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The brain's default network: Anatomy, function and relevance to disease
... Its main functions include the theory of mind, and cognitive processes of self-reference and social reference (Spreng & Grady, 2010;Whitfield-Gabrieli et al., 2011). Previous studies showed that ASD was altered in many of the processes that DMN was involved in, such as social and interpersonal cognition (Buckner et al., 2008). He et al. found that young children with ASD showed decreased dynamic functional connectivity variance within brain regions in the DMN compared with the TC group . ...
... Their activities enable perception of the environment and basic physiological responses. Secondly, high-level networks including SVA, DAN, Cont, and DMN are involved in complex cognitive functions, including attentional control, decision-making, language processing, and the cognitive processes of self-reference and social reference (Buckner et al., 2008;Fox et al., 2006;Menon & Uddin, 2010). They play pivotal roles in handling abstract concepts and executing advanced cognitive tasks. ...
... DMN is a spatially expansive system (Hagmann et al., 2008), consisting of prominent cortical nodes in the posterior cingulate cortex, ventromedial prefrontal cortex, retrosplenial cortex, angular gyrus, and both anterolateral and medial aspects of the temporal lobe (Lynch et al., 2013). The complex function of the DMN including the neural mechanisms underlying autobiographical memory, prospect, and theory of mind, cognitive processes of self-reference, and social reference (Spreng & Grady, 2010;Whitfield-Gabrieli et al., 2011), was determined by the spontaneous activity and interaction of widely scattered nodes (Buckner et al., 2008;Lynch et al., 2013). Previous studies showed that ASD is altered in many of the processes the DMN is involved in, like social and interpersonal cognition (Buckner et al., 2008). ...
Autism spectrum disorder (ASD) is a neurodevelopmental disorder with altered brain activity. However, little is known about the integrated temporospatial variation of dynamic spontaneous brain activity in ASD. In the present study, resting-state functional magnetic resonance imaging data were analyzed for 105 ASD and 102 demographically-matched typically developmental controls (TC) children obtained from the Autism Brain Imaging Data Exchange database. Using the sliding-window approach, temporal, spatial, and temporospatial variability of dynamic amplitude of low-frequency fluctuation (tvALFF, svALFF, and tsvALFF) were calculated for each participant. Group-comparisons were further performed at global, network, and brain region levels to quantify differences between ASD and TC groups. The relationship between temporospatial dynamic amplitude of low-frequency fluctuation variation alterations and clinical symptoms of ASD was finally explored by a support vector regression model. Relative to TC, we found enhanced tvALFF in visual network (Vis), somatomotor network (SMT), and salience/ventral attention network (SVA) of ASD, and weakened tvALFF in dorsal attention network (DAN) of ASD. Besides, ASD showed decreased svALFF in Vis, SVA, and limbic network (Limbic), and increased svALFF in DAN and default mode network (DMN). Elevated tsvALFF was found in the Vis, SMT, and DMN of ASD. More importantly, the altered tsvALFF from the DMN can predict the symptom severity of ASD. These findings demonstrate altered temporospatial dynamics of the spontaneous brain activity in ASD and provide novel insights into the neural mechanism underlying ASD.
... The components of such systems consist of brain regions that exhibit a high degree of homogeneity within and larger variation between the networks. The identified functional networks may relate to resting-state brain activity or to neural activity associated with intrinsic neural processing, cognitive, emotional, visual, and motor functions (Buckner et al., 2008;Smith et al., 2009). ...
... Several well-known functional networks have been consistently identified in both task and restingstate fMRI studies across different populations (Buckner et al., 2008;Damoiseaux et al., 2006;Laird et al., 2011;Smith et al., 2009). Some networks are identified more robustly than others, although it is unclear why. ...
... There has been an enormous amount of research devoted to FC over the past several years, with substantial interest focusing on resting-state FC. A set of resting state networks (RSNs) have been consistently identified in these investigations (Smith et al., 2009;Damoiseaux et al., 2006;Laird et al., 2011), most prominently the default mode network (DMN; Buckner et al., 2008). While our work focused on resting-state connectivity, our proposed methods extend to other studies involving task-related fMRI. ...
In recent years, there has been strong interest in neuroscience studies to investigate brain organization through networks of brain regions that demonstrate strong functional connectivity (FC). These networks are extracted from observed fMRI using data-driven analytic methods such as independent component analysis (ICA). A notable limitation of these FC methods is that they do not provide any information on the underlying structural connectivity (SC), which is believed to serve as the basis for interregional interactions in brain activity. We propose a new statistical measure of the strength of SC (sSC) underlying FC networks obtained from data-driven methods. The sSC measure is developed using information from diffusion tensor imaging (DTI) data, and can be applied to compare the strength of SC across different FC networks. Furthermore, we propose a reliability index for data-driven FC networks to measure the reproducibility of the networks through re-sampling the observed data. To perform statistical inference such as hypothesis testing on the sSC, we develop a formal variance estimator of sSC based a spatial semivariogram model with a novel distance metric. We demonstrate the performance of the sSC measure and its estimation and inference methods with simulation studies. For real data analysis, we apply our methods to a multimodal imaging study with resting-state fMRI and DTI data from 20 healthy controls and 20 subjects with major depressive disorder. Results show that well-known resting state networks all demonstrate higher SC within the network as compared to the average structural connections across the brain. We also found that sSC is positively associated with the reliability index, indicating that the FC networks that have stronger underlying SC are more reproducible across samples.
... Both tasks require thinking about someone else's thoughts and activate a network of cortical regions that includes the temporoparietal junction, the ventromedial and dorsomedial prefrontal cortex, the lateral temporal cortex, and the posteromedial cortex (16,(18)(19)(20). However, early observations noted that these same regions were recruited during other tasks (21)(22)(23)(24), including those involving not only social interactions without an explicit mentalizing component (25,26) but also tasks targeting more diverse processes such as autobiographical memory (27), self-oriented thinking (23,24,(28)(29)(30), and "episodic projection" (EP; i.e., thinking about the past or future) (31)(32)(33). The same set of association regions was also conceptualized as the canonical "default network" (DN) (21,34,35), which is definable from resting-state correlations of the BOLD signal (i.e., functional connectivity or FC) (36,37), exhibits connectivity to the MTL (21,(37)(38)(39), and shows increased activity during passive "rest" periods between active tasks (40). ...
... However, early observations noted that these same regions were recruited during other tasks (21)(22)(23)(24), including those involving not only social interactions without an explicit mentalizing component (25,26) but also tasks targeting more diverse processes such as autobiographical memory (27), self-oriented thinking (23,24,(28)(29)(30), and "episodic projection" (EP; i.e., thinking about the past or future) (31)(32)(33). The same set of association regions was also conceptualized as the canonical "default network" (DN) (21,34,35), which is definable from resting-state correlations of the BOLD signal (i.e., functional connectivity or FC) (36,37), exhibits connectivity to the MTL (21,(37)(38)(39), and shows increased activity during passive "rest" periods between active tasks (40). This overlap between ToM, the DN, and other memory-related processes led to the idea that the DN plays a domain-general role in introspection and mind wandering, which tends to include thoughts about others (31,(41)(42)(43)(44)(45)(46)(47)(48)(49) [e.g., see the twelfth figure in Buckner et al. (21) and first figure in Mars et al. (22)]. ...
... However, early observations noted that these same regions were recruited during other tasks (21)(22)(23)(24), including those involving not only social interactions without an explicit mentalizing component (25,26) but also tasks targeting more diverse processes such as autobiographical memory (27), self-oriented thinking (23,24,(28)(29)(30), and "episodic projection" (EP; i.e., thinking about the past or future) (31)(32)(33). The same set of association regions was also conceptualized as the canonical "default network" (DN) (21,34,35), which is definable from resting-state correlations of the BOLD signal (i.e., functional connectivity or FC) (36,37), exhibits connectivity to the MTL (21,(37)(38)(39), and shows increased activity during passive "rest" periods between active tasks (40). This overlap between ToM, the DN, and other memory-related processes led to the idea that the DN plays a domain-general role in introspection and mind wandering, which tends to include thoughts about others (31,(41)(42)(43)(44)(45)(46)(47)(48)(49) [e.g., see the twelfth figure in Buckner et al. (21) and first figure in Mars et al. (22)]. ...
Reasoning about someone’s thoughts and intentions—i.e., forming a “theory of mind”—is a core aspect of social cognition and relies on association areas of the brain that have expanded disproportionately in the human lineage. We recently showed that these association zones comprise parallel distributed networks that, despite occupying adjacent and interdigitated regions, serve dissociable functions. One network is selectively recruited by social cognitive processes. What circuit properties differentiate these parallel networks? Here, we show that social cognitive association areas are intrinsically and selectively connected to anterior regions of the medial temporal lobe that are implicated in emotional learning and social behaviors, including the amygdala at or near the basolateral complex and medial nucleus. The results suggest that social cognitive functions emerge through coordinated activity between internal circuits of the amygdala and a broader distributed association network, and indicate the medial nucleus may play an important role in social cognition in humans.
... The SN, anchored by the anterior insula (AI), identifies and filters salient stimuli, helping individuals focus on goal-relevant aspects of their environment (Menon and Uddin, 2010). In contrast, the DMN is typically engaged during internally focused cognitive processes and is implicated in the retrieval of past events and experiences (Buckner et al., 2008;Fox and Raichle, 2007;Fox et al., 2005;Greicius et al., 2008;Greicius and Menon, 2004;Laufs et al., 2003;Raichle, 2015;Raichle et al., 2001;Smallwood et al., 2021). The FPN is involved in the maintenance and manipulation of information within working memory and exerts top-down attentional control to regulate memory formation (Badre et al., 2005;Badre and Wagner, 2007;Helfrich and Knight, 2016;Jin et al., 2010;Simons and Spiers, 2003;Uncapher and Wagner, 2009;Wagner et al., 2001;Wagner et al., 2005). ...
... To further enhance our understanding of the dynamic activations within the three networks during episodic memory formation, we determined whether high-gamma band power in the AI, DMN, and FPN nodes depends on the phase of memory formation. Memory encoding, driven primarily by external stimulation, might invoke different neural responses compared to memory recall, which is more internally driven (Andrews-Hanna, 2012;Buckner et al., 2008). We hypothesized that DMN power would be suppressed during memory encoding as it is primarily driven by external stimuli, whereas an opposite pattern would be observed during memory recall which is more internally driven. ...
... Our analysis of local neuronal activity revealed a consistent and specific pattern of high-gamma power suppression in the PCC/precuneus compared to the AI during memory encoding across all four episodic memory tasks. This finding aligns with the typical deactivation of DMN nodes during attention-demanding tasks (Wen et al., 2013), while also extending our understanding of the DMN's role in episodic memory formation (Buckner et al., 2008;Menon, 2023). ...
Dynamic interactions between large-scale brain networks underpin human cognitive processes, but their electrophysiological mechanisms remain elusive. The triple network model, encompassing the salience network (SN), default mode network (DMN), and frontoparietal network (FPN), provides a framework for understanding these interactions. We analyzed intracranial electroencephalography (EEG) recordings from 177 participants across four diverse episodic memory experiments, each involving encoding as well as recall phases. Phase transfer entropy analysis revealed consistently higher directed information flow from the anterior insula (AI), a key SN node, to both DMN and FPN nodes. This directed influence was significantly stronger during memory tasks compared to resting state, highlighting the AI’s task-specific role in coordinating large-scale network interactions. This pattern persisted across externally driven memory encoding and internally governed free recall. Control analyses using the inferior frontal gyrus (IFG) showed an inverse pattern, with DMN and FPN exerting higher influence on IFG, underscoring the AI’s unique role. We observed task-specific suppression of high-gamma power in the posterior cingulate cortex/precuneus node of the DMN during memory encoding, but not recall. Crucially, these results were replicated across all four experiments spanning verbal and spatial memory domains with high Bayes replication factors. Our findings advance understanding of how coordinated neural network interactions support memory processes, highlighting the AI’s critical role in orchestrating large-scale brain network dynamics during both memory encoding and retrieval. By elucidating the electrophysiological basis of triple network interactions in episodic memory, our study provides insights into neural circuit dynamics underlying memory function and offer a framework for investigating network disruptions in memory-related disorders.
... Structural and functional impairments in the DMN (such as grey matter atrophy, amyloid-beta deposition, reduced connectivity) have knock-on effects on the cognitive abilities affected in dementia (e.g., memory, thinking, and planning). [17][18][19] Importantly, patterns of grey matter atrophy in DMNespecially medial temporal lobe and precuneusare already present in preclinical phases of dementia 20,21 and can predict transition to dementia within healthy and mild cognitive impairment groups. 22,23 Whilst these grey matter changes are observable long before the incidence of dementia, 24 it is currently unknown how early in the lifespan they begin and what factors contribute to them. ...
... We restricted regions of interest (ROI) analyses to nodes in DMN, given its established association with dementia and midlife cardiovascular health. 6,15 Cortical thickness and surface area analyses included eight cortical ROIs in DMN, as per 21 : caudal anterior cingulate cortex, parahippocampal gyrus, precuneus cortex, posterior cingulate cortex, inferior parietal cortex, middle temporal gyrus, entorhinal cortex, and cuneus cortex. Volumetric analyses focussed on one subcortical ROI within the DMN: hippocampus. ...
Background Cumulative exposures to obesity, hypertension, and physical inactivity from midlife (40-65 years) onwards are three known cardiovascular risk factors for dementia and associated cerebral structural damage. Exactly how early in the lifespan sensitive periods for exposure to these risk factors begin is yet to be established, specifically with respect to onset of cerebral structural changes. We aimed to investigate whether cardiovascular risk across childhood and adolescence is already associated with cerebral structure in regions previously linked with dementia, during young adulthood.
... variability of brain network interactions [8]. Researchers have associated schizophrenia with changes in both global and local brain network dynamics, which contribute to the disorder's cognitive impairments and emotional dysregulation [10]. However, there is still limited understanding of how these dynamic abnormalities precisely emerge in distinct brain states and how they interact with the symptoms of the disease [11]. ...
... These methods work on the assumption that functional connectivity between brain regions does not vary appreciably during the period of the scanning session, which normally lasts 5-15 min. However, this assumption does not seem to hold true in the face of accumulating evidence suggesting substantial changes in fMRI FC throughout time [10]. Therefore, recent investigations of fMRI resting state FC have increasingly focused on dynamic, or time-varying, FC. ...
Dynamic Functional Connectivity (DFC) captures temporal variations in brain network interactions, providing insights beyond traditional static connectivity, which is particularly relevant for understanding schizophrenia. This disorder, marked by symptoms like hallucinations, disorganized thinking, and cognitive impairments, has been associated with disruptions in functional networks, especially within the default mode (DMN) and salience networks (SN). However, static analyses overlook the temporal fluctuations essential to these brain functions. This study examines DFC patterns in schizophrenia patients compared to healthy controls using fMRI data. Employing clustering algorithms and a sliding window approach, we identify connectivity states and measure transition frequencies to reveal how unstable DFC may contribute to cognitive and emotional dysfunctions in schizophrenia. Results indicate that patients experience reduced stability and more frequent transitions in connectivity states within the DMN and SN, which are linked to symptoms like hallucinations and cognitive deficits. Demographic analysis shows that younger patients and males are more susceptible to hallucinatory symptoms, suggesting age- and gender-related vulnerabilities in brain network dynamics. Our findings support DFC as a valuable tool for understanding schizophrenia’s complex symptomatology and point toward personalized treatment approaches focused on stabilizing brain connectivity to improve clinical outcomes.
... It is also involved in attention and memory processes (Lenartowicz and McIntosh, 2005). The DMN is a highly robust resting-state brain network (Buckner et al., 2008). In a study examining the effects of tumors on the DMN, researchers found that the DMN exhibited resilience to the presence of tumors, with most brain regions showing little to no impact on its functioning (Ghumman et al., 2016). ...
Background: Temporal lobe mass lesions are the most common intracranial space-occupying lesions in children, among various brain lobes. The temporal lobe is critically involved in higher cognitive functions, and surgical interventions often risk causing damage to these functions. If necessary interventions and prehabilitation can be conducted preoperatively, it might be possible to achieve a larger extent of lesion resection with minimal cognitive impairment. However, research in this area has been relatively limited in the past. Our study aims to fill this gap.
Methods: We enrolled 15 children with temporal lobe mass lesions and 15 age- and gender-matched healthy children as controls. All participants underwent cognitive assessments and functional MRI scans. The cognitive testing data and functional MRI data were then analyzed and compared between the two groups.
Results: Our findings suggest that children with temporal lobe mass lesions primarily exhibit impairments in working memory and sustained attention. Multiple brain network indices were altered in the affected children, with the most prominent change being hyperactivation of the default mode network (DMN). This hyperactivation was correlated with cognitive impairments, indicating that the overactivation of the DMN might represent an inefficient compensatory mechanism within the brain’s networks.
Conclusion: Compared to healthy children, those with temporal lobe mass lesions experience deficits in working memory and sustained attention, and the hyperactivation of the DMN may be the underlying network mechanism driving these cognitive impairments. Our research offers a unique and clinically valuable reference for future studies on preoperative interventions and prehabilitation in this population.
... This enhanced thalamic engagement with sensorimotor regions, previously associated with schizophrenia's positive symptoms, underscores the potential role of neural integration disruptions in symptomatology [10,12,19,[74][75][76][77][78][79][80]. The DMN's heightened connectivity, implicated in self-referential thoughts and daydreaming, could relate to schizophrenia's reality distortion symptoms [81][82][83]. ...
Functional magnetic resonance imaging (fMRI) stands as a pivotal tool in advancing our comprehension of Schizophrenia, offering insights into functional segregations and integrations. Previous investigations employing either task-based or resting-state fMRI primarily focused on large main regions of interest (ROI), revealing the thalamus and superior temporal gyrus (STG) as prominently affected areas. Recent studies, however, unveiled the cytoarchitectural intricacies within these regions, prompting a more nuanced exploration. In this study, resting-state fMRI was conducted on 72 schizophrenic patients and 74 healthy controls to discern whether distinct thalamic nuclei and STG sub-regions exhibit varied functional integrational connectivity to main networks and to identify the most affected sub-regions in Schizophrenia. Employing seed-based analysis, six sub-ROIs – four in the thalamus and two in the STG – were selected. Our findings unveiled heightened positive functional connectivity in Schizophrenic patients, particularly toward the anterior STG (aSTG) and posterior STG (pSTG). Notably, positive connectivity emerged between the medial division of mediodorsal thalamic nuclei (MDm) and the visual network, while increased functional connectivity linked the ventral lateral nucleus of the thalamus with aSTG. This accentuated functional connectivity potentially influences these sub-regions, contributing to dysfunctions and manifesting symptoms such as language and learning difficulties alongside hallucinations. This study underscores the importance of delineating sub-regional dynamics to enhance our understanding of the nuanced neural alterations in Schizophrenia, paving the way for more targeted interventions and therapeutic approaches.
... Resting-state (intrinsic) functional connectivity (rsfc-MRI) has evolved to become one of the most common brain imaging phenotypes (Craddock et al., 2013;Fox and Raichle, 2007;Power et al., 2014b;Smith et al., 2013;Van Dijk et al., 2010), and has been critical for understanding fundamental properties of brain organization (Damoiseaux et al., 2006;Fox et al., 2005;Power et al., 2011;Yeo et al., 2011), brain development over the lifespan (Di-Martino et al., 2014;Dosenbach et al., 2011;Fair et al., 2008), and abnormalities associated with diverse clinical conditions (Baker et al., 2014;Buckner et al., 2008;Fair et al., 2010). rsfc-MRI has numerous advantages, including ease of acquisition and suitability for a wide and expanding array of analysis techniques. ...
Since initial reports regarding the impact of motion artifact on measures of functional connectivity, there has been a proliferation of confound regression methods to limit its impact. However, recent techniques have not been systematically evaluated using consistent outcome measures. Here, we provide a systematic evaluation of 12 commonly used confound regression methods in 193 young adults. Specifically, we compare methods according to three benchmarks, including the residual relationship between motion and connectivity, distance-dependent effects of motion on connectivity, and additional degrees of freedom lost in confound regression. Our results delineate two clear trade-offs among methods. First, methods that include global signal regression minimize the relationship between connectivity and motion, but unmask distance-dependent artifact. In contrast, censoring methods mitigate both motion artifact and distance-dependence, but use additional degrees of freedom. Taken together, these results emphasize the heterogeneous efficacy of proposed methods, and suggest that different confound regression strategies may be appropriate in the context of specific scientific goals.
... Commonly described modules include somatomotor (Biswal et al., 1995), visual (Corbetta et al., 1998), default mode (Raichle et al., 2001;Buckner et al., 2008), and frontoparietal systems Vincent et al., 2008). While brain network modules emerge very early in life (Fair et al., 2008;van den Heuvel et al., 2015;Thomason et al., 2013), a growing body of work has shown that these functional modules are refined during youth. ...
The human brain is organized into large-scale functional modules that have been shown to evolve in childhood and adolescence. However, it remains unknown whether structural brain networks are similarly refined during development, potentially allowing for improvements in executive function. In a sample of 882 participants (ages 8-22) who underwent diffusion imaging as part of the Philadelphia Neurodevelopmental Cohort, we demonstrate that structural network modules become more segregated with age, with weaker connections between modules and stronger connections within modules. Evolving modular topology facilitated network integration, driven by age-related strengthening of hub edges that were present both within and between modules. Critically, both modular segregation and network integration were associated with enhanced executive performance, and mediated the improvement of executive functioning with age. Together, results delineate a process of structural network maturation that supports executive function in youth.
... This result is in agreement with studies comparing healthy controls and major depressive disorder patients based on graph theory [44,45]. More broadly, the DMN has been implicated in the context of depression for behaviors such as self-referential image and rumination [46,47]. From the EMA analysis, we observed a trend for the subgroup with high depression index to have lower DMN efficiency, but it was not significant. ...
Stroke patients often experience post-stroke emotional impairments, yet the underlying pathophysiology remains unclear. At the brain level, dysregulation of socio-affective skills should be considered through alterations in brain networks instead of isolated regions. Investigating network alterations may be crucial in explaining emotional or cognitive deficits. In this context, and in line with the dysmetria of thought theory, cerebello-cortical networks’ alterations could explain socio-affective functioning. To examine whether impairments in intrinsic functional networks following a cerebellar stroke are associated with poor cognitive and socio-affective performance. Thirty-six cerebellar stroke patients underwent resting-state functional MRI scans at the early stage (T1). They were assessed through a battery of clinical evaluations for cognitive and socio-affective skills. At the chronic stage (T2), evaluations were repeated with additional ecological momentary assessments (EMA) for emotional behavior. The global efficiencies of four resting-state functional brain networks associated with the cerebellum were determined. Patients were classified into subgroups of high and low functioning based on the evaluations and compared. Poorer global efficiency in the default-mode network was present in the subgroup with higher depression (T1: p = 0.034, T2: p = 0.006) and low EMA positive mood (p = 0.048), while lower efficiency in the dorsal attentional network was shown in the subgroup with lower verbal memory (T1: p = 0.004, T2: p = 0.048). Disruptions in intrinsic functional networks are linked to poorer cognition and emotion for some cerebellar stroke patients, partially supporting the theory of ‘dysmetria of thought’.
... DMN and salience network are two different antagonistic networks and exhibit distinct activity profiles (Kucyi et al., 2020). DMN shows deactivation when one is engaged in externally oriented, stimulus-driven (bottom-up) attention and cognition (Buckner et al., 2008), while the salience network is activated (Uddin, 2015;Uddin, 2020). This difference possibly demonstrates distinct neural mechanisms under the aesthetic appreciation of two different artforms. ...
Aesthetic experiences are characterized by a conscious, emotionally and hedonically rewarding perceptions of a stimulus's aesthetic qualities and are thought to arise from a unique combination of cognitive and affective processes. To pinpoint neural correlates of aesthetic experiences, in the present study, we performed a series of meta-analyses based on the existing functional Magnetic Resonance Imaging (fMRI) studies of art appreciation in visual art (34 experiments, 692 participants) and music (34 experiments, 718 participants). The Activation Likelihood Estimation (ALE) analyses showed that the frontal pole (FP), ventromedial prefrontal cortex (vmPFC), and inferior frontal gyrus (IFG) were commonly activated in visual-art-induced aesthetic experiences, whilst bilateral superior temporal gyrus (STG) and striatal areas were commonly activated in music appreciation. Additionally, task-independent Resting-state Functional Connectivity (RSFC), task-dependent Meta-analytical Connectivity Modelling (MACM) analyses, as well as Activation Network Modeling (ANM) further showed that visual art and music engaged quite distinct brain networks. Our findings support the domain-specific view of aesthetic appreciation and challenge the notion that there is a general “common neural currency” for aesthetic experiences across domains.
... Despite promising early findings, the exact mechanisms through which oxytocin modulates states of consciousness remain unclear. Much of the current literature has focused on oxytocin's role in social behavior, leaving its broader impact on consciousness largely unexplored [27,28]. Nevertheless, emerging evidence suggests that oxytocin may serve as a biochemical catalyst for accessing pure consciousness by altering brain activity in key regions responsible for emotional regulation, social cognition, and self-awareness [29,30]. ...
Pure consciousness, often described as a state of heightened awareness or transcendence beyond ordinary perception, has long intrigued philosophers, neuroscientists, and psychologists alike. Recent advances in neuroendocrinology suggest that oxytocin, a hormone traditionally associated with social bonding, empathy, and trust, may play a significant role in modulating states of pure consciousness. This review explores the intersection between oxytocin and the neurobiology of awareness, investigating how the hormone influences various neural pathways and brain structures involved in consciousness. By examining current research on oxytocin’s effects on the prefrontal cortex, amygdala, and hippocampus—regions crucial for emotional regulation, memory, and self-awareness—we propose a model where oxytocin acts as a biochemical facilitator of deeper, more connected states of consciousness. Furthermore, we explore how oxytocin's role in social bonding may extend beyond interpersonal connections, fostering a sense of unity and interconnectedness often reported in higher states of consciousness. By bridging the neurochemical, psychological, and philosophical dimensions of consciousness, this review aims to provide a comprehensive understanding of oxytocin’s potential to shape human awareness, offering new insights into both the scientific and experiential dimensions of pure consciousness.
... In contrast to the higher prevalence of the global activation brain state, participants with insomnia had significantly less activation of the HMM brain state corresponding to the default mode network (see Figure 4). The default mode network is primarily related to internally oriented mental processes such as mind wandering, remembering and future planning (Buckner, Andrews-Hanna, & Schacter, 2008;Raichle, 2015;Smallwood et al., 2021). DMN activation has previously been linked to hyperarousal reduction in PTSD patients (King, Angstadt, Sripada, & Liberzon, 2017), and the reduced DMN activity seen in our insomnia participants could be interpreted as a result of hyperarousal. ...
Insomnia disorder is the most common sleep disorder, and neuroimaging research indicates that it is related to dysfunction in large-scale brain networks. Recently developed methods have enabled the investigation of the dynamic aspects of brain activity varying over time. In the present study, we used a novel data-driven approach to evaluate time-varying brain activity in adults with insomnia disorder compared to matched controls with no sleep problems. We acquired ten minutes resting state functional magnetic resonance images and T1-weighed images in all participants. We used Hidden Markov modelling for a data-driven definition of dynamic changes in whole-brain activity. The results showed that insomnia disorder is characterised by reduced switching rates between brain states. In line with the reduced switching, the HMM analyses suggested reduced prevalence of two whole-brain states - the default mode network and a fronto-parietal network - and an increase in just one brain state - a global activation state - in insomnia patients compared to controls. The findings suggest that insomnia disorder is characterised by less flexible transitions between brain states at wakeful rest, and thus highlight the importance of evaluating the spatiotemporal dynamics of brain activity to advance the understanding of the neural underpinnings of insomnia disorder.
... Scientists currently tend to consider brain functionality in terms of networks rather than in specific brain regions. Several studies have focused on the networks associated with MM, and they suggest the default mode network (DMN), which includes the medial PFC, posterior cingulate cortex (PCC), anterior precuneus, and inferior parietal lobule (Bonnelle et al., 2012;Buckner et al., 2008), is involved in selfreferential processing and is key for MM. Evidence from fMRI has shown that DMN regions exhibit relatively low activity in meditators in comparison with non-meditators, suggesting diminished self-referential processing (Brewer et al., 2011). ...
Objectives
Although internet gaming disorder (IGD) has become a serious mental health issue throughout the world, current treatment strategies face significant challenges. Mindfulness meditation (MM) is both versatile and widely accepted and has been proposed as an approach for treating IGD. However, its effects on IGD and the potential neural mechanisms underlying MM remain unknown.
Methods
Sixty-two participants with IGD were included, with 31 assigned to the MM group and 31 to the progressive muscle relaxation (PMR) group, all of them completed the entire experimental procedure, including the pre-test, eight MM training sessions (or progressive muscle relaxation), and the post-test. Two hundred and ten cortical and 36 subcortical subregions were arranged into eight brain networks according to Yeo’s functional template. The brain network features (intra- and inter-modular segregations) were compared between the different groups and tests.
Results
MM was found to reduce both addiction severity and gaming cravings in IGD subjects. In terms of brain networks, MM increased modular segregation in the subcortical network (SCN), especially between frontoparietal network (FPN)-SCN, and dorsal attentional network (DAN)-SCN, while also increasing connections in nodes in default mode networks (DMN), especially between FPN-DMN and DAN-DMN. Significant correlations between behavioral and network features were found. PMR also generated similar effects but inferior to MM.
Conclusions
MM was found decreased gaming craving and addiction severity in treating IGD. The process was associated with enhanced top-down control functions. The findings have implications for both clinicians and researchers.
Preregistration
The protocol of the trial has been pre-registered at the Chinese clinical trial registry (www.chictr.org.cn; ChiCTR2300075869).
... The increased connections between nodes mainly occurred between DMN-DAN, DMN-FPN and DAN-FPN. The DMN is a network that is closely related to the integration of cognitive and emotional processing and is responsible for directing thinking and mental activity 59 . Li et al. found that patients with SSNHL had increased network connectivity between the DAN, FPN and DMN 33 . ...
The topological attributes of structural covariance networks (SCNs) based on fractal dimension (FD) and changes in brain network connectivity were investigated using graph theory and network-based statistics (NBS) in patients with noise-induced hearing loss (NIHL). High-resolution 3D T1 images of 40 patients with NIHL and 38 healthy controls (HCs) were analyzed. FD-based Pearson correlation coefficients were calculated and converted to Fisher’s Z to construct the SCNs. Topological attributes and network hubs were calculated using the graph theory. Topological measures between groups were compared using nonparametric permutation tests. Abnormal connection networks were identified using NBS analysis. The NIHL group showed a significantly increased normalized clustering coefficient, normalized characteristic path length, and decreased nodal efficiency of the right medial orbitofrontal gyrus. Additionally, the network hubs based on betweenness centrality and degree centrality were both the right transverse temporal gyrus and left parahippocampal gyrus in the NIHL group. The NBS analysis revealed two subnetworks with abnormal connections. The subnetwork with enhanced connections was mainly distributed in the default mode, frontoparietal, dorsal attention, and somatomotor networks, whereas the subnetwork with reduced connections was mainly distributed in the limbic, visual, default mode, and auditory networks. These findings demonstrate the abnormal topological structure of FD-based SCNs in patients with NIHL, which may contribute to understand the complex mechanisms of brain damage at the network level, providing a new theoretical basis for neuropathological mechanisms.
... There is evidence to suggest that alterations in the functioning and connectivity of resting state networks (RSNs), including the default mode, salience, and central executive networks, may contribute to suicidal behavior by increasing negative rumination, impairing emotional regulation, and reducing cognitive control and decision-making abilities [1]. The default mode network (DMN) is considered a task-negative network of brain regions that deactivates during cognitive goal-directed tasks [2] while exhibiting increased activation during internally focused processes such as autobiographical memory retrieval and emotional and reward processing [3][4][5]. A growing number of studies consider the DMN to encompass functionally distinct subdivisions, including the dorsal medial prefrontal cortex (DMPFC), the core DMN, and the medial temporal lobe (MTL) subsystems [6][7][8]. ...
A moderating hub between resting state networks (RSNs) and the medial temporal lobe (MTL) is the parahippocampal cortex (PHC). Abnormal activity has been reported in depressed patients and suicide attempters in this region. Alterations in neuronal mitochondrial function may contribute to depression and suicidal behavior. However, little is known about the underlying molecular level changes in relevant structures. Specifically, expressional changes related to suicide have not been reported in the PHC. In this study, we compared the protein expression levels of genes encoding tricarboxylic acid (TCA) cycle enzymes in the PHC of adult individuals who died by suicide by reverse phase protein array (RPPA), which was corroborated by qRT-PCR at the mRNA level. Postmortem human brain samples were collected from 12 control and 10 suicidal individuals. The entorhinal cortex, which is topographically anterior to the PHC in the parahippocampal gyrus, and some other cortical brain regions were utilized for comparison. The results of the RPPA analysis revealed that the protein levels of DLD, OGDH, SDHB, SUCLA2, and SUCLG2 subunits were significantly elevated in the PHC but not in other cortical brain regions. In accordance with these findings, the mRNA levels of the respective subunits were also increased in the PHC. The subunits with altered levels are implicated in enzyme complexes involved in the oxidative decarboxylation branch of glutamine catabolism. These data suggest a potential role of glutaminolysis in the pathophysiology of suicidal behavior in the PHC.
... In contrast, the third state showed an activity pattern opposite to the second state, suggesting a functional switch, possibly indicative of a cognitive state or tasks transition . The fourth state showed the highest positive activity in the DMN and the most significant negative activity in visual-related regions, characteristic of internally focused cognitive processes such as mind-wandering or self-referential thinking (Buckner et al. 2008;Raichle and Snyder 2007). The fifth state was primarily active in visual regions, suggesting strong engagement in visual processing tasks. ...
Deception, a complex human behavior, demands greater cognitive engagement than honest responses. Recent studies have shown that dynamic brain states can rapidly shift in response to external stimuli and cognitive demands, offering insights into the brain's temporal and spatial dynamics. However, the specific brain state dynamics associated with deception remain unclear. In this study, we used functional magnetic resonance imaging (fMRI) to investigate the brain states associated with lie-telling, inverse-telling, and truth-telling, focusing on their dynamic attributes and spatial patterns to better understand the cognitive mechanisms underlying deception. We identified six representative brain states and analyzed their dynamic attributes across these tasks. Notably, two distinct states—termed "truth-preferred" and "lie-preferred"—exhibited significant differences in fractional occupancy and average dwelling time. The truth-preferred state showed higher occupancy and dwelling time during truth-telling, while the lie-preferred state demonstrated these characteristics during lie-telling. Using the average z-score BOLD signals of these two states, we applied generalized linear models (GLM) with elastic net regularization, achieving a classification accuracy of 88.46%, with a sensitivity of 92.31% and a specificity of 84.62% in distinguishing deception from truth-telling. Our findings revealed representative brain states associated with lie-telling, inverse-telling, and truth-telling, particularly highlighting two brain states specifically associated with truthful and deceptive behaviors. These results suggest that the spatial characteristics and dynamic attributes of certain brain states may serve as biomarkers of cognitive engagement in deceptive tasks.
... On the other hand, the differences in findings may also be due to the stricter FDR correction used in our analysis, or the use of different analysis methods, since this study only focused on the resting-state intra-network and inter-network changes and did not include every voxel in the whole brain. The DMN is primarily involved in autobiographical memory, self-reference, and emotional decision-making functions 40,41 , with the posterior cingulate cortex and aMPFC constituting the core of the DMN 42 . Multiple previous studies [43][44][45] have shown that the DMN is impaired in patients with T2DM and that the dysfunctional brain regions are mainly located in the posterior cingulate/precuneus. ...
Diabetic peripheral neuropathy (DPN) is the most common complication of type 2 diabetes mellitus (T2DM) and is often accompanied by a variety of cognitive and emotional deficits, but the neurologic mechanisms underlying these deficits have not been fully elucidated. Therefore, this study aimed to use independent component analysis to explore the changes in the characteristics within the intrinsic network and to reveal patterns of interactions between networks in patients with DPN. Forty-one patients with T2DM who showed DPN, 37 patients with T2DM who did not show DPN (NDPN group), and 43 healthy controls (HC) underwent a neuropsychological assessment and resting-state functional magnetic resonance imaging examinations to examine the patterns of intra- and inter-network variations in the patients with T2DM at different clinical stages (with and without DPN). The relationships of intra- and inter-network functional connectivity (FC) with clinical/cognitive variables were also examined. In comparison with the NDPN group and HC, patients with DPN showed decreased FC within the visual network and sensorimotor network (SMN). Moreover, in comparison with the HC group, patients with DPN showed decreased FC within the anterior default mode network and increased FC within the basal ganglia network. Inter-network analysis showed decreased FC between the SMN and salience network in patients with DPN relative to the NDPN and HC groups. The decreased FC within the bilateral paracentral lobule (BA 6) of SMN was associated with Color Trails Test part 1 scores (r = -0.302, P = 0.007) and disease duration (r = -0.328, P = 0.003) in all patients with T2DM. In conclusion, the results revealed that patients with DPN have abnormal FC in multiple resting-state intrinsic networks in addition to the SMN, and that decreased FC between the SMN and salience network may be involved in the neural basis of abnormal sensorimotor function in patients with DPN.
... Regarding functional networks, FC analysis showed reduced connectivity in regions within the default mode network (DMN) [104], central executive network (CEN) [103,105], and salience network (SN) [105] in chemotreated cancer survivors [106,107]. Within the DMN, altered functional activation in the precuneus has been linked to the types of cognitive impairments in CRCI, including episodic memory retrieval, visuospatial imagery, and self-referential processing [98]. ...
Advances in cancer diagnosis and treatment have substantially improved patient outcomes and survival in recent years. However, up to 75% of cancer patients and survivors, including those with non-central nervous system (non-CNS) cancers, suffer from “brain fog” or impairments in cognitive functions such as attention, memory, learning, and decision-making. While we recognize the impact of cancer-related cognitive impairment (CRCI), we have not fully investigated and understood the causes, mechanisms and interplays of various involving factors. Consequently, there are unmet needs in clinical oncology in assessing the risk of CRCI and managing patients and survivors with this condition in order to make informed treatment decisions and ensure the quality of life for cancer survivors. The state-of-the-art neuroimaging technologies, particularly clinical imaging modalities like magnetic resonance imaging (MRI) and positron emission tomography (PET), have been widely used to study neuroscience questions, including CRCI. However, in-depth applications of these functional and molecular imaging methods in CRCI and their clinical implementation for CRCI management are largely limited. This scoping review provides the current understanding of contributing neurological factors to CRCI and applications of the state-of-the-art multi-modal neuroimaging methods in investigating the functional and structural alterations related to CRCI. Findings from these studies and potential imaging-biomarkers of CRCI that can be used to improve the assessment and characterization of CRCI as well as to predict the risk of CRCI are also highlighted. Emerging issues and perspectives on future development and applications of neuroimaging tools to better understand CRCI and incorporate neuroimaging-based approaches to treatment decisions and patient management are discussed.
... A study found DMN to be active during self-reported instances of MW (Mooneyham and Schooler, 2013). However, DMN also exhibits heightened activity during purposeful internal thought, including future planning and episodic memory retrieval (Spreng et al., 2009;Buckner et al., 2008;Andrews-Hanna, 2012). This means activation of the DMN is not a specific indicator of MW. ...
Introduction
Mind-wandering is a highly dynamic phenomenon involving frequent fluctuations in cognition. However, the dynamics of functional connectivity between brain regions during mind-wandering have not been extensively studied.
Methods
We employed an analytical approach aimed at extracting recurring network states of multilayer networks built using amplitude envelope correlation and imaginary phase-locking value of delta, theta, alpha, beta, or gamma frequency band. These networks were constructed based on electroencephalograph (EEG) data collected while participants engaged in a video-learning task with mind-wandering and focused learning conditions. Recurring multilayer network states were defined via clustering based on overlapping node closeness centrality.
Results
We observed similar multilayer network states across the five frequency bands. Furthermore, the transition patterns of network states were not entirely random. We also found significant differences in metrics that characterize the dynamics of multilayer network states between mind-wandering and focused learning. Finally, we designed a classification algorithm, based on a hidden Markov model using state sequences as input, that achieved a 0.888 mean area under the receiver operating characteristic curve for within-participant detection of mind-wandering.
Discussion
Our approach offers a novel perspective on analyzing the dynamics of EEG data and shows potential application to mind-wandering detection.
... It plays an important role in cognitive processes, emotional regulation, motivation, and social interactions [51][52] It is a core node of the theory of mind network and is involved in various complex social tasks, such as inferring others' intentions from their actions [53]. Parallel studies have found that during social interactions, the connectivity between the SFGmed and amygdala [54] as well as the temporoparietal junction [55] is signi cantly reduced. Additionally, a fMRI study on irony tasks found that increased activation in the SFGmed is signi cantly associated with improved social function [56]. ...
Pragmatics, as it pertains to spoken language, plays a crucial role in effectively conveying messages across various social communication contexts. This aspect is frequently highlighted in the challenges experienced by children diagnosed with autism spectrum disorder (ASD). Notably, there remains a paucity of research investigating how the structural connectome (SC) predicts pragmatic language abilities within this population. Using diffusion tensor imaging (DTI) and deterministic tractography, we constructed the whole-brain white matter structural network (WMSN) in a cohort comprising 92 children with ASD and 52 typically developing (TD) preschoolers, matched for age and gender. Subsequent graph theoretical analyses were conducted to assess alterations in the global and node-based properties of the WMSN within both cohorts. To further elucidate these findings, we employed NBS-Predict, a novel methodology that integrates machine learning (ML) with network-based statistics (NBS), to identify dysconnected subnetworks associated with ASD. Our application of NBS-Predict allowed us to predict pragmatic language abilities based on the SC derived from the whole-brain WMSN in the ASD group. Initially, NBS-Predict identified a subnetwork characterized by 42 reduced connections across 37 brain regions ( p = 0.01), achieving a highest classification accuracy of 79.4% (95% CI: 0.791–0.796). The dysconnected regions were predominantly localized within the brain’s frontotemporal and subcortical areas, with the right superior medial frontal gyrus (SFGmed.R) emerging as the region exhibiting the most extensive disconnection. Moreover, NBS-Predict demonstrated that the optimal correlation coefficient between the predicted pragmatic language scores and the actual measured scores was 0.204 (95% CI: 0.181–0.226). This analysis revealed a significant association between the pragmatic language abilities of the ASD cohort and the white matter connections linking the SFGmed.R with the bilateral anterior cingulate gyrus (ACC). In summary, our findings suggest that the subnetworks displaying the most significant abnormal connections were concentrated in the frontotemporal and subcortical regions among the ASD group. Furthermore, the observed abnormalities in the white matter connection pathways between the SFGmed.R and ACC may underlie the neurobiological basis for pragmatic language deficits in preschool children with ASD.
... Our analysis uncovered an striking pattern within the brain's USFC blueprint: the DMN regions collectively possess the third highest nodal USFC values while more strikingly, seven of the top ten most heavily trafficked pathways involve either the PCG or medial prefrontal cortex, the two hub regions of the DMN 43 . Centrally located and occupy a large portion of the brain, the DMN is known for being "active" during rest and its versatile roles in self-reference, social cognition, episodic and autobiographical memory, language, sematic memory, among others [44][45][46] . All these functions involve complex communications within and between DMN and other brain regions which likely underlies our finding of its central role in the newly defined USFC system. ...
The brain’s white matter connections are thought to provide the structural basis for its functional connections between distant brain regions but how our brain selects the best structural routes for functional communications remains poorly understood. In this study, we propose a Unified Structural and Functional Connectivity (USFC) model and use an “economical assumption” to create the brain’s first “traffic map” reflecting how frequently each segment of the brain structural connection is used to achieve the global functional communication system. The resulting USFC map highlights regions in the subcortical, default-mode, and salience networks as the most heavily traversed nodes and a midline frontal-caudate-thalamus-posterior cingulate-visual cortex corridor as the backbone of the whole brain connectivity system. Our results further revealed a striking negative association between structural and functional connectivity strengths in routes supporting negative functional connections, as well as significantly higher efficiency metrics and better predictive performance for cognition in the USFC connectome when compared to structural and functional ones alone. Overall, the proposed USFC model opens up a new window for integrated brain connectome modeling and provides a major leap forward in brain mapping efforts for a better understanding of the brain’s fundamental communication mechanisms.
... Peaks of the individual deconvolved beta weights relative to the ROIs embedded in the DVAN were analyzed to evaluate the impact of stimulation combined with training on the attentional network. In addition, to control for networkspecific effects of stimulation, we also investigated whether tRNS and training impacted cortical activity within a different (control) network, the default mode network (DMN), which is typically active during passive or resting conditions ( [26], [54], [55], [56]). Next, we compared the change in beta weights measured within the DVAN and the DMN to test whether these two networks showed different modulation of the BOLD activity measured within their main ROIs after stimulation. ...
Neuromodulatory interventions are gaining interest for their potential to enhance key cognitive functions, including attention and learning. However, their effects on cortical activity during training remains limited. Our previous work demonstrated that bilateral transcranial random noise stimulation (tRNS) over the intraparietal sulcus (IPS), coupled with a multi-session attention-based perceptual learning increased functional connectivity within the dorsal-ventral attention network at rest (DVAN, Conto' et al., 2021). In this follow-up study we examined how the same multi-session stimulation protocol modulates BOLD signal in the DVAN during two attention tasks. Our findings show that tRNS targeting the IPS selectively enhanced BOLD responses during a spatial, but not a temporal task, indicating task-specific neural effects. Conversely, BOLD responses in the DVAN significantly decreased after sham. Control analyses within the default mode network (DMN) showed no significant changes, indicating the network specific effects of tRNS. The region-specific nature of these effects suggests that tRNS-induced modulation is constrained to key network nodes, enhancing the DVAN's cortical response in spatial tasks, a response that instead decreases after sham and has no benefit on behavior. This selectivity of the cortical response aligns with theories of neural efficiency, indicating that tRNS may prevent natural downregulation in task-relevant areas and promotes sustained plasticity. Our results highlight the potential of tRNS in augmenting cognitive training, providing a powerful tool for the precise modulation of attention networks in both healthy individuals and clinical population.
... These include the lateral temporal lobe, medial prefrontal cortex, cingulate cortex, and lateral/posterior parietal cortex (De Brigard et al., 2013). This "core" network overlaps substantially with the default mode network (Buckner et al., 2008) and is also preferentially engaged during episodic simulation of future events and episodic memory Hassabis et al., 2007;Okuda et al., 2003;Schacter et al., 2007;Szpunar et al., 2007). ...
Many of the most interesting cognitive feats that humans perform require us to consider not just the things that actually occur but also alternative possibilities. We often do this explicitly (e.g., when imagining precisely how a first date could have gone better), but other times we do it spontaneously and implicitly (e.g., when thinking, “I have to catch this bus,” implying bad alternatives if the bus is not caught). A growing body of research has identified a core set of neural processes involved in explicit, episodic counterfactual thinking. Little is known, however, about the processes supporting the spontaneous, possibly implicit representation of alternatives. To make progress on this question, we induced participants to spontaneously generate counterfactual alternatives by asking them to judge whether agents were forced to make a particular choice or chose freely—a judgment that implicitly depends on their alternative options. Using functional magnetic resonance imaging, we found 14 clusters that were preferentially engaged when participants were making force judgments (which elicit the spontaneous consideration of alternatives) compared to judgments of what actually occurred (which do not elicit alternatives). These clusters were widely distributed throughout the brain, including in the bilateral prefrontal cortex, bilateral inferior parietal lobule, bilateral middle and inferior temporal gyri, bilateral posterior cingulate, and bilateral caudate. In many of these regions, we additionally show that variability in the neural signal correlates with trial-by-trial variability in participants’ force judgments. Our findings provide a first characterization of the neural substrates of the spontaneous representation of counterfactual alternatives.
... A study with 16 participants (8 mediums and 8 controls) also reported higher activation of the OFC, bilateral occipital cortex, temporal pole, left middle temporal gyrus and middle frontal gyrus during mediumistic trance compared to the ordinary consciousness resting state condition (Fig. 3D) [60]. The PCC is a major integration center in the DMN associated with inwardly directed mental states [89]. The stronger activation of the PCC found during the mediumistic trance compared to the imaginetrance condition would reflect the sustained effort not to engage in any cognitively demanding task, and the orbitofrontal cortex would involve higher-order processes of integration, evaluation and regulation of sensory information [60]. ...
Background
Shamanism is a spiritual tradition in which trance practitioners deliberately modify their state of consciousness to seemingly interact with an invisible world to resolve their community members’ problems. This review aims to provide a multidisciplinary overview of scientific research on shamanic trance.
Methods
The search was performed using PubMed and Google Scholar databases. Twenty-seven articles were found to be eligible, and their data were classified into four dimensions, namely, a) phenomenology, b) psychology, c) neuro-physiological functions, and d) clinical applications.
Results
These studies suggest that these trances are non-pathological, different from normal states of consciousness in terms of phenomenology and neurophysiology, and influenced by multiple personal and environmental variables. Furthermore, while trances may offer therapeutic potential, their scope should be approached cautiously, underscoring the need for rigorous studies to assess the effectiveness of shamanic approaches for complementary therapies.
Conclusion
Overall, shamanic trance and its potential benefits remain an intriguing and multifaceted area of scientific study, offering insights into the intersections of consciousness, spirituality, and possibly therapy.
Open monitoring meditation is generally defined as the nonreactive, meta-aware observation of moment-by-moment phenomenal experiences associated with mental contents without focusing on predetermined mental or physical objects. However, in the current literature, neither general definitions nor more technical ones specify any particular mental state as the content of the meditator’s meta-awareness. In this article, we argue at both cognitive and neural levels that the object of the meditator’s meta-awareness consists solely of the phenomenal experiences associated with mind wandering contents, characterized as unguided, spontaneous thoughts. We demonstrate that out of the various definitions of mind wandering, only the one outlined in the dynamic framework aligns with our proposition, which defines open monitoring as the nonreactive meta-awareness of mind wandering.
OBJECTIVE
Mesial temporal lobe epilepsy (mTLE) and neocortical epilepsy (NE) have different anatomo-clinical characteristics. The authors hypothesized that this may be reflected in the different functional connectivity of the epileptogenic zone between mTLE and NE. The authors, therefore, examined preoperative resting-state functional connectivity MRI with regional global connectivity (rGC) analysis for surgically treated patients. The goal of this study was to detect the different functional networks associated with the epileptogenic zone between mTLE and NE.
METHODS
Twenty-four patients (12 with mTLE and 12 with NE) who underwent surgery were included in the study. All patients received resting-state functional MRI preoperatively. The mean rGC and number of high-rGC or low-rGC voxels were calculated using preoperative MRI in various regions of interest including the resected area.
RESULTS
The ratio of mean rGC in the resected area to that of the whole brain was significantly lower in mTLE patients than in NE patients. Mean rGC was significantly lower than that of the contralateral counterpart of the resected area in mTLE patients, although it was not significantly different in NE patients. Low rGC was more frequently observed in the resected area in mTLE patients than NE patients, and high rGC more frequently observed in NE than mTLE. Multivariate analysis showed that the etiology of hippocampal sclerosis, the ratio of mean rGC in the resected area to that in the whole brain, and the ratio of the number of low- and high-rGC voxels relative to the whole brain were significant factors to distinguish mTLE from NE.
CONCLUSIONS
The authors revealed a distinct brain network structure between mTLE and NE based on rGC analysis with resting-state functional MRI. The authors’ unique functional connectivity analysis may be helpful for providing landmarks for lateralization or epileptogenic zones in mTLE and NE.
Psychedelics are emerging as potential treatments for a range of mental health conditions, including anxiety and depression, treatment-resistant depression, and substance use disorders. Recent studies have also suggested that the psychedelic psilocybin may be able to treat obsessive compulsive disorder (OCD). Since the 1960s, case studies have reported improvements to obsessive and compulsive behaviours in patients taking psychedelics recreationally. The effects of psilocybin were then systematically assessed in a small, open-label trial in 2006, which found that psilocybin significantly reduced the symptoms of OCD. Reduced compulsive behaviours have also been seen in rodent models of OCD after administration of psilocybin. Nonetheless, the mechanisms underlying the effects of psychedelics for OCD are unclear, with hypotheses including their acute pharmacological effects, changes in neuroplasticity and resting state neural networks, and their psychological effects. This review will evaluate the evidence supporting the theory that psychedelics can be used for the treatment of OCD, as well as the data regarding claims about their mechanisms. It will also discuss issues with the current evidence and the ongoing trials of psilocybin that aim to address these knowledge gaps.
Major Depressive Disorder (MDD) is a common mental disorder characterized by cognitive impairment, and its pathophysiology remains to be explored. In this study, we aimed to explore the efficacy of brain network topological properties (TPs) in identifying MDD patients, revealing variational brain regions with efficient TPs. Functional connectivity (FC) networks were constructed from resting-state functional magnetic resonance imaging (rs-fMRI). Small-worldness did not exhibit significant variations in MDD patients. Subsequently, two-sample t-tests were employed to screen FC and reconstruct the network. The discriminative ability of TPs between MDD patients and healthy controls was analyzed using receiver operating characteristic (ROC), ROC analysis showed the small-worldness of binary reconstructed FC network (p < 0.05) was reduced in MDD patients, with area under the curve (AUC) of local efficiency (Le) and clustering coefficient (Cp) as sample features having AUC of 0.6351 and 0.6347 respectively being optimal. The AUC of Le and Cp for retained brain regions by T-test (p < 0.05) were 0.6795 and 0.6956 respectively. Further, support vector machine (SVM) model assessed the effectiveness of TPs in identifying MDD patients, and it identified the Le and Cp in brain regions selected by the least absolute shrinkage and selection operator (LASSO), with average accuracy from leave-one-site-out cross-validation being 62.03% and 61.44%. Additionally, shapley additive explanations (SHAP) was employed to elucidate variations in TPs across brain regions, revealing that predominant variations among MDD patients occurred within the default mode network. These results reveal efficient TPs that can provide empirical evidence for utilizing nodal TPs as effective inputs for deep learning on graph structures, contributing to understanding the pathological mechanisms of MDD.
Objectives
To observe the functional differences in the key brain areas in patients with different levels of consciousness after severe brain injury, and provide reference for confirming the objective diagnosis indicators for prolonged disorders of consciousness (pDoCs).
Methods
This prospective study enrolled patients with pDoCs hospitalized in the department of rehabilitation medicine of our Hospital. Levels of consciousness and clinical outcomes were assessed according to diagnostic criteria and behavioral scales. Resting-state functional magnetic resonance imaging (rs-fMRI) and diffusion tensor imaging (DTI) of 30 patients with different levels of consciousness was performed. The patients were grouped as conscious or unconscious according to whether they regained consciousness during the 12-month follow-up.
Results
Thirty patients were enrolled, including eight with unresponsive wakefulness syndrome/vegetative state, eight with minimally conscious state, six with emergence from the minimally conscious state, and eight with a locked-in syndrome. There were 19 and 11 patients in the conscious and unconscious groups. Compared with the unconscious group, the left basal nucleus was activated in the conscious group, and there were significant differences in white matter fiber bundles. Correlations were observed between the regional homogeneity (ReHo) value of the cerebellum and the Glasgow coma scale score (r = 0.387, P = 0.038) and between the ReHo value of the left temporal and the coma recovery scale-revised score (r = 0.394, P = 0.035).
Conclusions
The left insula and cerebellum might be important for regaining consciousness. The brain function activity and structural remodeling of the key brain regions and the activation level of the cerebellum are correlated with clinical behaviors and have potential application value for the prognosis prediction of pDoCs patients.
In everyday life, realizing that other people’s minds do not necessarily operate like our own minds deepens our understanding of how humans function. Thus, to fully understand human attitudes towards robots, one needs to take into account individual differences. For example, individual predispositions, such as the need for cognition, or the need for closure, play a crucial role in humans’ propensity to anthropomorphize robots. This chapter describes the findings addressing the relationship between people’s likelihood of adopting the Intentional Stance and two determinants related to individual differences: (1) individuals’ state of mind before (or during) the interaction with a robot, and (2) prior knowledge or expertise regarding robots. Taken together, these findings show that both determinants have a significant impact on individuals’ attitude to adopt the Intentional Stance, and they should be both taken into consideration in the design and development of robots that are to interact with humans.
The Default Mode Network (DMN) of the human brain is a central hub of introspection, creativity, and memory integration, facilitating processes such as self-referential thought, narrative construction, and social cognition. Active during rest and inward-directed mental activities, the DMN is responsible for weaving past experiences into coherent narratives, imagining future possibilities, and regulating emotions. These functions make it not only a cornerstone of human cognition but also an inspiring model for advancing artificial intelligence (AI). Recent advancements in AI, including generative models, reinforcement learning, and memory-augmented systems, have shown parallels with DMN processes, hinting at the potential for deeper integration of biological principles into machine learning. By emulating the DMN’s dynamic and adaptive functionalities, AI systems could achieve higher levels of creativity, introspection, and empathy, transforming fields such as education, mental health, and creative industries. This paper explores the potential of DMN-inspired AI architectures, the challenges in their development, and their implications for human-AI collaboration. It emphasizes the interdisciplinary nature of this endeavor, bridging neuroscience, AI, and ethics to create systems that not only replicate but enhance human cognitive and emotional capacities.
Keywords: Default Mode Network, neuro-inspired AI, creativity, memory integration, self-referential processing, generative models, reinforcement learning, introspection, emotional intelligence, interdisciplinary AI design. 40 pages.
Many musicians live with music performance anxiety (MPA), which may affect their psychological and physiological functioning. Mindfulness, being aware in the present moment without judgment, has been found to help ease anxiety. Mindfulness may also help alleviate the negative effects of MPA, but what is the neurophysiological basis for this effect? Core components of mindfulness, including emotional processing and acceptance, are related to specific patterns of brain activity. In the current study, 20 musicians with MPA underwent a resting-state functional magnetic resonance imaging (MRI) scan (Time 1), a method to examine the communication between brain regions at rest. Notably, 10 musicians then underwent 2 weeks of mindfulness training, while 10 did not. The same scan sequence was repeated in all participants 2 weeks later (Time 2). Compared with Time 1, participants in the mindfulness group exhibited decreased resting-state functional connectivity between areas of the prefrontal cortex and the vermis-6 and crus-II at Time 2. These two areas of the cerebellum are related to emotional processing and acceptance. Changes in communication between these brain regions and the prefrontal cortex suggest the neurophysiological influences of mindfulness and how mindfulness can be used to strengthen emotion regulation networks in musicians with MPA.
Depression is vastly heterogeneous in its symptoms, neuroimaging data, and treatment responses. As such, describing how it develops at the network level has been notoriously difficult. In an attempt to overcome this issue, a theoretical “negative prediction mechanism” is proposed. Here, eight key brain regions are connected in a transient, state-dependent, core network of pathological communication that could facilitate the development of depressive cognition. In the context of predictive processing, it is suggested that this mechanism is activated as a response to negative/adverse stimuli in the external and/or internal environment that exceed a vulnerable individual’s capacity for cognitive appraisal. Specifically, repeated activation across this network is proposed to update individual’s brain so that it increasingly predicts and reinforces negative experiences over time—pushing an individual at-risk for or suffering from depression deeper into mental illness. Within this, the negative prediction mechanism is poised to explain various aspects of prognostic outcome, describing how depression might ebb and flow over multiple timescales in a dynamically changing, complex environment.
Previous studies have reported a correlation between anxiety disorders and changes in brain structure, yet the specific alterations in brain region volumes remain unclear. This study aimed to infer the causal relationship between anxiety disorders and changes in brain structure volume through Mendelian Randomization analysis. We selected 63 cortical structure volumes from the GWAS database as exposure data and anxiety disorder data from the FinnGen and UK Biobank databases as outcomes. We found a significant correlation between atrophy in the Left precentral volume area (Odds Ratio [OR] = 0.935, 95% Confidence intervals [CI]: 0.891–0.981, P value, P = 0.007) and an increased risk of anxiety disorders. Additionally, changes identified in specific brain regions, such as atrophy in the Right rostral anterior cingulate area (OR = 0.993, 95% CI: 0.987–0.999, P = 0.025) and increased volume in the Left superior parietal area (OR = 1.001, 95% CI: 1.000–1.001, P = 0.028), may correlate with an increased risk of anxiety disorders. Furthermore, both phenotypes demonstrated directional consistency in their respective and overall meta-analyzed OR values pre- and post-merger, enhancing the reliability of the results. This study elucidates the causal relationship between anxiety disorders and specific brain structures, providing new insights for further research into psychiatric disorders.
Bulimia nervosa (BN) has been observationally linked to the functional connectivity (FC) of large-scale brain networks, but the biological mechanisms remain unclear. This study used two-sample Mendelian randomization (MR) with genetic variations as instrumental variables (IVs) to explore potential causal relationships between FC and BN. Summary data from genome-wide association studies (GWAS) involving 2,564 individuals were analyzed to identify genetically predicted BN. Functional magnetic resonance imaging parameters and materials were sourced from the UK Biobank. The variables underwent independent component analysis processing by the database to generate the final GWAS dataset. Various methods, including MR Pleiotropy RESidual Sum and Outlier, MR Egger, and weighted median, were employed to detect heterogeneity and pleiotropy, with inverse variance weighting serving as the principal estimation method (P < 0.05). The FC imaging-derived phenotypes revealed that BN exerted a causal influence on the FC between large-scale networks, including the visual network, default mode network (DMN), frontoparietal network, somatosensory network (SSN), and ventral attention network. Additionally, BN had a causal impact on the within-network FC of both the DMN and SSN. The study provides evidence that BN leads to further changes in FC patterns within and between large-scale brain networks.
Mounting neuroimaging evidence indicates that patients with thyroid-associated ophthalmopathy (TAO) demonstrate altered brain function and structure. Nonetheless, the alterations in the topological properties of the functional brain connectome in TAO patients are not yet fully understood. This study aimed to investigate the topological organization of the functional brain connectome in TAO patients using graph-theoretic methods. Twenty-five TAO patients (10 males and 15 females) and 25 age-, sex-, and education-matched healthy controls (HCs) (10 males and 15 females) (the TAO and HC data are from the same dataset in previous studies) underwent resting-state MRI scans. Graph-theoretic analysis was used to study the global, nodal, and edge topological properties of the brain’s functional connectome. Both the TAO and HC groups exhibited high-efficiency small-world networks in their brain functional networks. However, there were no significant differences in small-world properties (Cp, γ, λ, Lp, and σ) and network efficiency [global and local efficiencies (Eloc)] between the two groups. In addition, the TAO group demonstrated reduced betweenness centrality in the right fusiform and increased nodal Eloc in the right intraparietal sulcus ( P < 0.05, Bonferroni-corrected). Furthermore, the TAO group displayed altered functional connections among the default-mode network (DMN), visual network (VN), sensorimotor network (SMN), and cingulo-opercular network (CON). Patients with TAO exhibited abnormal topological organization of the human brain connectome, including decreased betweenness centrality and increased nodal Eloc. Moreover, the TAO group displayed altered functional connections primarily within the DMN, VN, SMN, and CON. These findings provide crucial insights into the neural mechanisms underlying visual loss, abnormal emotion regulation, and cognitive deficits in TAO patients.
Variants of the apolipoprotein E allele appear to account for most cases of late-onset Alzheimer's disease, and persons with two copies of the epsilon 4 allele appear to have an especially high risk of dementia. Positron-emission tomography (PET) has identified specific regions of the brain in which the rate of glucose metabolism declines progressively in patients with probable Alzheimer's disease. We used PET to investigate whether these same regions of the brain are affected in subjects homozygous for the epsilon 4 allele before the onset of cognitive impairment.
Apolipoprotein E genotypes were established in 235 volunteers 50 to 65 years of age who reported a family history of probable Alzheimer's disease. Neurologic and psychiatric evaluations, a battery of neuropsychological tests, magnetic resonance imaging, and PET were performed in 11 epsilon 4 homozygotes and 22 controls without the epsilon 4 allele who were matched for sex, age, and level of education. An automated method was used to generate an aggregate surface-projection map that compared regional rates of glucose metabolism in the two groups.
The epsilon 4 homozygotes were cognitively normal. They had significantly reduced rates of glucose metabolism in the same posterior cingulate, parietal, temporal, and prefrontal regions as in previously studied patients with probable Alzheimer's disease. They also had reduced rates of glucose metabolism in additional prefrontal regions, which may be preferentially affected during normal aging.
In late middle age, cognitively normal subjects who are homozygous for the epsilon 4 allele for apolipoprotein E have reduced glucose metabolism in the same regions of the brain as in patients with probable Alzheimer's disease. These findings provide preclinical evidence that the presence of the epsilon 4 allele is a risk factor for Alzheimer's disease. PET may offer a relatively rapid way of testing future treatments to prevent Alzheimer's disease.
Theory of development and the functional role of day-dreaming in behavior is examined. Score on a day-dream questionnaire for 44 female grad students is intercorrelated with the following: night dream frequency; parental identification; vocabulary (CAVD); 4 ratings of spontaneous daydream and story, Creativity, Needs achievement, Self-aggrandizement, and Affiliation; and 4 MMPI scales, Lie, Social-Introversion, Welsh Anxiety, Repression, "Daydreamers differ along a dimension which might be termed self-awareness." From Psyc Abstracts 36:01:3HJ25S. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
A MODEL IS PROPOSED FOR RELATING PRODUCTION OF SPONTANEOUS COGNITIVE EVENTS SUCH AS DAYDREAMS TO THE ORGANISM'S CONTINUOUS RESPONSE TO EXTERNAL STIMULI. EMPLOYING A SIMPLE SIGNAL-DETECTION TASK UNDER CONDITIONS OF PARTIAL SENSORY DEPRIVATION, A SERIES OF EXPERIMENTS WERE CARRIED OUT TO TEST SPECIFIC PREDICTIONS FROM THE MODEL. IN 1 EXPERIMENT INCREASING SPEED OF SIGNAL PRESENTATION OR DEMANDS UPON SHORT-TERM MEMORY BOTH SIGNIFICANTLY REDUCED REPORTS OF TASK-IRRELEVANT COGNITIVE ACTIVITY AND IMAGERY. IN A 2ND EXPERIMENT GRADED FINANCIAL REWARD FOR ACCURACY OF DETECTION LED TO PROGRESSIVE DECREASE IN EXTRANEOUS FANTASIES. IN A 3RD EXPERIMENT DISTRESSING INFORMATION PRIOR TO THE TRIALS SIGNIFICANTLY INCREASED REPORTS OF SPONTANEOUS DAYDREAMING DURING DETECTION PERFORMANCE. (19 REF.) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Measured the production of stimulus-independent thought (e.g., fantasy and imagery) as a function of the rate at which information was presented to 50 undergraduates. Information in the form of simple tones was presented at rates from .2-6 bits/sec. The linear regression of reported stimulus-independent thought on information rate accounted for 83% of the between cell variance. Results support a model in which both sensory and memory events are operated on by a common central cognitive unit. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Episodic memory is widely conceived as a fundamentally constructive, rather than reproductive, process that is prone to various kinds of errors and illusions. With a view towards examining the functions served by a constructive episodic memory system, we consider recent neuropsychological and neuroimaging studies indicating that some types of memory distortions reflect the operation of adaptive processes. An important function of a constructive episodic memory is to allow individuals to simulate or imagine future episodes, happenings and scenarios. Since the future is not an exact repetition of the past, simulation of future episodes requires a system that can draw on the past in a manner that flexibly extracts and recombines elements of previous experiences. Consistent with this constructive episodic simulation hypothesis, we consider cognitive, neuropsychological and neuroimaging evidence showing that there is considerable overlap in the psychological and neural processes involved in remembering the past and imagining the future.
Using retrospective reports, Giambra (1977-1978, 1979-1980) found an inverse relation between age and daydreaming/mind wandering. To deal with an alternate explanation of these results based on age-dependent memorial deficiencies and attitudes toward daydreaming/mind wandering and to provide independent convergent validity, five experiments were carried out. Task-unrelated thoughts (TUTs) were taken as the operational definition of daydreams/mind wanderings and their frequency recorded in vigilance tasks. All five experiments found an inverse relation between age (17-92 years, N = 471) and TUTs, confirming the reliability and validity of the earlier studies. The age-dependent reduction in TUTs was considered as evidence of reduced nonconscious information processing with increased age. The results of this study were incompatible with a recent theory that predicts for older individuals an increased input of irrelevant thoughts into working memory due to the older individual's reduced inhibitory control.
We use a new model of metarepresentational development to predict a cognitive deficit which could explain a crucial component of the social impairment in childhood autism. One of the manifestations of a basic metarepresentational capacity is a ‘theory of mind’. We have reason to believe that autistic children lack such a ‘theory’. If this were so, then they would be unable to impute beliefs to others and to predict their behaviour. This hypothesis was tested using Wimmer and Perner's puppet play paradigm. Normal children and those with Down's syndrome were used as controls for a group of autistic children. Even though the mental age of the autistic children was higher than that of the controls, they alone failed to impute beliefs to others. Thus the dysfunction we have postulated and demonstrated is independent of mental retardation and specific to autism.RésuméLes auteurs présentent un nouveau mod`éle de développement méta-cognitif pour prédire le déficit cognitif qui rendrait compte d'un composant essentiel du handicap social de l'enfant autiste. Une des manifestations d'une capacité de base méta-cognitive est une ‘theorie de l'esprit'. Nous avons des raisons de croire que cette théorie fait defaut chez l'enfant autiste. Celui-ci serait done incapable d'attribuer des croyances aux autres ou de prédire leur comportement. Cette hypothèse a été testée avec le paradigme de jeu des marionettes utilisé par Wimmer et Perner. Des enfants normaux et des enfants avec trisomie 21 ont servi de groupe contrôle. Bien que Page mental des enfants autistes ait été plus élevé que deux du groupe contrôle, seuls les enfants autistes Wont pu attribuer aux autres des croyances. Ainsi le dysfonctionnement prévu a pu être démontre, il s'avère indépendant du retard mental et spécifique a l'autiste.
Stimulus-independent thoughts (SITs) are streams of thoughts and images unrelated to immediate sensory input. Four experiments examined the contribution of aspects of working memory to production of SITs. In Experiments 1 and 2, interventions that were targeted on, respectively, phonological and visuospatial components of working memory both interfered with production of SITs, but there was evidence that these tasks also made demands on central executive resources. Experiments 3 and 4 specifically examined the hypothesis that production of SITs and control of nonproceduralized tasks both depend on central executive resources, and so should show mutual interference. In Experiment 3, prior practice on pursuit rotor and memory tasks reduced the interference with SITs from concurrent task performance. In Experiment 4, randomness within a task involving random-number generation was less when SITs were being produced concurrently than it was when they were not. The results suggest that production of SITs depends on central executive resources.
Thought-intrusions, automatic inferences, and other unintended thought are beginning to play an important role in the study of psychiatric disease as well as normal thought processes. We examine one method for the study of task-unrelated imagery and thought (TUIT). TUIT likelihood was shown to be reliably measured over a wide range of vigilance tasks, to have high short-term and long-term test-retest reliability, and to be sensitive to information processing demands. Likelihood of TUITs was shown to be different as a function of aging, hyperactivity, time of the day, and level of depression. Thus, we now can reliably measure the influence of endogenous and exogenous influences on TUITs. In addition, TUIT measurement was proposed as a minimally interfering and natural second task for determining resource utilization in a primary task. Finally, this method was offered as a reliable approach to quantification of such mental states as obsessions and drug craving and addiction.
This thoroughly revised new edition of a classic book provides a clinically inspired but scientifically guided approach to the biological foundations of human mental function in health and disease. It includes authoritative coverage of all the major areas related to behavioral neurology, neuropsychology, and neuropsychiatry. Each chapter, written by a world-renowned expert in the relevant area, provides an introductory background as well as an up-to-date review of the most recent developments. Clinical relevance is emphasized but is placed in the context of cognitive neuroscience, basic neuroscience, and functional imaging. Major cognitive domains such as frontal lobe function, attention and neglect, memory, language, prosody, complex visual processing, and object identification are reviewed in detail. A comprehensive chapter on behavioural neuroanatomy provides a background for brain-behaviour interactions in the cerebral cortex, limbic system, basal ganglia, thalamus, and cerebullum. Chapters on temperolimbic epilepsy, major psychiatric syndromes, and dementia provide in-depth analyses of these neurobehavioral entities and their neurobiological coordinates. Changes for this second edition include the reflection throughout the book of the new and flourishing alliance of behavioral neurology, neuropsychology, and neuropsychiatry with cognitive science;major revision of all chapters; new authorship of those on language and memory; and the inclusion of entirely new chapters on psychiatric syndromes and the dementias. Both as a textbook and a reference work, the second edition of Principles of Behavioral and Cognitive Neurology represents an invaluable resource for behavioural neurologists, neuropsychologists, neuropsychiatrists, cognitive and basic neuroscientists, geriatricians, physiatrists, and their students and trainees.
We review evidence for partially segregated networks of brain areas that carry out different attentional functions. One system, which includes parts of the intraparietal cortex and superior frontal cortex, is involved in preparing and applying goal-directed (top-down) selection for stimuli and responses. This system is also modulated by the detection of stimuli. The other system, which includes the temporoparietal cortex and inferior frontal cortex, and is largely lateralized to the right hemisphere, is not involved in top-down selection. Instead, this system is specialized for the detection of behaviourally relevant stimuli, particularly when they are salient or unexpected. This ventral frontoparietal network works as a 'circuit breaker' for the dorsal system, directing attention to salient events. Both attentional systems interact during normal vision, and both are disrupted in unilateral spatial neglect.
WE STUDIED 12 normal volunteers who were asked to imagine and plan their behavior in emotional and nonemotional situations while their regional cerebral blood flow was measured with positron emission tomography. The dorsolateral prefrontal and posterior temporal cortex were more activated during the nonemotional situation whereas the medial prefrontal cortex and anterior temporal cortex were more activated during the emotional situation. These results demonstrate that distinctive regions of the prefrontal and temporal cortex used to imagine and plan behavior are activated during the expression of emotional and non-emotional plans.
Presents a comprehensive, systematic, and unified theory of fantasy, based on extensive review of research on fantasy, fantasy-like phenomena, and relevant psychological topics such as properties of response processes and motivation. Included are discussions on play, dreams, serial order of behavior, and thematic apperceptive methods. (26 p ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The sections in this article are:
Amyloid plaques (APs) and neurofibrillary tangles (NFTs) are the two diagnostic markers of Alzheimer's disease (AD). The neuropsychological features of AD are closely correlated with the distribution of the NFTs and therefore favor a disease process revolving around neurofibrillary degeneration. The genetics, however, favor a disease process revolving around the APs, principally because mutations in the amyloid precursor protein (AβPP) are sufficient to cause AD. The inability to reconcile these two aspects of AD has prevented the formulation of a unified theory of pathogenesis. It is interesting to note that all genetic causes and risk factors of AD can increase the physiological burden of neuroplasticity. My hypothesis is that the resultant intensification of the plasticity burden leads to an initially adaptive upregulation of tau phosphorylation and AβPP turnover, to the subsequent formation of NFTs and APs as independent consequences of excessive plasticity-related cellular activity, and to the eventual loss of neurons, dendrites, and synapses as the ultimate expression of plasticity failure. The two pathological markers of AD are therefore independent manifestations of a more fundamental process through which the many different genotypes of AD trigger an identical clinical and neuropathological phenotype.
When performing tasks, humans are thought to adopt task sets that configure moment-to-moment data processing. Recently developed mixed blocked/event-related designs allow task set-related signals to be extracted in fMRI experiments, including activity related to cues that signal the beginning of a task block, "set-maintenance" activity sustained for the duration of a task block, and event-related signals for different trial types. Data were conjointly analyzed from mixed design experiments using ten different tasks and 183 subjects. Dorsal anterior cingulate cortex/medial superior frontal cortex (dACC/msFC) and bilateral anterior insula/frontal operculum (aI/fO) showed reliable start-cue and sustained activations across all or nearly all tasks. These regions also carried the most reliable error-related signals in a subset of tasks, suggesting that the regions form a "core" task-set system. Prefrontal regions commonly related to task control carried task-set signals in a smaller subset of tasks and lacked convergence across signal types.
An MRI time course of 512 echo-planar images (EPI) in resting human brain obtained every 250 ms reveals fluctuations in signal intensity in each pixel that have a physiologic origin. Regions of the sensorimotor cortex that were activated secondary to hand movement were identified using functional MRI methodology (FMRI). Time courses of low frequency (<0.1 Hz) fluctuations in resting brain were observed to have a high degree of temporal correlation (P < 10−3) within these regions and also with time courses in several other regions that can be associated with motor function. It is concluded that correlation of low frequency fluctuations, which may arise from fluctuations in blood oxygenation or flow, is a manifestation of functional connectivity of the brain.
Schizophrenia is often associated with cognitive deficits, particularly within the domains of memory and language. Specific cognitive deficits have recently been linked to psychotic phenomena, including verbal hallucinations and disorganized speech. Impairments of working and semantic memory are primarily due to dysfunction of the frontal cortex, temporal cortex, and hippocampus. Cognitive skills in schizophrenia predict social functioning and may serve as outcome measures in the development of effective treatment strategies.
Thesis (Ph. D.)--Washington University, 2006. Dept. of Biology and Biomedical Sciences. Includes bibliographical references.
Regional cerebral blood flow was measured with the intra-arterial 133 Xenon clearance technique using a multidetector device in 11 patients undergoing carotid angiography (with normal findings). During the flow studies the patients were awake and strict resting conditions were observed. The patients did not move or speak, and sensory stimulation was kept at a minimum. It was confirmed that the distribution of the grey matter blood flow showed a hyperfrontal pattern, the flow in frontal regions being significantly (20-40 %) higher than in postcentral, occipital and temporal regions. There were no technical factors or morphological features of the telencephalon which could explain this difference. It was also shown that the distribution of the white matter flow and the relative weight of the grey matter corresponded in general to hemisphere morphology.
Seven cases of Alzheimer's disease were studied in detail from a clinical and neuropathological point of view. The degenerative process was mapped with regard to regional variations in the intensity, extent and consistency of focal accentuations. The degeneration was regularly found to be most pronounced in certain areas: maximal cortical degeneration occurred in the medial temporal (limbic) area and, in the lateral hemisphere, consistently within a field expanding from the posterior inferior temporal areas to the adjoining portions of the parieto occipital lobes. In addition, the posterior cingulate gyrus was severely involved. On the other hand certain areas were notably and consistently spared or less involved, mainly the anterior cingulate gyrus and the calcarine and central sensory motor areas (primary projection areas). The frontal lobes occupied an intermediate position, being less severely involved than is usually reported. The clinical symptoms correlated well with this pattern of degeneration. Thus groups of symptoms such as memory dysfunction, emotional and personality alterations, and some symptoms of the Klüver-Bucy syndrome, were referable to the limbic lesions. The cortical lesions of the temporo-parieto-occipital association cortex correlated with the symptoms of agnosia, aphasia and apraxia, which were recorded in all cases. The relative sparing of the primary projection areas correspond well to findings of retained motility and perception even in later stages of the disease. The relative sparing of the frontal lobes and the anterior cingulate gyrus was related to the preservation of habitual personality traits. The pattern described may be related to ontogenetic features, and the tendency to focalization to the age of disease onset. The role of genetic factors and of other diseases is discussed.
Forty-seven patients with probable dementia of the Alzheimer type (DAT) and 30 healthy age-matched controls were scanned using [18F]-2-fluoro-2-deoxy-D-glucose on a Scanditronix PC 1024-7B tomograph (inplane resolution = 6 mm, axial resolution = 10 mm). Patients and controls were scanned in the resting state with their eyes patched and ears occluded. The regional cerebral metabolic rates for glucose (rCMRglc) in most major neocortical and subcortical gray matter regions, and certain metabolic ratios (rCMRglc/ calcarine rCMRglc), quantitatively discriminated even the mildly demented patients from healthy controls. The association neocortices showed metabolic abnormalities that were more severe than those in the sensorimotor and calcarine regions. All demented groups showed significant neuropsychological disturbances when compared to healthy controls. These data demonstrated widespread metabolic disturbances, particularly in the association areas, relatively early in Alzheimer's disease, and more profound involvement with disease progression.
In the primate brain, there are strong connections among the entorhinal cortex, the hippocampal formation, and the amygdala, 3 structures of the ventromedial temporal lobe that are related to memory function. Because memory impairment is a central feature of Alzheimer's disease, we examined the probable cells of origin and terminal zones of these connections in the brains of humans affected by the disease, using thioflavine S, Alz-50, and anti-A4 amyloid protein immunocytochemistry. Specific cytoarchitectural areas and lamina that give rise to projections from the entorhinal cortex, the hippocampal formation, and the amygdala consistently contained neurofibrillary tangles. The terminal zones of many of these projections contained neuritic plaques, Alz-50-positive neuritic alterations, and A4 deposition. Other cytoarchitectural areas and lamina, sometimes immediately adjacent, were consistently spared from these Alzheimer changes. This pattern of Alzheimer-related alterations would disrupt projections among the entorhinal cortex, hippocampal formation, and amygdala at multiple sites, and also disrupt projections between these structures and cortical and subcortical targets. In functional terms, this pattern of structural damage is likely to be as devastating as bilateral destruction of the ventromedial temporal lobe, and thus contribute substantially to the memory disorder seen in this condition.
Neurons depend upon the processes of axonal and transneuronal transport for intra- and intercellular communication and trophic support. Experimental studies in the last decade have elucidated the mechanisms underlying these processes, and provided evidence for their role in the spread of viral and toxic diseases through the nervous system. Recent advances in neuroanatomy, and in the pathological study of certain degenerative conditions, such as Alzheimer's disease, suggest that the same principles may underlie the anatomical specificity of cell loss in a variety of system degenerations. In Alzheimer's disease, as well as in olivo-ponto-cerebellar atrophy, progressive supranuclear palsy, amyotrophic lateral sclerosis, primary autonomic failure of the Shy-Drager type, and other system degenerations, the main feature that marks the affected populations of neurons is their anatomical interconnectivity. We consider here the possibility that, in these conditions, the processes of axonal and transneuronal transport may subserve the transmission from neuron to neuron of a toxic or infectious agent, or alternatively that the diseases may result from the failure of normal transport of a trophic agent. This hypothesis not only provides a unifying framework in which to view a variety of seemingly disparate conditions, but also suggests certain approaches to identifying the causative agents.
Injections of HRP-WGA in four cytoarchitectonic subdivisions of the posterior parietal cortex in rhesus monkeys allowed us to examine the major limbic and sensory afferent and efferent connections of each area. Area 7a (the caudal part of the posterior parietal lobe) is reciprocally interconnected with multiple visual-related areas: the superior temporal polysensory area (STP) in the upper bank of the superior temporal sulcus (STS), visual motion areas in the upper bank of STS, the dorsal prelunate gyrus, and portions of V2 and the parieto-occipital (PO) area. Area 7a is also heavily interconnected with limbic areas: the ventral posterior cingulate cortex, agranular retrosplenial cortex, caudomedial lobule, the parahippocampal gyrus, and the presubiculum. By contrast, the adjacent subdivision, area 7ip (within the posterior bank of the intraparietal sulcus), has few limbic connections but projects to and receives projections from widespread visual areas different than those that are connected with area 7a: the ventral bank and fundus of the STS including part of the STP cortex and the inferotemporal cortex (IT), areas MT (middle temporal) and possibly MTp (MT peripheral) and FST (fundal superior temporal) and portions of V2, V3v, V3d, V3A, V4, PO, and the inferior temporal (IT) convexity cortex. The connections between posterior parietal areas and visual areas located on the medial surface of the occipital and parieto-occipital cortex, containing peripheral representations of the visual field (V2, V3, PO), represent a major previously unrecognized source of visual inputs to the parietal association cortex. Area 7b (the rostral part of the posterior parietal lobe) was distinctive among parietal areas in its selective association with somatosensory-related areas: S1, S2, 5, the vestibular cortex, the insular cortex, and the supplementary somatosensory area (SSA). Like 7ip, area 7b had few limbic associations. Area 7m (on the medial posterior parietal cortex) has its own topographically distinct connections with the limbic (the posterior ventral bank of the cingulate sulcus, granular retrosplenial cortex, and presubiculum), visual (V2, PO, and the visual motion cortex in the upper bank of the STS), and somatosensory (SSA, and area 5) cortical areas.
Each parietal subdivision is extensively interconnected with areas of the contralateral hemisphere, including both the homotopic cortex and widespread heterotopic areas. Indeed, each area is interconnected with as many areas of the contralateral hemisphere as it is within the ipsilateral one, though less intensively. This pattern of distribution allows for a remarkable degree of interhemispheric integration.
These findings provide evidence that each major subdivision of posteriorparietal cortex has a unique set of reciprocal connections with limbic and sen-sory areas in both hemispheres. For the most part, each parietalsubdivision, rather than being a site of multimodal convergence, receives input from only one sensory modality, though often from different channels of information within that modality. For example, the two streams of visual information tra-ditionally linked to pattern and motion seem to converge in both areas 7a and 7ip. The areal parcellation of parietal cortex byits afferent and efferent con-nections provides an anatomical foundation for a parallel processing model of higher cortical functions.
Synopsis
In a sample of chronic schizophrenic patients, a group of symptoms which included poverty of speech and lack of spontaneous movement was found to be associated with poor performance in tests of conceptual thinking, object naming and long-term memory, and also with cortical neurological signs. A second group of symptoms which included formal thought disorder and inappropriate affect was associated with poor performance in tests of concentration, immediate recall and word learning, and with cortical neurological signs. The findings suggest that these two syndromes are associated with dysfunction at two different sites within the frontal lobes. A third group of symptoms, comprising various delusions and hallucinations, was associated with poor figure-ground perception, and might reflect temporal lobe dysfunction.
The classical tripartite concept of time divided into past/present/future components, has been applied to the analysis of the functional cerebral substrate of conscious awareness. Attempts have been made to localize and to separate the neuronal machineries which are responsible for the experience of a past, a present, and a future. One's experience of a past is obviously related to one's memories. Memory mechanisms (in the conventional sense) have a well known functional relation to superficial and deep parts of the temporal lobe. Some such mechanisms presumably have a more widespread distribution. The experience of a present or a "Now-situation" is mediated by the sensory input. This input also exerts a role for conscious awareness of an inner Now-situation, independent of current afferent impulses, as shown by numerous observations on sensory deprivation. The main discussion is devoted to the experience of a future. Evidence is summarized that the frontal/prefrontal cortex handles the temporal organization of behaviour and cognition, and that the same structures house the action programs or plans for future behaviour and cognition. As these programs can be retained and recalled, they might be termed "memories of the future". It is suggested that they form the basis for anticipation and expectation as well as for the short and long-term planning of a goal-directed behavioural and cognitive repertoire. This repertoire for future use is based upon experiences of past events and the awareness of a Now-situation, and it is continuously rehearsed and optimized. Lesions or dysfunctions of the frontal/prefrontal cortex give rise to states characterized by a "loss of future", with consequent indifference, inactivity, lack of ambition, and inability to foresee the consequences of one's future behaviour. It is concluded that the prefrontal cortex is responsible for the temporal organization of behaviour and cognition due to its seemingly specific capacity to handle serial information and to extract causal relations from such information. Possibly the serial action programs which are stored in the prefrontal cortex are also used by the brain as templates for extracting meaningful (serial) information from the enormous, mainly non-serial, random, sensory noise to which the brain is constantly exposed. Without a "memory of the future" such an extraction cannot take place.
Patients with Alzheimer's disease and multi-infarct dementia were studied with scans using fluorodeoxyglucose tagged with fluorine 18. The rates of glucose metabolism were calculated. Patients with Alzheimer's dementia showed decreased metabolism in all areas of the brain but with preferential sparing of the primary motor and sensory cortex. Patients with multi-infarct dementia also had global reductions in glucose metabolic rates when compared with normal control subjects, but the areas of hypometabolism were focal and asymmetric.
Understanding of another person's wrong belief requires explicit representation of the wrongness of this person's belief in relation to one's own knowledge. Three to nine year old children's understanding of two sketches was tested. In each sketch subjects observed how a protagonist put an object into a location x and then witnessed that in the absence of the protagonist the object was transferred from x to location y. Since this transfer came as a surprise they had to assume that the protagonist still believed that the object was in x. Subjects had to indicate where the protagonist will look for the object at his return. None of the 3–4-year old, 57% of 4–6-year old, and 86% of 6–9-year old children pointed correctly to location x in both sketches. Of the many cases where 4–6-year olds made an error they failed in only about 20% to remember the initial location correctly. As a test of the stability of children's representation of the protagonist's wrong belief the sketches continued with a statement about the protagonist's intention to either deceive an antagonist or truthfully inform a friend about the object's location. Independent of age, of those children who correctly thought that the protagonist would search in x, 85% of the time they also correctly thought that he would direct his antagonist to location y and his friend to location x. This shows that once children can represent a person's beliefs they can constrain their interpretation of this person's stated intentions to the person's beliefs. In a more story-like situation another group of children had to infer a deceptive plan from the depiction of a goal conflict between two story characters and one character's expedient utterance. At the age of 4–5 years children correctly judged this utterance as a lie only 28% of the time while 5–6-year olds did so 94% of the time. These results suggest that around the ages of 4 to 6 years the ability to represent the relationship between two or more person's epistemic states emerges and becomes firmly established.RésuméComprendre que ce que croit un tiers est erroné requiert une représentation explicitée de cette fausse croyance en relation avec son savoir propre.On a testé la compréhension de deux sketches par des enfants de 3 à 9 ans. Dans chacun des sketches les sujets observent un protagoniste placer un objet dans un lieu ‘x’, puis sont témoins du transfert de cet objet de ‘x’ en ‘y’ en l'absence du protagoniste. Ce transfert doit causer une surprise chez le protagoniste dont on assume qu'il croit que l'objet se trouve toujours en ‘x’. Les sujets doivent dire où le protagoniste va chercher l'objet. Aucun 3–4 ans n'indique correctement le lieu ‘x’, 57% des 4–6 ans et 86% des 6–9 ans le font. Parmi les nombreuses erreurs des 4–6 ans seules 20% sont attribuables à une incapacité de se souvenir du lieu ‘x’. Pour tester la stabilité de la représentation de la croyance erronée, on dit que le protagoniste a l'intention soit de tromper un adversaire soit d'informer un ami sur le lieu où se trouve l'objet. Indépendamment de leur âge, les enfants ayant donné des réponses correctes disent correctement dans 85% des cas que le protagoniste conduirait l'adversaire en ‘y’ et l'ami en ‘x’. Lorsque les enfants se représentent les croyances d'une personne, ils peuvent faire dépendre leurs interprétations des intentions exprimées par celles-ci à partir de ses croyances.Dans une situation de type histoire, un autre groupe d'enfants doit inférer un essai de tromperie à partir de la représentation d'un but conflictuel entre deux des personnages de l'énoncé tactique d'un des personnages. A 4–5 ans les enfants ne jugent correctement cet énoncé comme mensonger que dans 28% des cas alors qu'à 5–6 on a 94% de reponses correctes. Les résultats indiquent que vers 4–6 ans la capacité de représenter une relation entre les états épistémiques de deux personnes ou plus émerge et se confirme.
This study used positron emission tomography to examine two kinds of personal memory that are used in psychiatric evaluation: focused episodic memory (recall of past experience, employed in "taking a history") and random episodic memory (uncensored thinking about experience, examined during analytic therapy using free association). For comparison, a third memory task was used to tap impersonal memory that represents general information about the world ("semantic memory").
Thirteen subjects were studied using the [15O]H2O method to obtain quantitative measurements of cerebral blood flow. The three conditions were subtracted and their relative relationships examined.
The random episodic condition produced activations in widely distributed association cortex (right and left frontal, parietal, angular/supramarginal, and posterior inferior temporal regions). Focused episodic memory engaged a network that included the medial inferior frontal regions, precuneus/retrosplenial cingulate, anterior cingulate, thalamus, and cerebellum. The use of medial frontal regions and the precuneus/retrosplenial cingulate was common to both focused and random episodic memory. The major difference between semantic and episodic memory was activation of Broca's area and the left frontal operculum by semantic memory.
These results indicate that free-ranging mental activity (random episodic memory) produces large activations in association cortex and may reflect both active retrieval of past experiences and planning of future experiences. Focused episodic memory shares some components of this circuit (inferior frontal and precuneus), which may reflect the time-linked components of both aspects of episodic memory, and which permit human beings to experience personal identity, consciousness, and self-awareness.