Effects of feature-selective attention on auditory pattern and location processing

Recent neuroimaging studies have suggested that spatial versus nonspatial changes in acoustic stimulation are processed along separate cortical pathways. However, it has remained unclear in how far change-related responses are modulated by selective attention. Thus, we aimed at testing effects of feature-selective attention on the cortical representation of pattern and location of complex natural sounds using human functional magnetic resonance imaging (fMRI) adaptation. We consecutively presented the following pairs of animal vocalizations: (a) two identical animal vocalizations, (b) same animal vocalizations at different locations, (c) different animal vocalizations at the same location, and (d) different animal vocalizations at different locations. Subjects underwent this stimulation under two different task conditions requiring either to match sound identity or location. We observed significant fMRI adaptation effects within the bilateral superior temporal sulcus (STS), planum temporale (PT) and right anterior insula for location changes. For pattern changes, we found adaptation effects within the bilateral superior temporal lobe, in particular along the superior temporal gyrus (STG), PT and posterior STS, the bilateral anterior insula and inferior frontal areas. While the adaptation effects within the pattern-selective temporal lobe areas were robust to task requirements, adaptation within the more posterior location-selective areas was modulated by feature-specific attention. In contrast, inferior frontal cortex and anterior insular exhibited adaptation effects mainly during the location matching task. Given that the location matching task was significantly more difficult than the pattern matching, our data suggest that frontal and insular regions were modulated by task difficulty rather than feature-specific attention.     

Towards a fronto-temporal neural network for the decoding of angry vocal expressions

Vocal expressions commonly elicit activity in superior temporal and inferior frontal cortices, indicating a distributed network to decode vocally expressed emotions. We examined the involvement of this fronto-temporal network for the decoding of angry voices during attention towards (explicit attention) or away from emotional cues in voices (implicit attention) based on a reanalysis of previous data (Frühholz, S., Ceravolo, L., Grandjean, D., 2012. Cerebral Cortex 22, 1107-1117). The general network revealed high interconnectivity of bilateral inferior frontal gyrus (IFG) to different bilateral voice-sensitive regions in mid and posterior superior temporal gyri. Right superior temporal gyrus (STG) regions showed connectivity to the left primary auditory cortex and secondary auditory cortex (AC) as well as to high-level auditory regions. This general network revealed differences in connectivity depending on the attentional focus. Explicit attention to angry voices revealed a specific right-left STG network connecting higher-level AC. During attention to a nonemotional vocal feature we also found a left-right STG network implicitly elicited by angry voices that also included low-level left AC. Furthermore, only during this implicit processing there was widespread interconnectivity between bilateral IFG and bilateral STG. This indicates that while implicit attention to angry voices recruits extended bilateral STG and IFG networks for the sensory and evaluative decoding of voices, explicit attention to angry voices solely involves a network of bilateral STG regions probably for the integrative recognition of emotional cues from voices.     

Functional segregation of the temporal lobes into highly differentiated subsystems for auditory perception: an auditory rapid event-related fMRI-task

With this study, we explored the blood oxygen level-dependent responses within the temporal lobe to short auditory stimuli of different classes. To address this issue, we performed an attentive listening event-related fMRI study, where subjects were required to concentrate during the presentation of different types of stimuli. Because the order of stimuli was randomized and not predictable for the subject, the observed differences between the stimuli types were interpreted as an automatic effect and were not affected by attention. We used three types of stimuli: tones, sounds of animals and instruments, and words. We found in all cases bilateral activations of the primary and secondary auditory cortex. The strength and lateralization depended on the type of stimulus. The tone trials led to the weakest and smallest activations. The perception of sounds increased the activated network bilaterally into the superior temporal sulcus mainly on the right and the perception of words led to the highest activation within the left superior temporal sulcus as well as in left inferior frontal gyrus. Within the left temporal sulcus, we were able to distinguish between different subsystems, showing an extending activation from posterior to anterior for speech and speechlike information. Whereas posterior parts were involved in analyzing the complex auditory structure of sounds and speech, the middle and anterior parts responded strongest only in the perception of speech. In summary, a functional segregation of the temporal lobes into several subsystems responsible for auditory processing was visible. A lateralization for verbal stimuli to the left and sounds to the right was already detectable when short stimuli were used.     

The Effect of Task Relevance on the Cortical Response to Changes in Visual and Auditory Stimuli: An Event-Related fMRI Study

Attention is, in part, a mechanism for identifying features of the sensory environment of potential relevance to behavior. The network of brain areas sensitive to the behavioral relevance of multimodal sensory events has not been fully characterized. We used event-related fMRI to identify brain regions responsive to changes in both visual and auditory stimuli when those changes were either behaviorally relevant or behaviorally irrelevant. A widespread network of "context-dependent" activations responded to both task-irrelevant and task-relevant events but responded more strongly to task-relevant events. The most extensive activations in this network were located in right and left temporoparietal junction (TPJ), with smaller activations in left precuneus, left anterior insula, left anterior cingulate cortex, and right thalamus. Another network of "context-independent" activations responded similarly to all events, regardless of task relevance. This network featured a large activation encompassing left supplementary and cingulate motor areas (SMA/CMA) as well as right IFG, right/left precuneus, and right anterior insula, with smaller activations in right/left inferior temporal gyrus and left posterior cingulate cortex. Distinct context-dependent and context-independent subregions of activation were also found within the left and right TPJ, left anterior insula, and left SMA/CMA. In the right TPJ, a subregion in the supramarginal gyrus showed sensitivity to the behavioral context (i.e., relevance) of stimulus changes, while two subregions in the superior temporal gyrus did not. The results indicate a role for the TPJ in detecting behaviorally relevant events in the sensory environment. The TPJ may serve to identify salient events in the sensory environment both within and independent of the current behavioral context.     

Incidental effects of emotional valence in single word processing: an fMRI study

The present study aimed at identifying the neural responses associated with the incidental processing of the emotional valence of single words using event-related functional magnetic resonance imaging (fMRI). Twenty right-handed participants performed a visual lexical decision task, discriminating between nouns and orthographically and phonologically legal nonwords. Positive, neutral and negative word categories were matched for frequency, number and frequency of orthographic neighbors, number of letters and imageability. Response times and accuracy data differed significantly between positive and neutral, and positive and negative words respectively, thus, replicating the findings of a pilot study. Words showed distributed, mainly left hemisphere activations, indicating involvement of a neural network responsible for semantic word knowledge. The neuroimaging data further revealed areas in left orbitofrontal gyrus and bilateral inferior frontal gyrus with greater activation to emotional than to neutral words. These brain regions are known to be involved in processing semantic and emotional information. Furthermore, distinct activations associated with positive words were observed in bilateral middle temporal and superior frontal gyrus, known to support semantic retrieval, and a distributed network, namely anterior and posterior cingulate gyrus, lingual gyrus and hippocampus when comparing positive and negative words. The latter areas were previously associated with explicit and not incidental processing of the emotional meaning of words and emotional memory retrieval. Thus, the results are discussed in relation to models of processing semantic and episodic emotional information.     

Shared and distinct neural correlates of singing and speaking

Using a modified sparse temporal sampling fMRI technique, we examined both shared and distinct neural correlates of singing and speaking. In the experimental conditions, 10 right-handed subjects were asked to repeat intoned ("sung") and non-intoned ("spoken") bisyllabic words/phrases that were contrasted with conditions controlling for pitch ("humming") and the basic motor processes associated with vocalization ("vowel production"). Areas of activation common to all tasks included the inferior pre- and post-central gyrus, superior temporal gyrus (STG), and superior temporal sulcus (STS) bilaterally, indicating a large shared network for motor preparation and execution as well as sensory feedback/control for vocal production. The speaking more than vowel-production contrast revealed activation in the inferior frontal gyrus most likely related to motor planning and preparation, in the primary sensorimotor cortex related to motor execution, and the middle and posterior STG/STS related to sensory feedback. The singing more than speaking contrast revealed additional activation in the mid-portions of the STG (more strongly on the right than left) and the most inferior and middle portions of the primary sensorimotor cortex. Our results suggest a bihemispheric network for vocal production regardless of whether the words/phrases were intoned or spoken. Furthermore, singing more than humming ("intoned speaking") showed additional right-lateralized activation of the superior temporal gyrus, inferior central operculum, and inferior frontal gyrus which may offer an explanation for the clinical observation that patients with non-fluent aphasia due to left hemisphere lesions are able to sing the text of a song while they are unable to speak the same words.     

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。     

Syntactic and auditory spatial processing in the human temporal cortex: an MEG study

Processing syntax is believed to be a higher cognitive function involving cortical regions outside sensory cortices. In particular, previous studies revealed that early syntactic processes at around 100-200 ms affect brain activations in anterior regions of the superior temporal gyrus (STG), while independent studies showed that pure auditory perceptual processing is related to sensory cortex activations. However, syntax-related modulations of sensory cortices were reported recently, thereby adding diverging findings to the previous studies. The goal of the present magnetoencephalography study was to localize the cortical regions underlying early syntactic processes and those underlying perceptual processes using a within-subject design. Sentences varying the factors syntax (correct vs. incorrect) and auditory space (standard vs. change of interaural time difference (ITD)) were auditorily presented. Both syntactic and auditory spatial anomalies led to very early activations (40-90 ms) in the STG. Around 135 ms after violation onset, differential effects were observed for syntax and auditory space, with syntactically incorrect sentences leading to activations in the anterior STG, whereas ITD changes elicited activations more posterior in the STG. Furthermore, our observations strongly indicate that the anterior and the posterior STG are activated simultaneously when a double violation is encountered. Thus, the present findings provide evidence of a dissociation of speech-related processes in the anterior STG and the processing of auditory spatial information in the posterior STG, compatible with the view of different processing streams in the temporal cortex.     

Overlapping neural regions for processing rapid temporal cues in speech and nonspeech signals

Speech perception involves recovering the phonetic form of speech from a dynamic auditory signal containing both time-varying and steady-state cues. We examined the roles of inferior frontal and superior temporal cortex in processing these aspects of auditory speech and nonspeech signals. Event-related functional magnetic resonance imaging was used to record activation in superior temporal gyrus (STG) and inferior frontal gyrus (IFG) while participants discriminated pairs of either speech syllables or nonspeech tones. Speech stimuli differed in either the consonant or the vowel portion of the syllable, whereas the nonspeech signals consisted of sinewave tones differing along either a dynamic or a spectral dimension. Analyses failed to identify regions of activation that clearly contrasted the speech and nonspeech conditions. However, we did identify regions in the posterior portion of left and right STG and left IFG yielding greater activation for both speech and nonspeech conditions that involved rapid temporal discrimination, compared to speech and nonspeech conditions involving spectral discrimination. The results suggest that, when semantic and lexical factors are adequately ruled out, there is significant overlap in the brain regions involved in processing the rapid temporal characteristics of both speech and nonspeech signals.     

Brain networks involved in haptic and visual identification of facial expressions of emotion: An fMRI study

Previous neurophysiological and neuroimaging studies have shown that a cortical network involving the inferior frontal gyrus (IFG), inferior parietal lobe (IPL) and cortical areas in and around the posterior superior temporal sulcus (pSTS) region is employed in action understanding by vision and audition. However, the brain regions that are involved in action understanding by touch are unknown. Lederman et al. (2007) recently demonstrated that humans can haptically recognize facial expressions of emotion (FEE) surprisingly well. Here, we report a functional magnetic resonance imaging (fMRI) study in which we test the hypothesis that the IFG, IPL and pSTS regions are involved in haptic, as well as visual, FEE identification. Twenty subjects haptically or visually identified facemasks with three different FEEs (disgust, neutral and happiness) and casts of shoes (shoes) of three different types. The left posterior middle temporal gyrus, IPL, IFG and bilateral precentral gyrus were activated by FEE identification relative to that of shoes, regardless of sensory modality. By contrast, an inferomedial part of the left superior parietal lobule was activated by haptic, but not visual, FEE identification. Other brain regions, including the lingual gyrus and superior frontal gyrus, were activated by visual identification of FEEs, relative to haptic identification of FEEs. These results suggest that haptic and visual FEE identification rely on distinct but overlapping neural substrates including the IFG, IPL and pSTS region.     

Controlling for individual differences in fMRI brain activation to tones, syllables, and words

Previous neuroimaging studies have consistently reported bilateral activation to speech stimuli in the superior temporal gyrus (STG) and have identified an anteroventral stream of speech processing along the superior temporal sulcus (STS). However, little attention has been devoted to the possible confound of individual differences in hemispheric dominance for speech. The present study was designed to test for speech-selective activation while controlling for inter-individual variance in auditory laterality, by using only subjects with at least 10% right ear advantage (REA) on the dichotic listening test. Eighteen right-handed, healthy male volunteers (median age 26) participated in the study. The stimuli were words, syllables, and sine wave tones (220-2600 Hz), presented in a block design. Comparing words > tones and syllables > tones yielded activation in the left posterior MTG and the lateral STG (upper bank of STS). In the right temporal lobe, the activation was located in the MTG/STS (lower bank). Comparing left and right temporal lobe cluster sizes from the words > tones and syllables > tones contrasts on single-subject level demonstrated a statistically significant left lateralization for speech sound processing in the STS/MTG area. The asymmetry analyses suggest that dichotic listening may be a suitable method for selecting a homogenous group of subjects with respect to left hemisphere language dominance.     

Auditory processing of different types of pseudo-words: an event-related fMRI study

Imaging results on real word and pseudo-word processing have been heterogeneous, allowing only cautious claims about the neuroanatomical loci of lexico-semantic processing. In order to shed more light on this issue, we examined the impact of different structures of non-lexical stimuli on the outcome of comparisons between such items and matched real words. We anticipated that the degree to which a pseudo-word still resembles a particular real word template determines how word-like it is processed. To verify this idea, we tested different types of pseudo-words (either phonotactically legal and transparently or opaquely derived from real words or phonotactically illegal) in an event-related fMRI paradigm utilizing a lexical decision task. All types of pseudo-words elicited a stronger hemodynamic brain response than real words in the bilateral superior temporal gyri. Real words produced stronger brain activations than pseudo-words in the left posterior middle temporal and angular gyri, the rostral and caudal cingulate gyrus, the precuneus and the right inferior temporal gyrus. When contrasted to opaque pseudo-words transparent pseudo-words elicited a stronger brain response in a temporo-parietal region adjacent to the one observed for real words. Our results provide further support for the involvement of the left posterior middle temporal and angular gyri in lexical-semantic processing. The data also indicate that transparently derived pseudo-words are processed similarly to real words. In contrast, semantic operations are blocked when opaquely derived pseudo-words are processed.     

A voxel-based morphometry study of gray and white matter correlates of a need for uniqueness

People appear to derive intrinsic satisfaction from the perception that they are unique, special, and separable from the masses, which is referred to as a need for uniqueness (NFU). NFU is a universal human trait, along with a tendency to conform to the beliefs and attitudes of others and social norms. We used voxel-based morphometry and a questionnaire to determine individual NFU and its association with brain structures in healthy men (94) and women (91; age, 21.3±1.9years). Individual NFU was associated with smaller gray matter volume of a cluster that included areas in (a) the left middle temporal gyrus, left superior temporal gyrus, and left superior temporal sulcus (STS); (b) the dorsal part of the anterior cingulate gyrus and the anterior part of the middle cingulate gyrus; and (c) the right inferior frontal gyrus and the ventral part of the precentral gyrus. Individual NFU was also associated with larger white matter concentration of a cluster that mainly included the body of the corpus callosum. These findings demonstrated that variations in NFU reflect the gray and white matter structures of focal regions. These findings suggest a biological basis for individual NFU, distributed across different gray and white matter areas of the brain.     

Prefrontal cortex involvement in preattentive auditory deviance detection: neuroimaging and electrophysiological evidence

Previous electrophysiological and neuroimaging studies suggest that the mismatch negativity (MMN) is generated by a temporofrontal network subserving preattentive auditory change detection. In two experiments we employed event-related brain potentials (ERP) and event-related functional magnetic resonance imaging (fMRI) to examine neural and hemodynamic activity related to deviance processing, using three types of deviant tones (small, medium, and large) in both a pitch and a space condition. In the pitch condition, hemodynamic activity in the right superior temporal gyrus (STG) increased as a function of deviance. Comparisons between small and medium and between small and large deviants revealed right prefrontal activation in the inferior frontal gyrus (IFG; BA 44/45) and middle frontal gyrus (MFG; BA 46), whereas large relative to medium deviants led to left and right IFG (BA 44/45) activation. In the ERP experiment the amplitude of the early MMN (90-120 ms) increased as a function of deviance, by this paralleling the right STG activation in the fMRI experiment. A U-shaped relationship between MMN amplitude and the degree of deviance was observed in a late time window (140-170 ms) resembling the right IFG activation pattern. In a subsequent source analysis constrained by fMRI activation foci, early and late MMN activity could be modeled by dipoles placed in the STG and IFG, respectively. In the spatial condition no reliable hemodynamic activation could be observed. The MMN amplitude was substantially smaller than in the pitch condition for all three spatial deviants in the ERP experiment. In contrast to the pitch condition it increased as a function of deviance in the early and in the late time window. We argue that the right IFG mediates auditory deviance detection in case of low discriminability between a sensory memory trace and auditory input. This prefrontal mechanism might be part of top-down modulation of the deviance detection system in the STG.     

fMRI during natural sleep as a method to study brain function during early childhood

Many techniques to study early functional brain development lack the whole-brain spatial resolution that is available with fMRI. We utilized a relatively novel method in which fMRI data were collected from children during natural sleep. Stimulus-evoked responses to auditory and visual stimuli as well as stimulus-independent functional networks were examined in typically developing 2-4-year-old children. Reliable fMRI data were collected from 13 children during presentation of auditory stimuli (tones, vocal sounds, and nonvocal sounds) in a block design. Twelve children were presented with visual flashing lights at 2.5 Hz. When analyses combined all three types of auditory stimulus conditions as compared to rest, activation included bilateral superior temporal gyri/sulci (STG/S) and right cerebellum. Direct comparisons between conditions revealed significantly greater responses to nonvocal sounds and tones than to vocal sounds in a number of brain regions including superior temporal gyrus/sulcus, medial frontal cortex and right lateral cerebellum. The response to visual stimuli was localized to occipital cortex. Furthermore, stimulus-independent functional connectivity MRI analyses (fcMRI) revealed functional connectivity between STG and other temporal regions (including contralateral STG) and medial and lateral prefrontal regions. Functional connectivity with an occipital seed was localized to occipital and parietal cortex. In sum, 2-4 year olds showed a differential fMRI response both between stimulus modalities and between stimuli in the auditory modality. Furthermore, superior temporal regions showed functional connectivity with numerous higher-order regions during sleep. We conclude that the use of sleep fMRI may be a valuable tool for examining functional brain organization in young children.     

抑郁症及抑郁高血压共病患者脑部基于体素的磁共振扩散峰度成像研究

目的 探讨磁共振扩散峰度成像(DKI)在评价抑郁症及抑郁高血压共病患者脑部微观结构损害中的应用价值。方法 收集20例抑郁症患者(抑郁症组)、26例抑郁高血压共病患者(共病组)、26例高血压患者(高血压组)、23名健康志愿者(正常对照组),采用3.0T磁共振仪进行DKI扫描,使用DKE软件计算平均扩散峰度(MK)值;比较4组间MK值的差异;比较差异脑区平均MK值与17项汉密尔顿抑郁量表(HAMD-17)评分的相关性。结果 相对于正常对照组,抑郁症组MK值减低的脑区包括右额中回、右梭状回、右前扣带回、左中扣带回、左后扣带回、右岛叶、右海马、右枕下回及左枕中回、双侧楔前叶、双侧壳核、两侧颞下回和颞中回(P<0.05),共病组MK值减低的脑区包括右额上回、右梭状回、右前扣带回、右中扣带回、左后扣带回、双侧海马、双侧海马旁回、左枕中下回、双侧楔前叶、右壳核、左舌回、双侧颞中回及颞下回及左侧丘脑(P<0.05),高血压组无MK减低区。相对于抑郁症组,共病组MK下降脑区为右额下回、右梭状回、右岛叶、右扣带前回(P<0.05)。右侧海马(r=0.421,P<0.001)及右侧额中回(r=0.400,P=0.001)的平均MK值与HAMD-17评分呈负相关。结论 抑郁症和抑郁共病患者存在广泛的额叶-皮层下-边缘系统脑白质微观结构损害和功能异常;高血压可能对抑郁症有协同作用。     

遗忘型轻度认知障碍患者默认网络改变:基于后扣带回的脑连接研究

目的 探讨遗忘型轻度认知障碍(aMCI)患者后扣带回(PCC)功能连接的变化。 方法 选取性别、年龄和教育程度相匹配的18例aMCI患者(aMCI组)和20名健康老年人(健康老年组)进行GRE-EPI序列的静息状态fMRI检查,以PCC作为种子点,与全脑其他区域进行基于体素的时间序列相关分析。 结果 aMCI组与PCC有显著连接的脑区包括双侧背外侧前额叶(DLPFC)、左侧内侧前额叶(MPFC)及左侧前扣带回(ACC)、双侧顶下小叶(IPL)、双侧颞中回和双侧楔前叶。健康老年组与PCC有显著连接的脑区包括双侧DLPFC、右侧MPFC及ACC、双侧IPL、双侧颞中回、双侧颞下回和双侧楔前叶。健康老年组较aMCI组在右侧额上回、额中回、额下回的盖部及三角部、MPFC及ACC、颞中回及左侧楔前叶连接增强;aMCI组多个脑区功能连接较健康老年组增强,主要包括左侧半球的扣带回中部、顶上小叶(SPL)、IPL、颞中回及右侧IPL。 结论 PCC是aMCI患者脑代谢最先降低的区域,aMCI的PCC与多个功能区的连接破坏是其情节记忆功能减退的生物学基础,而其连接增强提示功能代偿可能。     

The brain basis of syntactic processes: functional imaging and lesion studies

Language comprehension can be subdivided into three processing steps: initial structure building, semantic integration, and late syntactic integration. The two syntactic processing phases are correlated with two distinct components in the event-related brain potential, namely an early left anterior negativity (ELAN) and a late centroparietal positivity (P600). Moreover, ERP findings from healthy adults suggest that early structure-building processes as reflected by the ELAN are independent of semantic processes. fMRI results have revealed that semantic and syntactic processes are supported by separable temporofrontal networks, with the syntactic processes involving the left superior temporal gyrus (STG), the left frontal operculum, and the basal ganglia (BG) in particular. MEG data from healthy adults have indicated that the left anterior temporal region and the left inferior frontal region subserve the early structure building processes. ERP data from patients with lesions in the left anterior temporal region and from patients with lesions in the left inferior frontal gyrus support this view, as these patients do not demonstrate an ELAN, although they do demonstrate a P600. Further results from patients with BG dysfunction suggest that parts of this subcortical structure are involved in late syntactic integrational processes. The data from the different experiments lead to the notion of separable brain systems responsible for early and late syntactic processes, with the former being subserved by the inferior frontal gyrus and the anterior STG and the latter being supported by the BG and more posterior portions of the STG.     

汉语言自由联想功能磁共振的初步研究

目的设计一种适合汉语言自由联想的脑功能磁共振刺激任务,探索汉语言自由联想脑功能区表现。材料与方法对19名健康汉语志愿者进行任务态自由联想语言功能刺激,同时采集功能性磁共振成像(functional magnetic resonance imaging,f MRI)数据,通过SPM8软件分析获取自由联想任务相关主要脑功能区位置,激活大小及最大激活强度。结果汉语自由联想主效应区位于右颞上回(BA21);左颞枕内侧回、左海马旁回在联想任务中没有激活信号,双侧海马的激活程度较低。结论利用该语言任务能激活正常人自由联想语言功能区;同时血氧水平依赖性功能磁共振成像(blood oxygen level dependent functional magnetic resonance imaging,BOLD-f MRI)可以准确定位激活区,量化激活区大小及最大激活强度,技术稳定可靠,适用于汉语言联想相关脑功能区疾病研究。     

Semantic and episodic memory of music are subserved by distinct neural networks

Numerous functional imaging studies have shown that retrieval from semantic and episodic memory is subserved by distinct neural networks. However, these results were essentially obtained with verbal and visuospatial material. The aim of this work was to determine the neural substrates underlying the semantic and episodic components of music using familiar and nonfamiliar melodic tunes. To study musical semantic memory, we designed a task in which the instruction was to judge whether or not the musical extract was felt as "familiar." To study musical episodic memory, we constructed two delayed recognition tasks, one containing only familiar and the other only nonfamiliar items. For each recognition task, half of the extracts (targets) were presented in the prior semantic task. The episodic and semantic tasks were to be contrasted by a comparison to two perceptive control tasks and to one another. Cerebral blood flow was assessed by means of the oxygen-15-labeled water injection method, using high-resolution PET. Distinct patterns of activations were found. First, regarding the episodic memory condition, bilateral activations of the middle and superior frontal gyri and precuneus (more prominent on the right side) were observed. Second, the semantic memory condition disclosed extensive activations in the medial and orbital frontal cortex bilaterally, the left angular gyrus, and predominantly the left anterior part of the middle temporal gyri. The findings from this study are discussed in light of the available neuropsychological data obtained in brain-damaged subjects and functional neuroimaging studies.