Human primary auditory cortex: cytoarchitectonic subdivisions and mapping into a spatial reference system

The transverse temporal gyrus of Heschl contains the human auditory cortex. Several schematic maps of the cytoarchitectonic correlate of this functional entity are available, but they present partly conflicting data (number and position of borders of the primary auditory areas) and they do not enable reliable comparisons with functional imaging data in a common spatial reference system. In order to provide a 3-D data set of the precise position and extent of the human primary auditory cortex, its putative subdivisions, and its topographical intersubject variability, we performed a quantitative cytoarchitectonic analysis of 10 brains using a recently established technique for observer-independent definition of areal borders. Three areas, Te1.1, Te1.0, and Te1.2, with a well-developed layer IV, which represent the primary auditory cortex (Brodmann area 41), can be identified along the mediolateral axis of the Heschl gyrus. The cell density was significantly higher in Te1.1 compared to Te1.2 in the left but not in the right hemisphere. The cytoarchitectonically defined areal borders of the primary auditory cortex do not consistently match macroanatomic landmarks like gyral and sulcal borders. The three primary auditory areas of each postmortem brain were mapped to a spatial reference system which is based on a brain registered by in vivo magnetic resonance imaging. The integration of a sample of postmortem brains in a spatial reference system allows one to estimate the spatial variability of each cytoarchitectonically defined region with respect to this reference system. In future, the transfer of in vivo structural and functional data into the same spatial reference system will enable accurate comparisons of cytoarchitectonic maps of the primary auditory cortex with activation centers as established with functional imaging procedures.     

Gender difference analysis of cortical thickness in healthy young adults with surface-based methods

We have examined gender differences of cortical thickness using a 3-D surface-based method that enables more accurate measurement in deep sulci and localized regional mapping compared to volumetric analyses. Cortical thickness was measured using a direct method for calculating the distance between corresponding vertices from inner and outer cortical surfaces. We normalized cortical surfaces using 2-D surface registration and performed diffusion smoothing to reduce the variability of folding patterns and to increase the power of the statistical analysis. In stereotaxic space, significant localized cortical thickening in women was found extensively in frontal, parietal and occipital lobes, including the superior frontal gyrus (SFG), superior parietal gyrus (SPG), inferior frontal gyrus (IFG) and postcentral gyrus (PoCG) in the left hemisphere and mostly in the parietal lobe, including the SPG in the right hemisphere. In the temporal lobe, small regions of the left and right caudal superior temporal gyrus (STG) and the left temporal pole showed significantly greater cortical thickness in women. The temporal lobe shows relatively less significant thickening than other lobes in both hemispheres. In native space, significantly greater cortical thickness in women was detected in left parietal region, including SPG and PoCG. No significant local increases of cortical thickness were observed in men in both spaces. These findings suggest statistically significant cortical thickening in women in localized anatomical regions, which is consistent with several previous studies and may support a hypothesis of sexual dimorphism.     

Probabilistic mapping and volume measurement of human primary auditory cortex

Despite their potential utility in clinical and research settings, the range of intra- and interindividual variations in size and location of cytoarchitectonically defined human primary auditory cortex (PAC) is largely unknown. This study demonstrates that gyral patterns and the size and location of PAC vary independently to a considerable degree. Thus, the cytoarchitectonic borders of PAC cannot be reliably inferred from macroscopic-MR visible-anatomy. Given the remarkable topographical variability of architectonic areal borders, standard brain mapping which is made solely on the basis of macroanatomic landmarks may lead to structural-functional mismatch. Consequently, interpretations of individual auditory activity patterns might often be inaccurate. In view of the anatomic discrepancies, we generated probability maps of PAC in which the degree of intersubject overlap in each stereotaxic position was quantified. These maps show that the location of PAC in Talairach space differs considerably between hemispheres and individuals. In contrast to earlier cytoarchitectonic work which is based in most cases on studies of single brains, our systematic approach provides extensive microanatomic data as a reference system for studies of human auditory function.     

A Population-Average, Landmark- and Surface-based (PALS) atlas of human cerebral cortex

This report describes a new electronic atlas of human cerebral cortex that provides a substrate for a wide variety of brain-mapping analyses. The Population-Average, Landmark- and Surface-based (PALS) atlas approach involves surface-based and volume-based representations of cortical shape, each available as population averages and as individual subject data. The specific PALS-B12 atlas introduced here is derived from structural MRI volumes of 12 normal young adults. Accurate cortical surface reconstructions were generated for each hemisphere, and the surfaces were inflated, flattened, and mapped to standard spherical configurations using SureFit and Caret software. A target atlas sphere was generated by averaging selected landmark contours from each of the 24 contributing hemispheres. Each individual hemisphere was deformed to this target using landmark-constrained surface registration. The utility of the resultant PALS-B12 atlas was demonstrated using a variety of analyses. (i) Probabilistic maps of sulcal identity were generated using both surface-based registration (SBR) and conventional volume-based registration (VBR). The SBR approach achieved markedly better consistency of sulcal alignment than did VBR. (ii) A method is introduced for 'multi-fiducial mapping' of volume-averaged group data (e.g., fMRI data, probabilistic architectonic maps) onto each individual hemisphere in the atlas, followed by spatial averaging across the individual maps. This yielded a population-average surface representation that circumvents the biases inherent in choosing any single hemisphere as a target. (iii) Surface-based and volume-based morphometry applied to maps of sulcal depth and sulcal identity demonstrated prominent left-right asymmetries in and near the superior temporal sulcus and Sylvian fissure. Moreover, shape variability in the temporal lobe is significantly greater in the left than the right hemisphere. The PALS-B12 atlas has been registered to other surface-based atlases to facilitate interchange of data and comparison across atlases. All data sets in the PALS-B12 atlas are accessible via the SumsDB database for online and offline visualization and analysis.     

An MRI study of spatial probability brain map differences between first-episode schizophrenia and normal controls

We created a spatial probability atlas of schizophrenia to provide information about the neuroanatomic variability of brain regions of patients with the disorder. Probability maps of 16 regions of interest (ROIs) were constructed by taking manually parcellated ROIs from subjects' magnetic resonance images (MRIs) and linearly transforming them into Talairach space using the Montreal Neurological Institute (MNI) template. ROIs included temporal, parietal, and prefrontal cortex subregions, with a principal focus on temporal lobe structures. Subject Ns ranged from 11 to 28 for the different ROIs. Our global measure of the spatial distribution of the transformed ROI was the sum of voxels with 50% overlap among subjects. The superior temporal gyrus (STG) and fusiform gyrus (FG) had lower values for schizophrenic subjects than for normal controls, suggestive of greater spatial variability for these ROIs in schizophrenic subjects. For the computation of statistical significance of group differences in portions of the ROI, we used voxel-wise comparisons and Fisher's exact test. First-episode schizophrenic patients compared with controls showed lower probability (P < 0.05) at dorso-posterior areas of planum temporale and Heschl's gyrus, lateral and anterior regions in the left hippocampus (HIPP), and dorsolateral regions of fusiform gyrus. Importantly, most ROIs of schizophrenic subjects showed a significantly lower spatial overlap than controls, even after nonlinear spatial normalization, suggesting a greater heterogeneity in the spatial distribution of ROIs. There is consequently a need for caution in neuroimaging studies where data from schizophrenic subjects are normalized to a particular stereotaxic coordinate system based on healthy controls. Apparent group differences in activation may simply reflect a greater heterogeneity of spatial distribution in schizophrenia.     

Cortical activation to auditory mismatch elicited by frequency deviant and complex novel sounds: a PET study

The analysis of auditory deviant events outside the focus of attention is a fundamental capacity of human information processing and has been studied in experiments on Mismatch Negativity (MMN) and the P3a component in evoked potential research. However, generators contributing to these components are still under discussion. Here we assessed cortical blood flow to auditory stimulation in three conditions. Six healthy subjects were presented with standard tones, frequency deviant tones (MMN condition), and complex novel sounds (Novelty condition), while attention was directed to a nondemanding visual task. Analysis of the MMN condition contrasted with thestandard condition revealed blood flow changes in the left and right superior temporal gyrus, right superior temporal sulcus and left inferior frontal gyrus. Complex novel sounds contrasted with the standard condition activated the left superior temporal gyrus and the left inferior and middle frontal gyrus. A small subcortical activation emerged in the left parahippocampal gyrus and an extended activation was found covering the right superior temporal gyrus. Novel sounds activated the right inferior frontal gyrus when controlling for deviance probability. In contrast to previous studies our results indicate a left hemisphere contribution to a frontotemporal network of auditory deviance processing. Our results provide further evidence for a contribution of the frontal cortex to the processing of auditory deviance outside the focus of directed attention.     

Sentence complexity and input modality effects in sentence comprehension: an fMRI study

Cortical regions engaged by sentence processing were mapped using functional MRI. The influence of input modality (spoken word vs. print input) and parsing difficulty (sentences containing subject-relative vs. object-relative clauses) was assessed. Auditory presentation was associated with pronounced activity at primary auditory cortex and across the superior temporal gyrus bilaterally. Printed sentences by contrast evoked major activity at several posterior sites in the left hemisphere, including the angular gyrus, supramarginal gyrus, and the fusiform gyrus in the occipitotemporal region. In addition, modality-independent regions were isolated, with greatest overlap seen in the inferior frontal gyrus (IFG). With respect to sentence complexity, object-relative sentences evoked heightened responses in comparison to subject-relative sentences at several left hemisphere sites, including IFG, the middle/superior temporal gyrus, and the angular gyrus. These sites showing modulation of activity as a function of sentence type, independent of input mode, arguably form the core of a cortical system essential to sentence parsing.     

Accurate prediction of V1 location from cortical folds in a surface coordinate system

Previous studies demonstrated substantial variability of the location of primary visual cortex (V1) in stereotaxic coordinates when linear volume-based registration is used to match volumetric image intensities [Amunts, K., Malikovic, A., Mohlberg, H., Schormann, T., and Zilles, K. (2000). Brodmann's areas 17 and 18 brought into stereotaxic space-where and how variable? Neuroimage, 11(1):66-84]. However, other qualitative reports of V1 location [Smith, G. (1904). The morphology of the occipital region of the cerebral hemisphere in man and the apes. Anatomischer Anzeiger, 24:436-451; Stensaas, S.S., Eddington, D.K., and Dobelle, W.H. (1974). The topography and variability of the primary visual cortex in man. J Neurosurg, 40(6):747-755; Rademacher, J., Caviness, V.S., Steinmetz, H., and Galaburda, A.M. (1993). Topographical variation of the human primary cortices: implications for neuroimaging, brain mapping, and neurobiology. Cereb Cortex, 3(4):313-329] suggested a consistent relationship between V1 and the surrounding cortical folds. Here, the relationship between folds and the location of V1 is quantified using surface-based analysis to generate a probabilistic atlas of human V1. High-resolution (about 200 microm) magnetic resonance imaging (MRI) at 7 T of ex vivo human cerebral hemispheres allowed identification of the full area via the stria of Gennari: a myeloarchitectonic feature specific to V1. Separate, whole-brain scans were acquired using MRI at 1.5 T to allow segmentation and mesh reconstruction of the cortical gray matter. For each individual, V1 was manually identified in the high-resolution volume and projected onto the cortical surface. Surface-based intersubject registration [Fischl, B., Sereno, M.I., Tootell, R.B., and Dale, A.M. (1999b). High-resolution intersubject averaging and a coordinate system for the cortical surface. Hum Brain Mapp, 8(4):272-84] was performed to align the primary cortical folds of individual hemispheres to those of a reference template representing the average folding pattern. An atlas of V1 location was constructed by computing the probability of V1 inclusion for each cortical location in the template space. This probabilistic atlas of V1 exhibits low prediction error compared to previous V1 probabilistic atlases built in volumetric coordinates. The increased predictability observed under surface-based registration suggests that the location of V1 is more accurately predicted by the cortical folds than by the shape of the brain embedded in the volume of the skull. In addition, the high quality of this atlas provides direct evidence that surface-based intersubject registration methods are superior to volume-based methods at superimposing functional areas of cortex and therefore are better suited to support multisubject averaging for functional imaging experiments targeting the cerebral cortex.     

White matter fiber tracts of the human brain: three-dimensional mapping at microscopic resolution, topography and intersubject variability

The position and extent of individual fiber tracts within the white matter of human brains can be identified in vivo using diffusion tensor imaging (DTI) and fiber tracking methods. Previous to this study, however, the lack of three-dimensional (3-D) probability maps precluded comparing the anatomical precision of MRI studies with microscopically defined fiber tracts in human postmortem brains. The present study provides 3-D registered maps of the topography, course and intersubject variability of major fiber tracts, which were identified at microscopic resolution. The analyzed tracts include the corticospinal tract, optic and acoustic radiations, fornix, cingulum, corpus callosum, superior longitudinal, superior and inferior occipito-frontal and uncinate fascicles; sources and targets of fiber tracts include the lateral and medial geniculate nuclei and mamillary bodies. Tracts and nuclei were identified in serial myelin-stained histological sections of ten postmortem brains. The sections were 3-D reconstructed and registered to a standardized stereotaxic space of an in vivo MR reference brain by means of linear and non-linear, elastic transformations. The individual fiber tracts and nuclei were superimposed in the reference space, and probability maps were generated as a quantitative measure of intersubject variability for each voxel of the stereotaxic space. This study presents the first stereotaxic atlas of the course, location and extent of fiber tracts and related nuclei based on microscopically defined localization and topographic data taken at multiple levels on each of the three orthogonal planes. The maps are useful for evaluating and identifying fiber bundles in DTI, for localizing subcortical lesions visible in anatomical MR images and for studying neuronal connectivity.     

Adults and children processing music: an fMRI study

The present study investigates the functional neuroanatomy of music perception with functional magnetic resonance imaging (fMRI). Three different subject groups were investigated to examine developmental aspects and effects of musical training: 10-year-old children with varying degrees of musical training, adults without formal musical training (nonmusicians), and adult musicians. Subjects made judgements on sequences that ended on chords that were music-syntactically either regular or irregular. In adults, irregular chords activated the inferior frontal gyrus, orbital frontolateral cortex, the anterior insula, ventrolateral premotor cortex, anterior and posterior areas of the superior temporal gyrus, the superior temporal sulcus, and the supramarginal gyrus. These structures presumably form different networks mediating cognitive aspects of music processing (such as processing of musical syntax and musical meaning, as well as auditory working memory), and possibly emotional aspects of music processing. In the right hemisphere, the activation pattern of children was similar to that of adults. In the left hemisphere, adults showed larger activations than children in prefrontal areas, in the supramarginal gyrus, and in temporal areas. In both adults and children, musical training was correlated with stronger activations in the frontal operculum and the anterior portion of the superior temporal gyrus.     

Differential brain activation patterns during perception of voice and tone onset time series: a MEG study

Evoked magnetic fields were recorded from 18 adult volunteers using magnetoencephalography (MEG) during perception of speech stimuli (the endpoints of a voice onset time (VOT) series ranging from /ga/ to /ka/), analogous nonspeech stimuli (the endpoints of a two-tone series varying in relative tone onset time (TOT), and a set of harmonically complex tones varying in pitch. During the early time window (approximately 60 to approximately 130 ms post-stimulus onset), activation of the primary auditory cortex was bilaterally equal in strength for all three tasks. During the middle (approximately 130 to 800 ms) and late (800 to 1400 ms) time windows of the VOT task, activation of the posterior portion of the superior temporal gyrus (STGp) was greater in the left hemisphere than in the right hemisphere, in both group and individual data. These asymmetries were not evident in response to the nonspeech stimuli. Hemispheric asymmetries in a measure of neurophysiological activity in STGp, which includes the supratemporal plane and cortex inside the superior temporal sulcus, may reflect a specialization of association auditory cortex in the left hemisphere for processing speech sounds. Differences in late activation patterns potentially reflect the operation of a postperceptual process (e.g., rehearsal in working memory) that is restricted to speech stimuli.     

Lateralization of ventral and dorsal auditory-language pathways in the human brain

Recent electrophysiological investigations of the auditory system in primates along with functional neuroimaging studies of auditory perception in humans have suggested there are two pathways arising from the primary auditory cortex. In the primate brain, a 'ventral' pathway is thought to project anteriorly from the primary auditory cortex to prefrontal areas along the superior temporal gyrus while a separate 'dorsal' route connects these areas posteriorly via the inferior parietal lobe. We use diffusion MRI tractography, a noninvasive technique based on diffusion-weighted MRI, to investigate the possibility of a similar pattern of connectivity in the human brain for the first time. The dorsal pathway from Wernicke's area to Broca's area is shown to include the arcuate fasciculus and connectivity to Brodmann area 40, lateral superior temporal gyrus (LSTG), and lateral middle temporal gyrus. A ventral route between Wernicke's area and Broca's area is demonstrated that connects via the external capsule/uncinate fasciculus and the medial superior temporal gyrus. Ventral connections are also observed in the lateral superior and middle temporal gyri. The connections are stronger in the dominant hemisphere, in agreement with previous studies of functional lateralization of auditory-language processing.     

Identification of degenerate neuronal systems based on intersubject variability

Group studies implicitly assume that all subjects activate one common system to sustain a particular cognitive task. Intersubject variability is generally treated as well-behaved and uninteresting noise. However, intersubject variability might result from subjects engaging different degenerate neuronal systems that are each sufficient for task performance. This would produce a multimodal distribution of intersubject variability. We have explored this idea with the help of Gaussian Mixture Modeling and Bayesian model comparison procedures. We illustrate our approach using a crossmodal priming paradigm, in which subjects perform a semantic decision on environmental sounds or their spoken names that were preceded by a semantically congruent or incongruent picture or written name. All subjects consistently activated the superior temporal gyri bilaterally, the left fusiform gyrus and the inferior frontal sulcus. Comparing a One and Two Gaussian Mixture Model of the unexplained residuals provided very strong evidence for two groups with distinct activation patterns: 6 subjects exhibited additional activations in the superior temporal sulci bilaterally, the right superior frontal and central sulcus. 11 subjects showed increased activation in the striate and the right inferior parietal cortex. These results suggest that semantic decisions on auditory-visual compound stimuli might be accomplished by two overlapping degenerate neuronal systems.     

Comparison of landmark-based and automatic methods for cortical surface registration

Group analysis of structure or function in cerebral cortex typically involves, as a first step, the alignment of cortices. A surface-based approach to this problem treats the cortex as a convoluted surface and coregisters across subjects so that cortical landmarks or features are aligned. This registration can be performed using curves representing sulcal fundi and gyral crowns to constrain the mapping. Alternatively, registration can be based on the alignment of curvature metrics computed over the entire cortical surface. The former approach typically involves some degree of user interaction in defining the sulcal and gyral landmarks while the latter methods can be completely automated. Here we introduce a cortical delineation protocol consisting of 26 consistent landmarks spanning the entire cortical surface. We then compare the performance of a landmark-based registration method that uses this protocol with that of two automatic methods implemented in the software packages FreeSurfer and BrainVoyager. We compare performance in terms of discrepancy maps between the different methods, the accuracy with which regions of interest are aligned, and the ability of the automated methods to correctly align standard cortical landmarks. Our results show similar performance for ROIs in the perisylvian region for the landmark-based method and FreeSurfer. However, the discrepancy maps showed larger variability between methods in occipital and frontal cortex and automated methods often produce misalignment of standard cortical landmarks. Consequently, selection of the registration approach should consider the importance of accurate sulcal alignment for the specific task for which coregistration is being performed. When automatic methods are used, the users should ensure that sulci in regions of interest in their studies are adequately aligned before proceeding with subsequent analysis.     

In vivo evidence of disseminated subpial T2* signal changes in multiple sclerosis at 7 T: a surface-based analysis

Cortical subpial demyelination is frequent in multiple sclerosis (MS) and is closely associated with disease progression and poor neurological outcome. Although cortical lesions have been difficult to detect using conventional MRI, preliminary data using T2*-weighted imaging at ultra-high field 7T MRI showed improved sensitivity for detecting and categorizing different histological types of cortical MS lesions. In this study we combined high-resolution 7T MRI with a surface-based analysis technique to quantify and map subpial T2*-weighted signal changes in seventeen patients with MS. We applied a robust method to register 7T data with the reconstructed cortical surface of each individual and used a general linear model to assess in vivo an increase in subpial T2*-weighted signal in patients versus age-matched controls, and to investigate the spatial distribution of cortical subpial changes across the cortical ribbon. We also assessed the relationship between subpial T2* signal changes at 7T, Expanded Disability Status Scale (EDSS) score and white matter lesion load (WMLL). Patients with MS showed significant T2*-weighted signal increase in the frontal lobes (parsopercularis, precentral gyrus, middle and superior frontal gyrus, orbitofrontal cortex), anterior cingulate, temporal (superior, middle and inferior temporal gyri), and parietal cortices (superior and inferior parietal cortex, precuneus), but also in occipital regions of the left hemisphere. We found significant correlations between subpial T2*-weighted signal and EDSS score in the precentral gyrus (ρ=0.56, P=0.02) and between T2*-weighted signal and WMLL in the lateral orbitofrontal, superior parietal, cuneus, precentral and superior frontal regions. Our data support the presence of disseminated subpial increases in T2* signal in subjects with MS, which may reflect the diffuse subpial pathology described in neuropathology.     

Mapping an intrinsic MR property of gray matter in auditory cortex of living humans: a possible marker for primary cortex and hemispheric differences

Recently, magnetic resonance properties of cerebral gray matter have been spatially mapped--in vivo--over the cortical surface. In one of the first neuroscientific applications of this approach, this study explores what can be learned about auditory cortex in living humans by mapping longitudinal relaxation rate (R1), a property related to myelin content. Gray matter R1 (and thickness) showed repeatable trends, including the following: (1) Regions of high R1 were always found overlapping posteromedial Heschl's gyrus. They also sometimes occurred in planum temporale and never in other parts of the superior temporal lobe. We hypothesize that the high R1 overlapping Heschl's gyrus (which likely indicates dense gray matter myelination) reflects auditory koniocortex (i.e., primary cortex), a heavily myelinated area that shows comparable overlap with the gyrus. High R1 overlapping Heschl's gyrus was identified in every instance suggesting that R1 may ultimately provide a marker for koniocortex in individuals. Such a marker would be significant for auditory neuroimaging, which has no standard means (anatomic or physiologic) for localizing cortical areas in individual subjects. (2) Inter-hemispheric comparisons revealed greater R1 on the left on Heschl's gyrus, planum temporale, superior temporal gyrus and superior temporal sulcus. This asymmetry suggests greater gray matter myelination in left auditory cortex, which may be a substrate for the left hemisphere's specialized processing of speech, language, and rapid acoustic changes. These results indicate that in vivo R1 mapping can provide new insights into the structure of human cortical gray matter and its relation to function.     

静息态fMRI观察遗忘型轻度认知障碍患者长-短程功能连接

目的 分析遗忘型轻度认知障碍（aMCI）患者长、短程功能连接的变化。方法 采集37例aMCI患者（aMCI组）和40名认知功能正常志愿者（对照组）的静息态fMRI数据,以GRETNA软件自动计算完成全脑长程和短程功能连接,比较2组间差异。结果 与对照组比较,aMCI组长程功能连接减低的脑区主要位于双侧楔前叶/中后扣带回、右侧中央沟盖,长程功能连接增强的脑区主要分布于双侧中央前回、左侧颞极/颞中回、左侧直回、右侧眶内额上回、左侧眶内额下回;其短程功能连接减低脑区位于左侧岛叶,短程功能连接增强脑区主要包括左侧颞极/颞上回、左侧颞中回、左侧直回、左侧眶内额下回、右侧海马、右侧颞上回、右侧额中回、右侧辅助运动区及左侧中央后回/楔前叶。结论 aMCI组患者脑长、短程功能连接模式均有所改变,有助于理解aMCI患者脑网络改变的病理生理机制。     

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.     

Neuroplasticity of semantic representations for musical instruments in professional musicians

Professional musicians constitute a model par excellence for understanding experience-dependent plasticity in the human brain, particularly in the auditory domain. Their intensive sensorimotor experience with musical instruments has been shown to entail plastic brain alterations in cortical perceptual and motor maps. It remains an important question whether this neuroplasticity might extend beyond basic perceptual and motor functions and even shape higher-level conceptualizations by which we conceive our physical and social world. Here we show using functional magnetic resonance imaging (fMRI) that conceptual processing of visually presented musical instruments activates auditory association cortex encompassing right posterior superior temporal gyrus, as well as adjacent areas in the superior temporal sulcus and the upper part of middle temporal gyrus (pSTG/MTG) only in musicians, but not in musical laypersons. These areas in and adjacent to auditory association cortex were not only recruited by conceptual processing of musical instruments during visual object recognition, but also by auditory perception of real sounds. Hence, the unique intensive experience of musicians with musical instruments establishes a link between auditory perceptual and conceptual brain systems. Experience-driven neuroplasticity in musicians is thus not confined to alterations of perceptual and motor maps, but even leads to the establishment of higher-level semantic representations for musical instruments in and adjacent to auditory association cortex. These findings highlight the eminent importance of sensory and motor experience for acquiring rich concepts.     

Spatiotemporal signatures of an abnormal auditory system in stuttering

People who stutter (PWS) can reduce their stuttering rates under masking noise and altered auditory feedback; such a response can be attributed to altered auditory input, which suggests that abnormal speech processing in PWS results from abnormal processing of auditory input. However, the details of this abnormal processing of basic auditory information remain unclear. In order to characterize such abnormalities, we examined the functional and structural changes in the auditory cortices of PWS by using a 306-channel magnetoencephalography system to assess auditory sensory gating (P50m suppression) and tonotopic organization. Additionally, we employed voxel-based morphometry to compare cortical gray matter (GM) volumes on structural MR images. PWS exhibited impaired left auditory sensory gating. The tonotopic organization in the right hemisphere of PWS is expanded compared with that of the controls. Furthermore, PWS showed a significant increase in the GM volume of the right superior temporal gyrus, consistent with the right tonotopic expansion. Accordingly, we suggest that PWS have impaired left auditory sensory gating during basic auditory input processing and that some error signals in the auditory cortex could result in abnormal speech processing. Functional and structural reorganization of the right auditory cortex appears to be a compensatory mechanism for impaired left auditory cortex function in PWS.