 subjects with diagnosed ADHD, contrasted against 1301 unaffected controls (total N = 2602; 1710 males (65.72%); mean age = 10.86 years, sd = 2.05). Cases and controls were 1:1 nearest neighbor matched on in-scanner motion and key demographic variables and drawn from multiple large cohorts. Associations between ADHD-traits and resting-state connectivity were also assessed in a large multi-cohort sample (N = 10,113). ADHD diagnosis was associated with less anticorrelation between the default mode and salience/ventral attention (B = 0.009, t = 3.45, p-FDR = 0.004, d = 0.14, 95% CI = 0.004, 0.014), somatomotor (B = 0.008, t = 3.49, p-FDR = 0.004, d = 0.14, 95% CI = 0.004, 0.013), and dorsal attention networks (B = 0.01, t = 4.28, p-FDR < 0.001, d = 0.17, 95% CI = 0.006, 0.015). These results were robust to sensitivity analyses considering comorbid internalizing problems, externalizing problems and psychostimulant medication. Similar findings were observed when examining ADHD traits, with the largest effect size observed for connectivity between the default mode network and the dorsal attention network (B = 0.0006, t = 5.57, p-FDR < 0.001, partial-r = 0.06, 95% CI = 0.0004, 0.0008). We report significant ADHD-related differences in interactions between the default mode network and task-positive networks, in line with default mode interference models of ADHD. Effect sizes (Cohen's d and partial-r, estimated from the mega-analytic models) were small, indicating subtle group differences. The overlap between the affected brain networks in the clinical and general population samples supports the notion of brain phenotypes operating along an ADHD continuum.

Relationships between resting-state EEG functional networks organization and individual differences in mind wandering

When performing cognitively demanding tasks, people tend to experience momentary distractions or personal associations that intercept their stream of consciousness. This phenomenon is known as Mind Wandering (MW) and it has become a subject of neuroscientific investigations. Off-task thoughts can be analyzed during task performance, but currently, MW is also understood as a dimension of individual differences in cognitive processing. We wanted to recognize the intrinsically-organized functional networks that could be considered the neuronal basis for MW dispositional variability. To achieve this goal we recruited a group of normal adults, and eventually divided the group in half, based on participants' scores on the scale measuring dispositional MW. Next, these groups were compared regarding the arrangement of preselected intrinsic functional networks, which were reconstructed based on multi-channel signal-source resting-state EEG. It appeared that subjects who tend to mind wander often exhibited decreased synchronization within the default mode network, and, simultaneously, strengthened connectivity between 'on-task' networks of diverse functional specificity. Such within- and between networks integrity patterns might suggest that greater Mind Wanderers present an atypical organization of resting-state brain activity, which may translate into attenuated resources needed to maintain attentional control in task-related conditions.

Focused attention meditation in healthy adults: A systematic review and meta-analysis of cross-sectional functional MRI studies

Meditation trains the mind to focus attention towards an object or experience. Among different meditation techniques, focused attention meditation is considered foundational for more advanced practices. Despite renewed interest in its functional neural correlates, there is no unified neurocognitive model of focused attention meditation developed via quantitative synthesis of contemporary literature. Hence, we performed a quantitative systematic review and meta-analysis of all functional MRI studies examining focussed attention meditation. Following PRISMA guidelines, 28 studies were included in this review, of which 10 studies (200 participants) were amenable to activation likelihood estimation meta-analysis. We found that regions comprising three key functional brain networks i.e., Default-mode, Salience, and Executive Control, were consistently implicated in focused attention meditation. Furthermore, meditation expertise, mindfulness levels and attentional skills were found to significantly influence the magnitude, but not regional extent, of activation and functional connectivity in these networks. Aggregating all evidence, we present a unified neurocognitive brain-network model of focused attention meditation.

White Matter Microstructure in Attention-Deficit/Hyperactivity Disorder: A Systematic Tractography Study in 654 Individuals

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by age-inappropriate levels of inattention and/or hyperactivity-impulsivity. ADHD has been related to differences in white matter (WM) microstructure. However, much remains unclear regarding the nature of these WM differences and which clinical aspects of ADHD they reflect. We systematically investigated whether fractional anisotropy (FA) is associated with current and/or lifetime categorical diagnosis, impairment in daily life, and continuous ADHD symptom measures.

METHODS

Diffusion-weighted imaging data were obtained from 654 participants (322 unaffected, 258 affected, 74 subthreshold; 7-29 years of age). We applied automated global probabilistic tractography on 18 major WM pathways. Linear mixed-effects regression models were used to examine associations of clinical measures with overall brain and tract-specific FA.

RESULTS

There were significant interactions of tract with all ADHD variables on FA. There were no significant associations of FA with current or lifetime diagnosis, nor with impairment. Lower FA in the right cingulum angular bundle was associated with higher hyperactivity-impulsivity symptom severity (p_{familywise error} = .045). There were no significant effects for other tracts.

CONCLUSIONS

This is the first time global probabilistic tractography has been applied to an ADHD dataset of this size. We found no evidence for altered FA in association with ADHD diagnosis. Our findings indicate that associations of FA with ADHD are not uniformly distributed across WM tracts. Continuous symptom measures of ADHD may be more sensitive to FA than diagnostic categories. The right cingulum angular bundle in particular may play a role in symptoms of hyperactivity and impulsivity.

Underlying mechanisms of mindfulness meditation: Genomics, circuits, and networks

Understanding neuropsychological mechanisms of mindfulness meditation (MM) has been a hot topic in recent years. This review was conducted with the goal of synthesizing empirical relationships via the genomics, circuits and networks between MM and mental disorders. We describe progress made in assessing the effects of MM on gene expression in immune cells, with particular focus on stress-related inflammatory markers and associated biological pathways. We then focus on key brain circuits associated with mindfulness practices and effects on symptoms of mental disorders, and expand our discussion to identify three key brain networks associated with mindfulness practices including default mode network, central executive network, and salience network. More research efforts need to be devoted into identifying underlying neuropsychological mechanisms of MM on how it alleviates the symptoms of mental disorders.

The initial Polish adaptation of the Mind Wandering Questionnaire: translation and verification of the scale internal consistency

Introduction: The aim of the current study was to present the results of the first step of the Mind Wandering Questionnaire (MWQ) adaptation to the Polish sample. The adaptation involved performing translation of the scale, verification of the translated items’ accessibility and the analysis of the internal consistency.

Material and methods: MWQ in original form is a single-factor short self-assessing questionnaire composed of five items with a 6-point Likert-type answering scale. The translation of items was performed by a professional language expert according to psychometric rules. The research group included 70 healthy young adults (students), aged 21.53, an equal number of males and females.

Results: The adapted questionnaire exhibited a single-factorial structure and satisfactory parameters of internal consistency: Cronbach’s alpha was 0.78, all individual items were significantly correlated with MWQ total score, and the mean value of correlation reached 0.74. The mean value of the adopted MWQ total score reached 15.84 (SD = 4.11).

The study showing the initial step of the questionnaire adaptation revealed that the scale in the Polish version has an internal structure comparable with the original one, and its internal consistency exhibited good parameters.

Conclusions: In the next steps of the scale full adaptation, a convergent validity assessment should be carried out together with correlations with other scales assessing psychological constructs and dimensions of individual differences associated with Mind Wandering, such as neuroticism and impulsiveness.

Generalizable predictive modeling of semantic processing ability from functional brain connectivity

Semantic processing (SP) is one of the critical abilities of humans for representing and manipulating conceptual and meaningful information. Neuroimaging studies of SP typically collapse data from many subjects, but its neural organization and behavioral performance vary between individuals. It is not yet understood whether and how the individual variabilities in neural network organizations contribute to the individual differences in SP behaviors. We aim to identify the neural signatures underlying SP variabilities by analyzing functional connectivity (FC) patterns based on a large‐sample Human Connectome Project (HCP) dataset and rigorous predictive modeling. We used a two‐stage predictive modeling approach to build an internally cross‐validated model and to test the model's generalizability with unseen data from different HCP samples and other out‐of‐sample datasets. FC patterns within a putative semantic brain network were significantly predictive of individual SP scores summarized from five SP‐related behavioral tests. This cross‐validated model can be used to predict unseen HCP data. The model generalizability was enhanced in the language task compared with other tasks used during scanning and was better for females than males. The model constructed from the HCP dataset can be partially generalized to two independent cohorts that participated in different semantic tasks. FCs connecting to the Perisylvian language network show the most reliable contributions to predictive modeling and the out‐of‐sample generalization. These findings contribute to our understanding of the neural sources of individual differences in SP, which potentially lay the foundation for personalized education for healthy individuals and intervention for SP and language deficits patients.

Revisiting consciousness: Distinguishing between states of conscious focused attention and mind wandering with EEG

Fluctuating between external conscious processing and mind wandering is inherent to the human condition. Past research showed that in tasks requiring sustained attention, mind wandering episodes in which attention is directed internally constrain conscious processing of external stimuli. Conversely, conscious processing of internal stimuli is enhanced during mind wandering. To investigate this, we developed and administered a visuomotor tracking task in which participants were instructed to track the path of a stimulus on a screen with a mouse while responding to rare targets. Prior to reports of mind wandering we found the following: The P3 event-related potential component for targets, indicative of conscious stimulus processing, was attenuated at electrodes Cz and Pz. Moreover, alpha power, indicative of internal mental states, increased globally. Theta power increased along the centroparietal area, and beta decreased along right frontal and right centroparietal areas. Interestingly, trait mind wandering was positively correlated with delta power and gamma power, but negatively correlated with the theta-beta ratio. These results demonstrate that mind wandering is characterized by distinct neural signatures at both a state and trait level.

Predicting response time variability from task and resting-state functional connectivity in the aging brain

Aging is associated with declines in a host of cognitive functions, including attentional control, inhibitory control, episodic memory, processing speed, and executive functioning. Theoretical models attribute the age-related decline in cognitive functioning to deficits in goal maintenance and attentional inhibition. Despite these well-documented declines in executive control resources, older adults endorse fewer episodes of mind-wandering when assessed using task-embedded thought probes. Furthermore, previous work on the neural basis of mind-wandering has mostly focused on young adults with studies predominantly focusing on the activity and connectivity of a select few canonical networks. However, whole-brain functional networks associated with mind-wandering in aging have not yet been characterized. In this study, using response time variability-the trial-to-trial fluctuations in behavioral responses-as an indirect marker of mind-wandering or an "out-of-the-zone" attentional state representing suboptimal behavioral performance, we show that brain-based predictive models of response time variability can be derived from whole-brain task functional connectivity. In contrast, models derived from resting-state functional connectivity alone did not predict individual response time variability. Finally, we show that despite successful within-sample prediction of response time variability, our models did not generalize to predict response time variability in independent cohorts of older adults with resting-state connectivity. Overall, our findings provide evidence for the utility of task-based functional connectivity in predicting individual response time variability in aging. Future research is needed to derive more robust and generalizable models.

ADHD and Interfering Thoughts in High and Low Conflict Conditions

BACKGROUND

Individuals with an ADHD diagnosis have increased levels of interfering thoughts, especially in the form of mind wandering. This was mostly investigated in sustained attention tasks; hence it is unclear whether the findings are only due to their difficulties in those types of tasks. Moreover, it is unclear how the amount of control invested in the task will affect those differences between control and ADHD groups.

METHOD

ADHD and matched control groups performed the Stroop task under high and low conflict conditions while measuring their interfering thoughts level.

RESULTS

Individuals with ADHD have more interfering thoughts compared to a control group even when they are able to change their control level according to the task conflict.

CONCLUSION

Interfering thoughts are an independent predictor of ADHD impairments, observed regardless of the degree of control invested in the task.

ssDefault mode network connectivity and attention-deficit/hyperactivity disorder in adolescence: Associations with delay aversion and temporal discounting, but not mind wandering

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) has been associated with reduced resting state connectivity in the core subsystem of the default mode network (DMN; medial prefrontal cortex - posterior cingulate cortex). However, the neuropsychological consequences of this hypoconnectivity remain to be determined. Building on recent theoretical models of DMN function, we tested the association between DMN hypo-connectivity and three neuropsychological processes previously implicated in ADHD: (i) excessive task-unrelated spontaneous thought (i.e., mind-wandering); (ii) sub-optimal decision-making due to exaggerated temporal discounting; and (iii) delay aversion - a heightened emotional response to the imposition or experience of delay.

METHODS

Twenty male adolescents with a clinical diagnosis of ADHD and 18 typically developing adolescents (all aged 11-16 years) underwent a resting-state fMRI scan to assess DMN connectivity. An experimental paradigm was used to assess temporal discounting and self-report questionnaires were used to measure mind wandering and delay aversion.

RESULTS

ADHD was significantly associated with DMN hypo-connectivity specifically in the core subsystem, elevated levels of mind-wandering, delay aversion, and temporal discounting. Mediation analysis suggested that DMN hypoconnectivity mediated the link between ADHD and delay aversion.

CONCLUSION

The results provide initial evidence that disturbances in the DMN may impair ability to regulate delay-related negative affect in adolescents with ADHD.

Transcranial Direct Current Stimulation Provides no Additional Benefit to Improvements in Self-Reported Craving Following Mindfulness-Based Relapse Prevention

Objectives

Mindfulness-Based Relapse Prevention (MBRP) and transcranial direct current stimulation (tDCS) have each demonstrated efficacy in improving outcomes in those with alcohol use disorder (AUD), however a recent study that combined MBRP with tDCS found tDCS provided no additional benefit to MBRP for AUD. Differences in treatment adherence between active versus sham tDCS groups may have contributed to this result. The current study examined whether treatment adherence interacted with tDCS condition in predicting post-treatment mindfulness and craving.

Methods

This study was a secondary data analysis from a randomized sham-controlled trial comparing MBRP paired with tDCS. Linear regression analyses were conducted examining the interaction between tDCS condition and two measures of treatment adherence (i.e., number of groups attended, number of tDCS administrations) on post-treatment mindfulness and craving.

Results

There was no effect of treatment adherence by tDCS condition in predicting mindfulness, however the interaction between treatment adherence and tDCS condition significantly predicted post-treatment craving. There was a significant negative association between treatment adherence and post-treatment craving in the sham group, but there was no association in the active tDCS group.

Conclusions

MBRP coupled with sham stimulation led to significant reductions in self-reported craving when patients attended more sessions and received a greater number of sham tDCS administrations, while no relationship was observed between treatment adherence and craving among those who received active tDCS. This result provides tentative evidence that, rather than improve the effects of MBRP on craving, this active tDCS protocol provides no additional benefit to MBRP in reducing craving.

Pre-registration

This study was registered with clinicaltrials.gov (NCT02861807).

Aberrant default mode connectivity in adolescents with early-onset psychosis: A resting state fMRI study

Abnormal default mode network (DMN) connectivity has been found in schizophrenia and other psychotic disorders. However, there are limited studies on early onset psychosis (EOP), and their results show lack of agreement. Here, we investigated within-network DMN connectivity in EOP compared to healthy controls (HC), and its relationship to clinical characteristics. A sample of 68 adolescent patients with EOP (mean age 16.53 ± 1.12 [SD] years, females 66%) and 95 HC (mean age 16.24 ± 1.50 [SD], females 60%) from two Scandinavian cohorts underwent resting state functional magnetic resonance imaging (rsfMRI). A group independent component analysis (ICA) was performed to identify the DMN across all participants. Dual regression was used to estimate spatial maps reflecting each participant's DMN network, which were compared between EOP and HC using voxel-wise general linear models and permutation-based analyses. Subgroup analyses were performed within the patient group, to explore associations between diagnostic subcategories and current use of psychotropic medication in relation to connectivity strength. The analysis revealed significantly reduced DMN connectivity in EOP compared to HC in the posterior cingulate cortex, precuneus, fusiform cortex, putamen, pallidum, amygdala, and insula. The subgroup analysis in the EOP group showed strongest deviations for affective psychosis, followed by other psychotic disorders and schizophrenia. There was no association between DMN connectivity strength and the current use of psychotropic medication. In conclusion, the findings demonstrate weaker DMN connectivity in adolescent patients with EOP compared to healthy peers, and differential effects across diagnostic subcategories, which may inform our understanding of underlying disease mechanisms in EOP.

The Connection Between Mind Wandering, ADHD, and Level of Performance on an Attention Task

Background: ADHD is related to increased mind wandering (MW). However, it is not clear whether this is restricted by the methods used to measure MW in those studies. Moreover, it is not certain whether MW is an independent characteristic of people with ADHD or only due to their poor performance level in the primary task (the task from which attention wanders). Method: Participants with ADHD were compared to two control groups: high performers and low performers in the primary task who had a similar performance level to the ADHD group. Results: The ADHD group had greater MW than the two control groups, while no difference in MW was found between the two control groups. Conclusion: Increased MW is an independent characteristic of ADHD. This was further discussed within the context of different theories regarding ADHD and MW.

Self, Me and I in the repertoire of spontaneously occurring altered states of Selfhood: eight neurophenomenological case study reports

This study investigates eight case reports of spontaneously emerging, brief episodes of vivid altered states of Selfhood (ASoSs) that occurred during mental exercise in six long-term meditators by using a neurophenomenological electroencephalography (EEG) approach. In agreement with the neurophenomenological methodology, first-person reports were used to identify such spontaneous ASoSs and to guide the neural analysis, which involved the estimation of three operational modules of the brain self-referential network (measured by EEG operational synchrony). The result of such analysis demonstrated that the documented ASoSs had unique neurophenomenological profiles, where several aspects or components of Selfhood (measured neurophysiologically and phenomenologically) are affected and expressed differently, but still in agreement with the neurophysiological three-dimensional construct model of the complex experiential Selfhood proposed in our earlier work (Fingelkurts et al. in Conscious Cogn 86:103031. 10.1016/j.concog.2020.103031, 2020).

Modulation of Working Memory and Resting-State fMRI by tDCS of the Right Frontoparietal Network

Many cognitive functions, including working memory, are processed within large-scale brain networks. We targeted the right frontoparietal network (FPN) with one session of transcranial direct current stimulation (tDCS) in an attempt to modulate the cognitive speed of a visual working memory task (WMT) in 27 young healthy subjects using a double-blind crossover design. We further explored the neural underpinnings of induced changes by performing resting-state fMRI prior to and immediately after each stimulation session with the main focus on the interaction between a task-positive FPN and a task-negative default mode network (DMN). Twenty minutes of 2 mA anodal tDCS was superior to sham stimulation in terms of cognitive speed manipulation of a subtask with processing of objects and tools in unconventional views (i.e., the higher cognitive load subtask of the offline WMT). This result was linked to the magnitude of resting-state functional connectivity decreases between the stimulated FPN seed and DMN seeds. We provide the first evidence for the action reappraisal mechanism of object and tool processing. Modulation of cognitive speed of the task by tDCS was reflected by FPN-DMN cross-talk changes.

Pleasantness of mind wandering is positively associated with focus back effort in daily life: Evidence from resting state fMRI

Despite the dynamic property of consciousness, little research has explored the characteristic of the effort in trying to focus back, in which attention is shifted from mind wandering to ongoing activities. In the current study, we assessed the frequency of daily mind wandering, the pleasantness of daily mind wandering content, and the daily focus back effort of 69 participants, and then collected their resting-state functional magnetic resonance imaging (rsfMRI) scans. Our results revealed that (1) participants who experienced more daily pleasant mind wandering tended to have higher effort in trying to focus back than individuals with less pleasant mind wandering whereas there were no significant relations between pleasantness of mind wandering and mind wandering frequency or between focus back effort and mind wandering frequency in everyday life; (2) the pleasantness of mind wandering and focus back effort were associated with two functional connectivity that related to focus back episodes (right dorsolateral prefrontal cortex-right middle frontal gyrus, right inferior parietal - right middle frontal gyrus). The nodes forming these functional connections belonged to the executive network. Taken together, these findings support the content regulation hypothesis that humans maintain their minds wandering away from unpleasant topics by engaging in executive control processes.

Prediction of stimulus-independent and task-unrelated thought from functional brain networks

Neural substrates of "mind wandering" have been widely reported, yet experiments have varied in their contexts and their definitions of this psychological phenomenon, limiting generalizability. We aimed to develop and test the generalizability, specificity, and clinical relevance of a functional brain network-based marker for a well-defined feature of mind wandering-stimulus-independent, task-unrelated thought (SITUT). Combining functional MRI (fMRI) with online experience sampling in healthy adults, we defined a connectome-wide model of inter-regional coupling-dominated by default-frontoparietal control subnetwork interactions-that predicted trial-by-trial SITUT fluctuations within novel individuals. Model predictions generalized in an independent sample of adults with attention-deficit/hyperactivity disorder (ADHD). In three additional resting-state fMRI studies (total n = 1115), including healthy individuals and individuals with ADHD, we demonstrated further prediction of SITUT (at modest effect sizes) defined using multiple trait-level and in-scanner measures. Our findings suggest that SITUT is represented within a common pattern of brain network interactions across time scales and contexts.

Connectome-based functional connectivity markers of suicide attempt

BACKGROUND

Functional brain markers of suicidality can help identify at-risk individuals and uncover underlying neurocognitive mechanism(s). Although some converging evidence has implicated dysfunction in several brain networks, suicide-related neuroimaging markers are inconsistent across studies, due to heterogeneity of neuroimaging approaches, clinical populations, and experimental methods.

METHODS

The current study aimed to address these limitations by examining resting-fMRI connectivity in a sample of post-9/11 veterans with a past suicide attempt (SA; n = 16) compared to a psychiatric control group (PC; n = 124) with no SA history but comparable past and present symptomatology, as well as a trauma control group (TC; n = 66) of trauma-exposed healthy controls. We used both a novel graph-analytic and seed-based approach to characterize SA-related connectivity differences across brain networks.

RESULTS

First, the graph-analytic approach identified the right amygdala and a region in the cognitive control network (right middle temporal gyrus; MTG) as regional SA-related hubs of dysfunction (HoD), or regions that exhibited a high number of SA-related connections. Aberrant SA-related connectivity between these hubs spanned multiple networks, including the cognitive control, default mode and visual networks. Second, the seed-based connectivity analysis that identifies SA-related differences in the strength of neural connections across the whole brain further implicated the right amygdala.

LIMITATIONS

Small sample size and potential underreporting of SA.

CONCLUSIONS

These two analytic approaches preliminarily suggest that the right amygdala and right MTG may be specific neural markers of SA that can be differentiated from neural markers of psychopathology more broadly.

Mind-Wandering in Adolescents Predicts Worse Affect and Is Linked to Aberrant Default Mode Network-Salience Network Connectivity

OBJECTIVE

Understanding the fluctuating emotional and cognitive states of adolescents with depressive symptoms requires fine-grained and naturalistic measurements. This study used ecological momentary assessment (EMA) to investigate the affective correlates and consequences of mind-wandering in adolescents with anhedonia (AH) and typically developing (TD) controls. In addition, we examined the association between mind-wandering and resting state functional connectivity between the medial prefrontal cortex (mPFC), a core hub of the default mode network (DMN) linked to internally oriented mentation, and networks linked to attentional control (dorsal attention network [DAN]) and affect/salience detection (salience network [SN]).

METHOD

A total of 65 adolescents, aged 12 to 18 years (TD = 36; AH = 29), completed a resting state functional magnetic resonance imaging scan and subsequently used a smartphone application for ecological momentary assessment (EMA) data collection (2-3 times/d for 5 days). Each survey (N = 678) prompted adolescents to report on their current positive and negative affect (PA and NA), cognition, and activity.

RESULTS

The frequency of mind-wandering was higher for AH (70.0% of EMA samples) relative to TD (59.2%) participants, and the participants with AH were more likely to mind-wander to unpleasant content. Mind-wandering was associated with higher concurrent NA, even when controlling for plausible confounds (eg, current activity, social companion, rumination). Time-lagged analyses revealed a bidirectional association between mind-wandering and PA. Greater levels of mind-wandering within the AH group were associated with stronger mPFC-SN/DAN connectivity.

CONCLUSION

Rates of mind-wandering were high, especially among adolescents with anhedonia, and predicted worse affect. The relation between mind-wandering and enhanced mPFC-SN coupling may reflect heightened bottom-up influence of affective and sensory salience on DMN-mediated internally oriented thought.

Integration and segregation across large-scale intrinsic brain networks as a marker of sustained attention and task-unrelated thought

Sustained attention is a fundamental cognitive process that can be decoupled from distinct external events, and instead emerges from ongoing intrinsic large-scale network interdependencies fluctuating over seconds to minutes. Lapses of sustained attention are commonly associated with the subjective experience of mind wandering and task-unrelated thoughts. Little is known about how fluctuations in information processing underpin sustained attention, nor how mind wandering undermines this information processing. To overcome this, we used fMRI to investigate brain activity during subjects' performance (n=29) of a cognitive task that was optimized to detect and isolate continuous fluctuations in both sustained attention (via motor responses) and task-unrelated thought (via subjective reports). We then investigated sustained attention with respect to global attributes of communication throughout the functional architecture, i.e., by the segregation and integration of information processing across large scale-networks. Further, we determined how task-unrelated thoughts related to these global information processing markers of sustained attention. The results show that optimal states of sustained attention favor both enhanced segregation and reduced integration of information processing in several task-related large-scale cortical systems with concurrent reduced segregation and enhanced integration in the auditory and sensorimotor systems. Higher degree of mind wandering was associated with losses of the favored segregation and integration of specific subsystems in our sustained attention model. Taken together, we demonstrate that intrinsic ongoing neural fluctuations are characterized by two converging communication modes throughout the global functional architecture, which give rise to optimal and suboptimal attention states. We discuss how these results might potentially serve as neural markers for clinically abnormal attention. SIGNIFICANCE STATEMENT: Most of our brain activity unfolds in an intrinsic manner, i.e., is unrelated to immediate external stimuli or tasks. Here we use a gradual continuous performance task to map this intrinsic brain activity to both fluctuations of sustained attention and mind wandering. We show that optimal sustained attention is associated with concurrent segregation and integration of information processing within many large-scale brain networks, while task-unrelated thought is related to sub-optimal information processing in specific subsystems of this sustained attention network model. These findings provide a novel information processing framework for investigating the neural basis of sustained attention, by mapping attentional fluctuations to genuinely global features of intra-brain communication.

Neuroimaging mechanisms of high-frequency repetitive transcranial magnetic stimulation for treatment of amnestic mild cognitive impairment: a double-blind randomized sham-controlled trial

Individuals with amnestic mild cognitive impairment (aMCI) have a high risk of developing Alzheimer’s disease. Although repetitive transcranial magnetic stimulation (rTMS) is considered a potentially effective treatment for cognitive impairment in patients with aMCI, the neuroimaging mechanisms are poorly understood. Therefore, we performed a double-blind randomized sham-controlled trial in which rTMS was applied to the left dorsolateral prefrontal cortex of aMCI patients recruited from a community near the Third Hospital Affiliated to Sun Yat-sen University, China. Twenty-four patients with aMCI were randomly assigned to receive true rTMS (treatment group, n = 12, 6 men and 6 women; age 65.08 ± 4.89 years) or sham stimulation (sham group, n = 12, 5 men and 7 women; age 64.67 ± 4.77 years). rTMS parameters included a stimulation frequency of 10 Hz, stimulation duration of 2 seconds, stimulation interval of 8 seconds, 20 repetitions at 80% of the motor threshold, and 400 pulses per session. rTMS/sham stimulation was performed five times per week over a period of 4 consecutive weeks. Our results showed that compared with baseline, Montreal Cognitive Assessment scores were significantly increased and the value of the amplitude of low-frequency fluctuation (ALFF) was significantly increased at the end of treatment and 1 month after treatment. Compared with the sham group, the ALFF values in the right inferior frontal gyrus, triangular part of the inferior frontal gyrus, right precuneus, left angular gyrus, and right supramarginal gyrus were significantly increased, and the ALFF values in the right superior frontal gyrus were significantly decreased in the treatment group. These findings suggest that high-frequency rTMS can effectively improve cognitive function in aMCI patients and alter spontaneous brain activity in cognitive-related brain areas. This study was approved by the Ethics Committee of Shenzhen Baoan Hospital of Southern Medical University, China (approval No. BYL20190901) on September 3, 2019, and registered in the Chinese Clinical Trials Registry (registration No. ChiCTR1900028180) on December 14, 2019.

A Systematic Review of Creativity-Related Studies Applying the Remote Associates Test From 2000 to 2019

The study examines how the remote associates test (RAT) has been used to examine theories of creativity through a review of recent studies on creativity. Creativity-related studies published between 2000 and 2019 were retrieved from the SCOPUS database. A total of 172 papers were chosen for further analysis. Content analysis shows that research on creativity using RAT mainly concerns remote association, insight problem-solving, general creative process, test development, individual difference, effect of treatment, clinical case, social interaction effect, and predictor or criterion. The study constructs a theoretical framework based on the 4P (Product–Person–Process–Place) model and demonstrates how empirical studies using the RAT explore the individual differences, internal processes, and external influences of creative thinking. In addition, the most commonly used version of the RAT is the Compound Remote Associates Problems (Bowden and Jung-Beeman, 2003a). Current research shows a trend whereby the creative thinking process has been receiving greater attention. In particular, a growing number of studies in this field have been carried out using cognitive neuroscience technologies. These findings suggest that the RAT provides researchers with a way to deepen their understanding of different levels of creativity.

Tracking resting-state functional connectivity changes and mind wandering: A longitudinal neuroimaging study

Mind wandering (MW) refers to a drift of attention away from the ongoing events to internal concerns and activates brain regions in the default mode network (DMN) and the frontoparietal control network (FPCN). Although a number of studies using rest-fMRI data have shown that static and dynamic functional connectivity within the DMN were related to individual variations in self-reported MW, whether the brain functional connectivity could predict MW remained unclear. Here, we carried out longitudinal data collection from 122 participants that underwent three times of MRI scans and simultaneously completed self-reported MW scales over the course of two years to clarify whether a direct relationship existed between brain functional connectivity and MW. We identified 16 functional connectivity involving the DMN and FPCN that were consistently and stably associated with MW across the three time points. However, there were only significant cross-lagged effects between DMN-involved connections and MW frequency rather than FPCN-involved connections. In addition, the results indicated that the mean value of functional connectivity involving the DMN (FC-DMN) in the low stable (LS) group was the weakest, followed by mean connectivity in the moderate increasing (MI) group and mean connectivity in the high stable (HS) group. These results support previous research linking MW with connections between partial areas involving the DMN and FPCN. Importantly, our findings indicated that brain functional connectivity involving DMN predicted the subsequent MW and provided further support for the trait-based nature of MW.

Cognitive and neural predictors of speech comprehension in noisy backgrounds in older adults

Older adults often experience difficulties comprehending speech in noisy backgrounds, which hearing loss does not fully explain. It remains unknown how cognitive abilities, brain networks, and age-related hearing loss may uniquely contribute to speech in noise comprehension at the sentence level. In 31 older adults, using cognitive measures and resting-state fMRI, we investigated the cognitive and neural predictors of speech comprehension with energetic (broadband noise) and informational masking (multi-speakers) effects. Better hearing thresholds and greater working memory abilities were associated with better speech comprehension with energetic masking. Conversely, faster processing speed and stronger functional connectivity between frontoparietal and language networks were associated with better speech comprehension with informational masking. Our findings highlight the importance of the frontoparietal network in older adults' ability to comprehend speech in multi-speaker backgrounds, and that hearing loss and working memory in older adults contributes to speech comprehension abilities related to energetic, but not informational masking.

Spontaneous Entry into an “Offline” State during Wakefulness: A Mechanism of Memory Consolidation?

Moments of inattention to our surroundings may be essential to optimal cognitive functioning. Here, we investigated the hypothesis that humans spontaneously switch between two opposing attentional states during wakefulness—one in which we attend to the external environment (an “online” state) and one in which we disengage from the sensory environment to focus our attention internally (an “offline” state). We created a data-driven model of this proposed alternation between “online” and “offline” attentional states in humans, on a seconds-level timescale. Participants (n = 34) completed a sustained attention to response task while undergoing simultaneous high-density EEG and pupillometry recording and intermittently reporting on their subjective experience. “Online” and “offline” attentional states were initially defined using a cluster analysis applied to multimodal measures of (1) EEG spectral power, (2) pupil diameter, (3) RT, and (4) self-reported subjective experience. We then developed a classifier that labeled trials as belonging to the online or offline cluster with &gt;95% accuracy, without requiring subjective experience data. This allowed us to classify all 5-sec trials in this manner, despite the fact that subjective experience was probed on only a small minority of trials. We report evidence of statistically discriminable “online” and “offline” states matching the hypothesized characteristics. Furthermore, the offline state strongly predicted memory retention for one of two verbal learning tasks encoded immediately prior. Together, these observations suggest that seconds-timescale alternation between online and offline states is a fundamental feature of wakefulness and that this may serve a memory processing function.

Reduced past-oriented mind wandering in left compared to right medial temporal lobe epilepsy

Mind wandering refers to a shift of attention away from a task at hand to task-unrelated thoughts. Several groups have shown increased activation of the left medial temporal lobe (MTL) before and during spontaneous thoughts suggesting that the left MTL may play a crucial role in mind wandering. Due to its relevance for long-term memory, we further hypothesized that the left MTL is particularly involved in mind wandering towards the past. Accordingly, we predicted a reduced propensity to mind wander and less past-oriented mind wandering in patients with left MTL epilepsies. To this end, we experimentally investigated mind wandering in 89 in-patients undergoing diagnostic evaluation of their putative epileptic disorder. Patients performed a sustained attention to response task with embedded experience sampling probes aiming to assess occurrence, meta-awareness and temporal orientation (past/present/future) of mind-wandering episodes. We did not find significant differences in the propensity to mind wander between patient subgroups. However, the left MTL epilepsy subgroup showed significantly reduced past-oriented mind wandering compared to right MTL epilepsies, as well as a trend towards diminished past-oriented mind wandering compared to idiopathic epilepsies. Possibly due to compensatory mechanisms, the right MTL epilepsy subgroup showed significantly increased past-oriented mind wandering compared to extratemporal epilepsies and patients with syncopes. These behavioural findings point to a rejection of the hypothesis that the amount of time engaged in mind wandering crucially depends on the left MTL. However, our data do support the idea that the left MTL is particularly involved in mind wandering towards the past.

The impact of state and dispositional mindfulness on prospective memory: A virtual reality study

Prospective memory (PM) consists of remembering to perform an action that was previously planned. The recovery and execution of these actions require attentional resources. Mindfulness, as a state or a dispositional trait, has been associated with better attentional abilities while mind wandering is linked with attentional failures. In this study, we investigated the impact of mindfulness on PM. Eighty participants learned 15 cue-action associations. They were, then, asked to recall the actions at certain moments (time-based items) or places (event-based items) during a walk in a virtual town. Before the PM task, participants were randomly assigned to a mindfulness or mind wandering (control condition) session. Dispositional mindfulness was measured via the Five Facets Mindfulness Questionnaire (FFMQ). Although considered as two opposite states, we did not report any difference between the two groups on PM abilities. Nevertheless, the natural tendency to describe one's own sensations (the Describing facet of the FFMQ) predicted time-based performance in both groups. We discuss different hypotheses to explain this finding in light of recent findings on the impact of mind wandering on future oriented cognition. Our main observation is a positive link between the Describing facet and time-based PM performances. We propose that this link could be due to the common association of this mindfulness facets and PM with attentional and interoceptive abilities. Additional studies are needed to explore this hypothesis.

What's in a Task? Complications in the Study of the Task-Unrelated-Thought Variety of Mind Wandering

In recent years, the number of studies examining mind wandering has increased considerably, and research on the topic has spread widely across various domains of psychological research. Athough the term mind wandering has been used to refer to various cognitive states, researchers typically operationalize mind wandering in terms of task-unrelated thought (TUT). Research on TUT has shed light on the various task features that require people's attention and on the consequences of task inattention. Important methodological and conceptual complications do persist, however, in current investigations of TUT. We argue that these complications may be dampening the development of a more nuanced scientific account of TUT. In this article, we outline three of the more prominent methodological and conceptual complications in the literature on TUT and discuss potential directions for researchers to take as they move forward in their investigations of TUT.

Personality Factors' Impact on the Structural Integrity of Mentalizing Network in Old Age: A Combined PET-MRI Study

The mentalizing network (MN) treats social interactions based on our understanding of other people's intentions and includes the medial prefrontal cortex (mPFC), temporoparietal junction (TPJ), posterior cingulate cortex (PCC), precuneus (PC), and amygdala. Not all elders are equally affected by the aging-related decrease of mentalizing abilities. Personality has recently emerged as a strong determinant of functional connectivity in MN areas. However, its impact on volumetric changes across the MN in brain aging is still unknown. To address this issue, we explored the determinants of volume decrease in MN components including amyloid burden, personality, and APOE genotyping in a previously established cohort of 130 healthy elders with a mean follow-up of 54 months. Personality was assessed with the Neuroticism Extraversion Openness Personality Inventory-Revised. Regression models corrected for multiple comparisons were used to identify predictors of volume loss including time, age, sex, personality, amyloid load, presence of APOE epsilon 4 allele, and cognitive evolution. In cases with higher Agreeableness scores, there were lower volume losses in PCC, PC, and amygdala bilaterally. This was also the case for the right mPFC in elders displaying lower Agreeableness and Conscientiousness. In multiple regression models, the effect of Agreeableness was still observed in left PC and right amygdala and that of Conscientiousness was still observed in right mPFC volume loss (26.3% of variability, significant age and sex). Several Agreeableness (Modesty) and Conscientiousness (order, dutifulness, achievement striving, and self-discipline) facets were positively related to increased volume loss in cortical components of the MN. In conclusion, these data challenge the beneficial role of higher levels of Agreeableness and Conscientiousness in old age, showing that they are associated with an increased rate of volume loss within the MN.

Dynamic brain network configurations during rest and an attention task with frequent occurrence of mind wandering

Mind wandering (MW) has become a prominent topic of neuroscientific investigation due to the importance of understanding attentional processes in our day-to-day experiences. Emerging evidence suggests a critical role for three large-scale brain networks in MW: the default network (DN), the central executive network (CEN), and the salience network (SN). Advances in analytical methods for neuroimaging data (i.e., dynamic functional connectivity, DFC) demonstrate that the interactions between these networks are not static but dynamically fluctuate over time (Chang & Glover, 2010, NeuroImage, 50(1), 81-98). While the bulk of the evidence comes from studies involving resting-state functional MRI, a few studies have investigated DFC during a task. Direct comparison of DFC during rest and task with frequent MW is scarce. The present study applies the DFC method to neuroimaging data collected from 30 participants who completed a resting-state run followed by two runs of sustained attention to response task (SART) with embedded probes indicating a high prevalence of MW. The analysis identified five DFC states. Differences between rest and task were noted in the frequency of three DFC states. One DFC state characterized by negative DN-CEN/SN connectivity along with positive CEN-SN connectivity was more frequently observed during task vs. rest. Two DFC states, one of which was characterized by weaker connectivity between networks, were more frequently observed during rest than task. These findings suggest that the dynamic relationships between brain networks may vary as a function of whether ongoing cognitive activity unfolds in an "unconstrained" manner during rest or is "constrained" by task demands.

Functional segregation of executive control network and frontoparietal network in Alzheimer's disease

Functional connectivity pattern altered of default mode network (DMN) is gaining more attention as a potential noninvasive biomarker to diagnose incipient Alzheimer's disease. However, the changed functional connectivity except for DMN, the longitudinal changes in executive control network (ECN) and frontoparietal network (FPN) also has attracted wide interest. Moreover, AD-related functional connectivity abnormalities within the DMN are well replicated research, but the (increased/decreased and reduced) functional connectivity in ECN and FPN weren't receive adequate attention. To address the above issues, in this paper, we adopt sparse inverse covariance estimation (SICE) approach to investigate the changed functional connectivity of ECN and FPN on the ADNI2 dataset. Our experimental results indicate the left superior frontal gyrus (SFGmed.L) and left thalamus (THA.L) regions of ECN has shown increased functional connectivity, the left anterior cingulate (ACG.L) region of ECN has shown decreased functional connectivity. The Superior Parietal Gyrus (SPG) regions and left paracentral lobule (PCL.L) of FPN has shown increased functional connectivity, the left supramarginal gyrus (SMG.L) regions has shown decreased functional connectivity in AD patients. On the other hand, the ACG.L regions in ECN, SMG.L and left inferior parietal (IPL.L) in FPN have shown significantly reduced functional connectivity. These results demonstrate that increased/decreased functional connectivity and reduced functional connectivity not only within DMN, but also associated with ECN and FPN. It also suggest that AD is associated with the characteristics of large-scale functional networks, and these changed functional connectivity possibly as a potential noninvasive biomarker to diagnose incipient Alzheimer's disease.

Thought Control Ability Moderates the Effect of Mind Wandering on Positive Affect via the Frontoparietal Control Network

Mind wandering is a phenomenon that involves thoughts shifting away from a primary task to the process of dealing with other personal goals. A large number of studies have found that mind wandering can predict negative emotions, but researchers have seldom focused on the positive role of mind wandering. The current study aimed to explore the relationships among mind wandering, emotions and thought control ability, which is the ability to inhibit one's own unpleasant or unwanted intrusive thoughts. Here, we collected resting-state functional magnetic resonance imaging (rsfMRI) data from 368 participants who completed a set of questionnaires involving mind wandering, thought control ability and positive or negative emotions. The results revealed that (1) rsfMRI connectivity features related to thought control ability and mind wandering could divide individuals into two groups: HMW (high mind-wandering) group and LMW (low mind-wandering) group. The HMW group scored lower in thought control ability (TCA), higher in negative emotion (NE) and lower in positive emotion (PE) than the LMW group. (2) TCA moderated the association between MW and positive affect (PA). (3) Two groups exhibited different segregation within key nodes (SWKN) of the frontoparietal control network (FPCN), and the subsequent analysis showed that the SWKN of the FPCN was negatively correlated with PA. These findings indicate that TCA moderates the effect of mind wandering on affect via the FPCN, which may have important implications for our understanding of the positive role of mind wandering.

Psychedelics, Meditation, and Self-Consciousness

In recent years, the scientific study of meditation and psychedelic drugs has seen remarkable developments. The increased focus on meditation in cognitive neuroscience has led to a cross-cultural classification of standard meditation styles validated by functional and structural neuroanatomical data. Meanwhile, the renaissance of psychedelic research has shed light on the neurophysiology of altered states of consciousness induced by classical psychedelics, such as psilocybin and LSD, whose effects are mainly mediated by agonism of serotonin receptors. Few attempts have been made at bridging these two domains of inquiry, despite intriguing evidence of overlap between the phenomenology and neurophysiology of meditation practice and psychedelic states. In particular, many contemplative traditions explicitly aim at dissolving the sense of self by eliciting altered states of consciousness through meditation, while classical psychedelics are known to produce significant disruptions of self-consciousness, a phenomenon known as drug-induced ego dissolution. In this article, we discuss available evidence regarding convergences and differences between phenomenological and neurophysiological data on meditation practice and psychedelic drug-induced states, with a particular emphasis on alterations of self-experience. While both meditation and psychedelics may disrupt self-consciousness and underlying neural processes, we emphasize that neither meditation nor psychedelic states can be conceived as simple, uniform categories. Moreover, we suggest that there are important phenomenological differences even between conscious states described as experiences of self-loss. As a result, we propose that self-consciousness may be best construed as a multidimensional construct, and that "self-loss," far from being an unequivocal phenomenon, can take several forms. Indeed, various aspects of self-consciousness, including narrative aspects linked to autobiographical memory, self-related thoughts and mental time travel, and embodied aspects rooted in multisensory processes, may be differently affected by psychedelics and meditation practices. Finally, we consider long-term outcomes of experiences of self-loss induced by meditation and psychedelics on individual traits and prosocial behavior. We call for caution regarding the problematic conflation of temporary states of self-loss with "selflessness" as a behavioral or social trait, although there is preliminary evidence that correlations between short-term experiences of self-loss and long-term trait alterations may exist.

Spontaneous Thoughts and Brain Connectivity: Possible Links Between Early Maltreatment and Later Depression

Maltreatment (MT) during childhood wreaks lasting havoc on the developing central nervous system and is one of the most salient risk factors for numerous psychiatric disorders, including depression.¹ Early intervention and prevention strategies to improve outcomes of youth who have experienced MT are sorely needed; advancement in this area will require a deeper understanding of the neurobiological trajectory between the occurrence of MT and the later emergence of illness. One approach is to select neurobiological measures that are known to be impaired in the fully fledged disorder and use them to assess youth with a history of MT who have not yet shown impairment. In depression research, an emerging research area is to study spontaneously generated thoughts that occur while awake but at unstructured times, when thoughts tend to wander. Mind wandering has been linked with intelligence, creative thought generation, and resting-state functional connectivity within the default mode network.² However, in depression, these wandering thoughts can get stuck on negative content^3,4 and could represent a core feature of the illness. Therefore, examination of spontaneously generated thoughts, and their neural correlates, is a promising avenue for research seeking precursors of depression in youth with a history of MT.