Interoceptive awareness moderates neural activity during decision-making

The current study examined the relationship between conscious perception of somatic feedback (interoceptive awareness) and neural responses preceding decision-making. Previous research has suggested that decision-making is influenced by body signals from the periphery or the central representation of the periphery. Using event-related fMRI, participants whose interoceptive awareness was assessed using a heartbeat perception paradigm performed the Iowa Gambling Task. The results show a positive relationship between the degree of interoceptive awareness and selection related activity in the right anterior insula and the left postcentral gyrus. Neural activity within the right anterior insula was associated with decision-making performance only in individuals with accurate but not in those with non-accurate interoceptive awareness. These findings support the role of somatic feedback in decision-making processes. They indicate that the right anterior insula holds a representation of somatic markers and that these are more strongly processed with increased interoceptive awareness.     

Resting State fMRI Demonstrates a Disturbance of the Cerebello-Cortical Circuit in Essential Tremor

Individuals with essential tremor (ET) have postural and active movement abnormalities. Disturbances in the cerebello-thalamo-cortical circuit may contribute to the several motor symptoms of ET. Resting state fMRI provides a valuable, noninvasive tool to study intrinsic activation in the human brain, particularly in the brains of individuals with neuropsychiatric diseases. To investigate the low frequency oscillation features of intrinsic activation in ET in this study, we performed a resting state fMRI analysis in 24 patients with ET and 23 healthy controls. The amplitudes of low frequency fluctuation (ALFF) were analyzed. When compared with healthy controls, patients showed significantly enhanced ALFF in the bilateral cerebral cortex, which is related to motor function, including the pre- and post-central gyrus, supplementary motor area and paracentral lobule. The larger ALFF value in the right precentral gyrus is related to a longer duration of tremor. The decreased ALFF in the bilateral cerebellum was also observed in patients. In addition, aberrant ALFF in the right cerebellar tonsil was negatively associated with the duration of tremor. Our findings suggest that abnormalities exist in the intrinsic activation of brain regions in patients with ET. These findings provide noninvasive evidence that supports the hypothesis that the abnormality of intrinsic activity in the cerebello-cerebral cortex pathway could be associated with the motor-related symptoms of ET. Furthermore, the duration of a tremor might relate to the severity of the alterations to the motor system of ET.     

利用脑局部一致性方法对儿童全身强直发作性癫痫的研究

目的　应用静息态功能磁共振局部一致性方法研究儿童全身强直发作性癫痫患者脑区异常活动,探讨其发生的病理生理机制。 方法　对8例儿童全身强直发作性癫痫患者和30例正常儿童进行磁共振扫描,并计算全脑局部一致性的值,进行组间比较并研究局部一致性与病程的相关性。 结果　与对照组相比,癫痫组ReHo值增高的脑区为大脑深部核团（扣带回,丘脑,楔前叶等）,运动相关脑区,额下回,枕叶,颞叶和小脑;ReHo值降低的脑区为双侧额中回、右侧颞中回、左侧颞上回、双侧中央后回、左侧舌回。全身强直发作性癫痫与病程呈正相关的脑区为左侧楔前叶、左侧顶上小叶、右侧中央前回、右侧中央后回;与病程呈负相关的脑区为右侧楔前叶、右侧角回、中央旁小叶。 结论　局部一致性分析方法可以有效地反映癫痫患者异常的神经功能变化,有助于发现强直发作性癫痫发生的病理生理机制。     

遭受多重侵害高职高专女生静息态脑功能局部一致性的研究

目的:探讨遭受多重侵害的高职高专女生静息态脑功能磁共振特点。方法:15名遭受多重侵害无创伤后应激症状被试(PV无PTSS组)、15名多重侵害有创伤后应激症状被试(PV有PTSS组)和15名正常对照接受静息态脑功能扫描。采用SPM8和静息态功能磁共振数据处理工具包分别进行数据预处理和ReHo分析。结果:静息状态下,与对照组相比,PV无PTSS组左侧额下回、左右额内侧回、右侧中央后回、左侧梭状回、左右海马旁回、右侧扣带回、左右豆状核和右侧岛叶的ReHo值降低;左右额上回、左右额中回、左右额下回、左右顶下小叶、左右楔前叶、左右颞上回、左侧颞横回、左右颞中回、右侧舌回和右侧扣带后回的ReHo值升高。与PV有PTSS组相比,PV无PTSS组在右侧额中回和额下回、左侧楔前叶、左侧舌回、左右海马旁回、左侧扣带回和左侧豆状核ReHo值降低;在左右额上回、左右额中回、左侧额内侧回、右侧中央后回、左侧缘上回、左右顶下小叶、左侧梭状回和左侧尾状核ReHo值升高。结论:遭受多重侵害但无创伤后应激症状的高职高专女生在静息状态下脑默认网络以及岛叶、基底神经节、海马旁回存在局部一致性信号异常,这些脑区异常可能为遭受多重侵害导致精神障碍的发病机制提供重要线索。     

Cortical and cerebellar modulation of autonomic responses to loud sounds

Detecting unexpected environmental change causes modulation of autonomic activity essential for survival. Understanding the neural mechanisms associated with responses to loud sounds may provide insights into the pathophysiology of posttraumatic stress disorder (PTSD), since individuals with PTSD exhibit heightened autonomic responses to unexpected loud sounds. We combined fMRI with autonomic psychophysiological assessment to investigate central and peripheral reactivity to loud tones in 20 healthy participants. Activity in anterior insula, pregenual anterior cingulate cortex, anterior midcingulate cortex, supplementary motor area, supramarginal gyrus, and cerebellar lobules VIII–IX was associated with both tones and concomitant skin conductance responses. Since regions signaling unexpected external events modulate autonomic activity, heightened loud tone autonomic responses in PTSD may reflect sensitization of this “salience” network.     

静息态脑功能技术对平衡针治疗中枢机制的分析应用

背景：平衡针治疗疾病疗效显著,但缺乏相关现代科学理论机制。 目的：利用静息态脑功能成像技术探讨平衡针疗法的中枢作用机制。 方法：纳入10例腰椎间盘突出腰腿痛患者及10例正常受试者,于平衡针针刺前后进行功能磁共振扫描,通过AFNI软件对与双侧杏仁核表现为显著联系的脑区进行功能连接分析,并对平衡针刺后腰椎间盘突出患者及正常受试者的脑功能连接的差异进行探讨。 结果与结论：经平衡针治疗后10例腰椎间盘突出患者疼痛均有好转。脑功能连接分析显示腰椎间盘突出患者丘脑、脑干、腹前核、腹外侧核、额内侧回、额上回、额叶眶上回、额下回、颞上回、颞中回、海马回、扣带回、岛叶等脑区功能连接增强。正常受试者双侧颞中回、双侧眶上回、双侧尾状核头、双侧岛叶、左侧腹背侧核、双侧额上回、左侧额中回、前扣带回、右侧顶下小叶与杏仁核连接增强;双侧小脑齿状核、小脑蚓、左侧小脑坡、双侧舌回、左侧枕中回、右侧额上回、右侧中央前回、双侧顶下小叶、右侧顶上小叶、右侧中央后回与杏仁核连接下降。提示通过静息脑功能成像技术对杏仁核的研究有助于更深入理解平衡针灸治疗腰腿痛的中枢机制。     

Interoceptive awareness changes the posterior insula functional connectivity profile

Interoceptive awareness describes the ability to consciously perceive inner bodily signals, such as one’s own heartbeat. The right anterior insula is assumed to mediate this ability. The role of the posterior insula, particularly posterior-to-anterior insula signal flows is less clear in this respect. We scanned 27 healthy people with either high or low interoceptive awareness using 3T fMRI, while they either monitored their own heartbeats, or external tones, respectively. We used a combination of network centrality and bivariate connectivity analyses to characterize changes in cortical signal flows between the posterior insula and the anterior insula during interoceptive awareness or exteroceptive awareness, respectively. We show that heartbeat monitoring was accompanied by reduced network centrality of the right posterior insula, and decreased functional connectivity strengths between the right posterior insula and the right mid and anterior insula. In addition, decreased signal flows between the right posterior insula and the bilateral anterior cingulate cortices, and the bilateral orbitofrontal cortices were observed during interoceptive awareness. Functional connectivity changes were only shown by people with high interoceptive awareness, and occurred specifically within the low-frequency range (i.e., <0.1 Hz). Both groups did not differ in their functional connectivity profiles during rest. Our results show for the first time that interoceptive awareness changes intra-insula signal flows in the low-frequency range. We speculate that the selective inhibition of slow signal progression along the posterior-to-anterior insula pathway during interoceptive awareness allows the salient and noiseless detection of one’s own heartbeat.     

Neural systems supporting interoceptive awareness

Influential theories of human emotion argue that subjective feeling states involve representation of bodily responses elicited by emotional events. Within this framework, individual differences in intensity of emotional experience reflect variation in sensitivity to internal bodily responses. We measured regional brain activity by functional magnetic resonance imaging (fMRI) during an interoceptive task wherein subjects judged the timing of their own heartbeats. We observed enhanced activity in insula, somatomotor and cingulate cortices. In right anterior insular/opercular cortex, neural activity predicted subjects' accuracy in the heartbeat detection task. Furthermore, local gray matter volume in the same region correlated with both interoceptive accuracy and subjective ratings of visceral awareness. Indices of negative emotional experience correlated with interoceptive accuracy across subjects. These findings indicate that right anterior insula supports a representation of visceral responses accessible to awareness, providing a substrate for subjective feeling states.     

青少年肌阵挛癫痫患者的大尺度脑网络研究

采用静息态功能性磁共振成像(rs-fMRI)数据探究青少年肌阵挛癫痫(JME)患者大尺度脑网络的变化。采集17例JME患者和15名正常志愿者的脑部静息态功能磁共振成像数据,两组均使用偏相关系数构建静息态脑网络。分别计算JME患者组与正常对照组的阈值,构建二值化脑网络。计算两组被试各个脑区的介数值,采用双样本t检验对比两组脑网络介数值的差异(Bonferroni 校正,P<0.01),找出介数值发生显著变化脑区。结果表明,偏相关系数构造的脑网络具有小世界属性。JME患者组脑网络中脑区的介数值相比正常对照组有显著性差异。与正常对照组相比,JME患者组介数值显著降低的脑区有2个,介数值显著升高的脑区有17个。其中属于默认模式网络(DMN)的脑区有8个,属于突显网络(SN)的脑区有5个。JME患者组介数值显著降低的脑区有右侧中央旁小叶和右侧后扣带回,介数值显著增高脑区主要是右侧背外侧额上回、左侧枕中回、右侧楔前叶和右侧舌回等。JME患者介数值发生显著改变的脑区主要属于默认模式网络和突显网络。可以推断出默认模式网络和突显网络内部脑区间连接发生改变,信息传递产生变化。由此可能会导致JME患者大脑功能发生改变,造成患者的认知能力与执行能力等功能受损。     

Excitotoxicity by kainate-induced seizure causes diacylglycerol kinase ζ to shuttle from the nucleus to the cytoplasm in hippocampal neurons

Little is known about how spontaneous brain activity during the resting state may be altered in posttraumatic stress disorder (PTSD) compared to traumatized individuals. In the current study, we used a measure of amplitude of low-frequency (0.01-0.08 Hz) fluctuation (ALFF) to investigate the regional baseline brain function of this disorder. Fifty-four medication-naive PTSD patients and seventy-two matched traumatized comparison subjects who experienced the Sichuan major earthquake participated in a functional magnetic resonance imaging (fMRI) scan. We analyzed the difference between the PTSD and comparison groups during a resting state using ALFF. PTSD patients showed decreased ALFF values in right lingual gyrus, cuneus, middle occipital gyrus, insula, and cerebellum, and increased ALFF values in right medial and middle frontal gyri, relative to traumatized individuals without PTSD. The ALFF value in the right medial frontal gyrus was positively correlated with severity of the disorder. Our findings show that abnormality of intrinsic brain activity exists under resting conditions in PTSD patients exposed to a major earthquake. Altered ALFF in predominantly right hemisphere cortical and subcortical regions and in cerebellum potentially contribute to the neural mechanisms underlying traumatic memory and symptoms in PTSD.     

基于低频振幅的吸烟成瘾者戒烟2周后脑功能活动变化的研究

探讨吸烟成瘾者戒烟前后的脑功能活动差异,使用3.0T磁共振扫描仪采集14名吸烟成瘾者戒烟前和戒烟后的静息态MRI数据,采用低频振幅(amplitude of low-frequency fluctuation, ALFF)的方法来比较分析吸烟成瘾者在戒烟前和戒烟两周后的脑功能活动情况.与戒烟前相比,吸烟成瘾者戒烟两周后静息状态下的右侧楔前叶、右侧后扣带回、左侧缘上回、左侧背外侧额上回和左侧额中回的ALFF活动降低;双侧距状裂周围皮层、双侧楔叶、左侧中央后回和左侧中央旁小叶的ALFF活动增加.研究结果表明:吸烟成瘾者在戒烟两周后额叶、边缘叶、顶叶和枕叶脑区的脑功能活动发生了改变,提示ALFF可作为监测或评价戒烟效果的潜在生理指标.     

The neural correlates of reward-related processing in major depressive disorder: A meta-analysis of functional magnetic resonance imaging studies

Background

A growing number of functional magnetic resonance imaging (fMRI) studies have been conducted in major depressive disorder (MDD) to elucidate reward-related brain functions. The aim of this meta-analysis was to examine the common reward network in the MDD brain and to further distinguish the brain activation patterns between positive stimuli and monetary rewards as well as reward anticipation and outcome.

Methods

A series of activation likelihood estimation (ALE) meta-analyses were performed across 22 fMRI studies that examined reward-related processing, with a total of 341 MDD patients and 367 healthy controls.

Results

We observed several frontostriatal regions that participated in reward processing in MDD. The common reward network in MDD was characterized by decreased subcortical and limbic areas activity and an increased cortical response. In addition, the cerebellum, lingual gyrus, parahippocampal gyrus and fusiform gyrus preferentially responded to positive stimuli in MDD, while the insula, precuneus, cuneus, PFC and inferior parietal lobule selectively responded to monetary rewards. Our results indicated a reduced caudate response during both monetary anticipation and outcome stages as well as increased activation in the middle frontal gyrus and dorsal anterior cingulate during reward anticipation in MDD.

Limitations

The reward-related tasks and mood states of patients included in our analysis were heterogeneous.

Conclusions

Our current findings suggest that there exist emotional or motivational pathway dysfunctions in MDD during reward-related processing. Future studies may be strengthened by paying careful attention to the types of reward used as well as the different components of reward processing examined.     

Attention to movement modulates activity in sensori-motor areas,including primary motor cortex

Attention to sensory stimulation modulates behavioural responses and cortical activity. Attention to movement can also modulate motor responses. For example, directing attention away from cued movements can increase reaction times. This study used fMRI to determine where in the motor cortex attention to movement modulates activity. Attention to movement was reduced by asking subjects to perform a concurrent distractor task (counting backwards). Sensori-motor areas showing a negative interaction between counting and movement (i.e. reduced activation in the dual task condition relative to the sum of the single task conditions) included the supplementary motor area (SMA), cingulate cortex, insula and post-central gyrus. A separate volumes-of-interest analysis revealed significant reductions in mean percent signal change in the dual task compared to the single task in a portion of the pre-central gyrus, deep in the central sulcus (thought to correspond to area 4p) and SMA. We conclude that the brain network for motor control is modulated by attention at multiple sites, including the primary motor cortex. These results are also discussed with reference to theories concerning the neural correlates of dual task performance and mental calculation and have implications for the interpretation of functional imaging studies of normal and impaired motor performance.     

Convergence of fMRI and ERP measures of emotional face processing in combat‐exposed U. S. military veterans

The late positive potential (LPP) and fMRI blood‐oxygen‐level dependent (BOLD) activity can provide complementary measures of the processing of affective and social stimuli. Separate lines of research using these measures have often employed the same stimuli, paradigms, and samples; however, there remains relatively little understanding of the way in which individual differences in one of these measures relates to the other, and all prior research has been conducted in psychiatrically healthy samples and using emotional scenes (not faces). Here, 32 combat‐exposed U. S. military veterans with varying levels of posttraumatic stress symptomatology viewed affective social stimuli (angry, fearful, and happy faces) and geometric shapes during separate EEG and fMRI BOLD recordings. Temporospatial principal component analysis was used to quantify the face‐elicited LPP in a data‐driven manner, prior to conducting whole‐brain correlations between resulting positivities and fMRI BOLD elicited by faces. Participants with larger positivities to fearful faces (> shapes) showed increased activation in the amygdala; larger positivities to angry and happy faces (> shapes) were associated with increased BOLD activation in the posterior fusiform gyrus and inferior temporal gyrus, respectively. Across all face types, larger positivities were associated with increased activation in the fusiform “face” area. Correlations using mean area amplitude LPPs showed an association with increased activation in the anterior insula for angry faces (> shapes). LPP‐BOLD associations were not moderated by PTSD. Findings provide the first evidence of correspondence between face‐elicited LPP and BOLD activation across a range of (normal to disordered) psychiatric health.     

Basal ganglia circuits changes in Parkinson's disease patients

Functional changes in basal ganglia circuitry are responsible for the major clinical features of Parkinson's disease (PD). Current models of basal ganglia circuitry can only partially explain the cardinal symptoms in PD. We used functional MRI to investigate the causal connectivity of basal ganglia networks from the substantia nigra pars compacta (SNc) in PD in the movement and resting state. In controls, SNc activity predicted increased activity in the supplementary motor area, the default mode network, and dorsolateral prefrontal cortex, but, in patients, activity predicted decreases in the same structures. The SNc had decreased connectivity with the striatum, globus pallidus, subthalamic nucleus, thalamus, supplementary motor area, dorsolateral prefrontal cortex, insula, default mode network, temporal lobe, cerebellum, and pons in patients compared to controls. Levodopa administration partially normalized the pattern of connectivity. Our findings show how the dopaminergic system exerts influences on widespread brain networks, including motor and cognitive networks. The pattern of basal ganglia network connectivity is abnormal in PD secondary to dopamine depletion, and is more deviant in more severe disease. Use of functional MRI with network analysis appears to be a useful method to demonstrate basal ganglia pathways in vivo in human subjects.     

The role of fearful beliefs in the relationship between situational self‐awareness and report of breathing‐related sensations

Background and aims. Gating models of sensory perception suggest that increased attention towards the self leads to more on‐line processing of sensory information and less report bias. However, little is known about the interaction of self‐awareness with fearful beliefs about bodily sensations. In the present study, we explored report bias of breathing‐related sensation under increased self‐awareness compared to increased focus on external cues related to breathlessness. We expected report bias under internal focus to be lower than under external focus. However, we expected this effect of internal focus to be moderated by fearful beliefs about bodily sensations. Methods. Thirty participants completed two appointments in which attention was directed either towards the self or towards the surroundings. On both sessions, participants' detection threshold for inspiratory loads, negative mood, and fear of bodily sensations was assessed. Changes in threshold were tested using repeated measures ANOVA. The role of fear of bodily sensations was tested in a within‐subject moderation analysis. Results and conclusion. Relative over report of sensations was lower under internal focus compared to external focus. However, this effect was moderated by fear of bodily sensations: the greater fear of bodily sensations was, the lower the effect of self‐awareness. Results encourage research on the interaction of self‐awareness and fearful beliefs in the top‐down modulation of perception.     

Motor and non-motor error and the influence of error magnitude on brain activity

It has been shown that frontal cortical areas increase their activity during error perception and error processing. However, it is not yet clear whether perception of motor errors is processed in the same frontal areas as perception of errors in cognitive tasks. It is also unclear whether brain activity level is influenced by the magnitude of error. For this purpose, we conducted a study in which subjects were confronted with motor and non-motor errors, and had them perform a sensorimotor transformation task in which they were likely to commit motor errors of different magnitudes (internal errors). In addition to the internally committed motor errors, non-motor errors (external errors) were added to the feedback in some trials. We found that activity in the anterior insula, inferior frontal gyrus (IFG), cerebellum, precuneus, and posterior medial frontal cortex (pMFC) correlated positively with the magnitude of external errors. The middle frontal gyrus (MFG) and the pMFC cortex correlated positively with the magnitude of the total error fed back to subjects (internal plus external). No significant positive correlation between internal error and brain activity could be detected. These results indicate that motor errors have a differential effect on brain activity compared with non-motor errors.     

Linking visual gamma to task‐related brain networks—a simultaneous EEG‐fMRI study

There is a growing interest in human gamma‐band oscillatory activity due to its direct link to neuronal populations, its associations with many cognitive processes, and its positive relationship with fMRI BOLD signal. Visual gamma has been successfully detected using concurrent EEG‐fMRI recordings and linked to activity in the visual cortex using voxel‐wise regression analysis. As gamma‐band oscillations reflect predominantly feedforward projections between brain regions, its inclusion in functional connectivity analysis is highly recommended; however, very few studies have investigated this line of research. In the current study, we aimed to explore this gap by asking which fMRI brain network is related to gamma activity induced by the color discrimination task. Advanced denoising strategies and multitaper spectral decomposition were applied to EEG data to detect gamma oscillations, and group independent component analysis was performed on fMRI data to identify task‐related neural networks. Despite using only trials without motor response (50% of the trials), the two neural measures were successfully coupled. One of the six task‐related networks, the occipito‐parietal network, exhibited significant trial‐by‐trial covariations with gamma oscillations. In addition to the expected extrastriate visual cortex, the network encompasses extensive brain activations in the precuneus, bilateral intraparietal, and anterior insular cortices. We argue that the visual cortex is the source of gamma, whereas the remaining brain regions exhibit feedforward and feedback connections related to this oscillatory activity. Our findings provide evidence for the electrophysiological basis of the connectivity revealed by BOLD signal and impart novel insights into the neural mechanism of color discrimination.     

A multimodal cortical network for the detection of changes in the sensory environment

Sensory stimuli undergoing sudden changes draw attention and preferentially enter our awareness. We used event-related functional magnetic-resonance imaging (fMRI) to identify brain regions responsive to changes in visual, auditory and tactile stimuli. Unimodally responsive areas included visual, auditory and somatosensory association cortex. Multimodally responsive areas comprised a right-lateralized network including the temporoparietal junction, inferior frontal gyrus, insula and left cingulate and supplementary motor areas. These results reveal a distributed, multimodal network for involuntary attention to events in the sensory environment. This network contains areas thought to underlie the P300 event-related potential and closely corresponds to the set of cortical regions damaged in patients with hemineglect syndromes.     

Visually cued motor synchronization: modulation of fMRI activation patterns by baseline condition

A well-known issue in functional neuroimaging studies, regarding motor synchronization, is to design suitable control tasks able to discriminate between the brain structures involved in primary time-keeper functions and those related to other processes such as attentional effort. The aim of this work was to investigate how the predictability of stimulus onsets in the baseline condition modulates the activity in brain structures related to processes involved in time-keeper functions during the performance of a visually cued motor synchronization task (VM). The rational behind this choice derives from the notion that using different stimulus predictability can vary the subject's attention and the consequently neural activity. For this purpose, baseline levels of BOLD activity were obtained from 12 subjects during a conventional-baseline condition: maintained fixation of the visual rhythmic stimuli presented in the VM task, and a random-baseline condition: maintained fixation of visual stimuli occurring randomly. fMRI analysis demonstrated that while brain areas with a documented role in basic time processing are detected independent of the baseline condition (right cerebellum, bilateral putamen, left thalamus, left superior temporal gyrus, left sensorimotor cortex, left dorsal premotor cortex and supplementary motor area), the ventral premotor cortex, caudate nucleus, insula and inferior frontal gyrus exhibited a baseline-dependent activation. We conclude that maintained fixation of unpredictable visual stimuli can be employed in order to reduce or eliminate neural activity related to attentional components present in the synchronization task.