Bilateral Posterior Cingulate Cortex Research Articles

Altered network homogeneity of the default-mode network in drug-naive obsessive−compulsive disorder

BackgroundDefault-mode network (DMN) plays a key role in the pathophysiology of obsessive−compulsive disorder (OCD). However, the network homogeneity (NH) of DMN in OCD remains equivocal. ObjectiveThis study aimed to investigate abnormalities in the NH of the DMN at rest and the correlation between the NH of DMN and clinical variables in patients with OCD. MethodsThis study used the independent component analysis and unbiased hypothesis-driven NH method to analyze the resting-state functional magnetic resonance imaging data of 40 drug-naive patients with OCD and 40 age-, gender-, and education-matched healthy controls (HCs). ResultsPatients with OCD exhibited decreased NH values in the left ventral medial prefrontal cortex and bilateral posterior cingulate cortex (PCC)/precuneus (PCu) compared with HCs. Furthermore, analyses of receiver operating characteristic curves indicated that the decreased NH values in the right PCC/PCu may be used as a candidate neuroimaging marker to distinguish patients with OCD from HCs. ConclusionThese findings contribute new evidence of the participation of the altered NH of the DMN in the pathophysiology of OCD. Trial RegistrationStudy on the mechanism of brain network in obsessive-compulsive disorder with multi-model magnetic resonance imaging (ChiCTR-COC-17013301).

Altered social cognition and connectivity of default mode networks in the co-occurrence of autistic spectrum disorder and attention deficit hyperactivity disorder.

As two common neurodevelopmental disorders, autistic spectrum disorder and attention deficit hyperactivity disorder frequently occur together. Until now, only a few studies have investigated the co-occurrence of attention deficit hyperactivity disorder and autistic spectrum disorder, this is due to restrictions associated with previous Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision. Most previous research has focused on the developmental trajectories for autistic spectrum disorder and attention deficit hyperactivity disorder separately, while the neural mechanisms underpinning the co-occurrence of autistic spectrum disorder and attention deficit hyperactivity disorder remain largely unknown. We studied 162 autistic spectrum disorder individuals (including 79 co-attention deficit hyperactivity disorder and 83 non-attention deficit hyperactivity disorder patients) and 177 typical developing individuals using resting-state functional magnetic resonance imaging data from the Autism Brain Imaging Data Exchange II, an aggregated magnetic resonance imaging dataset from 19 centers. Independent component analysis was used to extract sub-networks from the classic resting-state networks. Functional connectivity values within (intra-iFC) and between (inter-iFC) these networks were then determined. Subsequently, we compared the ASD_coADHD group with the ASD_nonADHD group in relation to the abnormal intra-iFC and inter-iFC of autistic spectrum disorder group relative to the typical developing group. The ASD_coADHD group showed more severe social impairment and decreased intra-iFC in the bilateral posterior cingulate cortex of the default mode network (independent component 17) and increased inter-iFC between the default mode network (independent component 8) and the somatomotor networks (independent component 2) compared to the ASD_nonADHD group. In addition, the strength of the intra-iFC in the default mode network was associated with the severity of autistic traits across the entire autistic spectrum disorder group and particularly the ASD_coADHD group. Our results showed that dysfunction of the default mode network is a central feature in the co-occurrence of autistic spectrum disorder and attention deficit hyperactivity disorder, including connectivity within the default mode network as well as between the default mode network and the somatomotor networks, thus supporting the existence of a clinically combined phenotype (autistic spectrum disorder + attention deficit hyperactivity disorder).

Enhanced Global-Brain Functional Connectivity in the Left Superior Frontal Gyrus as a Possible Endophenotype for Schizophrenia.

The notion of dysconnectivity in schizophrenia has been put forward for many years and results in substantial attempts to explore altered functional connectivity (FC) within different networks with inconsistent results. Clinical, demographical, and methodological heterogeneity may contribute to the inconsistency. Forty-four patients with first-episode, drug-naive schizophrenia, 42 unaffected siblings of schizophrenia patients and 44 healthy controls took part in this study. Global-brain FC (GFC) was employed to analyze the imaging data. Compared with healthy controls, patients with schizophrenia and unaffected siblings shared enhanced GFC in the left superior frontal gyrus (SFG). In addition, patients had increased GFC mainly in the thalamo-cortical network, including the bilateral thalamus, bilateral posterior cingulate cortex (PCC)/precuneus, left superior medial prefrontal cortex (MPFC), right angular gyrus, and right SFG/middle frontal gyrus and decreased GFC in the left ITG/cerebellum Crus I. No other altered GFC values were observed in the siblings group relative to the control group. Further ROC analysis showed that increased GFC in the left SFG could separate the patients or the siblings from the controls with acceptable sensitivities. Our findings suggest that increased GFC in the left SFG may serve as a potential endophenotype for schizophrenia.

Individualized fuctional targets optimize the effectiveness of TMS in modulation of brain activity

The site of stimulation target is critical for transcranial magnetic stimulation (TMS) modulation of brain cognitive function. However, targets in previous studies were usually identified through anatomical but not functional location method. This study aims to set up the functional target based on individual task functional magnetic resonance imaging (fMRI), and further explore whether this individualized functional target could optimize the modulation effect of TMS on brain activity. Fifty seven healthy volunteers were randomly recruited as anatomical group (14 female, 19±1 years old) and functional group (14 female, 18±1 years old). Two fMRI sessions of resting state and emotional face task were performed before and after a 40 s train of continuous theta burst TMS. The stimulation target of anatomical group was located in 5 cm anterior on aparasagittal line from the point of maximal stimulation of the first dorsal interosseous muscle. The target of functional group was located based on the functional connectivity of peak individual activation of amygdala in emotional face task. Modulation effect of TMS on brain activity was assessed through the analysis of amplitude of low-frequency fluctuation (ALFF) performed on the data of resting state sessions. Our results showed significant difference of the target location between the two groups in the coodinates of x (functional group -32±8 versus anatomical group - 37±7, p<0.01) and z (functional group 48±6 versus anatomical group 38±8, p<0.001). ALFF changes between pre-and post-TMS scans were mainly observed in functional group but not in anatomical group. These changes in bilateral amygdala, pregenual anterior cingulate cortex, bilateral posterior cingulate cortex were potentially related to emotional processing, suggesting that TMS with individualized functional targets could optimize the effectiveness of TMS in modulation of specific brain function. These findings will provide methodology references to further application and research of individualized TMS.

Intrinsic oscillations of auditory networks in schizophrenia and bipolar disorder

Objective: Several types of evidence have shown that auditory networks are dysfunctional in schizophrenia (Sch) and bipolar disorders (BD). Auditory cortices show abnormalities in hallucinations or during remission. This study aimed to assess resting-state connectivity of auditory cortices in Sch and BD. Method: Patients with BD-1 (n=28), BD-2 (n=21), Sch (n=30), and healthy controls (HC, n=30) were enrolled into the study. A 3 Tesla whole-body magnetic resonance imaging (MRI) system with a 32-channel phase-array head coil was used to acquire the MRI data. T1-weighted anatomical and gradient-echo based Echoplanar Imaging sequences were used. MATLAB and Freesurfer software packages were used for data analyses. Connectivity alterations within the auditory network guided our further seed-based connectivity analysis. Results: The left angular gyrus volume was decreased in Sch and BD-2 groups. The supramarginal gyrus had hyperconnectivity with the medial prefrontal cortices and decreased connectivity with the medial superior temporal gyrus (STG) in the BD-1 and BD-2 groups. The left superior temporal sulcus (STS) had increased connectivity with the bilateral posterior cingulate cortex in BD-1 and BD-2 and increased connectivity with the dorsal prefrontal cortices in the Sch group. The STS had increased connectivity with the medial STG in the BD-1 and Sch groups, whereas connectivity decreased in the BD-2 group. Conclusion: These findings suggest that functional connectivity of resting-state networks are altered in BD and Sch. Auditory network alterations may predispose to dysfunctional auditory information processing. Further studies are needed to determine the relationship between symptoms and auditory network dysfunction.

SU37 - RESTING STATE FUNCTIONAL DYNAMICS IN MAJOR DEPRESSIVE DISORDER AND RELATIONSHIP WITH POLYGENIC RISK LOADING: EVIDENCE FROM UK BIOBANK

Background Major Depressive Disorder (MDD) is a common psychiatric illness. Neuroimaging studies have indicated the involvement functional networks in the disorder. Resting-state functional magnetic resonance imaging (rs-fMRI) provides a non-invasive, task-free way of studying such distributed functional dynamics of the brain. Previous studies have found significant alteration in rs-fMRI functional connectivity in MDD patients. Hyperactivity of default mode network (DMN) has been reported to be associated with rumination of negative emotional stimuli, and abnormal connectivity between DMN and task-positive networks was associated with cognitive impairment within MDD, however other studies do not report such effects. Previous rs-fMRI studies were however often conducted on small sample sizes which may account for inconsistency in the literature, and few studies were conducted on the association between genetic risk of MDD and rs-fMRI functional connectivity. Therefore, the present study used imaging data from a large-population based sample from UK Biobank to test the association of brain functional connectivity with MDD status and its genetic risk. Methods We used IDPs (Imaging-Derived Phenotypes) from UK Biobank imaging project. The imaging data was collected on a single scanner and preprocessed using FSL packages by UK Biobank. Data was parcelled into 21 non-noise functional networks, and the L2-regularised partial correlation was estimated between each pair of networks. These estimated connections were then used for further analysis in the current study. MDD status was derived based on self-reported depressive symptoms and history of hospital admission data (Case: N=256, Control: N=488,). Polygenic risk of MDD (MDD-pgrs) was calculated based on the summary statistics from the PGC (N=914). Regression models were applied to test the MDD case-control difference and the associations of MDD-pgrs with rs-fMRI functional connectivity. Age, age2, sex and assessment centre were controlled for in the model of case-control differences, and genotype batch and the first 15 principal component of genetic variance were additionally controlled for MDD-pgrs. FDR correction was applied. All effect sizes reported were standardised. Results MDD cases showed higher positive connectivity between the precuneus, the bilateral superior posterior cingulate cortex and temporal-parietal junction (β=0.292, pcorr=0.047); all components of DMN. Higher MDD-pgrs was associated with less connectivity between posterior motor area and posterior parietal gyrus (PPG) (β=-0.123, pcor=0.045), less negative connectivity between precuneus and PPG (β=0.122, pcor=0.045) and higher negative connection of right fronto-temporal network (FTN) and left fronto-parietal network (FPN) (β=-0.124, pcor=0.045). Discussion In the present study, MDD cases exhibited significantly higher connection between two DMN components, and a higher negative connection between FTN and FPN. Conversely, higher genetic risk for MDD was associated with decreased connectivity between DMN regions and task-positive networks. These results were highly consistent with previous studies which found that altered functioning of DMN was related with MDD status. The present study also found functional connections that involve with DMN, FTN and FPN associated with MDD-pgrs.

Regional and sociodemographic differences in duration of untreated psychosis (DUP) in first episode schizophrenia: Results from a meta-analysis and exploratory meta-regression analysis

Performance of instrumental activities of daily living (IADLs) can become compromised in older adults with mild cognitive impairment (MCI). Patients’ level of insight into their everyday functioning varies both amongst individuals and across domains assessed, with some individuals exhibiting complete unawareness of deficits. The current cross-sectional study examined the neuroanatomical substrates of self-awareness in order to help explain the variability in this phenomenon in older adults across a continuum of cognitive impairment. Eighty-five participants (ages 54–88, mean age = 73 years, 57% female, 89% Caucasian) diagnosed with MCI or mild probable dementia underwent structural magnetic resonance imaging. Level of self-awareness was assessed by calculating the discrepancy between objective and subjective performance across six IADLs (Financial Management, Driving, Grocery Shopping, Nutrition Evaluation, Medication Management, and Telephone Use). Over-estimation of current abilities occurred in 13–31% of the sample depending on which IADL was evaluated. Poor awareness was significantly related to reduced volume in the bilateral medial prefrontal cortex, middle and posterior cingulate cortex, right insular cortex, and cerebellum. No associations were found with total white matter lesion load. These findings were broadly consistent across all functional domains assessed, supporting the theory that cortical midline and cerebellar structures are involved in self-referential processing across a variety of different cognitive and behavioral skills. Longitudinal studies are needed to confirm this association.

Default mode network connectivity is associated with long-term clinical outcome in patients with schizophrenia.

This study investigated whether resting-state functional connectivity is associated with long-term clinical outcomes of patients with schizophrenia. Resting-state brain images were obtained from 79 outpatients with schizophrenia and 30 healthy controls (HC), using a 3 T-MRI scanner. All patients were 20–50 years old with >3 years' duration of illness and appeared clinically stable. We assessed their psychopathology using the 18-item Brief Psychiatric Rating Scale (BPRS-18) and divided them into “good,” “moderate,” and “poor” outcome (SZ-GO, SZ-MO, and SZ-PO) groups depending on BPRS-18 total score. We obtained individual functional connectivity maps between a seed region of the bilateral posterior cingulate cortex (PCC) and all other brain regions and compared the functional connectivity of the default mode network (DMN) among the HC and 3 schizophrenia outcome groups, with a voxel-wise threshold of P < .001 within a cluster-extent threshold of 114 voxels. Additionally, we assessed correlations between functional connectivity and BPRS-18 scores. The SZ-MO and SZ-PO groups showed decreased functional connectivity between PCC and right ventromedial prefrontal cortex (vmPFC), left middle cingulate cortex, and left frontopolar cortex (FPC) compared to the SZ-GO and HC groups. DMN connectivity in the right vmPFC and left FPC negatively correlated with subscale scores of the BPRS-18, except the negative symptoms subscale. In this study, poorer clinical outcomes in patients with schizophrenia were associated with decreased DMN connectivity. In particular, the decreased functional connectivity might be related to the severity of positive and mood symptoms rather than negative symptoms.

Resting-State Default Mode Network Related Functional Connectivity Is Associated With Sustained Attention Deficits in Schizophrenia and Obsessive-Compulsive Disorder.

Background: Previous studies have indicated the resting-state default mode network (DMN) related connectivity serving as predictor of sustained attention performance in healthy people. Interestingly, sustained attention deficits as well as DMN-involved functional connectivity (FC) alterations are common in both patients with schizophrenia (SCZ) and with obsessive-compulsive disorder (OCD). Thus, the present study was designed to investigate whether the DMN related resting-state connectivity alterations in these two psychiatric disorders were neural correlates of their sustained attention impairments.Methods: The study included 17 SCZ patients, 35 OCD patients and 36 healthy controls (HCs). Sustained attention to response task was adopted to assess the sustained attention. Resting-state scan was administrated and seed-based whole-brain FC analyses were performed with seeds located in classical DMN regions including bilateral medial prefrontal cortex (mPFC) and posterior cingulate cortex (PCC).Results: Both SCZ and OCD patients had poorer sustained attention than HCs. Sustained attention deficits in OCD was negatively correlated with their impaired FC of right mPFC-left superior frontal gyrus (SFG) within DMN, and that in SCZ was significantly correlated with their altered FC of left mPFC-bilateral anterior cingulate cortex (ACC) which indicated interaction between DMN and salience network. In addition, the FC between left mPFC and right parietal lobe indicating the interaction between DMN and frontal-parietal network was correlated with sustained attention in both SCZ and OCD.Conclusion: These findings suggest the importance of DMN-involved connectivity, both within and between networks in underlying sustained attention deficits in OCD and SCZ. Results further support the potential of resting-state FC in complementing information for cognitive deficits in psychiatric disorders.

Abnormal Default Mode Network Homogeneity in Treatment-Naive Patients With First-Episode Depression.

Background and Objective: The default mode network (DMN) may be an important component involved in the broad-scale cognitive problems seen in patients with first-episode treatment-naive depression. Nevertheless, information is scarce regarding the changes in network homogeneity (NH) found in the DMN of these patients. Therefore, in this study, we explored the NH of the DMN in patients with first-episode treatment-naive depression.Methods: The study included 66 patients and 74 control participants matched by age, gender, educational level and health status who underwent resting-state functional magnetic resonance imaging (rs-fMRI) and the attentional network test (ANT). To assess data, the study utilizes NH and independent component analysis (ICA). Additionally, Spearman's rank correlation analysis is performed among significantly abnormal NH in depression patients and clinical measurements and executive control reaction time (ECRT).Results: In comparison with the control group, patients with first-episode treatment-naive depression showed lower NH in the bilateral angular gyrus (AG), as well as increased NH in the bilateral precuneus (PCu) and posterior cingulate cortex (PCC). Likewise, patients with first-episode treatment-naive depression had longer ECRT. No significant relation was found between abnormal NH values and the measured clinical variables.Conclusions: Our results suggest patients with first-episode treatment-naive depression have abnormal NH values in the DMN. This highlights the significance of DMN in the pathophysiology of cognitive problems in depression. Our study also found alterations in executive functions in patients with first-episode treatment-naive depression.

Psychoradiological investigations of gray matter alterations in patients with anorexia nervosa

Anorexia nervosa (AN) is a severe psychiatric disorder with high mortality. The underlying neurobiological mechanisms are not well understood, and high-resolution structural magnetic resonance brain imaging studies have given inconsistent results. Here we aimed to psychoradiologically define the most prominent and replicable abnormalities of gray matter volume (GMV) in AN patients, and to examine their relationship to demographics and clinical characteristics, by means of a new coordinate-based meta-analytic technique called seed-based d mapping (SDM). In a pooled analysis of all AN patients we identified decreased GMV in the bilateral median cingulate cortices and posterior cingulate cortices extending to the bilateral precuneus, and the supplementary motor area. In subgroup analysis we found an additional decreased GMV in the right fusiform in adult AN, and a decreased GMV in the left amygdala and left anterior cingulate cortex in AN patients without comorbidity (pure AN). Thus, the most consistent GMV alterations in AN patients are in the default mode network and the sensorimotor network. These psychoradiological findings of the brain abnormalities might underpin the neuropathophysiology in AN.

Differences in Neural Recovery From Acute Stress Between Cortisol Responders and Non-responders.

Adaptive recovery from a stressor fosters resilience. So far, however, few studies have examined brain functional connectivity in the aftermath of stress, with inconsistent results reported. Focusing on the immediate recovery from psychosocial stress, the current study compared amygdala resting-state functional connectivity (RSFC) before and immediately after psychosocial stress between cortisol responders and non-responders. Differences between groups were expected for amygdala RSFC with regions involved in down-regulation of the physiological stress response, emotion regulation, and memory consolidation. Eighty-six healthy participants (36 males/50 females) underwent a social stress paradigm inside the MRI scanner. Before and immediately after stress, resting-state (RS) fMRI scans were acquired to determine amygdala RSFC. Next, changes in connectivity from pre- to post-stress were compared between cortisol responders and non-responders. Responders demonstrated a cortisol increase, higher negative affect, and decreased heart rate variability (HRV) in response to stress compared to non-responders. A significant Sex-by-Responder-by-Time interaction was found between the bilateral amygdala and posterior cingulate cortex (PCC) and precuneus (p < 0.05, corrected). As males were also more likely to show a cortisol increase to the stress task than females, follow-up analyses were conducted for both sexes separately. Whereas no difference was observed between female responders and non-responders, male non-responders showed an increase in FC after stress between the bilateral amygdala and the PCC and precuneus (p < 0.05, corrected). The increased coupling of the amygdala with the PCC/precuneus, a core component of the default mode network (DMN), might indicate an increased engagement of the amygdala within the DMN directly after stress in non-responders. Although this study was carried out in healthy participants, and the results likely reflect normal variations in the neural response to stress, understanding the mechanisms that underlie these variations could prove beneficial in revealing neural markers that promote resilience to stress-related disorders.

Alterations of brain local functional connectivity in amnestic mild cognitive impairment

BackgroundResting-state functional magnetic resonance imaging studies using a regional homogeneity (ReHo) method have reported that amnestic mild cognitive impairment (aMCI) was associated with abnormalities in local functional connectivity. However, their results were not conclusive.MethodsSeed-based d Mapping was used to conduct a coordinate-based meta-analysis to identify consistent ReHo alterations in aMCI.ResultsWe identified 10 studies with 11 datasets suitable for inclusion, including 378 patients with aMCI and 435 healthy controls. This meta-analysis identified significant ReHo alterations in patients with aMCI relative to healthy controls, mainly within the default mode network (DMN) (bilateral posterior cingulate cortex [PCC], right angular gyrus, bilateral middle temporal gyri, and left parahippocampal gyrus/hippocampus), executive control network (right superior parietal lobule and dorsolateral prefrontal cortex), visual network (right lingual gyrus and left middle occipital gyrus), and sensorimotor network (right paracentral lobule/supplementary motor area, right postcentral gyrus and left posterior insula). Significant heterogeneity of ReHo alterations in the bilateral PCC, left parahippocampal gyrus/hippocampus, and right superior parietal lobule/angular gyrus was observed. Exploratory meta-regression analyses indicated that general cognitive function, gender distribution, age, and education level partially contributed to this heterogeneity.ConclusionsThis study provides provisional evidence that aMCI is associated with abnormal ReHo within the DMN, executive control network, visual network, and sensorimotor network. These local functional connectivity alterations suggest coexistence of functional deficits and compensation in these networks. These findings contribute to the modeling of brain functional connectomes and to a better understanding of the neural substrates of aMCI. Confounding factors merit much attention and warrant future investigations.

The age-dependent relationship between resting heart rate variability and functional brain connectivity

Resting heart rate variability (HRV), an index of parasympathetic cardioregulation and an individual trait marker related to mental and physical health, decreases with age. Previous studies have associated resting HRV with structural and functional properties of the brain – mainly in cortical midline and limbic structures. We hypothesized that aging affects the relationship between resting HRV and brain structure and function. In 388 healthy subjects of three age groups (140 younger: 26.0 ± 4.2 years, 119 middle-aged: 46.3 ± 6.2 years, 129 older: 66.9 ± 4.7 years), gray matter volume (GMV, voxel-based morphometry) and resting state functional connectivity (eigenvector centrality mapping and exploratory seed-based functional connectivity) were related to resting HRV, measured as the root mean square of successive differences (RMSSD). Confirming previous findings, resting HRV decreased with age. For HRV-related GMV, there were no statistically significant differences between the age groups, nor similarities across all age groups. In whole-brain functional connectivity analyses, we found an age-dependent association between resting HRV and eigenvector centrality in the bilateral ventromedial prefrontal cortex (vmPFC), driven by the younger adults. Across all age groups, HRV was positively correlated with network centrality in the bilateral posterior cingulate cortex. Seed-based functional connectivity analysis using the vmPFC cluster revealed an HRV-related cortico-cerebellar network in younger but not in middle-aged or older adults. Our results indicate that the decrease of HRV with age is accompanied by changes in functional connectivity along the cortical midline. This extends our knowledge of brain-body interactions and their changes over the lifespan.

Analysis of voxel-mirrored homotopic connectivity in medication-free, current major depressive disorder

BackgroundRecent neuroimaging studies suggest that abnormal function connectivity exists in patients with major depressive disorder (MDD). The aim of this study was to further analyze the underlying neural mechanism of MDD and explore whether clinical characteristics are correlated with the alerted homotopic connectivity in patients with MDD. MethodsUsing voxel-mirrored homotopic connectivity (VMHC) during resting state, we compared 80 medication-free patients having current episodes of MDD and 124 never-depressed healthy controls (HCs) matched for age and gender. ResultsWe found decreased VMHC in patients with MDD in bilateral posterior cingulate cortex (PCC) extending to precuneus (Pre) compared with the HCs, which provided strong support for the potential role of PCC/Pre in recognizing interhemispheric connectivity deficits of MDD. Negative correlation between illness course and VMHC in PCC was observed as well. LimitationsFirst, we just compared the functional connectivity at a rest state but not under a specific task. Second, we did not mitigate the delayed effect on the measurable alterations in homotopic brain activity. Third, we did not make a longitudinal comparison after patients receiving therapeutic drugs. ConclusionsThese findings that linking illness course with functional brain changes in depression help us understand the neural architecture of MDD.

BASELINE POSTERIOR CINGULATE CORTEX-MEDIAL TEMPORAL/HIPPOCAMPAL NETWORKS IN MCI PREDICTS THE EFFECT OF COGNITIVE TRAINING

Mild cognitive impairment (MCI) is well known as a state between normal aging and Alzheimer's disease (AD). Cognitive training has been widely studied for its prevention effect in MCI patients. The results are controversial in different clinical trials. Cognitive training might work by modulating neural plasticity, and the threshold of modulation varies between individuals. It is important to find out prognostic neural markers for the effect of cognitive training before such intervention. We recruited thirty MCI patients and trained them for six months. Training covered memory, attention, language, visual spatial and executive function. Mini-mental state examination (MMSE) was done before and after training. Resting state functional MRI (Rs-fMRI) was also performed before training. MMSE of AD patients decrease 2 points per year according to epidemiological study. After six-month intervention, we grouped these patients by their MMSE difference between endpoint and baseline. Progressed group has 12 patients, which is defined by 1 points MMSE reduction. Effective group has 18 patients, which is defined by less than 1 points reduction of MMSE. Blood oxygenation level-dependent signals (BOLD) from fMRI were analyzed after pre-processing. We used seed-based functional connectivity (FC) for extracting default mode network (DMN) by seed in the posterior cingulate cortex (PCC). We also explored the connectivity between bilateral hippocampus and other voxels in the brain and compared the two groups with each other. Two groups were similar in their age, education level and baseline cognitive tests (MMSE, auditory verbal learning test, shape trail test, symbol digit substitution test, stroop color-word test and complex figure test). Baseline DMN of effective group showed increased connectivity between cortex peripheral to right lateral fissure and PCC. FC between bilateral hippocampus and PCC was also stronger in effective group than progressed group.

Contextual interference enhances motor learning through increased resting brain connectivity during memory consolidation

Increasing contextual interference (CI) during practice benefits learning, making it a desirable difficulty. For example, interleaved practice (IP) of motor sequences is generally more difficult than repetitive practice (RP) during practice but leads to better learning. Here we investigated whether CI in practice modulated resting-state functional connectivity during consolidation. 26 healthy adults (11 men/15 women, age = 23.3 ± 1.3 years) practiced two sets of three sequences in an IP or RP condition over 2 days, followed by a retention test on Day 5 to evaluate learning. On each practice day, functional magnetic resonance imaging (fMRI) data were acquired during practice and also in a resting state immediately after practice. The resting-state fMRI data were processed using independent component analysis (ICA) followed by functional connectivity analysis, showing that IP on Day 1 led to greater resting connectivity than RP between the left premotor cortex and left dorsolateral prefrontal cortex (DLPFC), bilateral posterior cingulate cortices, and bilateral inferior parietal lobules. Moreover, greater resting connectivity after IP than RP on Day 1, between the left premotor cortex and the hippocampus, amygdala, putamen, and thalamus on the right, and the cerebellum, was associated with better learning following IP. Mediation analysis further showed that the association between enhanced resting premotor-hippocampal connectivity on Day 1 and better retention performance following IP was mediated by greater task-related functional activation during IP on Day 2. Our findings suggest that the benefit of CI to motor learning is likely through enhanced resting premotor connectivity during the early phase of consolidation.

Abnormal default-mode network homogeneity in patients with temporal lobe epilepsy.

Default-mode network (DMN) plays a key role in a broad-scale cognitive problem, which occurs in temporal lobe epilepsy (TLE). However, little is known about the alterations of the network homogeneity (NH) of DMN in TLE. In the present study, we employed NH method to investigate the NH of DMN in TLE at rest.A total of 47 patients with TLE (right TLE [rTLE] 29, and left TLE [lTLE] 18) and 35 healthy controls who underwent resting-state functional magnetic resonance imaging were enrolled. NH approach was used to analyze the data.rTLE exhibited decreased NH in the right middle temporal pole gyrus and increased NH in the bilateral posterior cingulate cortex compared to the control group. In lTLE, decreased NH was observed in left inferior temporal gyrus and left hippocampus. Meanwhile, we found that lTLE had a longer performance reaction time. No significant correlation was found between abnormal NH values and clinical variables in the patients.These findings suggested that abnormal NH of the DMN exists in rTLE and lTLE, and highlighted the significance of DMN in the pathophysiology of cognitive problems occurring in TLE and also found the existence of abnormality of executive function in lTLE.

Neuroanatomical Correlates of Advanced Paternal and Maternal Age at Birth in Autism Spectrum Disorder.

Although advanced paternal and maternal age at birth (PA/MA) increases the risk of autism spectrum disorder (ASD), the underlying neurobiological mechanisms are not fully understood. To explore the neuroanatomical correlates of advanced PA/MA, the current study conducted brain morphometric analyses in 39 high-functioning adult males with ASD and 39 age-, intellectual level-, and parental socioeconomic background-matched, typically developed (TD) males. Whole-brain analysis revealed that the regional gray matter volume (GMV) in bilateral posterior cingulate cortex (PCC) and precuneus (PCU) were significantly smaller in the individuals with ASD than in TD subjects (false discovery rate-corrected P = 0.014). Additional analyses of the constituents of GMV reduction in these brain regions revealed that the cortical thickness of the right ventral PCC was significantly thinner (P = 0.014) and the surface area of bilateral PCU was significantly smaller (left: P = 0.001; right: P = 0.049) in the adults with ASD, compared with TD subjects. Although the analyses were exploratory, the thinner cortical thickness of right ventral PCC was significantly correlated with older PA in the ASD individuals (P = 0.028). The current findings shed new light on the neurobiological mechanisms underlying the link between advanced PA and ASD.

Abnormal target detection and novelty processing neural response in posttraumatic stress disorder

Attention impairments are common symptoms of posttraumatic stress disorder (PTSD); however, the nature of these impairments remains elusive. Attention impairment may arise as the result of either excessive response to task-irrelevant stimuli or reduced response to task-relevant information. To test the association between PTSD and response to task-relevant and task-irrelevant stimuli, we used a 3-tone novelty auditory oddball task (AOD). We hypothesized that participants with PTSD relative to trauma controls would have less response during novelty processing in the dorsolateral prefrontal cortex (dlPFC) and the anterior cingulate cortex, as well as less response in the dlPFC and the orbitofrontal cortex during target detection. Thirty-one male veterans completed a 3-tone novelty AOD task during functional magnetic resonance imaging. Compared to trauma controls, the PTSD group had reduced response during novelty processing in ventromedial prefrontal cortex, superior/middle frontal gyrus (dlPFC), supplementary motor area/caudate, and in posterior regions including bilateral posterior cingulate cortex. The current results suggest PTSD is associated with a pattern of reduced response to novel stimuli. A disturbed orienting response in these brain regions could theoretically underlie PTSD attention-related symptoms.