Default Mode Network Activity Research Articles

Association of default-mode network neurotransmitters and inter-network functional connectivity in first episode psychosis.

Multiple psychiatric disorders are characterized by a failure to suppress default-mode network (DMN) activity during tasks and by weaker anti-correlations between DMN and other brain networks at rest. However, the cellular and molecular mechanisms underlying this phenomenon are poorly understood. At the cellular level, neuronal activity is regulated by multiple neurochemical processes including cycling of glutamate and GABA, the major excitatory and inhibitory neurotransmitters in brain. By combining functional MRI and magnetic resonance spectroscopy techniques, it has been shown that the neurotransmitter concentrations in DMN modulate not only functional activity during cognitive tasks, but also the functional connectivity between DMN and other brain networks such as frontoparietal executive control network (CN) at rest in the healthy brain. In the current study, we extend previous research to first episode psychosis (FEP) patients and their relatives. We detected higher glutamate (Glu) levels in the medial prefrontal cortex (MPFC) in FEP compared to healthy controls without a significant difference in GABA. We also observed a significantly lower functional anti-correlated connectivity between critical nodes within the DMN (MPFC) and CN (DLPFC) in FEP. Furthermore, the relationship between MPFC Glu and GABA concentrations and the functional anti-correlation that is seen in healthy people was absent in FEP patients. These findings imply that both the DMN Glu level and the interaction between DMN and CN are affected by the illness, as is the association between neurochemistry and functional connectivity. A better understanding of this observation could provide opportunities for developing novel treatment strategies for psychosis.

Brain activity during a working memory task after daily caffeine intake and caffeine withdrawal: a randomized double-blind placebo-controlled trial

Acute caffeine intake has been found to increase working memory (WM)-related brain activity in healthy adults without improving behavioral performances. The impact of daily caffeine intake—a ritual shared by 80% of the population worldwide—and of its discontinuation on working memory and its neural correlates remained unknown. In this double-blind, randomized, crossover study, we examined working memory functions in 20 young healthy non-smokers (age: 26.4 ± 4.0 years; body mass index: 22.7 ± 1.4 kg/m2; and habitual caffeine intake: 474.1 ± 107.5 mg/day) in a 10-day caffeine (150 mg × 3 times/day), a 10-day placebo (3 times/day), and a withdrawal condition (9-day caffeine followed by 1-day placebo). Throughout the 10th day of each condition, participants performed four times a working memory task (N-Back, comprising 3- and 0-back), and task-related blood-oxygen-level-dependent (BOLD) activity was measured in the last session with functional magnetic resonance imaging. Compared to placebo, participants showed a higher error rate and a longer reaction time in 3- against 0-back trials in the caffeine condition; also, in the withdrawal condition we observed a higher error rate compared to placebo. However, task-related BOLD activity, i.e., an increased attention network and decreased default mode network activity in 3- versus 0-back, did not show significant differences among three conditions. Interestingly, irrespective of 3- or 0-back, BOLD activity was reduced in the right hippocampus in the caffeine condition compared to placebo. Adding to the earlier evidence showing increasing cerebral metabolic demands for WM function after acute caffeine intake, our data suggest that such demands might be impeded over daily intake and therefore result in a worse performance. Finally, the reduced hippocampal activity may reflect caffeine-associated hippocampal grey matter plasticity reported in the previous analysis. The findings of this study reveal an adapted neurocognitive response to daily caffeine exposure and highlight the importance of classifying impacts of caffeine on clinical and healthy populations.

Neurophysiological and emotional influences on team communication and metacognitive cyber situational awareness during a cyber engineering exercise.

Background: Cyber operations unfold at superhuman speeds where cyber defense decisions are based on human-to-human communication aiming to achieve a shared cyber situational awareness. The recently proposed Orient, Locate, Bridge (OLB) model suggests a three-phase metacognitive approach for successful communication of cyber situational awareness for good cyber defense decision-making. Successful OLB execution implies applying cognitive control to coordinate self-referential and externally directed cognitive processes. In the brain, this is dependent on the frontoparietal control network and its connectivity to the default mode network. Emotional reactions may increase default mode network activity and reduce attention allocation to analytical processes resulting in sub-optimal decision-making. Vagal tone is an indicator of activity in the dorsolateral prefrontal node of the frontoparietal control network and is associated with functional connectivity between the frontoparietal control network and the default mode network. Aim: The aim of the present study was to assess whether indicators of neural activity relevant to the processes outlined by the OLB model were related to outcomes hypothesized by the model. Methods: Cyber cadets (N = 36) enrolled in a 3-day cyber engineering exercise organized by the Norwegian Defense Cyber Academy participated in the study. Differences in prospective metacognitive judgments of cyber situational awareness, communication demands, and mood were compared between cyber cadets with high and low vagal tone. Vagal tone was measured at rest prior to the exercise. Affective states, communication demands, cyber situational awareness, and metacognitive accuracy were measured on each day of the exercise. Results: We found that cyber cadets with higher vagal tone had better metacognitive judgments of cyber situational awareness, imposed fewer communication demands on their teams, and had more neutral moods compared to cyber cadets with lower vagal tone. Conclusion: These findings provide neuroergonomic support for the OLB model and suggest that it may be useful in education and training. Future studies should assess the effect of OLB-ing as an intervention on communication and performance.

Reflections on extraordinary knowing: Insight into the nature of the mind

Scientists have spent considerable time and effort studying and mapping the geography of the brain, with the expectation that this understanding will lead to insights related to the nature of the mind. This article discusses evidence that, while the mind utilizes sensory information processed by the brain, awareness is not limited to these structures. Research studies give evidence supporting the mind's ability to expand awareness to include perception of objects and events not available to the five senses. This awareness also extends to moments in the future, including the mind's ability to access information seconds or even days in advance of the occurrence. A major brain filter that limits this capacity for expanded awareness is the Default Mode Network (DMN). We summarize research showing that when the DMN activity is reduced, e.g., through meditation, ingestion of neuromodulatory drugs, or NDEs, filtering within the brain is reduced, there is a concomitant development of new connectivity, and these neural changes are correlated with access to expanded awareness.

Differential patterns of default mode network activity associated with negative and positive rumination in bipolar disorder

BackgroundPatients with bipolar disorder (BD) engage in both negative and positive rumination, defined as maladaptive self-focused thinking, and this tendency predicts depressive and manic episodes, respectively. Prior research in patients with major depression implicates regions of the default mode network (DMN) consistent with the self-focused nature of rumination. Little is known about the neural correlates of rumination in bipolar disorder. MethodsFifteen euthymic patients with BD (twelve with Type I) and 17 healthy controls (HC) performed negative and positive rumination induction tasks, as well as a distraction task, followed by a self-related trait judgment task while undergoing functional magnetic resonance imaging (fMRI). Participants also underwent resting state scans. We examined functional connectivity at rest and during the induction tasks, as well as task-based activation during the trait judgment task, in core regions of the DMN. ResultsCompared to HC, patients with BD showed greater functional connectivity between the posterior cingulate cortex (PCC) and medial prefrontal cortex (MPFC) at rest and during positive rumination, compared to distraction. They also showed greater activity in the PCC and MPFC during processing of positive traits, following positive rumination. At rest and during negative rumination compared to distraction, patients with BD showed greater functional connectivity between the PCC and inferior parietal lobule than HC. ConclusionsThese findings demonstrate that negative and positive rumination are subserved by different patterns of connectivity within the DMN in BD. Additionally, the PCC and MPFC are key regions involved in the processing of positive self-relevant traits following positive rumination.

Altered patterns of central executive, default mode and salience network activity and connectivity are associated with current and future depression risk in two independent young adult samples.

Neural markers of pathophysiological processes underlying the dimension of subsyndromal-syndromal-level depression severity can provide objective, biologically informed targets for novel interventions to help prevent the onset of depressive and other affective disorders in individuals with subsyndromal symptoms, and prevent worsening symptom severity in those with these disorders. Greater functional connectivity (FC) among the central executive network (CEN), supporting emotional regulation (ER) subcomponent processes such as working memory (WM), the default mode network (DMN), supporting self-related information processing, and the salience network (SN), is thought to interfere with cognitive functioning and predispose to depressive disorders. We examined in young adults (1) relationships among activity and FC in these networks and current depression severity, using a paradigm designed to examine WM and ER capacity in n = 90, age = 21.7 (2.0); (2) the extent to which these relationships were specific to depression versus mania/hypomania; (3) whether findings in a first, "discovery" sample could be replicated in a second, independent, "test" sample of young adults n = 96, age = 21.6 (2.1); and (4) whether such relationships also predicted depression at up to 12 months post scan and/or mania/hypomania severity in (n = 61, including participants from both samples, age = 21.6 (2.1)). We also examined the extent to which there were common depression- and anxiety-related findings, given that depression and anxiety are highly comorbid. In the discovery sample, current depression severity was robustly predicted by greater activity and greater positive functional connectivity among the CEN, DMN, and SN during working memory and emotional regulation tasks (all ps < 0.05 qFDR). These findings were specific to depression, replicated in the independent sample, and predicted future depression severity. Similar neural marker-anxiety relationships were shown, with robust DMN-SN FC relationships. These data help provide objective, neural marker targets to better guide and monitor early interventions in young adults at risk for, or those with established, depressive and other affective disorders.

Measuring Associations Between Physical Activity, Cognitive Ability, and AD‐Vulnerable Brain Networks in Periadolescent Children

AbstractBackgroundAs our population ages, and Alzheimer’s Disease (AD) and related pathologies become more prevalent, the need for preventative interventions continues to increase. Physical activity has been investigated as a mechanism to improve memory and other cognitive processes in both healthy and pathological aging. In adults, there is evidence that exercise increases hippocampal volume and strengthens connectivity within functional brain networks such as the Default Mode Network (DMN), Frontoparietal Network (FPN), and Dorsal Attention Network (DAN). These networks support cognitive functions such as spatial working memory (SWM) which involves maintenance and manipulation of visuospatial information; notably, SWM declines as AD progresses. Underlying connectivity in functional brain networks and SWM ability are both influenced by exercise in adults. However, this effect has not been replicated in younger cohorts. The effects of exercise on brain structure and function during periadolsecence, a neurodevelopmental period characterized by expansive changes to functional networks that support cognition, remains unclear. The current study tested associations between resting‐state functional connectivity (rs‐FC) in brain networks, SWM ability, and self‐reported physical activity in a group of periadolescents.MethodTypically‐developing periadolescent children aged 8 – 13 years (N = 60) completed the Cambridge Neuropsychological Test Automated Battery (CANTAB) SWM task, a self‐report physical activity questionnaire, and underwent an MRI of the brain to assess rs‐FC of several functional networks. MRI data were processed using the Human Connectome Project processing pipelines and AFNI software.ResultAnalysis of covariance between rs‐FC of the DMN and physical activity suggested greater within‐network connectivity was associated with more minutes of exercise. A similar pattern of within‐network connectivity in the DMN was also observed in association with SWM performance. The DAN and DMN demonstrated greater between‐network connectivity associated with increased physical activity. The FPN displayed a pattern of greater within‐network connectivity associated with SWM performance.ConclusionCharacterizing the influence of physical activity on development of brain networks that support memory may provide key insights on preserving those networks. Understanding these developmental trajectories, and ways to potentially enhance them, could be important for developing interventions to promote brain health by reducing the risk of neurological disease, including late‐life disorders such as AD.

Effect of Sleep on Motor Learning and Neural Activation Among Individuals with Traumatic Brain Injury

<h3>Research Objectives</h3> To examine the effect of a 45-minute nap on motor sequence learning and neural activation compared with a 45-minute period of resting wakefulness among individuals with traumatic brain injury (TBI). <h3>Design</h3> Cross-sectional. <h3>Setting</h3> Northeastern Rehabilitation Research Facility. <h3>Participants</h3> 23 individuals with a history of TBI between the ages of 21-63 (M=45.1, SD=12.9). Females comprised 13.6 % of the sample. <h3>Interventions</h3> Not Applicable. <h3>Main Outcome Measures</h3> E*Prime was used to deliver stimuli and capture the number of correct finger-tapping sequences over 12 learning trials and 6 retest trials after a 45-minute period of either sleep or relaxed wakefulness. A Siemens 3T Skyra MRI scanner was used to collect functional brain data while they completed the tapping sequence. Regressors corresponding to the time period of tapping sequence after the 45-minute Nap or Wake intervention were convolved with a canonical hemodynamic response function. The beta weights associated with the conditions of interest (tap vs non-tap) were entered in random-effects group analysis and corrected for multiple comparisons (z>1.6). <h3>Results</h3> Analysis of covariance demonstrated a significantly greater gain in the number of correct sequences in the Nap group (M=1.8, SD=1.7) compared with the Wake group (M=-.05, SD=2.9), controlling for age and learning capacity across training trials, F(1,18)=5.1, p=0.037. fMRI data revealed significant differences in activation between the Wake vs. Nap group in regions of the default mode network (DMN) (the precuneus and medial temporal lobe) as well as in the right ventrolateral prefrontal cortex (vlPFC). <h3>Conclusions</h3> The sleep-dependent enhancement of motor sequence learning is consistent with prior research after TBI. The fMRI findings suggest that this effect may be associated with a better ability in the Nap group to suppress DMN activation. At the same time, vlPFC activation might suggest greater reliance of the Wake group on working memory compared to the Nap group. <h3>Author(s) Disclosures</h3> Research was funded by the New Jersey Commission on Brain Injury Research. Authors have no conflicts of interest to disclose.

Default mode network mechanisms of repeated transcranial magnetic stimulation in heroin addiction.

Repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) has been shown to reduce cravings in heroin-dependent (HD) individuals, but the mechanisms underlying the anti-craving effects of rTMS are unknown. Abnormalities in the default mode network (DMN) are known to be consistent findings in HD individuals and are involved in cravings. We assessed the effect of rTMS on DMN activity and its relationship to the treatment response. Thirty HD individuals were included in this self-controlled study, and all HD participants received 10-Hz rTMS 7-session during a week. Data for cravings and withdrawal symptoms and resting-state functional magnetic resonance imaging data were collected before and after rTMS treatment. Thirty demographically matched healthy individuals who did not receive rTMS were included as controls. We focused on changes in coupling seeded from the medial prefrontal cortex (MPFC), posterior cingulate cortex (PCC), and bilateral inferior parietal lobe (IPL), which are the core regions of the DMN. The craving and withdrawal symptom score of HD individuals decreased significantly after rTMS treatment. The left IPL-left middle frontal gyrus coupling and the left IPL-right inferior occipital gyrus coupling decreased significantly, and the changes in the left IPL-left middle frontal gyrus coupling were positively correlated with changes in drug-cue induced cravings. rTMS could modulate the coupling between the DMN and executive control network (ECN). Alterations of the left IPL-left middle frontal gyrus coupling may play an important mechanistic role in reducing drug cue-induced cravings.

Dissociable neural mechanisms of cognition and well-being in youth versus healthy aging.

Mental health, cognition, and their underlying neural processes in healthy aging are rarely studied simultaneously. Here, in a sample of healthy younger (n = 62) and older (n = 54) adults, we compared subjective mental health as well as objective global cognition across several core cognitive domains with simultaneous electroencephalography (EEG). We found significantly greater symptoms of anxiety, depression, and loneliness in youth and in contrast, greater mental well-being in older adults. Yet, global performance across core cognitive domains was significantly worse in older adults. EEG-based source imaging of global cognitive task-evoked processing showed reduced suppression of activity in the anterior medial prefrontal default mode network (DMN) region in older adults relative to youth. Global cognitive performance efficiency was predicted by greater activity in the right dorsolateral prefrontal cortex in younger adults and in contrast, by greater activity in right inferior frontal cortex in older adults. Furthermore, greater mental well-being in older adults related to lesser global task-evoked activity in the posterior DMN. Overall, these results suggest dissociated neural mechanisms underlying global cognition and mental well-being in youth versus healthy aging. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Nasal airflow promotes default mode network activity

Background and objectivesDefault mode network (DMN) is a principal network that is more active at the baseline functional state of consciousness and spontaneous brain activity. Nasal breathing beyond the oxygen supply, entrained brain oscillations in widespread brain regions. Consistent with the important role of nasal breathing on neural oscillation for brain function, here we aimed to evaluate respiration entrained DMN rhythms. Materials and methodsUsing electroencephalography (EEG), we assessed the power spectral density and connectivity in DMN during the resting state among a group of sixteen healthy during three successive sessions. In addition to DMN, synchrony of the signal over the widespread cortical regions including somatosensory areas was investigated. Signal acquisition sessions consist of three times including nasal breathing, oral breathing, and nasal air-puff state that odorless air was puffed using a nasal cannula via an electrical valve (open duration of 630 ms) with a frequency of 0.2 Hz while subjects spontaneously breath orally. ResultsOur analyses demonstrated that nasal airflow, during both nasal breathing and nasal air-puff states, enhanced the power and connectivity of DMN regions specially at higher frequency bands, particularly gamma ranges. Enhancement in brain areas activity and connectivity including DMN and somatosensory due to the nasal airflow were not affected even in the condition that subjects were not attending to the nasal air-puff. ConclusionsNasal airflow promotes brain oscillations, particularly at the range of gamma that is very essential for higher brain functions.

The hidden brain-state dynamics of tACS aftereffects

Non-invasive techniques to electrically stimulate the brain such as transcranial direct and alternating current stimulation (tDCS/tACS) are increasingly used in human neuroscience and offer potential new avenues to treat brain disorders. Previous research has shown that stimulation effects may depend on brain-states. However, this work mostly focused on experimentally induced brain-states over the course of several minutes. Besides such global, long-term changes in brain-states, previous research suggests, that the brain is likely to spontaneously alternate between states in sub-second ranges, which is much closer to the time scale at which it is generally believed to operate. Here, we utilized Hidden Markov Models (HMM) to decompose magnetoencephalography data obtained before and after tACS into spontaneous, transient brain-states with distinct spatial, spectral and connectivity profiles. Only one out of four spontaneous brain-states, likely reflecting default mode network activity, showed evidence for an effect of tACS on the power of spontaneous α-oscillations. The identified state appears to disproportionally drive the overall (non-state resolved) tACS effect. No or only marginal effects were found in the remaining states. We found no evidence that tACS influenced the time spent in each state. Although stimulation was applied continuously, our results indicate that spontaneous brain-states and their underlying functional networks differ in their susceptibility to tACS. Global stimulation aftereffects may be disproportionally driven by distinct time periods during which the susceptible state is active. Our results may pave the ground for future work to understand which features make a specific brain-state susceptible to electrical stimulation.

Mindfulness-induced endogenous theta stimulation occasions self-transcendence and inhibits addictive behavior.

Self-regulation is instantiated by theta oscillations (4 to 8 Hz) in neurons of frontal midline brain regions. Frontal midline theta (FMΘ) is inversely associated with default mode network (DMN) activation, which subserves self-referential processing. Addiction involves impaired self-regulation and DMN dysfunction. Mindfulness is an efficacious self-regulatory practice for treating addiction, but little is known about the mechanisms by which mindfulness reduces addictive behavior. In this mechanistic study of long-term opioid users (N = 165), we assessed meditation-induced FMΘ as a mediator of changes in opioid misuse. Relative to a supportive psychotherapy control, participants treated with Mindfulness-Oriented Recovery Enhancement (MORE) exhibited increased FMΘ during a laboratory-based meditation session. FMΘ during meditation was associated with self-transcendent experiences characterized by ego dissolution, nondual awareness, and bliss. MORE’s effects on decreasing opioid misuse were mediated by increased FMΘ. Given the role of aberrant self-referential processing in addiction, mindfulness-induced endogenous theta stimulation might “reset” DMN dysfunction to inhibit addictive behavior.

Alteration of default mode network: association with executive dysfunction in frontal glioma patients.

Patients with frontal gliomas often experience executive dysfunction (EF-D) before surgery, and the changes in brain plasticity underlying this effect remain obscure. In this study, the authors aimed to assess whole-brain structural and functional alterations by using structural MRI and resting-state functional MRI (rs-fMRI) in frontal glioma patients with or without EF-D. Fifty-seven patients with frontal gliomas were admitted prospectively to the authors' institution and assigned to one of two groups: 1) the normal executive function (EF-N) group and 2) the EF-D group, based on patient results for the Trail Making Test, Part B and Stroop Color-Word Test, Part C. Twenty-nine baseline-matched healthy controls were also recruited. All participants underwent multimodal MRI examination. Cortical surface thickness, surface-based resting-state activity (fractional amplitude of low-frequency fluctuation [fALFF] and regional homogeneity [ReHo]), and edge-based network functional connectivity (FC) were measured with FreeSurfer and fMRIPrep. The correlation between altered MRI parameters and executive function (EF) was assessed using Pearson correlation and receiver operating characteristic (ROC) analysis. Demographic characteristics (sex, age, and education level) and clinical characteristics (location, volume, grade of tumor, and preoperative epilepsy) were not significantly different between the groups, but the Karnofsky Performance Scale score was worse in the EF-D group. There was no significant difference in cortical surface thickness between the EF-D and EF-N groups. In both low-grade and high-grade glioma patients the fALFF value (permutation test + threshold-free cluster enhancement, p value after family-wise error correction < 0.05) and ReHo value (t-test, p < 0.001) of the left precuneus cortex in the EF-D group were greater than those in the EF-N group, which were negatively correlated with EF (p < 0.05) and enabled prediction of EF (area under the ROC curve 0.826 for fALFF and 0.855 for ReHo, p < 0.001). Compared with the EF-N group, the FCs between the default mode network (DMN) from DMN node to DMN node (DMN-DMN) and from the DMN to the central executive network (DMN-CEN) in the EF-D group were increased significantly (network-based statistics corrected p < 0.05) and negatively correlated with EF (Pearson correlation, p < 0.05). Apart from local disruption, the abnormally activated DMN in the resting state is related to EF-D in frontal glioma patients. DMN activity should be considered during preoperative planning and postoperative neurorehabilitation for frontal glioma patients to preserve EF. Clinical trial registration no.: NCT03087838 (ClinicalTrials.gov).

Beyond the veil of duality-topographic reorganization model of meditation.

Meditation can exert a profound impact on our mental life, with proficient practitioners often reporting an experience free of boundaries between a separate self and the environment, suggesting an explicit experience of “nondual awareness.” What are the neural correlates of such experiences and how do they relate to the idea of nondual awareness itself? In order to unravel the effects that meditation has on the brain’s spatial topography, we review functional magnetic resonance imaging brain findings from studies specific to an array of meditation types and meditator experience levels. We also review findings from studies that directly probe the interaction between meditation and the experience of the self. The main results are (i) decreased posterior default mode network (DMN) activity, (ii) increased central executive network (CEN) activity, (iii) decreased connectivity within posterior DMN as well as between posterior and anterior DMN, (iv) increased connectivity within the anterior DMN and CEN, and (v) significantly impacted connectivity between the DMN and CEN (likely a nonlinear phenomenon). Together, these suggest a profound organizational shift of the brain’s spatial topography in advanced meditators—we therefore propose a topographic reorganization model of meditation (TRoM). One core component of the TRoM is that the topographic reorganization of DMN and CEN is related to a decrease in the mental-self-processing along with a synchronization with the more nondual layers of self-processing, notably interoceptive and exteroceptive-self-processing. This reorganization of the functionality of both brain and self-processing can result in the explicit experience of nondual awareness. In conclusion, this review provides insight into the profound neural effects of advanced meditation and proposes a result-driven unifying model (TRoM) aimed at identifying the inextricably tied objective (neural) and subjective (experiential) effects of meditation.

A distinct intra-individual suppression subnetwork in the brain's default mode network across cognitive tasks.

Suppression of the brain's default mode network (DMN) during external goal-directed cognitive tasks has been consistently observed in neuroimaging studies. However, emerging insights suggest the DMN is not a monolithic "task-negative" network but is comprised of subsystems that show functional heterogeneity. Despite considerable research interest, no study has investigated the consistency of DMN activity suppression across multiple cognitive tasks within the same individuals. In this study, 85 healthy 15- to 25-year-olds completed three functional magnetic resonance imaging tasks that were designed to reliably map DMN suppression from a resting baseline. Our findings revealed a distinct suppression subnetwork across the three tasks that comprised traditional DMN and adjacent regions. Specifically, common suppression was observed in the medial prefrontal cortex, the dorsal-to-mid posterior cingulate cortex extending to the precuneus, and the posterior insular cortex and parietal operculum. Further, we found the magnitude of suppression of these regions were significantly correlated within participants across tasks. Overall, our findings indicate that externally oriented cognitive tasks elicit common suppression of a distinct subnetwork of the broader DMN. The consistency to which the DMN is suppressed within individuals suggests a domain-general mechanism that may reflect a stable feature of cognitive function that optimizes external goal-directed behavior.

Nodes of the default mode network implicated in the quality of empathic responses: A clinical perspective of the empathic response

The ability to empathize with another person's inner experience is believed to be a central element of our social interactions. Previous research has focused on cognitive (e.g., theory of mind) and emotional (e.g., emotional contagion) empathy, and less on behavioral factors (i.e., the ability to respond empathically). Recent studies suggest that the Default Mode Network (DMN) mediates individual variability in distinct empathy-related behaviors. However, little is known about DMN activity during actual empathic responses, understood in this study as the ability to communicate our understanding of the others’ experience back to them. This study used an empathy response paradigm with 28 participants (22-37 years old) to analyze the relationship between the quality of empathic responses to 14 empathy-eliciting vignettes and patterns of attenuation in the DMN. Overall, the results suggest that high levels of empathic response, are associated with sustained activation of the DMN when compared with lower levels of empathy. Our results demonstrate that the DMN becomes increasingly involved in empathy-related behavior, as our level of commitment to the other's experience increases. This study represents a first attempt to understand the relation between the capacity for responding in a supportive way to others’ needs and the intra-individual variability of the pattern of the DMN attenuation. Here we underline the critical role that the DMN plays in high-level social cognitive processes and corroborate the DMN role in different psychiatric disorders associated with a lack of empathy.

Oxytocin modulates social brain network correlations in resting and task state.

The effects of oxytocin (OT) on the social brain can be tracked upon assessing the neural activity in resting and task states, and developing a system-level framework for characterizing the state-based functional relationships of its distinct effect. Here, we contribute to this framework by examining how OT modulates social brain network correlations during resting and task states, using fMRI. First, we investigated network activation, followed by an analysis of the relationships between networks and individual differences. Subsequently, we evaluated the functional connectivity in both states. Finally, the relationship between networks across states was represented by the predictive power of networks in the resting state for task-evoked activities. The differences in the predicted accuracy between the subjects displayed individual variations in this relationship. Our results showed that the activity of the dorsal default mode network in the resting state had the largest predictive power for task-evoked activation of the precuneus network (PN) only in the OT group. The results also demonstrated that OT reduced the individual variation in PN in the prediction process. These findings suggest a distributed but modulatory effect of OT on the association between resting and task-dependent brain networks.

Meditation reduces brain activity in the default mode network in children with active cancer and survivors.

Mounting evidence demonstrates that meditation can lower pain and emotional distress in adults, and more recently, in children. Children may benefit from meditation given its accessibility across a variety of settings (e.g., surgical preparation). Recent neuroimaging studies in adults suggest that meditation techniques are neurobiologically distinct from other forms of emotion regulation, such as distraction, that rely on prefrontal control mechanisms, which are underdeveloped in youth. Rather, meditation techniques may not rely on "top-down" prefrontal control and may therefore be utilized across the lifespan. We examined neural activation in children with cancer, a potentially distressing diagnosis. During neuroimaging, children viewed distress-inducing video clips while using martial arts-based meditation (focused attention, mindful acceptance) or non-meditation (distraction) emotion regulation techniques. In a third condition (control), participants passively viewed the video clip. We found that meditation techniques were associated with lower activation in default mode network (DMN) regions, including the medial frontal cortex, precuneus, and posterior cingulate cortex, compared to the control condition. Additionally, we found evidence that meditation techniques may be more effective for modulating DMN activity than distraction. There were no differences in self-reported distress ratings between conditions. Together, these findings suggest that martial arts-based meditation modulates negative self-referential processing associated with the DMN, and may have implications for the management of pediatric pain and negative emotion.

The effect of casein hydrolysate intake on cerebral neural regulation during cognitive tasks in the elderly.

Human and animal studies have shown that casein peptide (casein hydrolysate) has positive effects on cognitive function. This double-blind randomized controlled study aimed to investigate whether single ingestion of casein peptide could affect cognitive function (executive function) and cognitive neural activity in healthy older adults. We assigned 47 participants to one of the three dietary supplements as follows: casein peptide (TMP, n=15), casein (TMC, n=16), and indigestible dextrin (TMF, n=16). Dietary supplements were ingested 30min before starting the experiment; moreover, neural activity while performing the task-switching reaction time (SWT) trial was assessed through functional magnetic resonance imaging (fMRI). Additionally, we used a visual analog scale (VAS) test to assess the pre- and post-test feeling and mood. Regarding the parameters of the SWT trial, there were no significant among-group differences in the reaction time, accuracy rate, and %SwitchCost. Contrastingly, the fMRI experiment revealed among-group differences in the main effects in the medial frontal gyrus, Supplementary motor cortex (SMC), posterior cingulate gyrus (PCg), and amygdala (Amyg). Specifically, there was a significant decrease in the neural activities in the SMC and PCg in the TMP group than in the other two groups. Moreover, there was a significant increase in the neural activity in the Amyg in the TMP group compared with the TMF, but not the TMC, group. Furthermore, the VAS score was significantly higher in the TMP group than in the other two groups. There were no recorded adverse outcomes. Our findings suggested that TMP ingestion by older adults could temporarily suppress complementary neural activity in specific brain regions involved in executive functions, as well as default mode network activity, which could improve cognitive neural activities.