Standard Brain Space Research Articles

Anatomical specificity of vascular endothelial growth factor expression in glioblastomas: a voxel-based mapping analysis.

The expression of vascular endothelial growth factor (VEGF) is a common genetic alteration in malignant gliomas and contributes to the angiogenesis of tumors. This study aimed to investigate the anatomical specificity of VEGF expression levels in glioblastomas using voxel-based neuroimaging analysis. Clinical information, MR scans, and immunohistochemistry stains of 209 patients with glioblastomas were reviewed. All tumor lesions were segmented manually and subsequently registered to standard brain space. Voxel-based regression analysis was performed to correlate the brain regions of tumor involvement with the level of VEGF expression. Brain regions identified as significantly associated with high or low VEGF expression were preserved following permutation correction. High VEGF expression was detected in 123 (58.9 %) of the 209 patients. Voxel-based statistical analysis demonstrated that high VEGF expression was more likely in tumors located in the left frontal lobe and the right caudate and low VEGF expression was more likely in tumors that occurred in the posterior region of the right lateral ventricle. Voxel-based neuroimaging analysis revealed the anatomic specificity of VEGF expression in glioblastoma, which may further our understanding of genetic heterogeneity during tumor origination. This finding provides primary theoretical support for potential future application of customized antiangiogenic therapy.

Age-associated brain regions in gliomas: a volumetric analysis.

Both age of patients and tumor location are associated with tumor origin, genetic characteristics, and prognosis. The objective of this study was to investigate the relationship between tumor location and age at diagnosis in a large cohort of patients with a primary diagnosis of glioma. We consecutively enrolled a cohort of 200 adults with glioblastoma and another cohort of 200 adults with diffuse low-grade gliomas. The magnetic resonance images of all tumors were manually segmented and then registered to a standard brain space. By using voxel-by-voxel regression analysis, specific brains regions associated with advanced age at tumor diagnosis were localized. In the low-grade gliomas cohort, the brain regions associated with advanced age at tumor diagnosis were mainly located in the right middle frontal region, while a region in the left temporal lobe, particularly at the subgranular zone, was associated with lower age at tumor diagnosis. In the glioblastoma cohort, the brain regions associated with advanced age at tumor diagnosis were mainly located in the temporal lobe, particularly at the posterior region of the subventricular zones. A region in the left inferior frontal region was associated with lower age at tumor diagnosis. Significant differences in the age of patients were found between tumors located in the identified regions and those located elsewhere in both cohorts. The current study demonstrated the correlation between tumor location and age at diagnosis, which implies differences in the origin of gliomas in young and older patients.

Altered temporal features of intrinsic connectivity networks in boys with combined type of attention deficit hyperactivity disorder

PurposeInvestigating the altered temporal features within and between intrinsic connectivity networks (ICNs) for boys with attention-deficit/hyperactivity disorder (ADHD); and analyzing the relationships between altered temporal features within ICNs and behavior scores. Materials and methodsA cohort of boys with combined type of ADHD and a cohort of age-matched healthy boys were recruited from ADHD-200 Consortium. All resting-state fMRI datasets were preprocessed and normalized into standard brain space. Using general linear regression, 20 ICNs were taken as spatial templates to analyze the time-courses of ICNs for each subject. Amplitude of low frequency fluctuations (ALFFs) were computed as univariate temporal features within ICNs. Pearson correlation coefficients and node strengths were computed as bivariate temporal features between ICNs. Additional correlation analysis was performed between temporal features of ICNs and behavior scores. ResultsADHD exhibited more activated network-wise ALFF than normal controls in attention and default mode-related network. Enhanced functional connectivities between ICNs were found in ADHD. The network-wise ALFF within ICNs might influence the functional connectivity between ICNs. The temporal pattern within posterior default mode network (pDMN) was positively correlated to inattentive scores. The subcortical network, fusiform-related DMN and attention-related networks were negatively correlated to Intelligence Quotient (IQ) scores. ConclusionThe temporal low frequency oscillations of ICNs in boys with ADHD were more activated than normal controls during resting state; the temporal features within ICNs could provide additional information to investigate the altered network patterns of ADHD.

NI-34 * BRAIN LOCATIONS INVOLVED IN COGNITIVE ALTERATIONS AFTER RESECTIVE BRAIN SURGERY IDENTIFIED BY RESECTION PROBABILITY MAPS

INTRODUCTION: Cognition is at risk in patients with brain tumors. Cognitive alterations, improvement or decline, may result from brain tumor surgery, as well as from other factors such as direct tumor effects, radiotherapy, chemotherapy, anti-epileptic drugs, and steroids. In this study, cognitive alterations after brain tumor surgery are quantified and correlated with brain location using resection probability maps, which is a new approach. METHODS: Adult patients were included, who had (1) a brain tumor, (2) resective surgery between 2006 and 2011, (3) baseline and postoperative (9-12 months) neuropsychological assessment in seven cognitive domains, and (4) pre- and postoperative MRI available. Resective surgery was performed with intraoperative stimulation mapping until functional boundaries were met. Resection probability maps quantify the likelihood of resection throughout the brain in 3D at 1 mm resolution in standard brain space. We compared resection probability maps of patients with and without cognitive alterations. Considerations for spatial dependence and multiple comparisons were taken into account. PRELIMINARY RESULTS: Seventy-four patients were so far included. The cognitive domains with most frequent and most extensive alterations after surgery were attentional function and working memory capacity. Results on the correlation between these cognitive changes and brain location are pending, but will be available in October 2014. CONCLUSION: Brain locations involved in cognitive improvement as well as decline in relation to resective surgery can be identified using resection probability maps. Brain tumors which are located in regions to be identified are associated with alterations in attention and verbal working memory.

Correlation between LIFG and autonomic activation during stressful tasks: a functional near-infrared spectroscopy (fNIRS) study.

It remains unclear whether language tasks in one's first (L1) or second (L2) language can cause stress responses and whether frontal, autonomic and behavioral responses to stressful tasks are correlated. In this study, we studied 22 Chinese subjects whose L2 was English and measured the cerebral blood oxygenation in their frontal lobe by using functional near-infrared spectroscopy (fNIRS) as participants engaged in a mental arithmetic task (MAT) and verbal fluency tasks (VFTs) in L1 (Chinese) and L2 (English). To examine the activated cortical areas, we estimated the channel location based on Montreal Neurological Institute (MNI) standard brain space by using a probabilistic estimation method. We evaluated heart rate (HR) changes to analyze autonomic nervous system (ANS) functioning. We found that the MAT and VFTs induced greater increases in HR than did the control (Ctrl) task. Furthermore, subjects developed greater increases in HR in the MAT and VFTL2 than they did in the VFTL1. Compared with the Ctrl task, the MAT and both VFTL1 and VFTL2 produced robust and widespread bilateral activation of the frontal cortex. Interestingly, partial correlation analysis indicated that the activity in the left inferior frontal gyrus (LIFG) [Brodmann's area (BA) 47] was consistently correlated with the increases in HR across the three tasks (MAT, VFTL2, and VFTL1), after controlling for the performance data. The present results suggested that a VFT in L2 may be more stressful than in L1. The LIFG may affect the activation of the sympathetic system induced by stressful tasks, including MATs and VFTs.

P16.14 * BRAIN LOCATIONS INVOLVED IN COGNITIVE ALTERATIONS AFTER RESECTIVE BRAIN SURGERY IDENTIFIED BY RESECTION PROBABILITY MAPS

INTRODUCTION: Cognition is at risk in patients with brain tumors. Cognitive alterations, improvement or decline, may result from brain tumor surgery, as well as from other factors such as direct tumor effects, radiotherapy, chemotherapy, anti-epileptic drugs, and steroids. In this study, cognitive alterations after brain tumor surgery are quantified and correlated with brain location using resection probability maps, which is a new approach. METHODS: Adult patients were included, who had (1) a brain tumor, (2) resective surgery between 2006 and 2011, (3) baseline and postoperative (9-12 months) neuropsychological assessment in seven cognitive domains, and (4) pre- and postoperative MRI available. Resective surgery was performed with intraoperative stimulation mapping until functional boundaries were met. Resection probability maps quantify the likelihood of resection throughout the brain in 3D at 1 mm resolution in standard brain space. We compared resection probability maps of patients with and without cognitive alterations. Considerations for spatial dependence and multiple comparisons were taken into account. PRELIMINARY RESULTS: Seventy-four patients were so far included. The cognitive domains with most frequent and most extensive alterations after surgery were attentional function and working memory capacity. Results on the correlation between these cognitive changes and brain location are pending, but will be available in October 2014. CONCLUSION: Brain locations involved in cognitive improvement as well as decline in relation to resective surgery can be identified using resection probability maps. Brain tumors which are located in regions to be identified are associated with alterations in attention and verbal working memory.

Differences in Brainstem Fiber Tract Response to Radiation: A Longitudinal Diffusion Tensor Imaging Study

To determine whether radiation-induced changes in white matter tracts are uniform across the brainstem. We analyzed serial diffusion tensor imaging data, acquired before radiation therapy and over 48 to 72 months of follow-up, from 42 pediatric patients (age 6-20 years) with medulloblastoma. FSL software (FMRIB, Oxford, UK) was used to calculate fractional anisotropy (FA) and axial, radial, and mean diffusivities. For a consistent identification of volumes of interest (VOIs), the parametric maps of each patient were transformed to a standard brain space (MNI152), on which we identified VOIs including corticospinal tract (CST), medial lemniscus (ML), transverse pontine fiber (TPF), and middle cerebellar peduncle (MCP) at the level of pons. Temporal changes of DTI parameters in VOIs were compared using a linear mixed effect model. Radiation-induced white matter injury was marked by a decline in FA after treatment. The decline was often accompanied by decreased axial diffusivity, increased radial diffusivity, or both. This implied axonal damage and demyelination. We observed that the magnitude of the changes was not always uniform across substructures of the brainstem. Specifically, the changes in DTI parameters for TPF were more pronounced than in other regions (P<.001 for FA) despite similarities in the distribution of dose. We did not find a significant difference among CST, ML, and MCP in these patients (P>.093 for all parameters). Changes in the structural integrity of white matter tracts, assessed by DTI, were not uniform across the brainstem after radiation therapy. These results support a role for tract-based assessment in radiation treatment planning and determination of brainstem tolerance.

WE‐C‐BRA‐02: Best in Physics (Joint Imaging‐Therapy) ‐ Assessment of Radiation‐Induced White Matter Injury in Sub‐Structures of Normal‐Appearing Brainstem Using Diffusion Tensor Imaging

Purpose: To test the hypothesis that treatment‐induced white matter injury assessed by diffusion tensor imaging (DTI) is uniform across sub‐regions of the normal appearing brainstem. Methods: We analyzed serial DTI data, acquired before radiation/chemotherapy and over 4–6 years of follow‐up, from 11 pediatric patients (age 5‐16 years) with medulloblastoma. FSL4.1 software (FMRIB, Oxford, UK) was used to calculate fractional anisotropy (FA) and mean, axial, and radial diffusivities. For a consistent identification of regions of interest (ROIs), parametric maps of each patient were transformed to a standard brain space (ICBM), on which we identified motor (corticospinal tract, CST) and sensory (medial lemiscus, ML) tracts in the pons and transverse pontine fibers (TPF) involved in coordination. Temporal changes of DTI parameters in ROIs were evaluated using a linear mixed effect model. Results: Therapy‐induced white matter injury was marked by a decline in FA at 1–3 years after treatment. The decline was often accompanied by decreased axial diffusivity and/or increased radial diffusivity. This implied axonal damage and demyelination. We observed that the magnitude of the changes was not always uniform across sub‐regions of the brainstem. Specifically, the changes in DTI parameters for TPF were more pronounced than in other regions (p&lt;0.001 for FA) despite similarities in the distribution of dose. The mean dose to CST, TPF, and ML was 52.3, 56.0, and 56.6 Gy, respectively. We did not find a significant difference between CST and ML in these patients (p&gt;0.08 for all parameters). Conclusions: These results indicate that fiber tract sensitivity to radiation effect may be associated with the type and function of fiber tracts and support a role for tract‐based assessment in radiation treatment planning and evaluation of treatment response.

Automated Atlas Annotation for Transgenic Mouse Lines

Event Abstract Back to Event Automated Atlas Annotation for Transgenic Mouse Lines Ken Sugino1*, Yao Cheng1 and Sacha Nelson1 1 Brandeis University, United States The brain consists of a multitude of cell types that are connected in specific and intricate ways. The elucidation of neuronal cell types and their patterns of connection are critical steps in understanding brain function. However, while cellular phenotypes like morphology, marker expression and electrophysiology have successfully delineated component cell types in some brain regions, the identification of neuronal cell types in many other regions remains a matter of ongoing debate. Recently, transgenic mouse lines that label specific subpopulation of cells are being recognized as useful tools for the identification and investigation of neuronal cell types. Efforts in generating mouse lines for this purpose are underway in various places and a central database serving as a repository of information gained from those mouse lines is already established (http://www.credrivermice.org). Two of the most useful types of information needed for each cell type identified in a transgenic mouse lines are 1) the anatomical location of the labeled cells , and 2) the expression of previously recognized molecular markers, typically assessed in terms of the degree of overlap between cellular labeling and immunolabeling staining experiments. Those data can be analyzed manually, however, the work required is rather extensive (e.g.20 sections/line x 100 lines x 2 hr/section*person ~ 2 person-years) Hence, automated systems to replace or assist manual analysis are desired. Our approach for automated assignment of anatomical region consists of three steps: (1) detection of labeled cell bodies in each section, (2) registration of a series of sections from a given mouse line into a standard brain space such as Waxholm space, and (3) mapping the counts of detected cell bodies into anatomical regions assigned in the standard space. For the second problem of marker overlap counting, the cell body detection in one channel (i.e. step 1), is followed by detecting signal from one or more other channel (step 4). We have currently implemented steps (1) and (4), and are collaborating with other groups for realizing steps (2 and 3). Figure 1 Keywords: digital atlasing Conference: 4th INCF Congress of Neuroinformatics, Boston, United States, 4 Sep - 6 Sep, 2011. Presentation Type: Poster Presentation Topic: Digital atlasing Citation: Sugino K, Cheng Y and Nelson S (2011). Automated Atlas Annotation for Transgenic Mouse Lines. Front. Neuroinform. Conference Abstract: 4th INCF Congress of Neuroinformatics. doi: 10.3389/conf.fninf.2011.08.00035 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 17 Oct 2011; Published Online: 19 Oct 2011. * Correspondence: Dr. Ken Sugino, Brandeis University, Waltham, United States, sugino@brandeis.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Ken Sugino Yao Cheng Sacha Nelson Google Ken Sugino Yao Cheng Sacha Nelson Google Scholar Ken Sugino Yao Cheng Sacha Nelson PubMed Ken Sugino Yao Cheng Sacha Nelson Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Gender and age differences in normal adult human brain: Voxel-based morphometric study

The aim of this study was to evaluate the gender and age differences in the normal adult human brain, using voxel-based morphometry. In this study, 227 right-handed normal adults (male:female = 111:116) were examined. Three-dimensional magnetic resonance brain images of each subject were segmented into gray and white matter using statistical parametric mappings. All individual data were transformed to standard brain space and then divided into older and younger age groups before examining the effects of age and gender. There was a significant negative correlation between gray matter concentration and age in each gender group. The differences were more prominent in the older age groups compared with the younger age groups. Gray matter concentrations in the bilateral inferior frontal lobes, anterior cingulate gyrus, medial thalamus, and hypothalamus were more retained in females as they aged, whereas those in the occipital regions were more retained in aging males. Our findings are consistent with biologically and hormonally established gender differences.

Reproducibility of automated simplified voxel-based analysis of PET amyloid ligand [11C]PIB uptake using 30-min scanning data

Positron emission tomography (PET) with 11C-labelled Pittsburgh compound B ([11C]PIB) enables the quantitation of beta-amyloid accumulation in the brain of patients with Alzheimer's disease (AD). Voxel-based image analysis techniques conducted in a standard brain space provide an objective, rapid and fully automated method to analyze [11C]PIB PET data. The purpose of this study was to evaluate both region- and voxel-level reproducibility of automated and simplified [11C]PIB quantitation when using only 30 min of imaging data. Six AD patients and four healthy controls were scanned twice with an average interval of 6 weeks. To evaluate the feasibility of short scanning (convenient for AD patients), [11C]PIB uptake was quantitated using 30 min of imaging data (60 to 90 min after tracer injection) for region-to-cerebellum ratio calculations. To evaluate the reproducibility, a test-retest design was used to derive absolute variability (VAR) estimates and intraclass correlation coefficients at both region-of-interest (ROI) and voxel level. The reproducibility both at the region level (VAR 0.9-5.5%) and at the voxel level (VAR 4.2-6.4%) was good to excellent. Based on the variability estimates obtained, power calculations indicated that 90% power to obtain statistically significant difference can be achieved using a sample size of five subjects per group when a 15% change from baseline (increase or decrease) in [11C]PIB accumulation in the frontal cortex is anticipated in one group compared to no change in another group. Our results showed that an automated analysis method based on an efficient scanning protocol provides reproducible results for [11C]PIB uptake and appears suitable for PET studies aiming at the quantitation of amyloid accumulation in the brain of AD patients for the evaluation of progression and treatment effects.

Structural atlas-based spatial registration for functional near-infrared spectroscopy enabling inter-study data integration

The use of functional near-infrared spectroscopy (fNIRS) is growing, leading to a need for methods to summarise data from multiple studies. However, this is difficult using the current channel-based methods when experiments do not share a common channel (CH) arrangement. Thus, we proposed and implemented a CH-independent analysis method for summarising fNIRS data. We defined sub-regions as spatial bins to organise fNIRS data. Sub-regions were defined on the standard brain surface based on macro- and micro-structural information. After probabilistically estimating CH location in standard stereotaxic brain space, the CH-based data were reorganised into these spatial bins to evaluate sub-region-based activation. Sub-regions with sizes corresponding to fNIRS spatial resolution were defined. We demonstrated this method by integrating data from two of our fNIRS studies that shared the same region of interest but used different channel arrangements. Using this method, data from multiple fNIRS studies with different CH arrangements can be integrated in standard brain space, while keeping in mind the brain structure-function relationship. The current method will facilitate an effective use of accumulating fNIRS data by allowing integration of data from multiple studies.

Activation in ventro-lateral prefrontal cortex during the act of tasting: An fNIRS study

The act of tasting is the product of inseparable integrative behavior consisting of multi-sensory processing and orolingual motor coordination. Often tasting-induced brain activity is looked at in a reductionist manner as a set of isolated components. However, brain activity as a whole during tasting may not simply be the sum of isolated brain responses; therefore, attempting to look at the cortical activation in a more holistic manner is important. Using functional near-infrared spectroscopy (fNIRS), we assessed cortical responses during tasting, contrasting observed neuronal activation of the lateral prefrontal cortex (LPFC), of 19 healthy participants before and during tasting of 8 ml of sweet-based solutions. To examine the activated brain structure, we estimated the anatomical regions of the measured location in standard brain space. We also included simple tongue tapping movement (TT) and word fluency (WF) tasks as comparative functional markers. Significant activity was found in channels (CHs) estimated to be in the bilateral oral motor areas during the TT task, and those in the LPFC, primarily in the left hemisphere, during the WF task. During the tasting task, significant activation was observed in CHs estimated to lie in the ventral part of pre- and post-central gyri as well as in the ventro-LPFC (VLPFC). The activated regions partly overlapped with those detected during TT or WF tasks, but extended more anteriorly and ventrally. Our study suggests that, in addition to tongue motor areas, the VLPFC is involved in the act of tasting.

Abnormal Regional Cerebral Blood Flow in Cognitively Normal Elderly Subjects With Hypertension

The purpose of this study was to examine regional cerebral blood flow (rCBF) in normal cognitive-performing subjects with hypertension (HTN) using continuous arterial spin-labeled MRI. The most common explanation for the effect of blood pressure on cognition is that HTN increases the risk of cerebrovascular disease, and it may increase the risk for Alzheimer disease possibly through small vessel disease, ischemia, oxidative stress, and inflammation. However, few studies to date have examined the rCBF of cognitively normal subjects with HTN in population-based cohorts, and none have used continuous arterial spin-labeled MRI. This is a noninvasive technique that does not require either injections or ionizing radiation and can measure absolute rCBF rates over the entire brain. rCBF was measured at 1.5 T using continuous arterial spin-labeled MRI in 41 cognitively normal subjects who were participating in the Cardiovascular Health Study Cognition Study. A deformable atrophy-corrected registration method was used to warp the rCBF maps to the standard colin27 brain space. Image and cluster-based statistical analyses were performed between subject groups. Cognitively normal subjects with HTN (n=19) had decreased rCBF in the putamen, globus pallidus, bilaterally, and in the left hippocampus compared with normotensives (n=22). In addition, decreased rCBF was observed in the right and left anterior cingulate gyrus with extension to the subcallosal region, left posterior cingulate gyrus and medial precuneus, left lateral inferior and superior frontal, and inferior parietal, left orbitofrontal, and left superior temporal cortices. rCBF is affected in normal subjects with HTN, not only in the subcortical regions, but also in limbic and paralimbic structures. We hypothesize that the HTN creates a vulnerability state for the development of neurodegenerative disorders, especially Alzheimer disease.

Isolating physiologic noise sources with independently determined spatial measures

To properly account for the presence of physiologic noise in fMRI data, parallel measurement of pulse and respiratory data is necessary. In some cases, this parallel measurement is difficult or impossible due to the experimental paradigm or lack of available monitoring equipment. We present a robust method for determining the direct-sampled pulse and respiratory data for a subject from the fMRI data itself, utilizing an independently determined spatial weighting matrix. It is shown that temporal independent component analysis can reliably separate the spatial and temporal patterns of physiologic noise through correlation if the parallel measurement is made. The spatial patterns thus determined can be applied to a separate scan of the same subject to produce the temporal pattern specific to this independent scan. The robustness of this method leads to the more general method of creating spatial weight matrices in standard brain space averaged over multiple subjects in order to acquire the physiologic signals without the necessity of any (further) parallel measurements. The resulting cardiac and respiratory estimators can effectively be used in a manner similar to that of a direct-sampled physiologic signal, e.g., direct input to retrospective correction methods, evaluation of cardiac and respiratory effects of tasks, etc. Spatial mixing matrices for estimating cardiac and respiratory sources for the acquisition protocols described here (and others as they are developed) are offered to investigators and can be obtained through e-mail from the corresponding author.

Prefrontal activity during flavor difference test: Application of functional near-infrared spectroscopy to sensory evaluation studies

Sensory evaluation (SE) of food attributes involves various levels of cognitive functions, yet not much has been studied about its neural basis. Using multi-channel functional near-infrared spectroscopy (fNIRS), we examined the activation of the anterior portion of the lateral prefrontal cortex (LPFC) of 12 healthy volunteers during the SE of tea samples. The experimental task used corresponded to the early phase of the same-different test, and required subjects to attentively taste tea samples and memorize their flavors. To isolate activation associated with the cognitive functions involved in the task, we contrasted the results with those achieved by a control (Ctl) task during which subjects held familiar tea samples in their mouths without actively evaluating their flavor. We probabilistically registered the fNIRS data to the Montreal Neurological Institute standard brain space to examine the results as they correspond with other published neuroimaging studies. We found significant activation in the left LPFC and in the right inferior frontal gyrus. The activation pattern was consistent with earlier studies on encoding of other sensory stimuli, with cortical regions supposed to be involved in semantic and perceptual processing. This research makes a start on characterizing the cognitive process employed during SE from the neuroimaging perspective.

Prefrontal activity during taste encoding: An fNIRS study

To elucidate the function of the lateral prefrontal cortex (LPFC) in taste encoding, it is worth applying to taste, the psychological paradigms of intentional memorization that have been used with other extensively studied senses, and thus updating current models for LPFC functions to include a taste modality. Using multichannel functional near-infrared spectroscopy (fNIRS), we examined the LPFC's of healthy volunteers ( N = 18) during the intentional memorization of a basic taste. In order to minimize the confounding effects of verbal processes that are known to employ the left LPFC, we used quaternary taste mixtures that were difficult to verbalize, and confined analysis to those who did not use a verbal strategy during memorization ( N = 10). In order to examine the results in association with data in the literature, the location of activity was probabilistically estimated and anatomically labeled in the Montreal Neurological Institute (MNI) standard brain space. By contrasting the cortical activation under encoding conditions with that under control conditions without memory requirement, we found activation in the bilateral ventro-LPFC and the right posterior portion of the LPFC. The activation pattern was consistent with previous studies on the encoding of nonverbal materials using other senses. This suggests that models for LPFC functions that derive from previous studies can be generalized to intentional encoding processes of taste information, at least at a macro-structural level. The current study also demonstrates that, by using fNIRS, LPFC functions on taste can be examined with experimental paradigms relevant to those used for other senses.

Functional-anatomical validation and individual variation of diffusion tractography-based segmentation of the human thalamus.

Parcellation of the human thalamus based on cortical connectivity information inferred from non-invasive diffusion-weighted images identifies sub-regions that we have proposed correspond to nuclei. Here we test the functional and anatomical validity of this proposal by comparing data from diffusion tractography, cytoarchitecture and functional imaging. We acquired diffusion imaging data in eleven healthy subjects and performed probabilistic tractography from voxels within the thalamus. Cortical connectivity information was used to divide the thalamus into sub-regions with highest probability of connectivity to distinct cortical areas. The relative volumes of these connectivity-defined sub-regions correlate well with volumetric predictions based on a histological atlas. Previously reported centres of functional activation within the thalamus during motor or executive tasks co-localize within atlas regions showing high probabilities of connection to motor or prefrontal cortices, respectively. This work provides a powerful validation of quantitative grey matter segmentation using diffusion tractography in humans. Co-registering thalamic sub-regions from 11 healthy individuals characterizes inter-individual variation in segmentation and results in a population-based atlas of the human thalamus that can be used to assign likely anatomical labels to thalamic locations in standard brain space. This provides a tool for specific localization of functional activations or lesions to putative thalamic nuclei.

Gender differences in cerebral glucose metabolism: a PET study

Objective: Some studies have examined gender differences in brain function based on cerebral blood flow and cerebral metabolism by using positron emission tomography (PET). However, the findings of these studies are controversial and most of them were analyzed by the regions of interest (ROIs) method. Here, we evaluated gender differences of cerebral glucose metabolism under the resting state in a voxel-based analysis. Methods: We studied 44 healthy volunteers (22 females, 63.0±6.3 years, and 22 males, 63.1±8.4 years). Cerebral glucose metabolic images were obtained with 18F-fluorodeoxyglucose (FDG) and PET. All individual data were transformed to standard brain space and the male and female groups were compared using statistical parametric mapping (SPM). Results: The males had significantly higher glucose metabolism in the right insula, middle temporal gyrus, and medial frontal lobe than the females. Glucose metabolism in the hypothalamus was significantly higher in females than in males. There was a significant correlation between aging and glucose metabolism in the left thalamus in males and in the left caudate nucleus and hypothalamus in females. In males, but not females, there was a significant asymmetry between the bilateral hemispheres. Conclusion: We found that there were obvious gender differences in regional cerebral glucose metabolism and this is the first report of higher glucose metabolism in the hypothalamus in females than in males.

Cortical Systems for the Recognition of Emotion in Facial Expressions

This study is part of an effort to map neural systems involved in the processing of emotion, and it focuses on the possible cortical components of the process of recognizing facial expressions. We hypothesized that the cortical systems most responsible for the recognition of emotional facial expressions would draw on discrete regions of right higher-order sensory cortices and that the recognition of specific emotions would depend on partially distinct system subsets of such cortical regions. We tested these hypotheses using lesion analysis in 37 subjects with focal brain damage. Subjects were asked to recognize facial expressions of six basic emotions: happiness, surprise, fear, anger, disgust, and sadness. Data were analyzed with a novel technique, based on three-dimensional reconstruction of brain images, in which anatomical description of surface lesions and task performance scores were jointly mapped onto a standard brain-space. We found that all subjects recognized happy expressions normally but that some subjects were impaired in recognizing negative emotions, especially fear and sadness. The cortical surface regions that best correlated with impaired recognition of emotion were in the right inferior parietal cortex and in the right mesial anterior infracalcarine cortex. We did not find impairments in recognizing any emotion in subjects with lesions restricted to the left hemisphere. These data provide evidence for a neural system important to processing facial expressions of some emotions, involving discrete visual and somatosensory cortical sectors in right hemisphere.