Being a self: considerations from functional imaging

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).

High-Density EEG in a Charles Bonnet Syndrome Patient during and without Visual Hallucinations: A Case-Report Study

Charles Bonnet syndrome (CBS) is a rare clinical condition characterized by complex visual hallucinations in people with loss of vision. So far, the neurobiological mechanisms underlying the hallucinations remain elusive. This case-report study aims at investigating electrical activity changes in a CBS patient during visual hallucinations, as compared to a resting-state period (without hallucinations). Prior to the EEG, the patient underwent neuropsychological, ophthalmologic, and neurological examinations. Spectral and connectivity, graph analyses and signal diversity were applied to high-density EEG data. Visual hallucinations (as compared to resting-state) were characterized by a significant reduction of power in the frontal areas, paralleled by an increase in the midline posterior regions in delta and theta bands and by an increase of alpha power in the occipital and midline posterior regions. We next observed a reduction of theta connectivity in the frontal and right posterior areas, which at a network level was complemented by a disruption of small-worldness (lower local and global efficiency) and by an increase of network modularity. Finally, we found a higher signal complexity especially when considering the frontal areas in the alpha band. The emergence of hallucinations may stem from these changes in the visual cortex and in core cortical regions encompassing both the default mode and the fronto-parietal attentional networks.

Physical fitness and brain source localization during a working memory task in children with overweight/obesity: The ActiveBrains project

The present study aims (i) to examine the association of physical fitness components (i.e., cardiorespiratory fitness, speed-agility, and muscular fitness) with brain current source density during working memory; and (ii) to examine whether fitness-related current density was associated to working memory performance and academic achievement. Eighty-five children with overweight/obesity aged 8-11 years participated in this cross-sectional study. Physical fitness components were assessed using the ALPHA test battery. Electroencephalography recordings were performed during a Delayed Non-Match-to-Sample task that assessed working memory. Brain source analysis was carried out using sLORETA to estimate regional current source density differences between high and low (H-L) working memory loads. Academic achievement was measured by the Spanish version of the Woodcock-Johnson III test battery. The main results showed that higher cardiorespiratory fitness was associated with higher H-L current density differences in frontal, limbic, and occipital regions during encoding and maintenance task's phases (β≥0.412, p ≤ 0.019). A limbic area was further related to better working memory performance (β=0.267, p = 0.005). During retrieval, higher cardiorespiratory fitness was also associated with higher current density in temporal regions (β=0.265, p = 0.013), whereas lower muscular fitness was associated with higher current density in frontal regions (β=-0.261, p = 0.016). Our results suggest that cardiorespiratory fitness, but not speed-agility nor muscular fitness, is positively associated with brain current source density during working memory processes in children with overweight/obesity. Fitness-related current density differences in limbic regions were associated with better working memory.

Transdiagnostic and disease-specific abnormalities in the default-mode network hubs in psychiatric disorders: A meta-analysis of resting-state functional imaging studies

Background.

The default mode network (DMN) dysfunction has emerged as a consistent biological correlate of multiple psychiatric disorders. Specifically, there is evidence of alterations in DMN cohesiveness in schizophrenia, mood and anxiety disorders. The aim of this study was to synthesize at a fine spatial resolution the intra-network functional connectivity of the DMN in adults diagnosed with schizophrenia, mood and anxiety disorders, capitalizing on powerful meta-analytic tools provided by activation likelihood estimation.

Methods.

Results from 70 whole-brain resting-state functional magnetic resonance imaging articles published during the last 15 years were included comprising observations from 2,789 patients and 3,002 healthy controls.

Results.

Specific regional changes in DMN cohesiveness located in the anteromedial and posteromedial cortex emerged as shared and trans-diagnostic brain phenotypes. Disease-specific dysconnectivity was also identified. Unmedicated patients showed more DMN functional alterations, highlighting the importance of interventions targeting the functional integration of the DMN.

Conclusion.

This study highlights functional alteration in the major hubs of the DMN, suggesting common abnormalities in self-referential mental activity across psychiatric disorders.

Eye movement desensitization and reprocessing for post-traumatic stress disorder from the perspective of three-dimensional model of the experiential selfhood

Eye Movement Desensitization and Reprocessing (EMDR) therapy is included in many international trauma treatment guidelines and is also shortlisted as an evidence-based practice for the treatment of psychological trauma and Post-Traumatic Stress Disorder (PTSD). However, its neurobiological mechanisms have not yet been fully understood. In this brief article we propose a hypothesis that a recently introduced neurophysiologically based three-dimensional construct model for experiential selfhood may help to fill this gap by providing the necessary neurobiological rationale of EMDR. In support of this proposal we briefly overview the neurophysiology of eye movements and the triad selfhood components, as well as EMDR therapy neuroimaging studies.

Shared and differential default-mode related patterns of activity in an autobiographical, a self-referential and an attentional task

The default-mode network (DMN) comprises a set of brain regions that show deactivations during performance of attentionally demanding tasks, but also activation during certain processes including recall of autobiographical memories and processing information about oneself, among others. However, the DMN is not activated in a homogeneous manner during performance of such tasks, so it is not clear to what extent its activation patterns correspond to deactivation patterns seen during attention-demanding tasks. In this fMRI study we compared patterns of activation in response to an autobiographical memory task to those observed in a self/other-reflection task, and compared both to deactivations observed during the n-back working memory task. Autobiographical recall and self-reflection activated several common DMN areas, which were also deactivated below baseline levels by the n-back task. Activation in the medial temporal lobe was seen during autobiographical recall but not the self/other task, and right angular gyrus activity was specifically linked to other-reflection. ROI analysis showed that most, but not all DMN regions were activated above baseline levels during the autobiographical memory and self-reflection tasks. Our results provide evidence for the usefulness of the autobiographical memory task to study DMN activity and support the notion of interacting subsystems within this network.

Alterations in the Three Components of Selfhood in Persons with Post-Traumatic Stress Disorder Symptoms: A Pilot qEEG Neuroimaging Study

Background and Objective:

Understanding how trauma impacts the self-structure of individuals suffering from the Post-Traumatic Stress Disorder (PTSD) symptoms is a complex matter and despite several attempts to explain the relationship between trauma and the “Self”, this issue still lacks clarity. Therefore, adopting a new theoretical perspective may help understand PTSD deeper and to shed light on the underlying psychophysiological mechanisms.

Methods:

In this study, we employed the “three-dimensional construct model of the experiential selfhood” where three major components of selfhood (phenomenal first-person agency, embodiment, and reflection/narration) are related to three Operational Modules (OMs) of the self-referential brain network. These modules can be reliably estimated through operational synchrony analysis of the Electroencephalogram (EEG). Six individuals with PTSD symptoms and twenty-nine sex-, age- and demographic- (race, education, marital status) matched healthy controls underwent resting state EEG signal acquisition with the following estimation of the synchrony strength within every OM.

Results:

Our results indicate that subjects with PTSD symptoms had significantly stronger EEG operational synchrony within anterior and right posterior OMs as well as significantly weaker EEG operational synchrony within left posterior OM compared to healthy controls. Moreover, increased the functional integrity of the anterior OM was positively associated with hyperactivity symptoms, reduced synchrony of the left posterior OM was associated with greater avoidance, and increased right posterior OM integrity was positively correlated with intrusion and mood symptoms.

Conclusion:

The results are interpreted in light of the triad model of selfhood and its theoretical and clinical implications (including a new treatment approach) are discussed.

Neurobiology of Criterion A: self and interpersonal personality functioning

The Criterion A of the DSM-5 Alternative Model of Personality Disorders follows a functional approach to personality disorders which can be effectively related to abnormalities in brain circuits that are involved in processes related to the self and others. While brain circuits related to the self and others highly overlap supporting the notion of inseparable constructs, structural and functional neuroimaging data point to rather specific deviations in brain processes among the various types of personality disorders, with a focus on borderline and antisocial personality disorders. Neurobiological data have shed light on the problem areas of individuals with personality disorders that goes beyond what we know from either patients' reports or observing their behavior and may open new perspectives on treatment.

Longitudinal Dynamics of 3-Dimensional Components of Selfhood After Severe Traumatic Brain Injury: A qEEG Case Study

In this report, we describe the case of a patient who sustained extremely severe traumatic brain damage with diffuse axonal injury in a traffic accident and whose recovery was monitored during 6 years. Specifically, we were interested in the recovery dynamics of 3-dimensional components of selfhood (a 3-dimensional construct model for the complex experiential selfhood has been recently proposed based on the empirical findings on the functional-topographical specialization of 3 operational modules of brain functional network responsible for the self-consciousness processing) derived from the electroencephalographic (EEG) signal. The analysis revealed progressive (though not monotonous) restoration of EEG functional connectivity of 3 modules of brain functional network responsible for the self-consciousness processing, which was also paralleled by the clinically significant functional recovery. We propose that restoration of normal integrity of the operational modules of the self-referential brain network may underlie the positive dynamics of 3 aspects of selfhood and provide a neurobiological mechanism for their recovery. The results are discussed in the context of recent experimental studies that support this inference. Studies of ongoing recovery after severe brain injury utilizing knowledge about each separate aspect of complex selfhood will likely help to develop more efficient and targeted rehabilitation programs for patients with brain trauma.

Social and Nonsocial Relational Reasoning in Adolescence and Adulthood

Reasoning during social interactions requires the individual manipulation of mental representations of one’s own traits and those of other people as well as their joint consideration (relational integration). Research using nonsocial paradigms has linked relational integration to activity in the rostrolateral PFC. Here, we investigated whether social reasoning is supported by the same general system or whether it additionally relies on regions of the social brain network, such as the medial PFC. We further assessed the development of social reasoning. In the social task, participants evaluated themselves or a friend, or compared themselves with their friend, on a series of traits. In the nonsocial task, participants evaluated their hometown or another town or compared the two. In a behavioral study involving 325 participants (11–39 years old), we found that integrating relations, compared with performing single relational judgments, improves during adolescence, both for social and nonsocial information. Thirty-nine female participants (10–31 years old) took part in a neuroimaging study using a similar task. Activation of the relational integration network, including the rostrolateral PFC, was observed in the comparison condition of both the social and nonsocial tasks, whereas the medial PFC showed greater activation when participants processed social as opposed to nonsocial information across conditions. Developmentally, the right anterior insula showed greater activity in adolescents compared with adults during the comparison of nonsocial versus social information. This study shows parallel recruitment of the social brain and the relational reasoning network during the relational integration of social information in adolescence and adulthood.

Increased Local Spontaneous Neural Activity in the Left Precuneus Specific to Auditory Verbal Hallucinations of Schizophrenia

BACKGROUND

Auditory verbal hallucinations (AVHs) of schizophrenia have been associated with structural and functional alterations of some brain regions. However, the brain regional homogeneity (ReHo) alterations specific to AVHs of schizophrenia remain unclear. In the current study, we aimed to investigate ReHo alterations specific to schizophrenic AVHs.

METHODS

Thirty-five schizophrenic patients with AVH, 41 schizophrenic patients without AVHs, and fifty healthy subjects underwent resting-state functional magnetic resonance imaging. ReHo differences across the three groups were tested using a voxel-wise analysis.

RESULTS

Compared with the healthy control group, the two schizophrenia groups showed significantly increased ReHo in the right caudate and inferior temporal gyrus and decreased ReHo in the bilateral postcentral gyrus and thalamus and the right inferior occipital gyrus (false discovery rate corrected, P < 0.05). More importantly, the AVH group exhibited significantly increased ReHo in the left precuneus compared with the non-AVH group. However, using correlation analysis, we did not find any correlation between the auditory hallucination rating scale score and the ReHo of brain regions.

CONCLUSIONS

Our results suggest that increased ReHo in the left precuneus may be a pathological feature exclusive to schizophrenic AVHs.

Neuropsychological and neuroimaging underpinnings of schizoaffective disorder: a systematic review

OBJECTIVES

The neurobiological basis and nosological status of schizoaffective disorder remains elusive and controversial. This study provides a systematic review of neurocognitive and neuroimaging findings in the disorder.

METHODS

A comprehensive literature search was conducted via PubMed, ScienceDirect, Scopus and Web of Knowledge (from 1949 to 31st March 2015) using the keyword 'schizoaffective disorder' and any of the following terms: 'neuropsychology', 'cognition', 'structural neuroimaging', 'functional neuroimaging', 'multimodal', 'DTI' and 'VBM'. Only studies that explicitly examined a well defined sample, or subsample, of patients with schizoaffective disorder were included.

RESULTS

Twenty-two of 43 neuropsychological and 19 of 51 neuroimaging articles fulfilled inclusion criteria. We found a general trend towards schizophrenia and schizoaffective disorder being related to worse cognitive performance than bipolar disorder. Grey matter volume loss in schizoaffective disorder is also more comparable to schizophrenia than to bipolar disorder which seems consistent across further neuroimaging techniques.

CONCLUSIONS

Neurocognitive and neuroimaging abnormalities in schizoaffective disorder resemble more schizophrenia than bipolar disorder. This is suggestive for schizoaffective disorder being a subtype of schizophrenia or being part of the continuum spectrum model of psychosis, with schizoaffective disorder being more skewed towards schizophrenia than bipolar disorder.

The Chief Role of Frontal Operational Module of the Brain Default Mode Network in the Potential Recovery of Consciousness from the Vegetative State: A Preliminary Comparison of Three Case Reports

It has been argued that complex subjective sense of self is linked to the brain default-mode network (DMN). Recent discovery of heterogeneity between distinct subnets (or operational modules - OMs) of the DMN leads to a reconceptualization of its role for the experiential sense of self. Considering the recent proposition that the frontal DMN OM is responsible for the first-person perspective and the sense of agency, while the posterior DMN OMs are linked to the continuity of 'I' experience (including autobiographical memories) through embodiment and localization within bodily space, we have tested in this study the hypothesis that heterogeneity in the operational synchrony strength within the frontal DMN OM among patients who are in a vegetative state (VS) could inform about a stable self-consciousness recovery later in the course of disease (up to six years post-injury). Using EEG operational synchrony analysis we have demonstrated that among the three OMs of the DMN only the frontal OM showed important heterogeneity in VS patients as a function of later stable clinical outcome. We also found that the frontal DMN OM was characterized by the process of active uncoupling (stronger in persistent VS) of operations performed by the involved neuronal assemblies.

Network dynamics during the different stages of hallucinations in schizophrenia

The majority of patients with schizophrenia suffer from hallucinations. While the triple-network model, which includes the default mode network (DMN), the central executive network (CEN) and the salience network (SAL), has recently been applied to schizophrenia, how this framework could explain the emergence of hallucinations remains unclear. Therefore, complementary brain regions that have been linked to hallucinations, such as the left hippocampus, should also be considered and added to this model. Accordingly, the present study explored the effective connectivity across these four components (i.e., the quadripartite model) during the different stages of hallucinations. Twenty-five patients with schizophrenia participated in a single session of resting-state functional magnetic resonance imaging to capture hallucinatory experiences. Based on the participants' self-report of the psychosensory experiences that occurred during scanning, hallucinatory experiences were identified and divided into four stages: periods without hallucination ("OFF"), periods with hallucination ("ON"), transition periods between "OFF" and "ON", and the extinction of the hallucinatory experience ("END"). Using stochastic dynamic causal modeling analysis, this study first confirmed that the SAL played a critical and causal role in switching between the CEN and the DMN in schizophrenia. In addition, effective connectivity within the quadripartite model depended on the hallucinatory stage. In particular, "ON" periods were linked to memory-based sensory input from the hippocampus to the SAL, while "END" periods were associated with a takeover of the CEN in favor of a voluntary process. Finally, the pathophysiological and therapeutic implications of these findings are critically discussed. Hum Brain Mapp 37:2571-2586, 2016. © 2016 Wiley Periodicals, Inc.

Decentering and Related Constructs: A Critical Review and Metacognitive Processes Model

The capacity to shift experiential perspective-from within one's subjective experience onto that experience-is fundamental to being human. Scholars have long theorized that this metacognitive capacity-which we refer to as decentering-may play an important role in mental health. To help illuminate this mental phenomenon and its links to mental health, we critically examine decentering-related constructs and their respective literatures (e.g., self-distanced perspective, cognitive distancing, cognitive defusion). First, we introduce a novel metacognitive processes model of decentering. Specifically, we propose that, to varying degrees, decentering-related constructs reflect a common mental phenomenon subserved by three interrelated metacognitive processes: meta-awareness, disidentification from internal experience, and reduced reactivity to thought content. Second, we examine extant research linking decentering-related constructs and their underlying metacognitive processes to mental health. We conclude by proposing future directions for research that transcends decentering-related constructs in an effort to advance the field's understanding of this facet of human experience and its role in (mal)adaptation.

I think therefore I am: Rest-related prefrontal cortex neural activity is involved in generating the sense of self

The sense of self has always been a major focus in the psychophysical debate. It has been argued that this complex ongoing internal sense cannot be explained by any physical measure and therefore substantiates a mind-body differentiation. Recently, however, neuro-imaging studies have associated self-referential spontaneous thought, a core-element of the ongoing sense of self, with synchronous neural activations during rest in the medial prefrontal cortex (PFC), as well as the medial and lateral parietal cortices. By applying deep transcranial magnetic stimulation (TMS) over human PFC before rest, we disrupted activity in this neural circuitry thereby inducing reports of lowered self-awareness and strong feelings of dissociation. This effect was not found with standard or sham TMS, or when stimulation was followed by a task instead of rest. These findings demonstrate for the first time a critical, causal role of intact rest-related PFC activity patterns in enabling integrated, enduring, self-referential mental processing.

Acute aerobic exercise increases cortical activity during working memory: a functional MRI study in female college students

There is increasing evidence that acute aerobic exercise is associated with improved cognitive function. However, neural correlates of its cognitive plasticity remain largely unknown. The present study examined the effect of a session of acute aerobic exercise on working memory task-evoked brain activity as well as task performance. A within-subjects design with a counterbalanced order was employed. Fifteen young female participants (M = 19.56, SD = 0.81) were scanned using functional magnetic resonance imaging while performing a working memory task, the N-back task, both following an acute exercise session with 20 minutes of moderate intensity and a control rest session. Although an acute session of exercise did not improve behavioral performance, we observed that it had a significant impact on brain activity during the 2-back condition of the N-back task. Specifically, acute exercise induced increased brain activation in the right middle prefrontal gyrus, the right lingual gyrus, and the left fusiform gyrus as well as deactivations in the anterior cingulate cortexes, the left inferior frontal gyrus, and the right paracentral lobule. Despite the lack of an effect on behavioral measures, significant changes after acute exercise with activation of the prefrontal and occipital cortexes and deactivation of the anterior cingulate cortexes and left frontal hemisphere reflect the improvement of executive control processes, indicating that acute exercise could benefit working memory at a macro-neural level. In addition to its effects on reversing recent obesity and disease trends, our results provide substantial evidence highlighting the importance of promoting physical activity across the lifespan to prevent or reverse cognitive and neural decline.

The wandering mood: psychological and neural determinants of rest-related negative affect

Rest related negative affect (RRNA) has gained scientific interest in the past decade. However, it is mostly studied within the context of mind-wandering (MW), and the relevance of other psychological and neural aspects of the resting state to its’ occurrence has never been studied. Several indications associate RRNA with internally directed attention, yet the nature of this relation remains largely unknown. Moreover, the role of neural networks associated with rest related phenomenology – the default mode (DMN), executive (EXE), and salience (SAL) networks, has not been studied in this context. To this end, we explored two 5 (baseline) and 15-minute resting-state simultaneous fMRI-EEG scans of 29 participants. As vigilance has been shown to affect attention, and thus its availability for inward allocation, EEG-based vigilance levels were computed for each participant. Questionnaires for affective assessment were administered before and after scans, and retrospective reports of MW were additionally collected. Results revealed increased negative affect following rest, but only among participants who retained high vigilance levels. Among low-vigilance participants, changes in negative affect were negligible, despite reports of MW occurrence in both groups. In addition, in the high-vigilance group only, a significant increase in functional connectivity (FC) levels was found between the DMN-related ventral anterior cingulate cortex (ACC), associated with emotional processing, and the EXE-related dorsal ACC, associated with monitoring of self and other’s behavior. These heightened FC levels further correlated with reported negative affect among this group. Taken together, these results demonstrate that, rather than an unavoidable outcome of the resting state, RRNA depends on internal allocation of attention at rest. Results are discussed in terms of two rest-related possible scenarios which defer in mental and neural processing, and subsequently, in the occurrence of RRNA.

Current Trends in Moral Research

In this article, we identify five disparate themes that guide the processing of ethical judgment and behavior on the basis of current research drawn from multiple disciplinary fields. We then suggest directions for integrative research that consider ethical judgment and behavior as emergent outcomes of dynamic processing systems.

Self-specific stimuli interact differently than non-self-specific stimuli with eyes-open versus eyes-closed spontaneous activity in auditory cortex

Previous studies suggest that there may be a distinct relationship between spontaneous neural activity and subsequent or concurrent self-specific stimulus-induced activity. This study aims to test the impact of spontaneous activity as recorded in an eyes-open (EO) resting state as opposed to eyes-closed (EC) on self-specific versus non-self-specific auditory stimulus-induced activity in fMRI. In our first experiment we used self-specific stimuli comprised of the subject's own name and non-self-specific stimuli comprised of a friend's name and an unknown name, presented during EO versus EC baselines in a 3 name condition × 2 baseline design. In Experiment 2 we directly measured spontaneous activity in the absence of stimuli during EO versus EC to confirm a modulatory effect of the two baseline conditions in the regions found to show an interaction effect in Experiment 1. Spontaneous activity during EO was significantly higher than during EC in bilateral auditory cortex and non-self-specific names yielded stronger signal changes relative to EO baseline than to EC. In contrast, there was no difference in response to self-specific names relative to EO baseline than to EC despite the difference between spontaneous activity levels. These results support an impact of spontaneous activity on stimulus-induced activity, moreover an impact that depends on the high-level stimulus characteristic of self-specificity.

Failure of de-activation in the medial frontal cortex in mania: evidence for default mode network dysfunction in the disorder

OBJECTIVES

Manic patients have been found to show reduced activation in the prefrontal cortex and other regions during performance of cognitive tasks. However, little is known about de-activations associated with the disorder. This study aimed to examine, at the whole-brain level, abnormal patterns of task-related activation and de-activation during performance of a working memory task.

METHODS

Twenty-nine DSM-IV bipolar patients and 46 healthy controls underwent fMRI during performance of the n-back task. The patients were scanned while they were in a manic episode. Linear models were used to obtain maps of within-group activations and areas of differential activation between the groups.

RESULTS

The manic patients showed reduced activation compared to the controls in the bilateral dorsolateral prefrontal cortex and the right parietal cortex. They also showed failure of de-activation in the medial frontal cortex, extending to the temporal poles and parts of the limbic system bilaterally. The failure of activation in the dorsolateral prefrontal cortex disappeared when differences in task performance were controlled for in the analysis. However, the medial frontal failure of de-activation survived controlling for this.

CONCLUSIONS

This study suggests that, in addition to reduced prefrontal activation, failure of de-activation is an important functional imaging abnormality in mania. This, together with its location in the medial prefrontal cortex, implies default mode network dysfunction in the disorder.

The importance of velocity, or why speed may matter more than distance

Theory and research on self-regulation emphasizes the importance of goals for guiding human behavior. Critical phenomena within the self-regulation literature are discrepancies between actual states and goal states. When such discrepancies are detected, they capture attention and effort is mobilized to move actual states closer to goal states (or in some cases align the latter with the former). While discrepancy feedback, or the distance between actual and goal states, is important, so too is velocity feedback, or the rate at which actual–goal discrepancies are decreasing. Unfortunately, research has mostly ignored the role played by velocity in the self-regulation process. To redress this limitation, we review the concept of velocity, the empirical studies that have examined this concept, and how velocity is commonly measured. We then discuss the role of velocity as it pertains to three self-regulatory functions at work: achieving performance goals, satisfying belonging needs, and satisfying esteem needs.

EEG current source density and the phenomenology of the default network

In recent years, there has been an increasing line of research dedicated to the investigation of the default mode network (DMN) of the brain and resting state networks. However, the mental activity of the DMN has not been rigorously assessed to date. The specific aims of the current study were 2-fold: First, we sought to determine whether the current source density (CSD) levels in the DMN would correspond to other neuroimaging techniques. Second, we sought to understand the subjective mental activity of the DMN during baseline recordings. This study was conducted with 63 nonclinical participants, 34 female and 29 males with a mean age of 19.2 years (standard deviation = 2.0). The participants were recorded in 8 conditions. First, 4-minute eyes-closed baseline (ECB) and eyes-opened baseline (EOB) were obtained. The participants then completed 3 assessment instruments and 3 image conditions while the electroencephalography (EEG) was continuously recorded. Participants completed subjective reports for baselines and image conditions. These were rated by 3 independent raters and compared for reliability using a random effects model with an absolute agreement definition. The mean CSD between all conditions differed significantly, in many but not all regions of interest in the DMN. Interestingly, as suggested by other studies, the DMN appears preferential to self-relevant, self-specific, or self-perceptive processes. The reliability analyses show α for interrater agreement for ECB at .95 and EOB at .96. The subjective reports obtained from the participants regarding the mental activities employed during baseline recordings correspond to attentional and self-regulatory processes, which may also implicate the resting state or DMN as playing a direct role in the maintenance of a complex behavior (eg, being still, attending, and self-regulating). Thus, attention and self-regulation constitute the phenomenology of the resting state (DMN) in this study. The results also demonstrate that EEG CSD is a useful method to examine the DMN during concept-specific tasks to elucidate the neural activity associated with these concepts. Standardized low-resolution electromagnetic tomography (sLORETA) can localize to 5 mm(3), which is comparable to the findings in functional magnetic resonance imaging (fMRI). However, sLORETA can provide data about the difference in activity between groups, individuals, or populations which in many cases fMRI cannot provide.

DMN Operational Synchrony Relates to Self-Consciousness: Evidence from Patients in Vegetative and Minimally Conscious States

The default mode network (DMN) has been consistently activated across a wide variety of self-related tasks, leading to a proposal of the DMN’s role in self-related processing. Indeed, there is limited fMRI evidence that the functional connectivity within the DMN may underlie a phenomenon referred to as self-awareness. At the same time, none of the known studies have explicitly investigated neuronal functional interactions among brain areas that comprise the DMN as a function of self-consciousness loss. To fill this gap, EEG operational synchrony analysis [1, 2] was performed in patients with severe brain injuries in vegetative and minimally conscious states to study the strength of DMN operational synchrony as a function of self-consciousness expression. We demonstrated that the strength of DMN EEG operational synchrony was smallest or even absent in patients in vegetative state, intermediate in patients in minimally conscious state and highest in healthy fully self-conscious subjects. At the same time the process of ecoupling of operations performed by neuronal assemblies that comprise the DMN was highest in patients in vegetative state, intermediate in patients in minimally conscious state and minimal in healthy fully self-conscious subjects. The DMN’s frontal EEG operational module had the strongest decrease in operational synchrony strength as a function of selfconsciousness loss, when compared with the DMN’s posterior modules. Based on these results it is suggested that the strength of DMN functional connectivity could mediate the strength of self-consciousness expression. The observed alterations similarly occurred across EEG alpha, beta1 and beta2 frequency oscillations. Presented results suggest that the EEG operational synchrony within DMN may provide an objective and accurate measure for the assessment of signs of self-(un)consciousness in these challenging patient populations. This method therefore, may complement the current diagnostic procedures for patients with severe brain injuries and, hence, the planning of a rational rehabilitation intervention.

The neurodynamic organization of modality-dependent hallucinations

The pathophysiology of hallucinations remains mysterious. This research aims to specifically explore the interaction between hallucinations and spontaneous resting-state activity. We used multimodal magnetic resonance imaging during hallucinations occurrence in 20 drug-free adolescents with a "brief psychotic disorder." They were furthermore compared with 20 matched controls at rest or during exteroceptive stimuli. Anatomical and functional symptom-mapping demonstrated reduced cortical thickness and increased blood oxygen level-dependent signal in modality-dependent association sensory cortices during auditory, visual, and multisensory hallucinations. On the contrary, primary-sensory-cortex recruitment was not systematic and was shown to be associated with increased vividness of the hallucinatory experiences. Spatiotemporal activity patterns in the default-mode network (DMN) during hallucinations and symptom-free periods in patients were compared with patterns measured in healthy individuals. A disengagement of the DMN was concomitant to hallucinations, as for exogenous stimulations in healthy participants. Specifically, spatial and temporal instabilities of the DMN correlated with the severity of hallucinations but persisted during symptom-free periods. These results suggest that hallucinatory experiences emerge from a spontaneous DMN withdrawal, providing a convincing model for hallucinations beyond the auditory modality.

Medial prefrontal functional connectivity--relation to memory self-appraisal accuracy in older adults with and without memory disorders

It is tentatively estimated that 25% of people with early Alzheimer's disease (AD) show impaired awareness of disease-related changes in their own cognition. Research examining both normative self-awareness and altered awareness resulting from brain disease or injury points to the central role of the medial prefrontal cortex (MPFC) in generating accurate self-appraisals. The current project builds on this work - examining changes in MPFC functional connectivity that correspond to impaired self-appraisal accuracy early in the AD time course. Our behavioral focus was self-appraisal accuracy for everyday memory function, and this was measured using the Memory Function Scale of the Memory Awareness Rating Scale - an instrument psychometrically validated for this purpose. Using regression analysis of data from people with healthy memory (n=12) and people with impaired memory due to amnestic mild cognitive impairment or early AD (n=12), we tested the hypothesis that altered MPFC functional connectivity - particularly with other cortical midline structures and dorsolateral prefrontal cortex - explains variation in memory self-appraisal accuracy. We spatially constrained (i.e., explicitly masked) our regression analyses to those regions that work in conjunction with the MPFC to evoke self-appraisals in a normative group. This empirically derived explicit mask was generated from the result of a psychophysiological interaction analysis of fMRI self-appraisal task data in a separate, large group of cognitively healthy individuals. Results of our primary analysis (i.e., the regression of memory self-appraisal accuracy on MPFC functional connectivity) were generally consistent with our hypothesis: people who were less accurate in making memory self-appraisals showed attenuated functional connectivity between the MPFC seed region and proximal areas within the MPFC (including subgenual anterior cingulate cortex), bilateral dorsolateral prefrontal cortex, bilateral caudate, and left posterior hippocampus. Contrary to our expectations, MPFC functional connectivity with the posterior cingulate was not significantly related to accuracy of memory self-appraisals. Results reported here corroborate findings of variable memory self-appraisal accuracy during the earliest emergence of AD symptoms and reveal alterations in MPFC functional connectivity that correspond to impaired memory self-appraisal.

Differential neural activity in the recognition of old versus new events: an activation likelihood estimation meta-analysis

This study presents a meta-analysis comparing hit and correct rejection (CR) conditions across 48 fMRI studies. Old/new (hit > CR) effects associated most consistently with (1) components of the default-mode network, including the left angular gyrus, bilateral precuneus, and bilateral posterior cingulate regions, which may support the mental re-experiencing of an old event, or ecphory; (2) components of the cognitive-control network, involving the left dorsolateral and dorsomedial prefrontal cortex and bilateral intraparietal sulcus regions, which may mediate memory and non-memory control functions; and (3) the caudate nucleus, a key part of the brain's reward system that may support the satisfaction tied to target-detection. Direct comparisons of old/new effects between item versus source retrieval and "remember" versus "know" retrieval yielded three main sets of findings. First, default-mode network regions showed greater old/new effects in conditions associated with richer ecphoric processing. Second, cognitive-control network regions showed greater old/new effects in conditions associated with a greater demand for strategic-retrieval processing. Third, the caudate nucleus showed greater old/new effects in conditions tied to greater confidence in target-detection. New/old (CR > hit) effects most strongly associated with the bilateral medial temporal lobe, possibly reflecting greater encoding-related activity for new than for old items, and the right posterior middle temporal regions, possibly reflecting repetition-related neural priming for old items. In conclusion, neural activity distinguishing old from new events comprises an ensemble of multiple memory-specific activities, including encoding, retrieval, and priming, as well as multiple types of more general cognitive activities, including default-mode, cognitive-control, and reward processing.

Towards a neuroscience of mind-wandering

Mind-wandering (MW) is among the most robust and permanent expressions of human conscious awareness, classically regarded by philosophers, clinicians, and scientists as a core element of an intact sense of self. Nevertheless, the scientific exploration of MW poses unique challenges; MW is by nature a spontaneous, off task, internal mental process which is often unaware and usually difficult to control, document or replicate. Consequently, there is a lack of accepted modus operandi for exploring MW in a laboratory setup, leading to a relatively small amount of studies regarding the neural basis of MW. In order to facilitate scientific examination of MW the current review categorizes recent literature into five suggested strategies. Each strategy represents a different methodology of MW research within functional neuroimaging paradigms. Particular attention is paid to resting-state brain activity and to the “default-mode” network. Since the default network is known to exert high activity levels during off-task conditions, it stands out as a compelling candidate for a neuro-biological account of mind-wandering, in itself a rest-based phenomenon. By summarizing the results within and across strategies we suggest further insights into the neural basis and adaptive value of MW, a truly intriguing and unique human experience.

A framework for understanding leadership and individual requisite complexity

This paper examines the relation of individual perceptual, conscious, and self-regulatory processes to the generation of requisite complexity in formal and informal leaders. Requisite complexity is a complex adaptive systems concept that pertains to the ability of a system to adjust to the requirements of a changing environment by achieving equivalent levels of complexity. We maintain that requisite complexity has both static and dynamic aspects that involve four domains (general, social, self, and affective complexity), with each being more or less important for leaders depending upon the task requirements they face. Dynamic complexity draws on these static components and also creates new aspects of complexity through the interaction of mental processes. The implications of these issues for understanding leader adaptation and development are also discussed.

Correlated structural and functional brain abnormalities in the default mode network in schizophrenia patients

BACKGROUND

There is increasing evidence of default mode network (DMN) dysfunction in schizophrenia. It has also been suggested that brain structural changes are maximal in a medial frontal area which overlaps with the anterior midline node of this network.

METHODS

Brain deactivations were examined in 14 schizophrenic patients and 14 controls during performance of two tasks requiring identification or labelling of facial emotions. Grey matter and white matter volumes were compared using voxel-based morphometry.

RESULTS

Relative to the controls, the schizophrenic patients showed failure to deactivate in the anterior and posterior midline nodes of the default mode network, as well as other areas considered to be part of the network. Grey matter volume reductions in the patients were found in medial cortical regions which overlapped with the same parts of the network. The functional and structural changes showed significant correlations in a number of medial cortical areas.

CONCLUSIONS

Failure of deactivation in the default mode network is seen in schizophrenic patients when they perform facial emotion tasks. This failure is more extensive than that seen during performance of working memory tasks. The study also supports recent findings of brain structural changes in schizophrenia in the territory of the default mode network.

Persistent operational synchrony within brain default-mode network and self-processing operations in healthy subjects

Based on the theoretical analysis of self-consciousness concepts, we hypothesized that the spatio-temporal pattern of functional connectivity within the default-mode network (DMN) should persist unchanged across a variety of different cognitive tasks or acts, thus being task-unrelated. This supposition is in contrast with current understanding that DMN activated when the subjects are resting and deactivated during any attention-demanding cognitive tasks. To test our proposal, we used, in retrospect, the results from our two early studies (Fingelkurts, 1998; Fingelkurts et al., 2003). In both studies for the majority of experimental trails we indeed found a constellation of operationally synchronized cortical areas (indexed as DMN) that was persistent across all studied experimental conditions in all subjects. Furthermore, we found three major elements comprising this DMN: two symmetrical occipito-parieto-temporal and one frontal spatio-temporal patterns. This new data directly supports the notion that DMN has a specific functional connotation - it provides neurophysiologic basis for self-processing operations, namely first-person perspective taking and an experience of agency.

Self-specific processing in the default network: a single-pulse TMS study

In examining neural processing specific to the self, primarily by contrasting self-related stimuli with non-self-related stimuli (i.e., self vs. other), neuroimaging studies have activated a consistent set of regions, including medial prefrontal cortex (MPFC), precuneus, and right and left inferior parietal cortex. However, criticism has arisen that this network may not be specific to self-related processing, but instead reflects a more general aspect of cortical processing. For example, it is almost identical to the active network of the resting state, the "default" mode, when the subject is free to think about anything at all. We tested the self-specificity of this network by using transcranial magnetic stimulation (TMS) to briefly disrupt local cortical processing while subjects rated adjectives as like or unlike themselves or their best friend. Healthy volunteers show a self-reference effect (SRE) in this task, in which performance with self-related items is superior to that with other-related items. As individual adjectives appeared on a monitor, single-pulse TMS was applied at five different times relative to stimulus onset (SOA: stimulus onset asynchrony) ranging from 0 to 480 ms. In 18 subjects, TMS to left parietal cortex suppressed the SRE from 160 to 480 ms. SRE suppression occurred at later SOA with TMS to the right parietal cortex. In contrast, no effects were seen with TMS to MPFC. Together with our previous work, these results provide evidence for a self-specific processing system in which midline and lateral inferior parietal cortices, as elements of the default network, play a role in ongoing self-awareness.

Kafka, paranoic doubles and the brain: hypnagogic vs. hyper-reflexive models of disrupted self in neuropsychiatric disorders and anomalous conscious states

Kafka's writings are frequently interpreted as representing the historical period of modernism in which he was writing. Little attention has been paid, however, to the possibility that his writings may reflect neural mechanisms in the processing of self during hypnagogic (i.e., between waking and sleep) states. Kafka suffered from dream-like, hypnagogic hallucinations during a sleep-deprived state while writing. This paper discusses reasons (phenomenological and neurobiological) why the self projects an imaginary double (autoscopy) in its spontaneous hallucinations and how Kafka's writings help to elucidate the underlying cognitive and neural mechanisms. I further discuss how the proposed mechanisms may be relevant to understanding paranoid delusions in schizophrenia. Literature documents and records cognitive and neural processes of self with an intimacy that may be otherwise unavailable to neuroscience. To elucidate this approach, I contrast it with the apparently popularizing view that the symptoms of schizophrenia result from what has been called an operative (i.e., pre-reflective) hyper-reflexivity. The latter approach claims that pre-reflective self-awareness (diminished in schizophrenia) pervades all conscious experience (however, in a manner that remains unverifiable for both phenomenological and experimental methods). This contribution argues the opposite: the "self" informs our hypnagogic imagery precisely to the extent that we are not self-aware.

Medial prefrontal cortex pathology in schizophrenia as revealed by convergent findings from multimodal imaging

Neuroimaging studies have found evidence of altered brain structure and function in schizophrenia, but have had complex findings regarding the localization of abnormality. We applied multimodal imaging (voxel-based morphometry (VBM), functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) combined with tractography) to 32 chronic schizophrenic patients and matched healthy controls. At a conservative threshold of P=0.01 corrected, structural and functional imaging revealed overlapping regions of abnormality in the medial frontal cortex. DTI found that white matter abnormality predominated in the anterior corpus callosum, and analysis of the anatomical connectivity of representative seed regions again implicated fibres projecting to the medial frontal cortex. There was also evidence of convergent abnormality in the dorsolateral prefrontal cortex, although here the laterality was less consistent across techniques. The medial frontal region identified by these three imaging techniques corresponds to the anterior midline node of the default mode network, a brain system which is believed to support internally directed thought, a state of watchfulness, and/or the maintenance of one's sense of self, and which is of considerable current interest in neuropsychiatric disorders.

Interoception in anxiety and depression

We review the literature on interoception as it relates to depression and anxiety, with a focus on belief, and alliesthesia. The connection between increased but noisy afferent interoceptive input, self-referential and belief-based states, and top-down modulation of poorly predictive signals is integrated into a neuroanatomical and processing model for depression and anxiety. The advantage of this conceptualization is the ability to specifically examine the interface between basic interoception, self-referential belief-based states, and enhanced top-down modulation to attenuate poor predictability. We conclude that depression and anxiety are not simply interoceptive disorders but are altered interoceptive states as a consequence of noisily amplified self-referential interoceptive predictive belief states.

Contributions of frontopolar cortex to judgments about self, others and relations

Activation in frontopolar cortex (FPC; BA 10) has been associated both with attending to mental states and with integrating multiple mental relations. However, few previous studies have manipulated both of these cognitive processes, precluding a clear functional distinction among regions within FPC. To address this issue, we developed an fMRI task that combined mentalizing and relational integration processes. Participants saw blocks of single words and performed one of three judgments: how pleasant or unpleasant they found each word (Self condition), how a specific friend would evaluate the pleasantness of the word (Other condition), or the difference between their own pleasantness judgment and that of their friend (Relational condition). We found that medial FPC was modulated by Other relative to Self judgments, consistent with a role in mentalizing. Lateral FPC was significantly activated during Relational compared to Self judgements, suggesting that this region is particularly involved in relational integration. The results point to a strong functional dissociation between medial and lateral FPC. In addition, the data demonstrate a role for lateral FPC in the social domain, provided that the task requires the integration of one's preferences with those of others.

Theory of mind ability in the behavioural variant of frontotemporal dementia: an analysis of the neural, cognitive, and social levels

The paper reviews convergent evidence on the ability to attribute mental states to one's self and to others (i.e., theory of mind, ToM) in patients affected by the behavioural variant of frontotemporal dementia (bv-FTD). This disease represents a particular challenge for researchers and clinicians, due to its insidious onset and ambiguous clinical features, which frequently render difficult a precise and timely diagnosis. The paper proposes a way to shed new light on the hypothesis that the neuropsychiatric profile of individuals with bv-FTD can be at least partially explained by a deficit in ToM ability. We examined both neuroimaging data on the neural correlates of ToM ability in healthy participants and studies investigating the progressive cerebral atrophy in patients with bv-FTD. Our findings suggest a link between the progressive degeneration of the anterior regions of medial frontal structures characterising the early stages of the bv-FTD and the ToM deficit these patients show. They also suggest the importance of using ToM tests during the diagnostic process of bv-FTD.