Left Lateral Parietal Cortex Research Articles

Functional connectivity of the anterior cingulate cortex predicts treatment outcome for rTMS in treatment-resistant depression at 3-month follow-up

Background and objectiveRepetitive transcranial magnetic stimulation (rTMS) is a first-line treatment for treatment-resistant depression (TRD). The mechanisms of action of rTMS are not fully understood, and no biomarkers are available to assist in clinical practice to predict response to rTMS. This study aimed to demonstrate that after-rTMS clinical improvement is associated with functional connectivity (FC) changes of the subgenual cingulate cortex (sgACC) and rostral anterior cingulate (rACC), and FC of sgACC and rACC might serve as potential predictors for treatment response. MethodsResting-state functional magnetic resonance imaging (rs-fMRI) data were collected within 1 week before rTMS initiation in 50 TRD patients to predict subsequent response to rTMS on the left dorsolateral prefrontal cortex (DLPFC). Follow-up rs-fMRI was obtained 12 weeks after completion of rTMS and neural correlates of rTMS in sgACC- and rACC-related FC patterns were compared to before rTMS data and with rs-fMRI from healthy participants. ResultsTreatment response was associated with lower FC of sgACC to right DLPFC and higher FC of rACC to left lateral parietal cortex (IPL) measured at baseline. Using sgACC-DLPFC and rACC-IPL connectivity as features, responder-nonresponder classification accuracies of 84% and 76% (end-of-treatment), 88% and 81% (3-month follow-up), respectively were achieved. Longitudinal rs-fMRI data analyses revealed that the hyperconnectivity between sgACC and visual cortex was normalized to a level which was comparable to that of healthy participants. ConclusionsBrain activity patterns in depression are predictive of treatment response to rTMS, and longitudinal change of brain activity in relevant brain circuits after rTMS is associated with treatment response in depression. Target engagement paradigms may offer opportunities to increase the efficacy of rTMS in TRD by optimal selection of patients for treatment. Trial registrationClinicalTrials.gov Identifiers: NCT01887782 and NCT02800226.

Dopamine Enhances Item Novelty Detection via Hippocampal and Associative Recall via Left Lateral Prefrontal Cortex Mechanisms.

The involvement of fronto-striatal circuits in item and associative memory retrieval as well as in the stabilization of memories by retrieval practice suggests that both retrieval and re-encoding of stored memories might rely on dopaminergic mechanisms in humans. We tested these hypotheses in a placebo-controlled pharmacological fMRI study using 2 mg of the D2 antagonist haloperidol administered acutely before a cued associative recall task of previously encoded picture-word pairs in 53 healthy humans of both sexes. The cued associative recall was moreover repeated 3 d later outside the scanner without pharmacological intervention. Dopaminergic modulation significantly improved associative recall performance and recognition accuracy of verbal items. Moreover, we observed a significant dopamine effect on re-encoding in terms of increased specificity of associative memories from the first to the second cued associative recall. Better association memory under haloperidol was linked with higher activity in the left lateral prefrontal cortex and right parietal cortex, suggesting that dopamine facilitates associative retrieval through increased recruitment of frontoparietal monitoring processes. In contrast, improved recognition of verbal items under haloperidol was reflected by enhanced novelty detection in the hippocampus and increased activity in saliency networks. Together, these results show distinct but concomitant positive effects of dopamine on associative recall and item recognition and suggest that the specificity of associative recall through re-encoding mechanisms is likewise augmented by dopamine.SIGNIFICANCE STATEMENT Although the neurotransmitter dopamine has been linked with learning and memory for a long time, dopaminergic effects on item recognition in humans were demonstrated only recently. The involvement of fronto-striatal monitoring processes in association retrieval suggests that associative memory might be particularly affected by dopamine. Moreover, fronto-striatal dopaminergic signals have been hypothesized to determine the updating and re-encoding of previously retrieved memories. We here demonstrate clear facilitative effects of dopamine on associative recall and item recognition mediated by prefrontal and hippocampal mechanisms respectively. Additionally, effects on re-encoding were reflected by increased specificity of associative memories. These results augment our understanding of dopaminergic processes in episodic memory retrieval and offer new perspectives on memory impairments in dopamine-related disorders and their treatment.

Late positive complex in event-related potentials tracks memory signals when they are decision relevant

The Late Positive Complex (LPC) is an Event-Related Potential (ERP) consistently observed in recognition-memory paradigms. In the present study, we investigated whether the LPC tracks the strength of multiple types of memory signals, and whether it does so in a decision dependent manner. For this purpose, we employed judgements of cumulative lifetime exposure to object concepts, and judgements of cumulative recent exposure (i.e., frequency judgements) in a study-test paradigm. A comparison of ERP signatures in relation to degree of prior exposure across the two memory tasks and the study phase revealed that the LPC tracks both types of memory signals, but only when they are relevant to the decision at hand. Another ERP component previously implicated in recognition memory, the FN400, showed a distinct pattern of activity across conditions that differed from the LPC; it tracked only recent exposure in a decision-dependent manner. Another similar ERP component typically linked to conceptual processing in past work, the N400, was sensitive to degree of recent and lifetime exposure, but it did not track them in a decision dependent manner. Finally, source localization analyses pointed to a potential source of the LPC in left ventral lateral parietal cortex, which also showed the decision-dependent effect. The current findings highlight the role of decision making in ERP markers of prior exposure in tasks other than those typically used in studies of recognition memory, and provides an initial link between the LPC and the previously suggested role of ventral lateral parietal cortex in memory judgements.

MEASURING BRAIN AND COGNITIVE CHANGES IN MEMORY SYSTEMS AFTER TARGETED MULTIDAY REPETITIVE TRANSCRANIAL MAGNETIC STIMULATION OF HEALTHY YOUNG, HEALTHY OLD, AND AMNESTIC MILD COGNITIVE IMPAIRMENT PARTICIPANTS

Healthy and pathological aging processes contribute to declines in memory abilities in older adults, and current treatments offer limited remediation. One novel approach — targeted non-invasive brain stimulation (NBS) of intrinsic memory networks — is reported to enhance memory abilities in healthy young adults by 20% (Wang et al., 2014). To test generalizability of this finding, we are administering a clinical trial (ClinicalTrials.gov #NCT03574207) which replicates previously-reported NBS approaches in healthy young adults, healthy older adults, and patients with amnestic mild cognitive impairment (aMCI). Enrollment is continuing during this interim update; target enrollment for healthy young, healthy old, and aMCI groups is N=16 each. Our approach replicates methods from Wang et al. (2014). Enrolled participants complete two interventions (two weeks apart) consisting of pre-stimulation brain and cognitive measurement, NBS (treatment or sham for five consecutive days), and post-stimulation brain and cognitive measurement. The one-week interventions are identically formatted except for NBS parameters. Pre-/post-stimulation, brain variables measured include structural and resting-state functional MRI data; cognitive variables measured include cognitive abilities (e.g., hippocampal-dependent memory). In both intervention formats, we apply repetitive transcranial magnetic stimulation (rTMS) using β-frequency pulse sequences which alternate 2-sec. 20 Hz stimulation with 28-sec. rest for 20 min; the stimulation location is constant (left lateral parietal cortex coactive with hippocampus). Stimulation intensity is tailored to each participant's resting motor threshold (RMT) and varies by condition: treatment condition, 100% RMT; sham condition, 10% RMT. Participants complete both conditions in a counterbalanced order. Participant condition assignment is currently blinded per our trial design, but we will discuss our design and preliminary findings. We anticipate observing changes in brain and cognitive measures related to stimulation condition. Changes in brain variables are anticipated to include differences in regional resting-state functional connectivity, while changes in cognitive variables are expected to be positive following treatment NBS (vs. sham). Our ongoing clinical trial measures changes in brain and cognitive variables associated with NBS of a functional brain network supporting memory processes. Our expected findings will elucidate the plasticity of intrinsic networks supporting memory — conditioned on age and cognitive status — in response to NBS.

<p>Chronic widespread pain patients show disrupted cortical connectivity in default mode and salience networks, modulated by pain sensitivity</p>

Purpose: The remodeling of functional neuronal connectivity in chronic widespread pain (CWP) patients remains largely unexplored. This study aimed to investigate functional connectivity in CWP patients in brain networks related to chronic pain for changes related to pain sensitivity, psychological strain, and experienced pain.Patients and methods: Functional connectivity strength of the default mode network (DMN) and the salience network (SN) was assessed with functional magnetic resonance imaging. Between-group differences were investigated with an independent component analysis for altered connectivity within the whole DMN and SN. Then, changes in connectivity between nodes of the DMN and SN were investigated with the use of a seed-target analysis in relation to the covariates clinical pain intensity, pressure pain sensitivity, psychological strain, and as an effect of experienced experimental cuff-pressure pain.Results: CWP patients showed decreased connectivity in the inferior posterior cingulate cortex (PCC) in the DMN and increased connectivity in the left anterior insula/superior temporal gyrus in the SN when compared to controls. Moreover, higher pain sensitivity in CWP when compared to controls was related to increased connectivity within the SN (between left and right insula) and between SN and DMN (between right insula and left lateral parietal cortex).Conclusion: This study shows that connectivity within the DMN was decreased and connectivity within the SN was increased for CWP. Furthermore, we present a novel finding of interaction of pain sensitivity with SN and DMN-SN functional connectivity in CWP.

Methylphenidate Alters Functional Connectivity of Default Mode Network in Drug-Naive Male Adults With ADHD

Objective: This study evaluated the hypothesis that methylphenidate immediate release (MPH-IR) treatment would improve Default Mode Network (DMN) within-connectivity. Method: Resting-state functional connectivity of the main nodes of DMN was evaluated in a highly homogeneous sample of 18 drug-naive male adult participants with ADHD. Results: Comparing resting-state functional connectivity functional magnetic resonance imaging (R-fMRI) scans before and after MPH treatment focusing exclusively on within-DMN connectivity, we evidenced the strengthening of functional connectivity between two nodes of the DMN: posterior cingulate cortex (PCC) and left lateral parietal cortex (LLP). Conclusion: Our results contribute to the further understanding on how MPH affects functional connectivity within DMN of male adults with ADHD and corroborate the hypothesis of ADHD being a delayed neurodevelopmental disorder.

Classifying early and late mild cognitive impairment stages of Alzheimer\u2019s disease by fusing default mode networks extracted with multiple seeds

BackgroundThe default mode network (DMN) in resting state has been increasingly used in disease diagnosis since it was found in 2001. Prior work has mainly focused on extracting a single DMN with various techniques. However, by using seeding-based analysis with more than one desirable seed, we can obtain multiple DMNs, which are likely to have complementary information, and thus are more promising for disease diagnosis. In the study, we used 18 early mild cognitive impairment (EMCI) participants and 18 late mild cognitive impairment (LMCI) participants of Alzheimer’s disease (AD). First, we used seeding-based analysis with four seeds to extract four DMNs for each subject. Then, we conducted fusion analysis for all different combinations of the four DMNs. Finally, we carried out nonlinear support vector machine classification based on the mixing coefficients from the fusion analysis.ResultsWe found that (1) the four DMNs corresponding to the four different seeds indeed capture different functional regions of each subject; (2) Maps of the four DMNs in the most different joint source from fusion analysis are centered at the regions of the corresponding seeds; (3) Classification results reveal the effectiveness of using multiple seeds to extract DMNs. When using a single seed, the regions of posterior cingulate cortex (PCC) extractions of EMCI and LMCI show the largest difference. For multiple-seed cases, the regions of PCC extraction and right lateral parietal cortex (RLP) extraction provide complementary information for each other in fusion, which improves the classification accuracy. Furthermore, the regions of left lateral parietal cortex (LLP) extraction and RLP extraction also have complementary effect in fusion. In summary, AD diagnosis can be improved by exploiting complementary information of DMNs extracted with multiple seeds.ConclusionsIn this study, we applied fusion analysis to the DMNs extracted by using different seeds for exploiting the complementary information hidden among the separately extracted DMNs, and the results supported our expectation that using the complementary information can improve classification accuracy.

Behavioral and Resting State Functional Connectivity Effects of High Frequency rTMS on Disorders of Consciousness: A Sham-Controlled Study.

Objectives: A combined approach of behavioral characteristics and network properties was applied to explore the effect of repetitive transcranial magnetic stimulation (rTMS) on disorders of consciousness (DOC) and to observe changes in brain network connections before and after the stimulation.Methods: A total of 7 DOC patients and 11 healthy controls were enrolled. The study was designed as a randomized, sham-controlled study. All DOC patients were given 20 Hz rTMS real and sham stimuli to the left M1 region, with each stimulus lasting for 5 consecutive working days and the interval between two stimuli being 1 week. Coma Recovery Scale-Revised (CRS-R) and resting state functional MRI data before and after stimuli were collected. The functional connection (FC) of the default mode network and the frontoparietal network were chosen as the central target to compare differences in network connections between the DOC group and the normal control group. For DOC patients, changes in behavior and brain function before and after real and sham stimuli were also assessed as a group and individually.Results: (1). The overall analyses showed no significant changes of CRS-R scores or brain FC following real or sham rTMS stimuli in the DOC patients. However, real rTMS stimuli tended to enhance the FC of nodes in left lateral parietal cortex (LPC), left inferior temporal cortex (ITC) and right dorsolateral prefrontal cortex (DLPFC). (2). The individual analyses showed one minimally conscious state (MCS) patient presented with a obviously increased CRS-R score following real rTMS stimuli, and a visibly enhanced connectivity was observed in the nodes of left LPC, left ITC and right DLPFC of this patient.Conclusion: Our findings did not provide sufficient evidence of therapeutic effect of 20 Hz rTMS over the left M1 in DOC. However, MCS patients shortly after brain injury may possibly benefit from rTMS. Reconstruction of the left LPC, the left ITC and the right DLPFC may be the brain networking foundation of improvements in consciousness from rTMS.

Increased Functional Connectivity Between Ventral Attention and Default Mode Networks in Adolescents With Bulimia Nervosa.

Bulimia nervosa (BN) is characterized by excessive attention to self and specifically to body shape and weight, but the ventral attention (VAN) and default mode (DMN) networks that support attentional and self-referential processes are understudied in BN. This study assessed whether altered functional connectivity within and between these networks contributes to such excessive concerns in adolescents with BN early the course of the disorder. Resting-state functional magnetic resonance images were acquired from 33 adolescents with BN and 37 healthy control adolescents (12-21 years) group matched by age and body mass index. Region-of-interest analyses were performed to examine group differences in functional connectivity within and between the VAN and DMN. In addition associations of VAN-DMN connectivity with BN symptoms, body shape/weight concerns, and sustained attention were explored using the Continuous Performance Test (CPT). Compared with control adolescents, those with BN showed significantly increased positive connectivity between the right ventral supramarginal gyrus and all DMN regions and between the right ventrolateral prefrontal cortex and the left lateral parietal cortex. Within-network connectivity did not differ between groups. VAN-DMN connectivity was associated with BN severity and body shape/weight concerns in the BN group. No significant group-by-CPT interactions on VAN-DMN connectivity were detected. Increased positive VAN-DMN connectivity in adolescents with BN could reflect abnormal engagement of VAN-mediated attentional processes at rest, perhaps related to their excessive attention to self-referential thoughts about body shape/weight. Future studies should further investigate these circuits as targets for the development of early interventions aimed at decreasing excessive body shape/weight concerns.

P303 Transcranial direct current stimulation over parietal cortex and associative memory

Background Memory enhancement is one of the most challenging issues in neurorehabilitation. Memory functions are affected by different neurological conditions as well as by normal aging. Recent data suggest that it may be possible to improve performance on some of the memory tests by physiological modulation of the activity within a neural loop which plays crucial role in formation and maintenance of the associative memory and which consists of the hippocampus and the lateral parietal cortex. Aims To check the differential effects of facilitatory and inhibitory noninvasive neuromodulation by transcranial direct current stimulation (TDCS) on associative memory. Methods Nineteen healthy right-handed participants (8 male, age 22–35) were enrolled in a cross-over placebo-controlled study. Following 20-min of either anodal (facilitatory), cathodal (inhibitory) or sham (placebo) TDCS over left lateral parietal cortex (P3 of 10–20 EEG system), in 3 separate sessions with 5–7 days inter-session intervals, participants completed a face-cued word recall test of associative memory. The test consisted of two blocks: (a) learning block, in which random words were paired with unfamiliar faces, and (b) recall block in which participants were asked to identify the target faces and recall the word previously presented together with each face. In each session, participants also completed a verbal fluency task, as a control task. Results The repeated measures ANOVA showed significant main effect of stimulation type ( F ( 2 , 36 ) = 3.71 , p = . 034 , η 2 = . 171 ). Post-hoc tests revealed that participant performed better on the associative memory task after anodal than cathodal stimulation ( p . 05 ), and the same trend was observed between anodal and sham stimulation. No difference was found between sham and cathodal stimulation. No effect of stimulation on verbal fluency task. Conclusions Noninvasive brain modulation has a potential to improve performance on tasks requiring associative memory engagement. The effect may prove to be beneficial for cognitive neurorehabilitation.

Connectivity Neurofeedback Training Can Differentially Change Functional Connectivity and Cognitive Performance.

Advances in functional magnetic resonance imaging have made it possible to provide real-time feedback on brain activity. Neurofeedback has been applied to therapeutic interventions for psychiatric disorders. Since many studies have shown that most psychiatric disorders exhibit abnormal brain networks, a novel experimental paradigm named connectivity neurofeedback, which can directly modulate a brain network, has emerged as a promising approach to treat psychiatric disorders. Here, we investigated the hypothesis that connectivity neurofeedback can induce the aimed direction of change in functional connectivity, and the differential change in cognitive performance according to the direction of change in connectivity. We selected the connectivity between the left primary motor cortex and the left lateral parietal cortex as the target. Subjects were divided into 2 groups, in which only the direction of change (an increase or a decrease in correlation) in the experimentally manipulated connectivity differed between the groups. As a result, subjects successfully induced the expected connectivity changes in either of the 2 directions. Furthermore, cognitive performance significantly and differentially changed from preneurofeedback to postneurofeedback training between the 2 groups. These findings indicate that connectivity neurofeedback can induce the aimed direction of change in connectivity and also a differential change in cognitive performance.

Imagining the future: The core episodic simulation network dissociates as a function of timecourse and the amount of simulated information

Neuroimaging data indicate that episodic memory (i.e., remembering specific past experiences) and episodic simulation (i.e., imagining specific future experiences) are associated with enhanced activity in a common set of neural regions, often referred to as the core network. This network comprises the hippocampus, parahippocampal cortex, lateral and medial parietal cortex, lateral temporal cortex, and medial prefrontal cortex. Evidence for a core network has been taken as support for the idea that episodic memory and episodic simulation are supported by common processes. Much remains to be learned about how specific core network regions contribute to specific aspects of episodic simulation. Prior neuroimaging studies of episodic memory indicate that certain regions within the core network are differentially sensitive to the amount of information recollected (e.g., the left lateral parietal cortex). In addition, certain core network regions dissociate as a function of their timecourse of engagement during episodic memory (e.g., transient activity in the posterior hippocampus and sustained activity in the left lateral parietal cortex). In the current study, we assessed whether similar dissociations could be observed during episodic simulation. We found that the left lateral parietal cortex modulates as a function of the amount of simulated details. Of particular interest, while the hippocampus was insensitive to the amount of simulated details, we observed a temporal dissociation within the hippocampus: transient activity occurred in relatively posterior portions of the hippocampus and sustained activity occurred in anterior portions. Because the posterior hippocampal and lateral parietal findings parallel those observed during episodic memory, the present results add to the evidence that episodic memory and episodic simulation are supported by common processes. Critically, the present study also provides evidence that regions within the core network support dissociable processes.

Dissociable Changes of Frontal and Parietal Cortices in Inherent Functional Flexibility across the Human Life Span

Extensive evidence suggests that frontoparietal regions can dynamically update their pattern of functional connectivity, supporting cognitive control and adaptive implementation of task demands. However, it is largely unknown whether this flexibly functional reconfiguration is intrinsic and occurs even in the absence of overt tasks. Based on recent advances in dynamics of resting-state functional resonance imaging (fMRI), we propose a probabilistic framework in which dynamic reconfiguration of intrinsic functional connectivity between each brain region and others can be represented as a probability distribution. A complexity measurement (i.e., entropy) was used to quantify functional flexibility, which characterizes heterogeneous connectivity between a particular region and others over time. Following this framework, we identified both functionally flexible and specialized regions over the human life span (112 healthy subjects from 13 to 76 years old). Across brainwide regions, we found regions showing high flexibility mainly in the higher-order association cortex, such as the lateral prefrontal cortex (LPFC), lateral parietal cortex, and lateral temporal lobules. In contrast, visual, auditory, and sensory areas exhibited low flexibility. Furthermore, we observed that flexibility of the right LPFC improved during maturation and reduced due to normal aging, with the opposite occurring for the left lateral parietal cortex. Our findings reveal dissociable changes of frontal and parietal cortices over the life span in terms of inherent functional flexibility. This study not only provides a new framework to quantify the spatiotemporal behavior of spontaneous brain activity, but also sheds light on the organizational principle behind changes in brain function across the human life span. Recent neuroscientific research has demonstrated that the human capability of adaptive task control is primarily the result of the flexible operation of frontal brain networks. However, it remains unclear whether this flexibly functional reconfiguration is intrinsic and occurs in the absence of an overt task. In this study, we propose a probabilistic framework to quantify the functional flexibility of each brain region using resting-state fMRI. We identify regions showing high flexibility mainly in the higher-order association cortex. In contrast, primary and unimodal visual and sensory areas show low flexibility. On the other hand, our findings reveal dissociable changes of frontal and parietal cortices in terms of inherent functional flexibility over the life span.

Functional Connectivity Is Altered in Concussed Adolescent Athletes Despite Medical Clearance to Return to Play: A Preliminary Report

Recovery following sports-related concussion (SRC) is slower and often more complicated in young adolescent athletes than in collegiate players. Further, the clinical decision to return to play is currently based on symptoms and cognitive performance without direct knowledge of brain function. We tested the hypothesis that brain functional connectivity (FC) would be aberrant in recently concussed, asymptomatic athletes who had been cleared to return to play. A seed-based FC analysis measured the FC of the default mode network (DMN) (seeds = anterior cingulate cortex, posterior cingulate cortex (PCC), right lateral parietal cortex, and left lateral parietal cortex) 30 days after SRC in asymptomatic high school athletes cleared to return to play (n = 13) and was compared to the FC of high school athletes with orthopedic injury (OI) (n = 13). The SRC group demonstrated greater FC than the OI group between the PCC and the ventral lateral prefrontal cortex, as well as between the right lateral parietal cortex and lateral temporal cortex (with regions both outside of and within the DMN). Additionally, the OI group demonstrated greater FC than the SRC group between right lateral parietal cortex and supramarginal gyrus. When relating the FC results to verbal memory performance approximately 1 week and 1 month after injury, significantly different between-group relations were found for the posterior cingulate and right lateral parietal cortex seeds. However, the groups did not differ in verbal memory at 1 month. We suggest that changes in FC are apparent 1-month post-SRC despite resolution of post-concussion symptoms and recovery of cognitive performance in adolescent athletes cleared to return to play.

Impaired functional default mode network in patients with mild neurological Wilson’s disease

Wilson’s disease (WD) is an autosomal recessive metabolic disorder characterized by cognitive, psychiatric and motor signs and symptoms that are associated with structural and pathological brain abnormalities, in addition to liver changes. However, functional brain connectivity pattern of WD patients remains largely unknown. In the present study, we investigated functional brain connectivity pattern of WD patients using resting state functional magnetic resonance imaging. Particularly, we studied default mode network (DMN) using posterior cingulate cortex (PCC) based seed functional connectivity analysis and graph theoretic functional brain network analysis tools, and investigated the relationship between the DMN’s functional connectivity pattern of WD patients and their attention functions examined using the attention network test (ANT). Our results demonstrated that WD patients had altered DMN’s functional connectivity and lower local and global network efficiency compared with normal controls (NCs). In addition, the functional connectivity between left inferior temporal cortex and right lateral parietal cortex was correlated with altering function, one of the attention functions, across WD and NC subjects. These findings indicated that the DMN’s functional connectivity was altered in WD patients, which might be correlated with their attention dysfunction.

How are different neural networks related to consciousness?

We aimed to investigate the roles of different resting-state networks in predicting both the actual level of consciousness and its recovery in brain injury patients. We investigated resting-state functional connectivity within different networks in patients with varying levels of consciousness: unresponsive wakefulness syndrome (UWS; n = 56), minimally conscious state (MCS; n = 29), and patients with brain lesions but full consciousness (BL; n = 48). Considering the actual level of consciousness, we compared the strength of network connectivity among the patient groups. We then checked the presence of connections between specific regions in individual patients and calculated the frequency of this in the different patient groups. Considering the recovery of consciousness, we split the UWS group into 2 subgroups according to recovery: those who emerged from UWS (UWS-E) and those who remained in UWS (UWS-R). The above analyses were repeated on these 2 subgroups. Functional connectivity strength in salience network (SN), especially connectivity between the supragenual anterior cingulate cortex (SACC) and left anterior insula (LAI), was reduced in the unconscious state (UWS) compared to the conscious state (MCS and BL). Moreover, at the individual level, SACC-LAI connectivity was more present in MCS than in UWS. Default-mode network (DMN) connectivity strength, especially between the posterior cingulate cortex (PCC) and left lateral parietal cortex (LLPC), was reduced in UWS-R compared with UWS-E. Furthermore, PCC-LLPC connectivity was more present in UWS-E than in UWS-R. Our findings show that SN (SACC-LAI) connectivity correlates with behavioral signs of consciousness, whereas DMN (PCC-LLPC) connectivity instead predicts recovery of consciousness.

Influences of Long-Term Memory-Guided Attention and Stimulus-Guided Attention on Visuospatial Representations within Human Intraparietal Sulcus.

The human parietal lobe contains multiple maps of the external world that spatially guide perception, action, and cognition. Maps in each cerebral hemisphere code information from the opposite side of space, not from the same side, and the two hemispheres are symmetric. Paradoxically, damage to specific parietal regions that lack spatial maps can cause patients to ignore half of space (hemispatial neglect syndrome), but only for right (not left) hemisphere damage. Conversely, the left parietal cortex has been linked to retrieval of vivid memories regardless of space. Here, we investigate possible underlying mechanisms in healthy individuals. We demonstrate two forms of dynamic changes in parietal spatial representations: an asymmetric one for stimulus-guided attention and a symmetric one for long-term memory-guided attention.

Examining the resting-state vascular connectivity using fMRA in comparison with fMRI: a preliminary study.

This study examined resting-state functional connectivity in the vascular system of the brain using functional magnetic resonance angiography (fMRA) with an ultra-high-field 7 T MRI. Four healthy individuals participated in the functional imaging study using fMRA and functional MRI (fMRI) for determination of vascular and blood oxygenation level-dependent (BOLD) connectivity, respectively. We calculated voxel-wise connectivity maps and measured the correlation coefficients of the region of interest (ROI)-wise connectivity in the resting-state human brain. Z-map in the posterior cingulate cortex showed more correlated voxels in fMRA than fMRI. There was little or weak interhemispheric vascular connectivity using fMRA in the lateral parietal cortex and the lateral temporal cortex. In contrast, both vascular and BOLD interhemispheric correlations in the precentral gyrus were strong. Correlation coefficients for ROI-wise connectivity analysis were statistically different between fMRA and fMRI in the left and right lateral parietal cortex and lateral temporal cortex (P=0.029). Unlike BOLD connectivity, vascular connectivity showed little interhemispheric correlation in the default mode network. These results could provide the vascular connectivity on the basis of arterial response that can only be obtained by fMRA with an ultra-high-field environment along with further studies. Therefore, this method could provide additional and supplementary information for investigating the vascular effect in patients with cerebrovascular disease.

Resting State Neural Network Properties in Sickle Cell Disease Patients

IntroductionOne major challenge in the treatment of pain from sickle cell disease (SCD) is the current lack of an objective measure of pain. Therefore, we used functional magnetic imaging (fMRI) to compare a specific brain network in SCD patients with healthy subjects to develop objective methods to assess pain. We hypothesize that in SCD patients, the default-mode-network (DMN) is less active in comparison to healthy subjects. DMN is a prevalent network dynamic that appears in the absence of overt behavior and is thought to be responsible for a host of visceral mental activities. This DMN difference may be due to prolonged SCD-related pain.MethodsTen healthy subjects (6 males and 4 females; age: mean=23.3, SD= 3.3 years) and ten SCD patients (5 males, 5 females; age: mean= 28.5, SD=7.1 years) participated in the study following informed consent to the procedures approved by the IRB of the University of Minnesota. Patients were recruited by hematologists at the University of Minnesota Medical Center. None of the patients were experiencing acute crisis during the experiments. FMRI data was acquired with a 3T Siemens Trio whole-body scanner with echo-planar imaging (EPI) sequence. Each fMRI recording lasted about 6minutes. The experiment procedures were well tolerated by all subjects. Both independent component analysis (ICA) and seed-based region of interest (ROI) analysis were applied to the fMRI data, and the analysis was performed using the BrainVoyager QX software.ResultsExperimental and analyticalprocedures were applied to both groups under similar conditions and the recorded data in the two groups have comparable quality. Using the data driven ICA-based analysis, each fMRI data set was decomposed into thirty independent components. The DMN component waseasilyidentified in all of the ten healthy subjects. In contrast, none of the ten SCD patients had any identifiable DMN component in the ICA-based analysis. Seed-based ROI analysis was also performed to find correlational networks. The ROIs were predetermined to be in medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC), left and right lateral parietal cortex (LP). Using the time course extracted from the ROIs, DMN was revealed in all ten healthy subjects. However, DMN can only be found in three SCD patients.The identified DMN in patients showed incomplete clusters and had smaller cluster size comparing with the DMNin healthy subjects. By examining different possible ROI locations, DMN identified in patients consistently showed smaller number of voxels compared to controls.ConclusionsOur findings suggest that the neurological signature of SCD patients may be altered by the chronic painful condition caused by the disease. Diminished activity in the DMN during rest has been previously reported by studies on both cognitive impairments and other types of chronic pain. It is currently unclear whether synchrony among the nodes in the default mode network can be reestablished once the pain condition is alleviated. Knowledge of the neurological characteristics of SCD patients may shed light in understanding in disease and the role of pain in SCD. Changes in DMN activity may also serve as a potential biomarker to quantify pain severity in the future.(This work was supported in part by NIH U01 HL117664 and NSF DGE-1069104.)ReferencesBaliki, M.N. (2008), 'Beyond feeling: chronic pain hurts the brain, disrupting the default-mode network dynamics’, The Journal of Neuroscience, vol. 28, no. 6, pp. 1398-1403.Fox, M.D. (2005), 'The human brain is intrinsically organized into dynamic, anticorrelated functional networks’,ProcNatlAcadSci USA, vol. 102, pp. 9673–9678. DisclosuresNo relevant conflicts of interest to declare.

Spontaneous default mode network phase-locking moderates performance perceptions under stereotype threat.

This study assessed whether individual differences in self-oriented neural processing were associated with performance perceptions of minority students under stereotype threat. Resting electroencephalographic activity recorded in white and minority participants was used to predict later estimates of task errors and self-doubt on a presumed measure of intelligence. We assessed spontaneous phase-locking between dipole sources in left lateral parietal cortex (LPC), precuneus/posterior cingulate cortex (P/PCC), and medial prefrontal cortex (MPFC); three regions of the default mode network (DMN) that are integral for self-oriented processing. Results revealed that minorities with greater LPC-P/PCC phase-locking in the theta band reported more accurate error estimations. All individuals experienced less self-doubt to the extent they exhibited greater LPC-MPFC phase-locking in the alpha band but this effect was driven by minorities. Minorities also reported more self-doubt to the extent they overestimated errors. Findings reveal novel neural moderators of stereotype threat effects on subjective experience. Spontaneous synchronization between DMN regions may play a role in anticipatory coping mechanisms that buffer individuals from stereotype threat.