Functional connectivity in fronto-subcortical circuitry during the resting state in obsessive-compulsive disorder

Obsessions and compulsions mediated by cognitive inflexibility might be associated with abnormal resting state functional connectivity in the default mode network (DMN) that represents intrinsically generated neuronal activity. It was hypothesized that decreased functional connectivity in the DMN would occur in components of fronto-subcortical circuits in patients with obsessive-compulsive disorder (OCD). Twenty-two unmedicated OCD patients and 22 age- and sex-matched healthy controls received resting state functional scanning runs. The posterior cingulate cortex (PCC) region was chosen as the seed region for the connectivity analysis. Correlations between temporal connectivity with the seed region and scores on clinical measures and obsessive-compulsive symptom dimensions were also assessed. OCD patients demonstrated less functional connectivity within the DMN in the anterior cingulate cortex, middle frontal gyrus, and putamen compared to controls. The functional connectivity to the PCC seed region in OCD patients was in the direction opposite to that in the prefrontal areas with regard to scores on cleaning and obsessions/checking dimensions of OCD. These data provide evidence for fronto-subcortical dysfunction in OCD. Results from this study also support the notion that OCD is a heterogeneous disorder mediated by distinct circuits.     

Resting-state fMRI changes in Alzheimer's disease and mild cognitive impairment

Regional functional connectivity (FC) of 39 patients with Alzheimer's disease (AD), 23 patients with mild cognitive impairment (MCI), and 43 healthy elderly controls was studied using resting-state functional magnetic resonance imaging (rs-fMRI). After a mean follow-up of 2.8 ± 1.9 years, 7 MCI patients converted to AD, while 14 patients remained cognitively stable. Resting-state functional magnetic resonance imaging scans were analyzed using independent component analysis (ICA), followed by a "dual-regression" technique to create and compare subject-specific maps of each independent spatiotemporal component, correcting for age, sex, and gray matter atrophy. AD patients displayed lower FC within the default-mode network (DMN) in the precuneus and posterior cingulate cortex compared with controls, independent of cortical atrophy. Regional FC values of MCI patients were numerically in between AD patients and controls, but only the difference between AD and stable MCI patients was statistically significant. Correlation with cognitive dysfunction demonstrated the clinical relevance of FC changes within the DMN. In conclusion, clinically relevant decreased FC within the DMN was observed in AD.     

Resting state fMRI in Alzheimer's disease: beyond the default mode network

Using resting state (RS) functional magnetic resonance imaging (fMRI), the connectivity patterns of the default mode (DMN), frontoparietal, executive, and salience networks were explored in 13 Alzheimer's disease (AD) patients, 12 amnestic mild cognitive impairment (aMCI) patients, and 13 healthy controls. Compared with controls and aMCI, AD was associated with opposing connectivity effects in the DMN (decreased) and frontal networks (enhanced). The only RS abnormality found in aMCI patients compared with controls was a precuneus connectivity reduction in the DMN. RS fMRI group differences were only partly related to gray matter atrophy. In AD patients, the mean executive network connectivity was positively associated with frontal-executive and language neuropsychological scores. These results suggest that AD is associated with an alteration of large-scale functional brain networks, which extends well beyond the DMN. In AD, the limited resources of the DMN may be paralleled, in an attempt to maintain cognitive efficiency, by an increased prefrontal connectivity. A medial parietal RS fMRI signal change seems to be present since the early phase of AD.     

Connectivity pattern changes in default-mode network with deep non-REM and REM sleep

Recent studies have compared default-mode network (DMN) connectivity in different arousal levels to investigate the relationship between consciousness and DMN. The comparison between the DMN in rapid eye movement (REM) sleep with that in non-REM (NREM) sleep is useful for revealing the relationship between arousal level and DMN, because the arousal level is at its lowest during deep NREM, while during REM sleep it is as high as wakefulness. Functional magnetic resonance imaging (fMRI) and polysomnogram data were acquired from participants in REM, deep NREM, and light NREM sleep, and the DMN was compared using functional connectivity analysis. Our analysis revealed that functional connectivity among the DMN core regions - the posterior cingulate cortex, rostral anterior cingulate cortex, and inferior parietal lobule - remained consistent across sleep states. In contrast, connectivity involving the DMN subsystems of REM sleep differs from that of NREM sleep, and the change well accounts for the characteristics of REM sleep. Our results suggest that both the DMN core region and subsystems may not relate to the maintenance of arousal. The DMN core network and subsystems may respectively serve to integrate brain regions and perform function specific to each level of arousal.     

Changes of functional connectivity of the motor network in the resting state in Parkinson's disease

We used functional MRI (fMRI) and a network model based on graph theory to measure functional connectivity of brain motor network in the resting state in patients with Parkinson's disease (PD). FMRIs were acquired in 22 PD patients before and after levodopa administration, and in age- and sex-matched normal controls. The total connectivity degree of each region within the motor network was calculated and compared between patients and controls. We found that PD patients at off state had significantly decreased functional connectivity in the supplementary motor area, left dorsal lateral prefrontal cortex and left putamen, and had increased functional connectivity in the left cerebellum, left primary motor cortex, and left parietal cortex compared to normal subjects. Administration of levodopa relatively normalized the pattern of functional connectivity in PD patients. The functional connectivity in most of regions in the motor network correlated with the Unified Parkinson's Disease Rating Scale motor score in the patients. Our findings demonstrate that the pattern of functional connectivity of the motor network in the resting state is disrupted in PD. This change is secondary to dopamine deficiency, and related to the severity of the disease. We postulate that this abnormal functional connectivity of motor network in the baseline state is possibly an important factor contributing to some motor deficits in PD, e.g. akinesia.     

Resting state connectivity of the medial prefrontal cortex covaries with individual differences in high‐frequency heart rate variability

Resting high‐frequency heart rate variability (HF‐HRV) relates to cardiac vagal control and predicts individual differences in health and longevity, but its functional neural correlates are not well defined. The medial prefrontal cortex (mPFC) encompasses visceral control regions that are components of intrinsic networks of the brain, particularly the default mode network (DMN) and the salience network (SN). Might individual differences in resting HF‐HRV covary with resting state neural activity in the DMN and SN, particularly within the mPFC? This question was addressed using fMRI data from an eyes‐open, 5‐min rest period during which echoplanar brain imaging yielded BOLD time series. Independent component analysis yielded functional connectivity estimates defining the DMN and SN. HF‐HRV was measured in a rest period outside of the scanner. Midlife (52% female) adults were assessed in two studies (Study 1, N = 107; Study 2, N = 112). Neither overall DMN nor SN connectivity strength was related to HF‐HRV. However, HF‐HRV related to connectivity of one region within mPFC shared by the DMN and SN, namely, the perigenual anterior cingulate cortex, an area with connectivity to other regions involved in autonomic control. In sum, HF‐HRV does not seem directly related to global resting state activity of intrinsic brain networks, but rather to more localized connectivity. A mPFC region was of particular interest as connectivity related to HF‐HRV was shared by the DMN and SN. These findings may indicate a functional basis for the coordination of autonomic cardiac control with engagement and disengagement from the environment.     

Interleukin-1 beta C-511T polymorphism modulates functional connectivity of anterior midcingulate cortex in non-demented elderly Han males

Recent resting fMRI studies have suggested that the functional connectivity of the brain’s large-scale networks is associated with the cognitive decline of aging and is modulated by genetic factors. Our previous study found a significant association between interleukin-1 (IL-1 beta) C-511T polymorphism and working memory performance among elderly people. This study investigates the effects of IL-1 beta C-511T polymorphism on the functional connectivity of the cognitive division of the cingulate cortex [i.e., the anterior midcingulate (aMCC)] in non-demented Han elderly people and tests the hypothesis that T/T carriers are associated with lowered FC. Non-demented elderly males (n = 95) received resting MRI scanning, genotyping, and cognitive evaluation using the cognitive abilities screening instrument (CASI) and the Wechsler digit span task test. The functional connectivity map in each subject was derived based on positive correlations of low-frequency fMRI fluctuations with a seed in the aMCC according to structural definition. Between-group difference was compared by random effect analysis. Compared to the C/C or C/T carriers, the T/T carriers had a significantly worse CASI performance, especially in the abstraction scores. For the functional connectivity analysis, the T/T carriers exhibited significantly lower functional connectivity with several prefrontal areas and the left putamen. The cortico-striatal connection between the aMCC and left putamen was correlated with the CASI abstraction and attention scores. The results were consistent with our hypothesis and supported that the brains’ functional connectivity in elderly people may be modulated by genetic polymorphism associated with local inflammation processes.     

Effects of transcutaneous auricular vagus nerve stimulation on brain functional connectivity of medial prefrontal cortex in patients with primary insomnia

As a representative of acupuncture and nonpharmaceutical therapy, auricular acupuncture has been widely for the treatment of insomnia. Transcutaneous auricular vagus nerve stimulation (taVNS) is a combination of auricular point stimulation and vagus nerve stimulation. It can not only treat primary insomnia effectively, but also is noninvasive, painless, portable and economical. The medial prefrontal cortex (mPFC) is a core region of default mode network (DMN), which is important for maintenance of sleep. However, the mechanism of taVNS in alleviating primary insomnia (PI) remains to be clarified. In this study, we found that taVNS could not only effectively reduce the score of Pittsburgh Sleep Quality Index, but also decreased functional connection (FC) between the left mPFC and bilateral dorsal anterior cingulate gyrus as well as FC between the right mPFC and the occipital cortex in patients with PI. Furthermore, the decrease in FC was positively correlated with the decline of sleep index score. Therefore, we proposed that treatment with taVNS can improve sleep quality and prolong sleep duration in patients with PI by reducing FC within DMN, FC between DMN and salience network, as well as FC between DMN and the occipital cortex. This may be one of mechanisms of taVNS in treating PI.     

原发全面强直阵挛癫痫患者皮层-纹状体-丘脑-小脑网络的静息态功能MRI的对照研究

目的 探讨应用静息态功能MRI网络技术描绘原发全面强直阵挛癫痫 (IGE-GTCS)患者皮层-纹状体-丘脑-小脑网络的模式。方法 前瞻性纳入2009年7月—2016年10月IGE-GTCS患者60例为IGE-GTCS组,同时纳入与IGE-GTCS组患者年龄、性别相匹配的健康志愿者60名为正常对照组。两组受试者于3 T超导MR仪下行静息态功能MRI数据收集,采用北京师范大学脑影像处理分析软件DPARSF 4.4完成预处理。采用皮层分区模板,将整个大脑分成额叶皮层、运动皮层、感觉皮层、顶枕皮层、颞叶皮层5个感兴趣区域(ROI),自动解剖标记模板定义丘脑、纹状体(包括尾状核、壳核、苍白球)和小脑的皮层下结构,构建皮层-皮层下核团-小脑网络。分别计算5个皮层区域与皮层下核团体素间的功能连接系数,获得系数图;并将得到的相关系数通过Fisher Z 转换,符合正态分布的功能连接系数图用于后续统计分析。使用SPM 12软件的两样本t检验,对IGE-GTCS组与正常对照组间皮层-皮层下核团-小脑功能连接的异常进行比较,应用高斯随机场理论(GRF)进行多重比较校正,体素校正水平取P＜0.01,团块校正水平取P＜0.05,双尾校正;并将IGE-GTCS患者功能连接改变的区域与临床病程进行Pearson相关分析。结果 因头动过大, IGE-GTCS组排除5例,最终纳入55例,男35例、女20例,年龄(25.11±6.0)岁,病程(11.3±6.6)年;正常对照组共60名,其中男37名、女23名,年龄(26.38±6.5)岁。两组受试者年龄、性别差异均无统计学意义(t=1.086、χ²=0.048, P值均＞0.05)。相比于正常对照组,IGE-GTCS组功能连接结果差异均有统计学意义(GRF校正,体素水平P值均＜0.01、团块水平P值均＜0.05):(1)额叶皮层,与双侧小脑脚2区(左右半球体素分别为115、182, t值分别为-5.57、-3.82)、右侧苍白球(体素=28, t=-7.42)连接降低,与双侧丘脑(左右半球体素分别为121、134, t值分别为10.48、9.16)、尾状核(左右半球体素分别为206、199, t值分别为13.40、11.59)、壳核(左右半球体素分别为178、219, t值分别为7.29、8.79)及小脑4、5区(左右半球体素分别为55、45, t值分别为2.63、2.74)连接增加。(2)运动皮层,与左侧小脑脚1区(体素=98, t=-3.10)、双侧苍白球(左右半球体素分别为26、31, t值分别为-7.05、-6.86)连接降低,与丘脑(左右半球体素分别为137、145, t值分别为11.06、9.77)、尾状核(左右半球体素分别为202、197, t值分别为12.88、11.79)、壳核(左右半球体素分别为104、120, t值分别为7.54、10.71)、小脑4、5区(左右半球体素分别为64、43, t值分别为4.62、5.13)及小脑脚2区(左右半球体素分别为85、85, t值分别为4.23、4.23)连接增加。(3)感觉皮层,与左侧小脑脚1区(体素=103, t=-3.87)连接降低,小脑4、5区(左右半球体素分别为72、63, t值分别为4.58、5.96)、双侧小脑脚2区(左右半球体素分别为173、173, t值分别为4.22、4.22)、丘脑(左右半球体素分别为143、151, t值分别为10.41、7.91)、尾状核(左右半球体素分别为198、195, t值分别为10.30、8.82)、壳核(左右半球体素分别为105、110, t值分别为6.38、8.06)、苍白球(左右半球体素分别为8、9, t分别为4.95、4.31)连接增加。(4)顶枕皮层,与右侧苍白球(体素=23, t=-7.45)连接降低,与小脑4、5区(左右半球体素分别为32、28, t值分别为3.56、3.89)、左侧小脑脚2区(体素=15, t=4.56)、丘脑(左右半球体素分别为107、118, t值分别为10.57、10.62)、尾状核(左右半球体素分别为201、197, t值分别为7.52、8.43)及壳核(左右半球体素分别为112、164, t值分别为6.53、7.21)连接增加。(5)颞叶皮层,与右侧小脑4、5区(体素=29, t=6.35)、双侧小脑脚2区(左右半球体素分别为58、128, t值分别为4.66、2.77)、丘脑(左右半球体素分别为128、136, t值分别为10.32、10.48)、尾状核(左右半球体素分别为207、203, t值分别为10.88、10.31)及壳核(左右半球体素分别为134、157, t值分别为7.39、6.75)连接均增加。额叶皮层-左侧小脑8区、运动皮层-左侧小脑8区、感觉皮层-小脑蚓部6区、顶枕皮层-左侧小脑8区、颞叶皮层-右侧小脑脚2区功能连接与病程相关系数分别为-0.385、-0.455、-0.362、-0.332、-0.544,差异均有统计学意义(P值均＜0.01)。结论 IGE-GTCS存在广泛的皮层-纹状体-丘脑-小脑网络功能连接的异常,表现为特异核团的功能连接的增高与降低,部分功能连接的改变与病程呈负相关。     

Emotional faces and the default mode network

The default-mode network (DMN) of the human brain has become a central topic of cognitive neuroscience research. Although alterations in its resting state activity and in its recruitment during tasks have been reported for several mental and neurodegenerative disorders, its role in emotion processing has received relatively little attention. We investigated brain responses to different categories of emotional faces with functional magnetic resonance imaging (fMRI) and found deactivation in ventromedial prefrontal cortex (VMPFC), posterior cingulate gyrus (PC) and cuneus. This deactivation was modulated by emotional category and was less prominent for happy than for sad faces. These deactivated areas along the midline conformed to areas of the DMN. We also observed emotion-dependent deactivation of the left middle frontal gyrus, which is not a classical component of the DMN. Conversely, several areas in a fronto-parietal network commonly linked with attention were differentially activated by emotion categories. Functional connectivity patterns, as obtained by correlation of activation levels, also varied between emotions. VMPFC, PC or cuneus served as hubs between the DMN-type areas and the fronto-parietal network. These data support recent suggestions that the DMN is not a unitary system but differentiates according to task and even type of stimulus. The emotion-specific differential pattern of DMN deactivation may be explored further in patients with mood disorder, where the quest for biological markers of emotional biases is still ongoing.     

Alterations of regional spontaneous neuronal activity and corresponding brain circuit changes during resting state in migraine without aura

Although previous resting‐state studies have reported abnormal functional cerebral changes in patients with migraine without aura (MwoA), few have focused on alterations in both regional spontaneous neuronal activity and corresponding brain circuits in MwoA patients during rest. Eighteen MwoA patients and 18 age‐ and gender‐matched healthy controls (HC) were recruited in the current study. Baseline cerebral alterations were investigated using amplitude of low‐frequency fluctuation (ALFF) and region of interest (ROI)‐based functional connectivity (FC) analyses. Compared with HC, MwoA patients showed decreased ALFF values in the left rostral anterior cingulate cortex (rACC) and bilateral prefrontal cortex (PFC) as well as increased ALFF values in the right thalamus. FC analysis also revealed abnormal FCs associated with these ROIs. In addition, ALFF values of the left rACC correlated with duration of disease in MwoA. Our findings could lead to a better understanding of intrinsic functional architecture of baseline brain activity in MwoA, providing both regional and brain circuit spontaneous neuronal activity properties. Copyright © 2013 John Wiley & Sons, Ltd.     

Increased default mode network connectivity associated with meditation

Areas associated with the default mode network (DMN) are substantially similar to those associated with meditation practice. However, no studies on DMN connectivity during resting states have been conducted on meditation practitioners. It was hypothesized that meditators would show heightened functional connectivity in areas of cortical midline activity. Thirty-five meditation practitioners and 33 healthy controls without meditation experience were included in this study. All subjects received 4.68-min resting state functional scanning runs. The posterior cingulate cortex and medial prefrontal cortex were chosen as seed regions for the DMN map. Meditation practitioners demonstrated greater functional connectivity within the DMN in the medial prefrontal cortex area (xyz=339-21) than did controls. These results suggest that the long-term practice of meditation may be associated with functional changes in regions related to internalized attention even when meditation is not being practiced.     

基于独立成分分析和时间相关分析的脑功能连通研究方法[英文]

目的:利用静息状态功能磁共振成像(functional magnetic resonance imaging,fMRI)技术,提出联合独立成分分析(independent component analysis,ICA)和时间相关分析的人脑功能连通性研究方法。方法:首先采用空间ICA定位任务激活的脑区;然后选择一个激活区作为感兴趣区域(region of interest,ROI),采用时间相关分析方法检测静息状态大脑特定皮层的功能连通性,并通过检测人脑运动皮层的功能连通性验证方法的有效性。结果:大脑运动皮层功能连通网络包括初级运动区、辅助运动区、初级感觉皮层、背侧前运动区和后顶骨体觉区。实验结果表明,静息状态下,时间相关分析检测到的运动皮层的功能连通网络与已知的解剖连通相一致。结论:利用静息fMRI,结合空间ICA和时间相关分析方法,检测了静息时人脑运动皮层的功能连通网络,为脑区间功能连通的研究提供了一种简便的、无损的、有效的研究方法。     

Functional connectivity in the cognitive control network and the default mode network in late-life depression

BackgroundAbnormalities have been identified in the Cognitive Control Network (CCN) and the Default Mode Network (DMN) during episodes of late-life depression. This study examined whether functional connectivity at rest (FC) within these networks characterizes late-life depression and predicts antidepressant response.Methods26 non-demented, non-MCI older adults were studied. Of these, 16 had major depression and 10 had no psychopathology. Depressed patients were treated with escitalopram (target dose 20 mg) for 12 weeks after a 2-week placebo phase. Resting state time series was determined prior to treatment. FC within the CCN was determined by placing seeds in the dACC and the DLPFC bilaterally. FC within the DMN was assessed from a seed placed in the posterior cingulate.ResultsLow resting FC within the CCN and high resting FC within the DMN distinguished depressed from normal elderly subjects. Beyond this “double dissociation”, low resting FC within the CCN predicted low remission rate and persistence of depressive symptoms and signs, apathy, and dysexecutive behavior after treatment with escitalopram. In contrast, resting FC within the DMN was correlated with pessimism but did not predict treatment response.ConclusionsIf confirmed, these findings may serve as a signature of the brain's functional topography characterizing late-life depression and sustaining its symptoms. By identifying the network abnormalities underlying biologically meaningful characteristics (apathy, dysexecutive behavior, pessimism) and sustaining late-life depression, these findings can provide a novel target on which new somatic and psychosocial treatments can be tested.     

Functional brain connectivity and cognition: effects of adult age and task demands

Previous neuroimaging research has documented that patterns of intrinsic (resting state) functional connectivity (FC) among brain regions covary with individual measures of cognitive performance. Here, we examined the relation between intrinsic FC and a reaction time (RT) measure of performance, as a function of age group and task demands. We obtained filtered, event-related functional magnetic resonance imaging data, and RT measures of visual search performance, from 21 younger adults (19–29 years old) and 21 healthy, older adults (60–87 years old). Age-related decline occurred in the connectivity strength in multiple brain regions, consistent with previous findings. Among 8 pairs of regions, across somatomotor, orbitofrontal, and subcortical networks, increasing FC was associated with faster responding (lower RT). Relative to younger adults, older adults exhibited a lower strength of this RT-connectivity relation and greater disruption of this relation by a salient but irrelevant display item (color singleton distractor). Age-related differences in the covariation of intrinsic FC and cognitive performance vary as a function of task demands.     

Combining spatial and temporal information to explore resting-state networks changes in abstinent heroin-dependent individuals

Majority of previous heroin fMRI studies focused on abnormal brain function in heroin-dependent individuals. However, few fMRI studies focused on the resting-state abnormalities in heroin-dependent individuals and assessed the relationship between the resting-state functional connectivity changes and duration of heroin use. In the present study, discrete cosine transform (DCT) was employed to explore spatial distribution of low frequency BOLD oscillations in heroin-dependent individuals and healthy subjects during resting-state; meanwhile resting-state functional connectivity analysis was used to investigate the temporal signatures of overlapping brain regions obtained in DCT analysis among these two groups. Main finding of the present study is that the default mode network (DMN) and rostral anterior cingulate cortex (rACC) network of heroin-dependent individuals were changed compared with healthy subjects. More importantly, these changes negatively correlated with duration of heroin use. These resting-state functional abnormalites in heroin-dependent individuals provided evidence for abnormal functional organization in heroin-dependent individuals, such as functional impairments in decision-making and inhibitory control.     

State-dependent functional connectivity of rat olfactory system assessed by fMRI

Functional connectivity between the piriform cortex and limbic and neocortical areas was assessed using functional magnetic resonance imaging (fMRI) of urethane anesthetized rats that spontaneously cycled between slow-wave and fast-wave states. Slow-wave and fast-wave states were determined indirectly through monitoring of respiration rate, which was confirmed to co-vary with state as determined by electrophysiological recordings. Previous electrophysiological data have suggested that the piriform cortex shifts between responsiveness to afferent odor input during fast-wave states and enhanced functional connectivity with limbic areas during slow-wave state. The present results demonstrate that fMRI-based resting state functional connectivity between the piriform cortex and both limbic and neocortical areas is enhanced during slow-wave state compared to fast-wave state using respiration as an indirect measure of state in urethane anesthetized rats. This state-dependent shift in functional connectivity may be important for sleep-dependent odor memory consolidation.     

原发性失眠患者大脑背外侧前额叶的异常静息态功能连接

目的:利用功能连接方法观察原发性失眠患者静息态下的背外侧前额叶的异常功能连接。方法:采集33 例原 发性失眠患者以及33 例年龄、性别和受教育程度相匹配的健康对照的功能磁共振图像,以背外侧前额叶为感兴趣区 域,与全脑其他体素进行功能连接分析,得到两组之间功能连接的差异脑区,再对异常功能连接脑区与临床的量表分 数做相关分析。结果:与对照组相比,发现失眠患者左侧背外侧前额叶与左侧枕下回、右侧枕下回、右侧枕中回、右侧 颞叶、左侧额中回,左侧额下回以及右侧梭状回之间的功能连接增强（P<0.05,体素簇个数≥100,FDR校正）,与左侧前 扣带皮层、右侧海马旁回、右侧脑岛、右侧背外侧额上回、右侧顶上回、右侧中央后回以及右侧中央前回之间的功能连 接减弱（P<0.05,体素簇个数≥100,FDR校正）。并且左侧背外侧前额叶与左侧枕叶下回的功能连接值与睡眠状况自评 量表分数成正相关（P=0.035）。结论:原发性失眠患者背外侧前额叶与大脑多个脑区出现异常的功能连接,可能为理 解原发性失眠患者的神经机制提供一些新的影像学依据。     

Age effect on the default mode network,inner thoughts,and cognitive abilities

Age-related effects on the default mode network (DMN) connectivity as measured at rest using functional magnetic resonance imaging (fMRI) are now well described. Little is known however about the relationships between these changes and age-related effects on cognition or on the unconstrained thoughts which occur during the resting-state scan, called inner experience. Brain resting-state activity, inner experience, and cognitive ability measurements were obtained in 70 participants aged 19–80 years. The anterior-posterior disruption of DMN activity with age reported in previous studies was recovered here. A significant effect of age was also found on cognitive abilities but not on inner experience. Finally, age-related changes in DMN connectivity were found to correlate with cognitive abilities, and more specifically with autobiographical memory performance. These findings provide new information to fuel the debate on the role of the brain default mode and more specifically on the effect of age-related changes in resting-state activity as measured with fMRI.     

Measurement of spontaneous signal fluctuations in fMRI: adult age differences in intrinsic functional connectivity

Functional connectivity (FC) reflects the coherence of spontaneous, low-frequency fluctuations in functional magnetic resonance imaging (fMRI) data. We report a behavior-based connectivity analysis method, in which whole-brain data are used to identify behaviorally relevant, intrinsic FC networks. Nineteen younger adults (20–28 years) and 19 healthy, older adults (63–78 years) were assessed with fMRI and diffusion tensor imaging (DTI). Results indicated that FC involving a distributed network of brain regions, particularly the inferior frontal gyri, exhibited age-related change in the correlation with perceptual-motor speed (choice reaction time; RT). No relation between FC and RT was evident for younger adults, whereas older adults exhibited a significant age-related slowing of perceptual-motor speed, which was mediated by decreasing FC. Older adults’ FC values were in turn associated positively with white matter integrity (from DTI) within the genu of the corpus callosum. The developed FC analysis illustrates the value of identifying connectivity by combining structural, functional, and behavioral data.