Change detection in children with autism: an auditory event-related fMRI study

Autism involves impairments in communication and social interaction, as well as high levels of repetitive, stereotypic, and ritualistic behaviours, and extreme resistance to change. This latter dimension, whilst required for a diagnosis, has received less research attention. We hypothesise that this extreme resistance to change in autism is rooted in atypical processing of unexpected stimuli. We tested this using auditory event-related fMRI to determine regional brain activity associated with passive detection of infrequently occurring frequency-deviant and complex novel sounds in a no-task condition. Participants were twelve 10- to 15-year-old children with autism and a group of 12 age- and sex-matched healthy controls. During deviance detection, significant activation common to both groups was located in the superior temporal and inferior frontal gyri. During 'novelty detection', both groups showed activity in the superior temporal gyrus, the temporo-parietal junction, the superior and inferior frontal gyri, and the cingulate gyrus. Children with autism showed reduced activation of the left anterior cingulate cortex during both deviance and novelty detection. During novelty detection, children with autism also showed reduced activation in the bilateral temporo-parietal region and in the right inferior and middle frontal areas. This study confirms previous evidence from ERP studies of atypical brain function related to automatic change detection in autism. Abnormalities involved a cortical network known to have a role in attention switching and attentional resource distribution. These results throw light on the neurophysiological processes underlying autistic 'resistance to change'.     

Differential cortical activation during voluntary and reflexive saccades in man

A saccade involves both a step in eye position and an obligatory shift in spatial attention. The traditional division of saccades into two types, the "reflexive" saccade made in response to an exogenous stimulus change in the visual periphery and the "voluntary" saccade based on an endogenous judgement to move gaze, is supported by lines of evidence which include the longer onset latency of the latter and the differential effects of lesions in humans and primates on each. It has been supposed that differences between the two types of saccade derive from differences in how the spatial attention shifts involved in each are processed. However, while functional imaging studies have affirmed the close link between saccades and attentional shifts by showing they activate overlapping cortical networks, attempts to contrast exogenous with endogenous ("covert") attentional shifts directly have not revealed separate patterns of cortical activation. We took the "overt" approach, contrasting whole reflexive and voluntary saccades using event-related fMRI. This demonstrated that, relative to reflexive saccades, voluntary saccades produced greater activation within the frontal eye fields and the saccade-related area of the intraparietal sulci. The reverse contrast showed reflexive saccades to be associated with relative activation of the angular gyrus of the inferior parietal lobule, strongest in the right hemisphere. The frequent involvement of the right inferior parietal lobule in lesions causing hemispatial neglect has long implicated this parietal region in an important, though as yet uncertain, role in the awareness and exploration of space. This is the first study to demonstrate preferential activation of an area in its posterior part, the right angular gyrus, during production of exogenously triggered rather than endogenously generated saccades, a finding which we propose is consistent with an important role for the angular gyrus in exogenous saccadic orienting.     

Cortical mechanisms of person representation: recognition of famous and personally familiar names

Personally familiar people are likely to be represented more richly in episodic, emotional, and behavioral contexts than famous people, who are usually represented predominantly in semantic context. To reveal cortical mechanisms supporting this differential person representation, we compared cortical activation during name recognition tasks between personally familiar and famous names, using an event-related functional magnetic resonance imaging (fMRI). Normal subjects performed familiar- or unfamiliar-name detection tasks during visual presentation of personally familiar (Personal), famous (Famous), and unfamiliar (Unfamiliar) names. The bilateral temporal poles and anterolateral temporal cortices, as well as the left temporoparietal junction, were activated in the contrasts Personal-Unfamiliar and Famous-Unfamiliar to a similar extent. The bilateral occipitotemporoparietal junctions, precuneus, and posterior cingulate cortex showed activation in the contrasts Personal-Unfamiliar and Personal-Famous. Together with previous findings, differential activation in the occipitotemporoparietal junction, precuneus, and posterior cingulate cortex between personally familiar and famous names is considered to reflect differential person representation. The similar extent of activation for personally familiar and famous names in the temporal pole and anterolateral temporal cortex is consistent with the associative role of the anterior temporal cortex in person identification, which has been conceptualized as a person identity node in many models of person identification. The left temporoparietal junction was considered to process familiar written names. The results illustrated the neural correlates of the person representation as a network of discrete regions in the bilateral posterior cortices, with the anterior temporal cortices having a unique associative role.     

Neuroanatomical dissociation between bottom-up and top-down processes of visuospatial selective attention

Allocation of attentional resources to portions of the available sensory input can be regulated by bottom-up processes, i.e., spontaneous orientation towards an oncoming stimulus (stimulus-driven attention), and by top-down processes, i.e., intentionally and driven by knowledge, expectation and goals. The present study aimed at advancing the understanding of brain networks mediating bottom-up and top-down control of visuospatial attention by employing a paradigm that parametrically varied demands on these two processes. Spatial predictability of peripheral targets was parametrically varied by centrally cueing one, two, three or four of four possible locations. Reaction time decreased linearly with more precise valid cueing of the target location and increased with more precise invalid cueing. Event-related functional magnetic resonance imaging (fMRI) enabled measurement of blood oxygenation level-dependent (BOLD) responses to cues and to targets. A mostly left-hemispheric network consisting of left intraparietal sulcus, inferior and superior parietal lobule, bilateral precuneus, middle frontal gyri including superior frontal sulci, and middle occipital gyri displayed BOLD responses to cues that increased linearly with more precise spatial cueing, indicating engagement by top-down spatial selective attention. In contrast, bilateral temporoparietal junction, cingulate gyrus, right precentral gyrus and anterior and posterior insula, bilateral fusiform gyri, lingual gyri and cuneus displayed BOLD responses to targets that increased with their spatial unpredictability, indicating engagement by stimulus-driven orienting. The results suggest two largely dissociated neural networks mediating top-down and bottom-up control of visuospatial selective attention.     

The effect of appraisal level on processing of emotional prosody in meaningless speech

In visual perception of emotional stimuli, low- and high-level appraisal processes have been found to engage different neural structures. Beyond emotional facial expression, emotional prosody is an important auditory cue for social interaction. Neuroimaging studies have proposed a network for emotional prosody processing that involves a right temporal input region and explicit evaluation in bilateral prefrontal areas. However, the comparison of different appraisal levels has so far relied upon using linguistic instructions during low-level processing, which might confound effects of processing level and linguistic task. In order to circumvent this problem, we examined processing of emotional prosody in meaningless speech during gender labelling (implicit, low-level appraisal) and emotion labelling (explicit, high-level appraisal). While bilateral amygdala, left superior temporal sulcus and right parietal areas showed stronger blood oxygen level-dependent (BOLD) responses during implicit processing, areas with stronger BOLD responses during explicit processing included the left inferior frontal gyrus, bilateral parietal, anterior cingulate and supplemental motor cortex. Emotional versus neutral prosody evoked BOLD responses in right superior temporal gyrus, bilateral anterior cingulate, left inferior frontal gyrus, insula and bilateral putamen. Basal ganglia and right anterior cingulate responses to emotional versus neutral prosody were particularly pronounced during explicit processing. These results are in line with an amygdala-prefrontal-cingulate network controlling different appraisal levels, and suggest a specific role of the left inferior frontal gyrus in explicit evaluation of emotional prosody. In addition to brain areas commonly related to prosody processing, our results suggest specific functions of anterior cingulate and basal ganglia in detecting emotional prosody, particularly when explicit identification is necessary.     

Endogenous and exogenous attention shifts are mediated by the same large-scale neural network

Event-related fMRI was used to examine the neural basis of endogenous (top-down) and exogenous (bottom-up) spatial orienting. Shifts of attention were induced by central (endogenous) or peripheral (exogenous) cues. Reaction times on subsequently presented targets showed the expected pattern of facilitation and inhibition in both conditions. No difference in brain activity was observed when the two orienting conditions were contrasted with a liberal threshold, showing that both forms of orienting were mediated by the same neural network. Compared to within-block control trials, both endogenous and exogenous orienting activated a fronto-parietal network consisting of premotor cortex, posterior parietal cortex, medial frontal cortex and right inferior frontal cortex. Within these regions, equally strong activation was observed for both orienting conditions. It is concluded that endogenous and exogenous orienting are mediated by the same large-scale network of frontal and parietal brain areas.     

The large-scale neural network for spatial attention displays multifunctional overlap but differential asymmetry

Functional magnetic resonance imaging (fMRI) was used to determine the brain regions activated by two types of covert visuospatial attentional shifts: one based on exogenous spatial priming and the other on foveally presented cues which endogenously regulated the direction of spatial expectancy. Activations were seen in the cortical and subcortical components of a previously characterized attentional network, namely, the frontal eye fields, posterior parietal cortex, the cingulate gyrus, the putamen, and the thalamus. Additional activations occurred in the anterior insula, dorsolateral prefrontal cortex, temporo-occipital cortex in the middle and inferior temporal gyri, the supplementary motor area, and the cerebellum. Direct comparisons showed a nearly complete overlap in the location of activations resulting from the two tasks. However, the spatial priming task displayed a more pronounced rightward asymmetry of parietal activation, and a conjunction analysis showed that the area of posterior parietal cortex jointly activated by both tasks was more extensive in the right hemisphere. Furthermore, the posterior parietal and temporo-occipital activations were more pronounced in the task of endogenous attentional shifts. The results show that both exogenous (based on spatial priming) and endogenous (based on expectancy cueing) shifts of attention are subserved by a common network of cortical and subcortical regions. However, the differences between the two tasks, especially in the degree of rightward asymmetry, suggests that the pattern of activation within this network may show variations that reflect the specific attributes of the attentional task.     

Attentional systems in target and distractor processing: a combined ERP and fMRI study

The interplay of "top-down" and "bottom-up" regulated mechanisms is of particular relevance for the rapid (re-)focusing of attention to environmental changes. The purpose of the study was to explore the differential contributions of frontoparietal attentional networks involved in top-down and stimulus-driven processing to the detection of "target" and "distractor" events in a visual three-stimulus oddball paradigm. Thirteen healthy subjects underwent separate event-related potential (ERP) and whole-brain functional magnetic resonance imaging (fMRI) measurements during the oddball task. The targets, which were difficult to detect, elicited a classical posterior P3b whereas the distractor stimuli were followed by a centro-frontal P3a ERP. The fMRI data showed activation of the temporoparietal junction (TPJ) bilaterally and right prefrontal cortex associated with both the target and distractor conditions. This network has previously been described as an attentional system that is predominantly stimulus driven and that responds to rare events. Furthermore, target processing produced bilateral perisylvian activity, which has been related to the "retrieval mode". Processing of the distractors activated the frontal eye fields (FEFs) and bilateral superior parietal cortex, areas engaged in attention switching and voluntary allocation of attention. Additional left prefrontal activation suggested an involvement of the cortical system for working memory encoding. Our results thus demonstrate that distractor and target processing engage a common neuronal system for the detection of rare events, but also task-specific subsystems related to attention and memory processes.     

The neural networks underlying endogenous auditory covert orienting and reorienting

Auditory information communicated through vocalizations, music, or sounds in the environment is commonly used to orient and direct attention to different locations in extrapersonal space. The neural networks subserving attention to auditory space remain poorly understood in comparison to our knowledge about attention in the visual system. The present study investigated whether a parietal-prefrontal right-hemisphere network controls endogenous orienting and reorienting of attention to the location of sounds just as it does for visual-spatial information. Seventeen healthy adults underwent event-related functional magnetic resonance imaging (FMRI) while performing an endogenous auditory orienting task, in which peripheral cues correctly (valid) or incorrectly (invalid) specified the location of a forthcoming sound. The results showed that a right precuneus and bilateral temporal-frontal network mediated the reorienting of auditory attention at both short and long stimulus onset asynchronies (SOAs). In contrast, the more automatic stage of auditory reorienting at the shorter SOA was associated with activation in a bilateral inferior parietal-frontal oculomotor network. These findings suggest that the reorienting of auditory attention is generally supported by a similar inferior parietal-frontal network as visual attention, but in both hemispheres. However, peripheral auditory cues also appear to elicit an automatic orienting response to the spatial location of a sound followed by a period of reduced processing of information that occurs in the same location later in time.     

儿童阻塞性睡眠呼吸暂停低通气综合征脑皮质厚度改变MRI研究

目的:利用皮质厚度分析技术探讨阻塞性睡眠呼吸暂停低通气综合征儿童脑皮质厚度异常.方法:收集OSAHS患儿16例,以及与OSAHS组年龄、性别相匹配的正常对照者13例,所有受试者进行头颅的3D T1 MRI扫描,采集数据通过FreeSurfer软件进行分割重建,并计算获得所有受试者各脑区的皮质厚度,以独立样本t检验进行病...     

电针周围性面瘫患者穴位的功能磁共振成像研究

目的 探讨功能磁共振成像(fMRI)研究电针周围性面瘫患者不同穴位时脑功能区变化.方法 将18例左侧周围性面瘫患者随机分为3组,分别电针左侧地仓穴(6例)、左侧合谷穴(6例)、左侧后溪穴(6例),同时行全脑fMRI 扫描.以SPM 软件进行图像后处理,t检验(P<0.05)分析得出电针不同穴位的脑功能图像. 结果电针左侧地仓穴、左侧合谷穴信号降低区:双侧额中回,左扣带回;信号升高区:右侧中央前回,双侧中央后回,左侧颞上回,右侧脑岛.电针左侧后溪信号降低区:双侧额下回,左侧豆状核,右侧颞中回,右侧小脑扁桃体;信号升高区:右侧尾状核头,右侧扣带回,脑干,小脑蚓,右侧海马回. 结论 电针周围性面瘫患者合谷穴和地仓穴可引起大脑相应的功能区激活,而电针后溪穴未见和前两者有相似的激活区域,推测穴位与大脑的联系与其所属的经脉有密切联系.     

弱视儿童的MRI全脑皮层厚度分析

目的 利用皮层厚度分析技术探讨弱视患儿脑灰质发育的异常.方法 对11例弱视患儿和10名视力正常儿童行3D T1WI扫描,数据应用Freesurfer软件进行后处理,以双样本独立t检验进行病例组和对照组的全脑皮层厚度比较,将具有统计学意义(P<0.05)的像素在标准脑模板上生成伪彩图.选取像素阈值为500个相邻像素,分析弱视患者皮层厚度改变的区域.结果 弱视组在双侧中央前回、左侧距状回前部、左侧颞上回和右侧额中回、额上回皮层厚度大于对照组;而在双侧舌回、枕颞外侧回、顶上小叶的区域,对照组皮层厚度大于弱视组.结论 皮层厚度分析研究能够发现弱视患儿与视觉相关的大脑区域的灰质皮层发育异常,从而为探讨弱视相关的神经结构发育异常提供有用信息.     

Dynamic interactions in the fronto-parietal network during a manual stimulus-response compatibility task

Attentional orienting can be modulated by stimulus-driven bottom-up as well as task-dependent top-down processes. In a recent study we investigated the interaction of both processes in a manual stimulus-response compatibility task. Whereas the intraparietal sulcus (IPS) and the dorsal premotor cortex (dPMC) were involved in orienting towards the stimulus side facilitating congruent motor responses, the right temporoparietal junction (TPJ), right dorsolateral prefrontal cortex (DLPFC) as well as the preSMA sustained top-down control processes involved in voluntary reorienting. Here we used dynamic causal modelling to investigate the contributions and task-dependent interactions between these regions. Thirty-six models were tested, all of which included bilateral IPS, dPMC and primary motor cortex (M1) as a network transforming visual input into motor output as well as the right TPJ, right DLPFC and the preSMA as task-dependent top-down regions influencing the coupling within the dorsal network. Our data showed the right temporoparietal junction to play a mediating role during attentional reorienting processes by modulating the inter-hemispheric balance between both IPS. Analysis of connection strength supported the proposed role of the preSMA in controlling motor responses promoting or suppressing activity in primary motor cortex. As the results did not show a clear tendency towards a role of the right DLPFC, we propose this region, against the usual interpretation of an inhibitory influence in stimulus-response compatibility tasks, to subserve generic monitoring processes. Our DCM study hence provides evidence for context-dependent top-down control of right TPJ and DLPFC as well as the preSMA in stimulus-response compatibility.     

Genetic variation in nicotinic receptors affects brain networks involved in reorienting attention

Prior evidence suggests that a genetic variation in nicotinic receptors modulates visuospatial attention in humans. Brain areas contributing to this modulation are largely unknown. Here we investigate the influence of the nicotinic receptor gene CHRNA4 (rs 1044396) on brain networks involved in detecting unattended events. Subjects were genotyped and studied with functional magnetic resonance imaging while performing a cued target detection task with valid, neutral and invalid trials. Two brain areas within a core region of the attention network, the right temporoparietal junction, showed a genotype dependent modulation. CHRNA4 C/C homozygotes showed differentially higher neural activity in the right middle temporal gyrus when reorienting attention was required in invalid trials. In contrast, T/T homozygotes had stronger activations within the right superior temporal gyrus. An analysis of functional connectivity further revealed that these temporoparietal regions have a distinct connectivity pattern. The superior temporal gyrus recruited by T/T homozygotes shows stronger connections to temporal and parietal brain regions, which are primarily involved in shifting attention, independent of stimulus frequency. In contrast, the middle temporal gyrus exhibits stronger connections to the caudate nucleus, which is involved in detecting violations of expectations. These findings suggest that, depending on genotype, detection of stimuli outside the focus of attention is more driven by reorienting or by expectation signals.     

低频振幅算法功能磁共振成像观察屈光参差性弱视患者脑活动

目的 应用基于低频振幅(ALFF)算法的功能磁共振成像(fMRI)观察屈光参差性弱视患者脑活动的变化。方法 对9例左眼单眼屈光参差性弱视患者(弱视组)和12名健康志愿者(对照组)在黑白棋盘格刺激下行fMRI,应用t检验对ALFF脑图进行组间和组内统计学分析。结果 1例弱视组患者数据在预处理后被剔除。左眼接受刺激时,弱视组较对照组左侧舌回、右侧枕中回、右侧中央前回、左侧后扣带回、左侧顶上小叶、左侧楔前叶和楔叶等区域ALFF减弱,左侧额中间回、左侧额上回、左侧颞上回、右侧杏仁体和右侧壳核等区域ALFF显著增强;右眼接受刺激时,弱视组较对照组胼胝体和左侧颞中回ALFF减弱,双侧枕叶、右侧额中回和右侧尾状核等区域ALFF显著增强。弱视组中,与右眼接受视觉刺激时比较,左眼接受视觉刺激时右侧额下回、左侧尾状核、丘脑及前扣带回等脑区ALFF显著增强,双侧枕叶ALFF显著减弱。结论 任务状态下基于ALFF算法的fMRI不仅可反映弱视患者视皮层的功能损害,还可反映多脑区神经活动的变化。     

慢性应激与抑郁症患者脑影像学改变及预后的关系

目的  探索慢性应激与抑郁症患者脑影像学改变及预后的关系。方法  选取2019年2月~2021年2月120例抑郁症患者,采用生活事件量表（LES）评估患者慢性应激状态,根据评分结果分为慢性应激组（n=78）和非慢性应激组（n=42）,另选取同期30例健康志愿者作为对照组。受试者均行头颅MRI扫描,采集得到的3DT1数据采用FreeSurfer自动化处理,计算并比较全脑脑区皮层厚度,并采用17项汉密尔顿抑郁量表（HAMD-17）评估抑郁症状,分别比较慢性应激组、非慢性应激组、对照组全脑皮层厚度及HAMD-17评分,并采用Pearson相关系数分析LES评分与全脑皮层厚度、HAMD-17评分的相关性;抑郁症患者出院后随访6~12月,比较慢性应激组、非慢性应激组抑郁症发作时间及6月内临床治愈率。结果  对照组、非慢性应激组、慢性应激组左侧额叶三角部、双侧额上回、左侧额缘、双侧楔前叶、双侧颞中回、左侧顶下缘上回、左侧扣带回、右侧额叶岛盖部、右侧额下回及皮层平均厚度均呈下降趋势,组间差异均有统计学意义（P<0.05）,未见皮层厚度增加脑区;对照组、非慢性应激组、慢性应激组HAMD-17评分呈升高趋势,组间差异均有统计学意义（P<0.05）;Pearson相关性分析显示,LES评分与大脑皮层平均厚度呈负相关关系（P<0.05）,与HAMD-17评分呈正相关关系（P<0.05）;慢性应激组6月临床治愈低于非慢性应激组（P<0.05）,抑郁发作时间长于非慢性应激组（P<0.05）。结论  慢性应激可加剧抑郁症患者大脑皮层萎缩,且与患者病情程度及预后密切相关。     

Wernicke-Geschwind语言模型的fMRI初步检验

目的利用fMRI方法检验经典的Wernicke-Geschwind语言模型.方法以Block Design设计模式,对10名正常中国人的听觉性语言(词语水平)功能进行BOLD磁共振脑功能成像,并与经典的Wernicke-Geschwind语言模型进行比较与检验.结果所有受试者均完成了实验要求,且头动范围小于1个像素大小.语言任务激活的脑区包括:双侧颞上回、双侧运动区(前后运动区及辅助运动区)、双侧小脑半球及视皮层,左侧颞横回、左侧角回,右侧颞中回及以及扣带回后部.结论经典的语言模型存在较明显的不足与缺陷,需要进一步完善.     

阅读半规则汉字时的脑激活模式:声调的作用

目的引入声调因素,运用功能磁共振成像技术进一步研究汉字规则性效应的脑激活模式.方法13名被试在磁共振扫描过程中执行视觉方式呈现的汉字出声阅读任务,根据形声字声旁与整字间读音及声调相同与否,将刺激材料细分为同音同调字、同音异调字、异音同调字和异音异调字,每类20字.结果四种条件均激活双侧额中回、额下回、前运动区及辅助运动区、左侧顶下小叶、双侧颞上回、双侧岛叶和右侧小脑,同时还各自激活了梭状回、颞中回、左内侧额叶等区域.另外,本实验还观察到这四种条件在右侧颞上回、双侧额下回等区域激活模式的特征性变化.结论存在汉字加工的半规则效应,声调的作用不应忽略.     

针刺足少阳胆经五输穴脑fMRI研究

目的 采用fMRI观察针刺足少阳胆经五输穴的脑功能区激活情况。方法 选取男性健康青年志愿者12名, 针刺右侧足少阳胆经五输穴, 在静息段与针刺段交替采集fMRI图像, 获得数据通过random effect法对数据行组分析, 以P <0.05的像素构成统计参数图, 即实验任务脑激活区, 按Talairach坐标行解剖定位, 获得试验任务激活的脑区。结果 受试者脑激活区包括左侧眶回(BA11)、双侧顶上小叶(BA7)、右侧颞上回(BA22)。负激活区包括右侧舌回(BA18)、右侧扣带回(BA24)、双侧顶上小叶(BA7)、右侧颞下回(BA20)。结论 针刺足少阳胆经五输穴可影响边缘系统、听觉系统、语言、记忆等。针灸叠加针刺引起对应的脑功能区变化是大脑传导通路重新整合与分配的结果。     

Differentiating maturational and training influences on fMRI activation during music processing

Two major influences on how the brain processes music are maturational development and active musical training. Previous functional neuroimaging studies investigating music processing have typically focused on either categorical differences between "musicians versus nonmusicians" or "children versus adults." In the present study, we explored a cross-sectional data set (n=84) using multiple linear regression to isolate the performance-independent effects of age (5 to 33 years) and cumulative duration of musical training (0 to 21,000 practice hours) on fMRI activation similarities and differences between melodic discrimination (MD) and rhythmic discrimination (RD). Age-related effects common to MD and RD were present in three left hemisphere regions: temporofrontal junction, ventral premotor cortex, and the inferior part of the intraparietal sulcus, regions involved in active attending to auditory rhythms, sensorimotor integration, and working memory transformations of pitch and rhythmic patterns. By contrast, training-related effects common to MD and RD were localized to the posterior portion of the left superior temporal gyrus/planum temporale, an area implicated in spectrotemporal pattern matching and auditory-motor coordinate transformations. A single cluster in right superior temporal gyrus showed significantly greater activation during MD than RD. This is the first fMRI which has distinguished maturational from training effects during music processing.