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DeCasien AR, Sherwood CC, Schapiro SJ, Higham JP. Greater variability in chimpanzee ( Pan troglodytes) brain structure among males. Proc Biol Sci 2020; 287:20192858. [PMID: 32315585 PMCID: PMC7211446 DOI: 10.1098/rspb.2019.2858] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/23/2020] [Indexed: 01/15/2023] Open
Abstract
Across the animal kingdom, males tend to exhibit more behavioural and morphological variability than females, consistent with the 'greater male variability hypothesis'. This may reflect multiple mechanisms operating at different levels, including selective mechanisms that produce and maintain variation, extended male development, and X chromosome effects. Interestingly, human neuroanatomy shows greater male variability, but this pattern has not been demonstrated in any other species. To address this issue, we investigated sex-specific neuroanatomical variability in chimpanzees by examining relative and absolute surface areas of 23 cortical sulci across 226 individuals (135F/91M), using permutation tests of the male-to-female variance ratio of residuals from MCMC generalized linear mixed models controlling for relatedness. We used these models to estimate sulcal size heritability, simulations to assess the significance of heritability, and Pearson correlations to examine inter-sulcal correlations. Our results show that: (i) male brain structure is relatively more variable; (ii) sulcal surface areas are heritable and therefore potentially subject to selection; (iii) males exhibit lower heritability values, possibly reflecting longer development; and (iv) males exhibit stronger inter-sulcal correlations, providing indirect support for sex chromosome effects. These results provide evidence that greater male neuroanatomical variability extends beyond humans, and suggest both evolutionary and developmental explanations for this phenomenon.
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Affiliation(s)
- Alex R. DeCasien
- Department of Anthropology, New York University, New York, NY, USA
- New York Consortium in Evolutionary Primatology, New York, NY, USA
| | - Chet C. Sherwood
- Department of Anthropology and Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, DC, USA
| | - Steven J. Schapiro
- Department of Comparative Medicine, The University of Texas MD Anderson Cancer Center, Bastrop, TX, USA
- Department of Experimental Medicine, The University of Copenhagen, Copenhagen, Denmark
| | - James P. Higham
- Department of Anthropology, New York University, New York, NY, USA
- New York Consortium in Evolutionary Primatology, New York, NY, USA
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Duffau H. A two-level model of interindividual anatomo-functional variability of the brain and its implications for neurosurgery. Cortex 2016; 86:303-313. [PMID: 26920729 DOI: 10.1016/j.cortex.2015.12.009] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 10/06/2015] [Accepted: 12/11/2015] [Indexed: 10/22/2022]
Abstract
The classical dogma of localizationism implicitly resulted in the principle of a similar brain functional anatomy between individuals, as for example the pars opercularis of the left "dominant" hemisphere corresponding to the speech area. This fixed "single brain" model led neurosurgeons to define a set of "eloquent" areas, for which injury would induce severe and persistent neurological worsening, making their surgical resections impossible. Therefore, numerous patients with a cerebral lesion justifying surgery were a priori not selected for resection and lost a chance to be treated. In fact, advances in brain mapping showed a considerable inter-individual variability explained by a networking organization of the brain, in which one function is not underpinned by one specific region, but by interactions between dynamic large-scale delocalized sub-circuits. Indeed, using non-invasive neuroimaging, a variability of both structural and functional anatomy was demonstrated in healthy volunteers. Moreover, intraoperative electrical stimulation mapping of cortex and white matter tracts in awake patients who underwent surgery for tumor or epilepsy also showed an important anatomo-functional variability. However, a remarkable observation is that this variability is huge at the cortical level, while it is very low at the subcortical level. Based upon these intrasurgical findings, the goal of this review is to propose a two-level model of inter-individual variability (high cortical variation, low subcortical variation), breaking with the traditional rigid workframe, and making neurosurgery in traditionally presumed "eloquent" areas feasible without permanent deficits, on condition nonetheless to preserve the "invariant common core" of the brain.
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Affiliation(s)
- Hugues Duffau
- Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France; National Institute for Health and Medical Research (INSERM), U1051 Laboratory, Team "Brain Plasticity, Stem Cells and Glial Tumors", Institute for Neurosciences of Montpellier, Montpellier University Medical Center, Montpellier, France.
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3
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Architectonic Mapping of the Human Brain beyond Brodmann. Neuron 2015; 88:1086-1107. [DOI: 10.1016/j.neuron.2015.12.001] [Citation(s) in RCA: 266] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 10/13/2015] [Accepted: 11/20/2015] [Indexed: 12/25/2022]
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4
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Seeing is not feeling: posterior parietal but not somatosensory cortex engagement during touch observation. J Neurosci 2015; 35:1468-80. [PMID: 25632124 DOI: 10.1523/jneurosci.3621-14.2015] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Observing touch has been reported to elicit activation in human primary and secondary somatosensory cortices and is suggested to underlie our ability to interpret other's behavior and potentially empathy. However, despite these reports, there are a large number of inconsistencies in terms of the precise topography of activation, the extent of hemispheric lateralization, and what aspects of the stimulus are necessary to drive responses. To address these issues, we investigated the localization and functional properties of regions responsive to observed touch in a large group of participants (n = 40). Surprisingly, even with a lenient contrast of hand brushing versus brushing alone, we did not find any selective activation for observed touch in the hand regions of somatosensory cortex but rather in superior and inferior portions of neighboring posterior parietal cortex, predominantly in the left hemisphere. These regions in the posterior parietal cortex required the presence of both brush and hand to elicit strong responses and showed some selectivity for the form of the object or agent of touch. Furthermore, the inferior parietal region showed nonspecific tactile and motor responses, suggesting some similarity to area PFG in the monkey. Collectively, our findings challenge the automatic engagement of somatosensory cortex when observing touch, suggest mislocalization in previous studies, and instead highlight the role of posterior parietal cortex.
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Li K, Langley J, Li Z, Hu XP. Connectomic profiles for individualized resting state networks and regions of interest. Brain Connect 2014; 5:69-79. [PMID: 25090040 DOI: 10.1089/brain.2014.0229] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Functional connectivity analysis of human brain resting state functional magnetic resonance imaging (rsfMRI) data and resultant functional networks, or RSNs, have drawn increasing interest in both research and clinical applications. A fundamental yet challenging problem is to identify distinct functional regions or regions of interest (ROIs) that have accurate functional correspondence across subjects. This article presents an algorithmic framework to identify ROIs of common RSNs at the individual level. It first employed a dual-sparsity dictionary learning algorithm to extract group connectomic profiles of ROIs and RSNs from noisy and high-dimensional fMRI data, with special attention to the well-known inter-subject variability in anatomy and then identified the ROIs of a given individual by employing both anatomic and group connectomic profile constraints using an energy minimization approach. Applications of this framework demonstrated that it can identify individualized ROIs of RSNs with superior performance over commonly used registration methods in terms of functional correspondence, and a test-retest study revealed that the framework is robust and consistent across both short-interval and long-interval repeated sessions of the same population. These results indicate that our framework can provide accurate substrates for individualized rsfMRI analysis.
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Affiliation(s)
- Kaiming Li
- 1 Huaxi MR Research Center, Huaxi Hospital of Sichuan University , Chengdu, China
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6
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Harnessing graphics processing units for improved neuroimaging statistics. COGNITIVE AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2014; 13:587-97. [PMID: 23625719 DOI: 10.3758/s13415-013-0165-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Simple models and algorithms based on restrictive assumptions are often used in the field of neuroimaging for studies involving functional magnetic resonance imaging, voxel based morphometry, and diffusion tensor imaging. Nonparametric statistical methods or flexible Bayesian models can be applied rather easily to yield more trustworthy results. The spatial normalization step required for multisubject studies can also be improved by taking advantage of more robust algorithms for image registration. A common drawback of algorithms based on weaker assumptions, however, is the increase in computational complexity. In this short overview, we will therefore present some examples of how inexpensive PC graphics hardware, normally used for demanding computer games, can be used to enable practical use of more realistic models and accurate algorithms, such that the outcome of neuroimaging studies really can be trusted.
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7
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In vivo imaging of the 18-kDa translocator protein (TSPO) with [18F]FEDAA1106 and PET does not show increased binding in Alzheimer’s disease patients. Eur J Nucl Med Mol Imaging 2013; 40:921-31. [DOI: 10.1007/s00259-013-2359-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 01/28/2013] [Indexed: 12/11/2022]
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8
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Rheu KH, Jahng GH, Ryu CW, Lim S. Investigation of the delayed neuronal effects of acupuncture manipulations. J Altern Complement Med 2012; 17:1021-7. [PMID: 22087612 DOI: 10.1089/acm.2010.0679] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
OBJECTIVES The aim of this study was to investigate the delayed neuronal effects of acupuncture manipulations by observing blood oxygen level-dependent (BOLD) signal intensities. SUBJECTS Fifteen (15) healthy, acupuncture-naive, right-handed subjects (all males; mean age, 23 years; range, 21-24 years) participated in this study. DESIGN AND INTERVENTIONS Each subject was scanned in eight sessions that consisted of two repeated baseline scans (Period 1), two repeated scans with acupuncture stimulation at right LR2 (Period 2), two repeated scans with retention (Period 3), and two repeated scans after removal of the needle (Period 4). OUTCOME MEASURES Sixteen (16) regions of interest (ROI) were defined. The BOLD signals for each session were obtained for each ROI. A mixed-effects analysis of variance (ANOVA) test was performed in order to investigate the BOLD signal differences of the Periods in the 16 ROIs. RESULTS The BOLD signal intensities increased in Periods 2 and 3, and then started to decrease in Period 4 in the right amygdala, supramarginal gyrus, temporal pole, and superior temporal gyrus. However, the BOLD signal intensity in Period 4 was significantly higher than that of Period 1. Especially, BOLD signal intensity was elevated promptly in the insula and the parahippocampal gyrus, whereas it was persistently elevated (delayed effect) in the amygdala. CONCLUSIONS BOLD signals were persistently elevated for at least 8 minutes after removal of the acupuncture needle or for at least 19 minutes after rotation of an acupuncture needle in some specific brain areas previously linked with LR2. In those specific brain ROIs, neuronal activation accompanying and following acupuncture showed both prompt and delayed effects.
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Affiliation(s)
- Kyoung-Hwan Rheu
- Department of Meridian and Acupuncture, Graduate School of Applied Eastern Medicine, Kyung Hee University, Seoul, Republic of Korea
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9
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Yamamoto H, Fukunaga M, Takahashi S, Mano H, Tanaka C, Umeda M, Ejima Y. Inconsistency and uncertainty of the human visual area loci following surface-based registration: Probability and Entropy Maps. Hum Brain Mapp 2011; 33:121-9. [PMID: 21438077 DOI: 10.1002/hbm.21200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Revised: 09/29/2011] [Accepted: 10/11/2011] [Indexed: 11/07/2022] Open
Abstract
Here we created two different multisubject maps (16 subjects) to characterize interindividual variability in the positions of human visual areas (V1, dorsal and ventral parts of V2/3, V3A, V3B, V7, LOc, MT+, and hV4 [or V4v and V8]), which were localized using fMRI and coregistered using a surface-based method. The first is a probability map representing the degree of alignment inconsistency for each area, in which each point in space is associated with the probability affiliated with a given area. The second, a novel map termed an entropy map in which each point is associated with Shannon entropy computed from the probabilities, represents the degree of uncertainty regarding the area that resides there, and is maximal when all areas are equally probable. The overall average probability and entropy values were about 0.27 and 1.15 bits, respectively, with dependencies on the visual areas. The probability and entropy maps generated here will benefit any application which requires predictions of areas that are most likely present at an anatomical point and know the uncertainty associated with such predictions.
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Affiliation(s)
- Hiroki Yamamoto
- Graduate School of Human and Environmental Studies, Kyoto University, Kyoto, Japan.
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10
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Schmitt O, Birkholz H. Improvement in cytoarchitectonic mapping by combining electrodynamic modeling with local orientation in high-resolution images of the cerebral cortex. Microsc Res Tech 2011; 74:225-43. [DOI: 10.1002/jemt.20897] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 05/28/2010] [Indexed: 11/11/2022]
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11
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Hinds O, Polimeni JR, Rajendran N, Balasubramanian M, Amunts K, Zilles K, Schwartz EL, Fischl B, Triantafyllou C. Locating the functional and anatomical boundaries of human primary visual cortex. Neuroimage 2009; 46:915-22. [PMID: 19328238 DOI: 10.1016/j.neuroimage.2009.03.036] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Revised: 03/05/2009] [Accepted: 03/10/2009] [Indexed: 10/21/2022] Open
Abstract
The primary visual cortex (V1) can be delineated both functionally by its topographic map of the visual field and anatomically by its distinct pattern of laminar myelination. Although it is commonly assumed that the specialized anatomy V1 exhibits corresponds in location with functionally defined V1, demonstrating this in human has not been possible thus far due to the difficulty of determining the location of V1 both functionally and anatomically in the same individual. In this study we use MRI to measure the anatomical and functional V1 boundaries in the same individual and demonstrate close agreement between them. Functional V1 location was measured by parcellating occipital cortex of 10 living humans into visual cortical areas based on the topographic map of the visual field measured using functional MRI. Anatomical V1 location was estimated for these same subjects using a surface-based probabilistic atlas derived from high-resolution structural MRI of the stria of Gennari in 10 intact ex vivo human hemispheres. To ensure that the atlas prediction was correct, it was validated against V1 location measured using an observer-independent cortical parcellation based on the laminar pattern of cell density in serial brain sections from 10 separate individuals. The close agreement between the independent anatomically and functionally derived V1 boundaries indicates that the whole extent of V1 can be accurately predicted based on cortical surface reconstructions computed from structural MRI scans, eliminating the need for functional localizers of V1. In addition, that the primary cortical folds predict the location of functional V1 suggests that the mechanism giving rise to V1 location is tied to the development of the cortical folds.
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Affiliation(s)
- Oliver Hinds
- Brain and Cognitive Sciences, Massachusetts Institute of Technology, USA.
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12
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Klein A, Andersson J, Ardekani BA, Ashburner J, Avants B, Chiang MC, Christensen GE, Collins DL, Gee J, Hellier P, Song JH, Jenkinson M, Lepage C, Rueckert D, Thompson P, Vercauteren T, Woods RP, Mann JJ, Parsey RV. Evaluation of 14 nonlinear deformation algorithms applied to human brain MRI registration. Neuroimage 2009; 46:786-802. [PMID: 19195496 DOI: 10.1016/j.neuroimage.2008.12.037] [Citation(s) in RCA: 1491] [Impact Index Per Article: 99.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 12/08/2008] [Accepted: 12/15/2008] [Indexed: 11/26/2022] Open
Abstract
All fields of neuroscience that employ brain imaging need to communicate their results with reference to anatomical regions. In particular, comparative morphometry and group analysis of functional and physiological data require coregistration of brains to establish correspondences across brain structures. It is well established that linear registration of one brain to another is inadequate for aligning brain structures, so numerous algorithms have emerged to nonlinearly register brains to one another. This study is the largest evaluation of nonlinear deformation algorithms applied to brain image registration ever conducted. Fourteen algorithms from laboratories around the world are evaluated using 8 different error measures. More than 45,000 registrations between 80 manually labeled brains were performed by algorithms including: AIR, ANIMAL, ART, Diffeomorphic Demons, FNIRT, IRTK, JRD-fluid, ROMEO, SICLE, SyN, and four different SPM5 algorithms ("SPM2-type" and regular Normalization, Unified Segmentation, and the DARTEL Toolbox). All of these registrations were preceded by linear registration between the same image pairs using FLIRT. One of the most significant findings of this study is that the relative performances of the registration methods under comparison appear to be little affected by the choice of subject population, labeling protocol, and type of overlap measure. This is important because it suggests that the findings are generalizable to new subject populations that are labeled or evaluated using different labeling protocols. Furthermore, we ranked the 14 methods according to three completely independent analyses (permutation tests, one-way ANOVA tests, and indifference-zone ranking) and derived three almost identical top rankings of the methods. ART, SyN, IRTK, and SPM's DARTEL Toolbox gave the best results according to overlap and distance measures, with ART and SyN delivering the most consistently high accuracy across subjects and label sets. Updates will be published on the http://www.mindboggle.info/papers/ website.
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Affiliation(s)
- Arno Klein
- New York State Psychiatric Institute, Columbia University, NY, NY 10032, USA.
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13
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Bezgin G, Wanke E, Krumnack A, Kötter R. Deducing logical relationships between spatially registered cortical parcellations under conditions of uncertainty. Neural Netw 2008; 21:1132-45. [DOI: 10.1016/j.neunet.2008.05.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 05/02/2008] [Accepted: 05/29/2008] [Indexed: 10/22/2022]
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14
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Hinds O, Polimeni JR, Rajendran N, Balasubramanian M, Wald LL, Augustinack JC, Wiggins G, Rosas HD, Fischl B, Schwartz EL. The intrinsic shape of human and macaque primary visual cortex. ACTA ACUST UNITED AC 2008; 18:2586-95. [PMID: 18308709 DOI: 10.1093/cercor/bhn016] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Previous studies have reported considerable variability in primary visual cortex (V1) shape in both humans and macaques. Here, we demonstrate that much of this variability is due to the pattern of cortical folds particular to an individual and that V1 shape is similar among individual humans and macaques as well as between these 2 species. Human V1 was imaged ex vivo using high-resolution (200 microm) magnetic resonance imaging at 7 T. Macaque V1 was identified in published histological serial section data. Manual tracings of the stria of Gennari were used to construct a V1 surface, which was computationally flattened with minimal metric distortion of the cortical surface. Accurate flattening allowed investigation of intrinsic geometric features of cortex, which are largely independent of the highly variable cortical folds. The intrinsic shape of V1 was found to be similar across human subjects using both nonparametric boundary matching and a simple elliptical shape model fit to the data and is very close to that of the macaque monkey. This result agrees with predictions derived from current models of V1 topography. In addition, V1 shape similarity suggests that similar developmental mechanisms are responsible for establishing V1 shape in these 2 species.
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Affiliation(s)
- Oliver Hinds
- Department of Cognitive and Neural Systems, Boston University, Boston, MA 02215, USA.
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15
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Abstract
The neocortex is an ultracomplex, six-layered structure that develops from the dorsal palliai sector of the telencephalic hemispheres (Figs. 2.24, 2.25, 11.1). All mammals, including monotremes and marsupials, possess a neocortex, but in reptiles, i.e. the ancestors of mammals, only a three-layered neocortical primordium is present [509, 511]. The term neocortex refers to its late phylogenetic appearance, in comparison to the “palaeocortical” olfactory cortex and the “archicortical” hippocampal cortex, both of which are present in all amniotes [509].
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16
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Hinds OP, Rajendran N, Polimeni JR, Augustinack JC, Wiggins G, Wald LL, Diana Rosas H, Potthast A, Schwartz EL, Fischl B. Accurate prediction of V1 location from cortical folds in a surface coordinate system. Neuroimage 2007; 39:1585-99. [PMID: 18055222 DOI: 10.1016/j.neuroimage.2007.10.033] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Revised: 09/04/2007] [Accepted: 10/18/2007] [Indexed: 10/22/2022] Open
Abstract
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.
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Affiliation(s)
- Oliver P Hinds
- Department of Cognitive and Neural Systems, Boston University, MA 02215, USA.
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17
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Caulo M, Briganti C, Mattei PA, Perfetti B, Ferretti A, Romani GL, Tartaro A, Colosimo C. New morphologic variants of the hand motor cortex as seen with MR imaging in a large study population. AJNR Am J Neuroradiol 2007; 28:1480-5. [PMID: 17846195 PMCID: PMC8134386 DOI: 10.3174/ajnr.a0597] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The hand motor cortex (HMC) has been classically described as having an omega or epsilon shape in axial-plane images obtained with CT and MR imaging. The aim of this study was to use MR imaging and Talairach normalization in a large sample population that was homogeneous for age and handedness to evaluate in a sex model a new classification with 5 morphologic variants of the HMC in the axial plane (omega, medially asymmetric epsilon, epsilon, laterally asymmetric epsilon, and null). MATERIALS AND METHODS Structural brain MR images were obtained from 257 right-handed healthy subjects (143 men and 114 women; mean age, 23.1 +/- 1.1 years) via a Talairach space transformed 3D magnetization-prepared rapid acquisition of gradient echo sequence. The frequencies of the different HMC variants were reported for hemisphere and sex. RESULTS The new variants of the HMC (medially asymmetric epsilon, laterally asymmetric epsilon, and null) were observed in 2.9%, 7.0%, and 1.8% of the hemispheres, respectively. Statistically significant sex differences were observed: The epsilon variant was twice as frequent in men, and an interhemispheric concordance for morphologic variants was observed only for women. CONCLUSION The large study population permitted the description of a new morphologic classification that included 3 new variants of the HMC. This new morphologic classification should facilitate the identification of the precentral gyrus in subsequent studies and in everyday practice.
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Affiliation(s)
- M Caulo
- Institute Advanced Biomedical Technologies of the Department of Clinical Sciences and Bioimaging, University G. d'Annunzio, Chieti, Italy.
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18
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Snyder HR, Feigenson K, Thompson-Schill SL. Prefrontal cortical response to conflict during semantic and phonological tasks. J Cogn Neurosci 2007; 19:761-75. [PMID: 17488203 DOI: 10.1162/jocn.2007.19.5.761] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Debates about the function of the prefrontal cortex are as old as the field of neuropsychology--often dated to Paul Broca's seminal work. Theories of the functional organization of the prefrontal cortex can be roughly divided into those that describe organization by process and those that describe organization by material. Recent studies of the function of the posterior, left inferior frontal gyrus (pLIFG) have yielded two quite different interpretations: One hypothesis holds that the pLIFG plays a domain-specific role in phonological processing, whereas another hypothesis describes a more general function of the pLIFG in cognitive control. In the current study, we distinguish effects of increasing cognitive control demands from effects of phonological processing. The results support the hypothesized role for the pLIFG in cognitive control, and more task-specific roles for posterior areas in phonology and semantics. Thus, these results suggest an alternative explanation of previously reported phonology-specific effects in the pLIFG.
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Gholipour A, Kehtarnavaz N, Briggs R, Devous M, Gopinath K. Brain functional localization: a survey of image registration techniques. IEEE TRANSACTIONS ON MEDICAL IMAGING 2007; 26:427-51. [PMID: 17427731 DOI: 10.1109/tmi.2007.892508] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Functional localization is a concept which involves the application of a sequence of geometrical and statistical image processing operations in order to define the location of brain activity or to produce functional/parametric maps with respect to the brain structure or anatomy. Considering that functional brain images do not normally convey detailed structural information and, thus, do not present an anatomically specific localization of functional activity, various image registration techniques are introduced in the literature for the purpose of mapping functional activity into an anatomical image or a brain atlas. The problems addressed by these techniques differ depending on the application and the type of analysis, i.e., single-subject versus group analysis. Functional to anatomical brain image registration is the core part of functional localization in most applications and is accompanied by intersubject and subject-to-atlas registration for group analysis studies. Cortical surface registration and automatic brain labeling are some of the other tools towards establishing a fully automatic functional localization procedure. While several previous survey papers have reviewed and classified general-purpose medical image registration techniques, this paper provides an overview of brain functional localization along with a survey and classification of the image registration techniques related to this problem.
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Affiliation(s)
- Ali Gholipour
- Electrical Engineering Department, University of Texas at Dallas, 2601 North Floyd Rd., Richardson, TX 75083, USA.
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20
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Toga AW, Thompson PM, Mori S, Amunts K, Zilles K. Towards multimodal atlases of the human brain. Nat Rev Neurosci 2006; 7:952-66. [PMID: 17115077 PMCID: PMC3113553 DOI: 10.1038/nrn2012] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Atlases of the human brain have an important impact on neuroscience. The emergence of ever more sophisticated imaging techniques, brain mapping methods and analytical strategies has the potential to revolutionize the concept of the brain atlas. Atlases can now combine data describing multiple aspects of brain structure or function at different scales from different subjects, yielding a truly integrative and comprehensive description of this organ. These integrative approaches have provided significant impetus for the human brain mapping initiatives, and have important applications in health and disease.
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Affiliation(s)
- Arthur W Toga
- Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Los Angeles, California, USA.
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21
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Thirion B, Flandin G, Pinel P, Roche A, Ciuciu P, Poline JB. Dealing with the shortcomings of spatial normalization: multi-subject parcellation of fMRI datasets. Hum Brain Mapp 2006; 27:678-93. [PMID: 16281292 PMCID: PMC6871283 DOI: 10.1002/hbm.20210] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The analysis of functional magnetic resonance imaging (fMRI) data recorded on several subjects resorts to the so-called spatial normalization in a common reference space. This normalization is usually carried out on a voxel-by-voxel basis, assuming that after coregistration of the functional images with an anatomical template image in the Talairach reference system, a correct voxel-based inference can be carried out across subjects. Shortcomings of such approaches are often dealt with by spatially smoothing the data to increase the overlap between subject-specific activated regions. This procedure, however, cannot adapt to each anatomo-functional subject configuration. We introduce a novel technique for intra-subject parcellation based on spectral clustering that delineates homogeneous and connected regions. We also propose a hierarchical method to derive group parcels that are spatially coherent across subjects and functionally homogeneous. We show that we can obtain groups (or cliques) of parcels that well summarize inter-subject activations. We also show that the spatial relaxation embedded in our procedure improves the sensitivity of random-effect analysis.
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Affiliation(s)
- Bertrand Thirion
- Service Hospitalier Frédéric Joliot, Département de Recherche Médicale-CEA-DSV-UNAF, Orsay Cedex, France.
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Klein A, Hirsch J. Mindboggle: a scatterbrained approach to automate brain labeling. Neuroimage 2005; 24:261-80. [PMID: 15627570 DOI: 10.1016/j.neuroimage.2004.09.016] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2003] [Revised: 09/16/2004] [Accepted: 09/17/2004] [Indexed: 12/01/2022] Open
Abstract
Mindboggle (http://www.binarybottle.com/mindboggle.html) is a fully automated, feature matching approach to label cortical structures and activity anatomically in human brain MRI data. This approach does not assume that the existence of component structures and their relative spatial relationship is preserved from brain to brain, but instead disassembles a labeled atlas and reassembles its pieces to match corresponding pieces in an unlabeled subject brain before labeling. Mindboggle: (1) converts linearly coregistered subject and atlas MRI data into sulcus pieces, (2) matches each atlas piece with a combination of subject pieces by minimizing a cost function, (3) transforms atlas label boundaries to the matching subject pieces, (4) warps atlas labels to their transformed boundaries, and (5) propagates labels to fill remaining gaps in a mask derived from the subject brain. We compared Mindboggle with four registration methods: linear registration, and nonlinear registration using SPM2, AIR, and ANIMAL. Automated labeling by all of the nonlinear methods was found to be at least comparable with linear registration. Mindboggle outperformed every other method, as measured by the agreement between overlapping atlas labels and manually assigned subject labels, with respect to the union or the intersection of voxels. After applying the same procedure that Mindboggle uses to fill a subject's segmented gray matter mask with labels (step 5), the results of the other methods improved. However, after performing a one-way ANOVA (and Tukey's honestly significant difference criterion) in a multiple comparison between the results obtained by the different methods, Mindboggle was still found to be the only nonlinear method whose labeling performance was significantly better than that of linear registration or SPM2. Further advantages to Mindboggle include a high degree of robustness against image artifacts, poor image quality, and incomplete brain data. We tested the latter hypothesis by conducting all of the tests again, this time registering the atlas to an artificially lesioned version of itself, and found that Mindboggle was the only method whose performance did not degrade significantly as the lesion size increased.
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Affiliation(s)
- Arno Klein
- fMRI Research Center, Columbia University, New York 10032, USA.
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23
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Régis J, Mangin JF, Ochiai T, Frouin V, Riviére D, Cachia A, Tamura M, Samson Y. "Sulcal Root" Generic Model: a Hypothesis to Overcome the Variability of the Human Cortex Folding Patterns. Neurol Med Chir (Tokyo) 2005; 45:1-17. [PMID: 15699615 DOI: 10.2176/nmc.45.1] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The great variability of cerebral cortical folding patterns raises major problems for the systematic study of functional-structural relationships. This paper describes a novel perspective for explaining this variability, a perspective that relies on gyri buried in the depth of the sulci. From this perspective we propose a generic model of folding, based on indivisible units, called sulcal roots, which correspond to the first folding locations during antenatal life. These units are organized according to a basic scheme allowing us to describe the cortical surface using a system of meridians and parallels. This scheme is thought to be stable across individuals at the fetal stage, and may be related to the protomap model. Variability at the adult stage is thought to result from the chaotic behavior of the folding process: inter-individual differences in cortical areas can lead to qualitatively different folding patterns. We have tested the capacity of this model to match actual cortical anatomy with a database of magnetic resonance images of 20 normal subjects, using new three-dimensional visualization tools giving access to shapes buried in the cortex.
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Affiliation(s)
- Jean Régis
- Stereotactic and Functional Neurosurgery Department, Timone Hospital, A.P.M., Marseille, France.
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Mangin JF, Rivière D, Coulon O, Poupon C, Cachia A, Cointepas Y, Poline JB, Le Bihan D, Régis J, Papadopoulos-Orfanos D. Coordinate-based versus structural approaches to brain image analysis. Artif Intell Med 2004; 30:177-97. [PMID: 14992763 DOI: 10.1016/s0933-3657(03)00064-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2002] [Revised: 04/27/2003] [Accepted: 05/06/2003] [Indexed: 11/27/2022]
Abstract
A basic issue in neurosciences is to look for possible relationships between brain architecture and cognitive models. The lack of architectural information in magnetic resonance images, however, has led the neuroimaging community to develop brain mapping strategies based on various coordinate systems without accurate architectural content. Therefore, the relationships between architectural and functional brain organizations are difficult to study when analyzing neuroimaging experiments. This paper advocates that the design of new brain image analysis methods inspired by the structural strategies often used in computer vision may provide better ways to address these relationships. The key point underlying this new framework is the conversion of the raw images into structural representations before analysis. These representations are made up of data-driven elementary features like activated clusters, cortical folds or fiber bundles. Two classes of methods are introduced. Inference of structural models via matching across a set of individuals is described first. This inference problem is illustrated by the group analysis of functional statistical parametric maps (SPMs). Then, the matching of new individual data with a priori known structural models is described, using the recognition of the cortical sulci as a prototypical example.
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Affiliation(s)
- J-F Mangin
- Service Hospitalier Frédéric Joliot, CEA, Orsay, France.
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25
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Momenan R, Rawlings R, Fong G, Knutson B, Hommer D. Voxel-based homogeneity probability maps of gray matter in groups: assessing the reliability of functional effects. Neuroimage 2004; 21:965-72. [PMID: 15006663 DOI: 10.1016/j.neuroimage.2003.10.038] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2003] [Revised: 10/23/2003] [Accepted: 10/29/2003] [Indexed: 11/24/2022] Open
Abstract
A subject of increasing importance in magnetic resonance imaging (MRI) is the analysis of intersubject structural differences, particularly when comparing groups of subjects with different conditions or diagnoses. On the other hand, determining structural homogeneity across subjects using voxel-based morphological (VBM) methods has become even more important to investigators who test for group brain activation using functional magnetic resonance images (fMRI) or positron emission tomography (PET). In the absence of methods that evaluate structural differences, one does not know how much reliability to assign to the functional differences. Here, we describe a voxel-based method for quantitatively assessing the homogeneity of tissues from structural magnetic resonance images of groups. Specifically, this method determines the homogeneity of gray matter for a group of subjects. Homogeneity probability maps (HPMs) of a given tissue type (e.g., gray matter) are generated by using a confidence interval based on binomial distribution. These maps indicate for each voxel the probability that the tissue type is gray for the population being studied. Therefore, HPMs can accompany functional analyses to indicate the confidence one can assign to functional difference at any given voxel. In this paper, examples of HPMs generated for a group of control subjects are shown and discussed. The application of this method to functional analysis is demonstrated.
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Affiliation(s)
- Reza Momenan
- Section for Brain Electrophysiology and Imaging, LCS, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892-1256, USA.
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26
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Annese J, Pitiot A, Dinov ID, Toga AW. A myelo-architectonic method for the structural classification of cortical areas. Neuroimage 2004; 21:15-26. [PMID: 14741638 DOI: 10.1016/j.neuroimage.2003.08.024] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We describe an automatic and reproducible method to analyze the histological design of the cerebral cortex as applied to brain sections stained to reveal myelinated fibers. The technique provides an evaluation of the distribution of myelination across the width of the cortical mantle in accordance with a model of its curvature and its intrinsic geometry. The profile lines along which the density of staining is measured are generated from the solution of a partial differential equation (PDE) that models the intermediate layers of the cortex. Cortical profiles are classified according to significant components that emerge from wavelet analysis. Intensity profiles belonging to each distinct class are normalized and averaged to produce area-specific templates of cortical myelo-architecture.
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Affiliation(s)
- J Annese
- Laboratory of Neuro Imaging, Department of Neurology, UCLA School of Medicine, Los Angeles, CA 90095-1769, USA
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27
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Ehrsson HH, Geyer S, Naito E. Imagery of Voluntary Movement of Fingers, Toes, and Tongue Activates Corresponding Body-Part-Specific Motor Representations. J Neurophysiol 2003; 90:3304-16. [PMID: 14615433 DOI: 10.1152/jn.01113.2002] [Citation(s) in RCA: 382] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigate whether imagery of voluntary movements of different body parts activates somatotopical sections of the human motor cortices. We used functional magnetic resonance imaging to detect the cortical activity when 7 healthy subjects imagine performing repetitive (0.5-Hz) flexion/extension movements of the right fingers or right toes, or horizontal movements of the tongue. We also collected functional images when the subjects actually executed these movements and used these data to define somatotopical representations in the motor areas. In this study, we relate the functional activation maps to cytoarchitectural population maps of areas 4a, 4p, and 6 in the same standard anatomical space. The important novel findings are 1) that imagery of hand movements specifically activates the hand sections of the contralateral primary motor cortex (area 4a) and the contralateral dorsal premotor cortex (area 6) and a hand representation located in the caudal cingulate motor area and the most ventral part of the supplementary motor area; 2) that when imagining making foot movements, the foot zones of the posterior part of the contralateral supplementary motor area (area 6) and the contralateral primary motor cortex (area 4a) are active; and 3) that imagery of tongue movements activates the tongue region of the primary motor cortex and the premotor cortex bilaterally (areas 4a, 4p, and 6). These results demonstrate that imagery of action engages the somatotopically organized sections of the primary motor cortex in a systematic manner as well as activating some body-part-specific representations in the nonprimary motor areas. Thus the content of the mental motor image, in this case the body part, is reflected in the pattern of motor cortical activation.
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Affiliation(s)
- H Henrik Ehrsson
- Department of Neuroscience and Motor Control Laboratory, Karolinska Institutet, S-17176 Stockholm, Sweden.
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28
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Crum WR, Griffin LD, Hill DLG, Hawkes DJ. Zen and the art of medical image registration: correspondence, homology, and quality. Neuroimage 2003; 20:1425-37. [PMID: 14642457 DOI: 10.1016/j.neuroimage.2003.07.014] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Nonrigid registration (NRR) is routinely used in the study of neuroanatomy and function and is a standard component of analysis packages such as SPM. There remain many unresolved correspondence problems that arise from attempts to associate functional areas with specific neuroanatomy and to compare both function and anatomy across patient groups. Problems can result from ignorance of the underlying neurology which is then compounded by unjustified inferences drawn from the results of NRR. Usually the magnitude, distribution, and significance of errors in NRR are unknown so the errors in correspondences determined by NRR are also unknown and their effect on experimental results cannot easily be quantified. In this paper we review the principles by which the presumed correspondence and homology of structures is used to drive registration and identify the conceptual and algorithmic areas where current techniques are lacking. We suggest that for applications using NRR to be robust and achieve their potential, context-specific definitions of correspondence must be developed which properly characterise error. Prior knowledge of image content must be utilised to monitor and guide registration and gauge the degree of success. The use of NRR in voxel-based morphometry is examined from this context and found wanting. We conclude that a move away from increasingly sophisticated but context-free registration technology is required and that the veracity of studies that rely on NRR should be keenly questioned when the error distribution is unknown and the results are unsupported by other contextual information.
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Affiliation(s)
- W R Crum
- Division of Imaging Sciences, The Guy's King's and St. Thomas' School of Medicine, London SE1 9RT, UK.
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29
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Dumoulin SO, Hoge RD, Baker CL, Hess RF, Achtman RL, Evans AC. Automatic volumetric segmentation of human visual retinotopic cortex. Neuroimage 2003; 18:576-87. [PMID: 12667835 DOI: 10.1016/s1053-8119(02)00058-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Previous identification of early visual cortical areas in humans with phase-encoded retinotopic mapping techniques have relied on an accurate cortical surface reconstruction. Here a 3D phase-encoded retinotopic mapping technique that does not require a reconstruction of the cortical surface is demonstrated. The visual field sign identification is completely automatic and the method directly supplies volumes for a region-of-interest analysis, facilitating the application of cortical mapping to a wider population. A validation of the method is provided by simulations and comparison to cortical surface-based methodology.
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Affiliation(s)
- Serge O Dumoulin
- Department of Ophthalmology, McGill University, Montréal, Québec, Canada.
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30
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Robbins S, Evans AC, Collins DL, Whitesides S. Tuning and Comparing Spatial Normalization Methods. LECTURE NOTES IN COMPUTER SCIENCE 2003. [DOI: 10.1007/978-3-540-39903-2_111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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31
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Crivello F, Schormann T, Tzourio-Mazoyer N, Roland PE, Zilles K, Mazoyer BM. Comparison of spatial normalization procedures and their impact on functional maps. Hum Brain Mapp 2002; 16:228-50. [PMID: 12112765 PMCID: PMC6871934 DOI: 10.1002/hbm.10047] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The alignment accuracy and impact on functional maps of four spatial normalization procedures have been compared using a set of high resolution brain MRIs and functional PET volumes acquired in 20 subjects. Simple affine (AFF), fifth order polynomial warp (WRP), discrete cosine basis functions (SPM), and a movement model based on full multi grid (FMG) approaches were applied on the same dataset for warping individual volumes onto the Human Brain Atlas (HBA) template. Intersubject averaged structural volumes and tissue probability maps were compared across normalization methods and to the standard brain. Thanks to the large number of degrees of freedom of the technique, FMG was found to provide enhanced alignment accuracy as compared to the other three methods, both for the grey and white matter tissues; WRP and SPM exhibited very similar performances whereas AFF had the lowest registration accuracy. SPM, however, was found to perform better than the other methods for the intra-cerebral cerebrospinal fluid (mainly in the ventricular compartments). Limited differences in terms of activation morphology and detection sensitivity were found between low resolution functional maps (FWHM approximately 10 mm) spatially normalized with the four methods, which overlapped in 42.8% of the total activation volume. These findings suggest that the functional variability is much larger than the anatomical one and that precise alignment of anatomical features has low influence on the resulting intersubject functional maps. When increasing the spatial resolution to approximately 6 mm, however, differences in localization of activated areas appear as a consequence of the different spatial normalization procedure used, restricting the overlap of the normalized activated volumes to only 6.2%.
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Affiliation(s)
- Fabrice Crivello
- Groupe d'Imagerie Neurofonctionnelle, UMR 6095, CNRS-CEA LRC36V Université de Caen & Paris 5, Caen, France.
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32
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Brett M, Johnsrude IS, Owen AM. The problem of functional localization in the human brain. Nat Rev Neurosci 2002; 3:243-9. [PMID: 11994756 DOI: 10.1038/nrn756] [Citation(s) in RCA: 839] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Functional imaging gives us increasingly detailed information about the location of brain activity. To use this information, we need a clear conception of the meaning of location data. Here, we review methods for reporting location in functional imaging and discuss the problems that arise from the great variability in brain anatomy between individuals. These problems cause uncertainty in localization, which limits the effective resolution of functional imaging, especially for brain areas involved in higher cognitive function.
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Affiliation(s)
- Matthew Brett
- MRC Cognition and Brain Sciences Unit, Cambridge, UK.
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33
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Davatzikos C, Bryan RN. Morphometric analysis of cortical sulci using parametric ribbons: a study of the central sulcus. J Comput Assist Tomogr 2002; 26:298-307. [PMID: 11884791 DOI: 10.1097/00004728-200203000-00024] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Interhemispheric and gender differences of the central sulcus were examined via a parametric ribbon approach. The central sulcus was found to be deeper and larger in the right nondominant hemisphere than in the left dominant hemisphere, both in males and in females. Based on its pattern, that asymmetry could be attributed to increased connectivity between motor and somatosensory cortex, facilitating fine movement, which could constrain the in-depth growth of the central sulcus. Position asymmetries were also found, which might be explained by a relative larger parietal association cortex in men but not in women.
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Affiliation(s)
- Christos Davatzikos
- Center for Biomedical Image Computing, Department of Radiology, Johns Hopkins University, Baltimore, MD 21287, USA.
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34
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Fink GR, Marshall JC, Weiss PH, Toni I, Zilles K. Task instructions influence the cognitive strategies involved in line bisection judgements: evidence from modulated neural mechanisms revealed by fMRI. Neuropsychologia 2002; 40:119-30. [PMID: 11640935 DOI: 10.1016/s0028-3932(01)00087-2] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Manual line bisection and a perceptual variant thereof (the Landmark test) are widely used to assess visuospatial neglect in neurological patients, but little is known about the cognitive strategies involved. In the Landmark test, one could explicitly compare the lengths of the left and right line segments; alternatively, one could compute the centre of mass of the display. We here investigate with functional MRI if these cognitive strategies modulate the neural mechanisms underlying judgements whether pre-transected horizontal lines are correctly bisected (the Landmark test) in normal volunteers. Functional neuroimaging (fMRI) was carried out in 12 healthy volunteers who judged: (a) whether the line segments on either side of the transection mark were of equal length, and (b) whether the transection mark was in the centre of the line. Line centre judgements were made significantly faster than line length comparisons. Increased neural activity common to both strategies was observed in inferior parietal lobes bilaterally and right temporooccipital cortex. Further activations, most likely reflecting general task demands like response selection and motor control, were found in the precentral gyrus bilaterally, supplementary motor area bilaterally, right anterior cingulate, right dorsolateral prefrontal cortex, cerebellar vermis, and right thalamus and right putamen. Explicit length comparisons (relative to line centre judgements) differentially activated left superior posterior parietal cortex, with a tendency toward activation of the equivalent area on the right, while the reverse comparison revealed differential activation in the lingual gyrus bilaterally and anterior cingulate cortex. The activations observed in inferior parietal cortex during task performance using either strategy are consistent with the results of lesion studies. The differential activation of superior posterior parietal cortex following length instructions suggests that explicit comparisons of spatial extent were implicated. The differential activation of bilateral occipital cortex following centre judgements suggests that the centre of a line is extracted at an early stage of visual processing.
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Affiliation(s)
- G R Fink
- Institute of Medicine, Forschungszentrum Jülich, 52425, Jülich, Germany.
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35
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Grefkes C, Geyer S, Schormann T, Roland P, Zilles K. Human somatosensory area 2: observer-independent cytoarchitectonic mapping, interindividual variability, and population map. Neuroimage 2001; 14:617-31. [PMID: 11506535 DOI: 10.1006/nimg.2001.0858] [Citation(s) in RCA: 280] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We analyzed the topographical variability of human somatosensory area 2 in 10 postmortem brains. The brains were serially sectioned at 20 microm, and sections were stained for cell bodies. Area 2 was delineated with an observer-independent technique based on significant differences in the laminar densities of cell bodies. The sections were corrected with an MR scan of the same brain obtained before histological processing. Each brain's histological volume and representation of area 2 was subsequently reconstructed in 3-D. We found that the borders of area 2 are topographically variable. The rostral border lies between the convexity of the postcentral gyrus and some millimeters deep in the rostral wall of the postcentral sulcus. The caudal border lies between the fundus of the postcentral sulcus and some millimeters above it in the rostral wall. In contrast to Brodmann's map, area 2 does not extend onto the mesial cortical surface or into the intraparietal sulcus. When the postcentral sulcus is interrupted by a gyral bridge, area 2 crosses this bridge and is not separated into two segments. After cytoarchitectonic analysis, the histological volumes were warped to the reference brain of a computerized atlas and superimposed. A population map was generated in 3-D space, which describes how many brains have a representation of area 2 in a particular voxel. This microstructurally defined population map can be used to demonstrate activations of area 2 in functional imaging studies and therefore help to further understand the role of area 2 in somatosensory processing.
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Affiliation(s)
- C Grefkes
- C. and O. Vogt Brain Research Institute, University of Düsseldorf, 40001 Düsseldorf, Germany
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36
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Fink GR, Marshall JC, Weiss PH, Zilles K. The neural basis of vertical and horizontal line bisection judgments: an fMRI study of normal volunteers. Neuroimage 2001; 14:S59-67. [PMID: 11373134 DOI: 10.1006/nimg.2001.0819] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Bisection of horizontal lines is used as a clinical test of spatial cognition in patients with left visuospatial neglect after right hemisphere lesions. Bisection of vertical lines has also been employed, albeit less frequently. Interestingly, normal subjects often bisect horizontal lines too far left and vertical lines too high. We used fMRI to investigate whether vertical/horizontal stimulus orientation interacts with the neural mechanisms associated with line bisection judgments (the Landmark task). For control of orientation per se, subjects performed a visual detection task with the same stimuli. Statistical analysis of evoked BOLD responses employed SPM99. The Landmark task increased neural activity (P < 0.05, corrected) in the superior and inferior parietal lobes bilaterally, though predominantly on the right; early visual processing areas bilaterally; and cerebellar vermis, left cerebellar hemisphere, anterior cingulate, and prefrontal cortex bilaterally. Vertical lines (relative to horizontal lines and vice versa) increased neural activity in early visual processing areas, consistent with differential retinotopic stimulation. In addition, vertical lines activated right parietooccipital and superior posterior parietal cortex bilaterally. No significant interactions between the neural mechanisms associated with task and stimuli were observed. Increased neural activation in parietal and parietooccipital cortex associated with vertical lines may reflect increased attentional demands associated with this stimulus orientation. The right hemispheric dominance observed in posterior parietal during the Landmark task irrespective of stimulus orientation is consistent with lesion studies. Our results suggest that the behavioral patterns observed in normal subjects and neurological patients result from different stimulus effects rather than differential task demands.
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Affiliation(s)
- G R Fink
- Institute of Medicine, Forschungszentrum Jülich, Jülich, 52425, Germany.
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37
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Zilles K, Palomero-Gallagher N. Cyto-, Myelo-, and Receptor Architectonics of the Human Parietal Cortex. Neuroimage 2001; 14:S8-20. [PMID: 11373127 DOI: 10.1006/nimg.2001.0823] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Various cyto- and myeloarchitectonic maps of the human parietal cortex have been published since the beginning of the past century. However, the parietal lobe remains an uncharted region, since these anatomical findings fail to explain the much greater areal differentiation, especially in the posterior parietal cortex, which has recently been revealed by functional imaging studies. This lack of congruence does not imply a total lack of correspondence between anatomical and functional data, since several practically forgotten architectonic studies published during the first 5 decades of the past century demonstrate a much more differentiated map of the parietal cortex than the popular map of Brodmann and others. Moreover, recent receptor-architectonic studies also demonstrate a detailed architectonic pattern the functional aspects of which will be explored in the near future.
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Affiliation(s)
- K Zilles
- Institute of Medicine, Research Center Jülich, Jülich, D-52425, Germany.
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38
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Ehrsson HH, Fagergren E, Forssberg H. Differential fronto-parietal activation depending on force used in a precision grip task: an fMRI study. J Neurophysiol 2001; 85:2613-23. [PMID: 11387405 DOI: 10.1152/jn.2001.85.6.2613] [Citation(s) in RCA: 228] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recent functional magnetic resonance imaging (fMRI) studies suggest that the control of fingertip forces between the index finger and the thumb (precision grips) is dependent on bilateral frontal and parietal regions in addition to the primary motor cortex contralateral to the grasping hand. Here we use fMRI to examine the hypothesis that some of the areas of the brain associated with precision grips are more strongly engaged when subjects generate small grip forces than when they employ large grip forces. Subjects grasped a stationary object using a precision grip and employed a small force (3.8 N) that was representative of the forces that are typically used when manipulating small objects with precision grips in everyday situations or a large force (16.6 N) that represents a somewhat excessive force compared with normal everyday usage. Both force conditions involved the generation of time-variant static and dynamic grip forces under isometric conditions guided by auditory and tactile cues. The main finding was that we observed stronger activity in the bilateral cortex lining the inferior part of the precentral sulcus (area 44/ventral premotor cortex), the rostral cingulate motor area, and the right intraparietal cortex when subjects applied a small force in comparison to when they generated a larger force. This observation suggests that secondary sensorimotor related areas in the frontal and parietal lobes play an important role in the control of fine precision grip forces in the range typically used for the manipulation of small objects.
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Affiliation(s)
- H H Ehrsson
- Motor Control Laboratory, Department of Woman and Child Health, Karolinska Institutet, Stockhom, Sweden.
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39
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Fink GR, Marshall JC, Weiss PH, Shah NJ, Toni I, Halligan PW, Zilles K. 'Where' depends on 'what': a differential functional anatomy for position discrimination in one- versus two-dimensions. Neuropsychologia 2001; 38:1741-8. [PMID: 11099732 DOI: 10.1016/s0028-3932(00)00078-6] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Line bisection is widely used as a clinical test of spatial cognition in patients with left visuospatial neglect after right hemisphere lesion. Surprisingly, many neglect patients who show severe impairment on marking the center of horizontal lines can accurately mark the center of squares. That these patients with left neglect are also typically poor at judging whether lines are correctly prebisected implies that the deficit can be perceptual rather than motoric. These findings suggest a differential neural basis for one- and two-dimensional visual position discrimination that we investigated with functional neuroimaging (fMRI). Normal subjects judged whether, in premarked lines or squares, the mark was placed centrally. Line center judgements differentially activated right parietal cortex, while square center judgements differentially activated the lingual gyrus bilaterally. These distinct neural bases for one- and two-dimensional visuospatial judgements help explain the observed clinical dissociations by showing that as a stimulus becomes a better, more 'object-like' gestalt, the ventral visuoperceptive route assumes more responsibility for assessing position within the object.
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Affiliation(s)
- G R Fink
- Neurologische Klinik, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.
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40
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Zilles K, Kawashima R, Dabringhaus A, Fukuda H, Schormann T. Hemispheric shape of European and Japanese brains: 3-D MRI analysis of intersubject variability, ethnical, and gender differences. Neuroimage 2001; 13:262-71. [PMID: 11162267 DOI: 10.1006/nimg.2000.0688] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hemispheric shape is studied using magnetic resonance imaging and 3-D reconstructions in right-handed, male and female, European and Japanese subjects. Japanese hemispheres are relatively shorter, but wider than European hemispheres. Regions of maximal intersubject variability in hemispheric shape are present in the occipital and temporal lobes in each sample. Deviations from this general pattern are found in the (i) right inferior parietal lobule (European hemispheres are more variable than Japanese), (ii) lower third of the pre- and postcentral gyri (female Japanese hemispheres are less variable than the other samples), (iii) right inferior frontal gyrus (male European hemispheres are more variable than the other samples), and (iv) polar part of the frontal lobe (female European hemispheres are less variable than the other samples). The distribution of intersubject variability between the hemispheres is less asymmetric in female than male brains. Male Japanese hemispheres are shorter but wider than female Japanese hemispheres, whereas European hemispheres show the inverse gender relations. These results demonstrate that hemispheric shape shows a considerable intersubject variability, which is not randomly distributed over the cortical surface but displays distinct regions of higher variability. Despite this intersubject variability significant interethnic- and gender-related differences in hemispheric shape are present, which may be relevant if individual brains have to be warped to a single or mean reference brain or realistic brain models are to be constructed.
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Affiliation(s)
- K Zilles
- C. & O. Vogt Institute of Brain Research and Institute of Neuroanatomy, University of Duesseldorf, P.O. Box 101007, D-40001 Duesseldorf, Germany
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41
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Baillet S, Riera JJ, Marin G, Mangin JF, Aubert J, Garnero L. Evaluation of inverse methods and head models for EEG source localization using a human skull phantom. Phys Med Biol 2001; 46:77-96. [PMID: 11197680 DOI: 10.1088/0031-9155/46/1/306] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We used a real-skull phantom head to investigate the performances of representative methods for EEG source localization when considering various head models. We describe several experiments using a montage with current sources located at multiple positions and orientations inside a human skull filled with a conductive medium. The robustness of selected methods based on distributed source models is evaluated as various solutions to the forward problem (from the sphere to the finite element method) are considered. Experimental results indicate that inverse methods using appropriate cortex-based source models are almost always able to locate the active source with excellent precision, with little or no spurious activity in close or distant regions, even when two sources are simultaneously active. Superior regularization schemes for solving the inverse problem can dramatically help the estimation of sparse and focal active zones, despite significant approximation of the head geometry and the conductivity properties of the head tissues. Realistic head models are necessary, though, to fit the data with a reasonable level of residual variance.
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Affiliation(s)
- S Baillet
- Cognitive Neuroscience and Brain Imaging Laboratory, CNRS UPR640-LENA, H pital de la Salpêtrière, Paris, France.
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Lancaster JL, Woldorff MG, Parsons LM, Liotti M, Freitas CS, Rainey L, Kochunov PV, Nickerson D, Mikiten SA, Fox PT. Automated Talairach atlas labels for functional brain mapping. Hum Brain Mapp 2000. [PMID: 10912591 DOI: 10.1002/1097-0193(200007)10:3<120::aid-hbm30>3.0.co;2-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
An automated coordinate-based system to retrieve brain labels from the 1988 Talairach Atlas, called the Talairach Daemon (TD), was previously introduced [Lancaster et al., 1997]. In the present study, the TD system and its 3-D database of labels for the 1988 Talairach atlas were tested for labeling of functional activation foci. TD system labels were compared with author-designated labels of activation coordinates from over 250 published functional brain-mapping studies and with manual atlas-derived labels from an expert group using a subset of these activation coordinates. Automated labeling by the TD system compared well with authors' labels, with a 70% or greater label match averaged over all locations. Author-label matching improved to greater than 90% within a search range of +/-5 mm for most sites. An adaptive grey matter (GM) range-search utility was evaluated using individual activations from the M1 mouth region (30 subjects, 52 sites). It provided an 87% label match to Brodmann area labels (BA 4 & BA 6) within a search range of +/-5 mm. Using the adaptive GM range search, the TD system's overall match with authors' labels (90%) was better than that of the expert group (80%). When used in concert with authors' deeper knowledge of an experiment, the TD system provides consistent and comprehensive labels for brain activation foci. Additional suggested applications of the TD system include interactive labeling, anatomical grouping of activation foci, lesion-deficit analysis, and neuroanatomy education.
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Affiliation(s)
- J L Lancaster
- Research Imaging Center, University of Texas Health Science Center at San Antonio,78284, USA.
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43
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Schleicher A, Amunts K, Geyer S, Kowalski T, Schormann T, Palomero-Gallagher N, Zilles K. A stereological approach to human cortical architecture: identification and delineation of cortical areas. J Chem Neuroanat 2000; 20:31-47. [PMID: 11074342 DOI: 10.1016/s0891-0618(00)00076-4] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Stereology offers a variety of procedures to analyze quantitatively the regional and laminar organization in cytoarchitectonically defined areas of the human cerebral cortex. Conventional anatomical atlases are of little help in localizing specific cortical areas, since most of them are based on a single brain and use highly observer-dependent criteria for the delineation of cortical areas. In consequence, numerous cortical maps exist which greatly differ with respect to number, position, size and extent of cortical areas. We describe a novel algorithm-based procedure for the delineation of cortical areas, which exploits the automated estimation of volume densities of cortical cell bodies. Spatial sampling of the laminar pattern is performed with density profiles, followed by multivariate analysis of the profiles' shape, which locates the cytoarchitectonic borders between neighboring cortical areas at sites where the laminar pattern changes significantly. The borders are then mapped to a human brain atlas system comprising tools for three dimensional reconstruction, visualization and morphometric analysis. A sample of brains with labeled cortical areas is warped into the reference brain of the atlas system in order to generate a population map of the cortical areas, which describes the intersubject variability in spatial conformation of cortical areas. These population maps provide a novel tool for the interpretation of images obtained with functional imaging techniques.
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Affiliation(s)
- A Schleicher
- C.&O. Vogt Institute of Brain Research, University of Düsseldorf, PO Box 101007, D-40001, Düsseldorf, Germany.
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44
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Ehrsson HH, Naito E, Geyer S, Amunts K, Zilles K, Forssberg H, Roland PE. Simultaneous movements of upper and lower limbs are coordinated by motor representations that are shared by both limbs: a PET study. Eur J Neurosci 2000; 12:3385-98. [PMID: 10998121 DOI: 10.1046/j.1460-9568.2000.00209.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The purpose of this study was to examine the cerebral control of simultaneous movements of the upper and lower limbs. We examined two hypotheses on how the brain coordinates movement: (i) by the involvement of motor representations shared by both limbs; or (ii) by the engagement of specific neural populations. We used positron emission tomography to measure the relative cerebral blood flow in healthy subjects performing isolated cyclic flexion-extension movements of the wrist and ankle (i.e. movements of wrist or ankle alone), and simultaneous movements of the wrist and ankle (a rest condition was also included). The simultaneous movements were performed in the same directions (iso-directional) and in opposite directions (antidirectional). There was no difference in the brain activity between these two patterns of coordination. In several motor-related areas (e.g. the contralateral ventral premotor area, the dorsal premotor area, the supplementary motor area, the parietal operculum and the posterior parietal cortex), the representation of the isolated wrist movement overlapped with the representation of the isolated ankle movement. Importantly, the simultaneous movements activated the same set of motor-related regions that were active during the isolated movements. In the contralateral ventral premotor cortex, dorsal premotor cortex and parietal operculum, there was less activity during the simultaneous movements than for the sum of the activity for the two isolated movements (interaction analysis). Indeed, in the ventral premotor cortex and parietal operculum, the activity was practically identical regardless whether only the wrist, only the ankle, or both the wrist and the ankle were moved. Taken together, these findings suggest that interlimb coordination is mediated by motor representations shared by both limbs, rather than being mediated by specific additional neural populations.
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Affiliation(s)
- H H Ehrsson
- Division of Human Brain Research and PET, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
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45
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Lancaster JL, Woldorff MG, Parsons LM, Liotti M, Freitas CS, Rainey L, Kochunov PV, Nickerson D, Mikiten SA, Fox PT. Automated Talairach atlas labels for functional brain mapping. Hum Brain Mapp 2000; 10:120-31. [PMID: 10912591 PMCID: PMC6871915 DOI: 10.1002/1097-0193(200007)10:3<120::aid-hbm30>3.0.co;2-8] [Citation(s) in RCA: 2614] [Impact Index Per Article: 108.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/1999] [Accepted: 04/28/2000] [Indexed: 11/12/2022] Open
Abstract
An automated coordinate-based system to retrieve brain labels from the 1988 Talairach Atlas, called the Talairach Daemon (TD), was previously introduced [Lancaster et al., 1997]. In the present study, the TD system and its 3-D database of labels for the 1988 Talairach atlas were tested for labeling of functional activation foci. TD system labels were compared with author-designated labels of activation coordinates from over 250 published functional brain-mapping studies and with manual atlas-derived labels from an expert group using a subset of these activation coordinates. Automated labeling by the TD system compared well with authors' labels, with a 70% or greater label match averaged over all locations. Author-label matching improved to greater than 90% within a search range of +/-5 mm for most sites. An adaptive grey matter (GM) range-search utility was evaluated using individual activations from the M1 mouth region (30 subjects, 52 sites). It provided an 87% label match to Brodmann area labels (BA 4 & BA 6) within a search range of +/-5 mm. Using the adaptive GM range search, the TD system's overall match with authors' labels (90%) was better than that of the expert group (80%). When used in concert with authors' deeper knowledge of an experiment, the TD system provides consistent and comprehensive labels for brain activation foci. Additional suggested applications of the TD system include interactive labeling, anatomical grouping of activation foci, lesion-deficit analysis, and neuroanatomy education.
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Affiliation(s)
- J L Lancaster
- Research Imaging Center, University of Texas Health Science Center at San Antonio,78284, USA.
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46
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Geyer S, Schormann T, Mohlberg H, Zilles K. Areas 3a, 3b, and 1 of human primary somatosensory cortex. Part 2. Spatial normalization to standard anatomical space. Neuroimage 2000; 11:684-96. [PMID: 10860796 DOI: 10.1006/nimg.2000.0548] [Citation(s) in RCA: 227] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Interindividual topographical variability of cytoarchitectonically defined somatosensory areas 3a, 3b, and 1 was analyzed in the standard anatomical format of a computerized brain atlas. T1-weighted magnetic resonance images were obtained from 10 postmortem brains. The brains were serially sectioned at 20 mcm, sections were stained for cell bodies, and areas 3a, 3b, and 1 were defined with an observer-independent cytoarchitectonic technique. After correction of the sections for deformations due to histological processing, the 3-D reconstructed histological volumes of the individual brains and the volume representations of the cytoarchitectonic areas were adapted to the reference brain of a computerized atlas. Corresponding areas were superimposed in the 3-D space of the reference brain. These population maps describe, for each voxel, how many brains have a representation of one particular cytoarchitectonic area. Each area's extent is very variable across different brains, but representations of areas 3a, 3b, and 1 in >/=50% of the brains were found in the fundus of the central sulcus, its caudal bank, and on the crown of the postcentral gyrus, respectively. Volumes of interest (VOIs) were defined for each area in which >/=50% of the brains have a representation of that area. Despite close spatial relationship of areas 3a, 3b, and 1 in the postcentral gyrus, the three VOIs overlap by <1% of their volumes. Functional imaging data can now be brought into the same standard anatomical format, and changes in regional cerebral blood flow can be calculated in VOIs of areas 3a, 3b, and 1, which are derived from genuine cytoarchitectonic data.
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Affiliation(s)
- S Geyer
- Department of Neuroanatomy, University of Düsseldorf, Düsseldorf, 40001, Germany
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47
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48
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Naito E, Kinomura S, Geyer S, Kawashima R, Roland PE, Zilles K. Fast reaction to different sensory modalities activates common fields in the motor areas, but the anterior cingulate cortex is involved in the speed of reaction. J Neurophysiol 2000; 83:1701-9. [PMID: 10712490 DOI: 10.1152/jn.2000.83.3.1701] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined which motor areas would participate in the coding of a simple opposition of the thumb triggered by auditory, somatosensory and visual signals. We tested which motor areas might be active in response to all three modalities, which motor structures would be activated specifically in response to each modality, and which neural populations would be involved in the speed of the reaction. The subjects were required to press a button with their right thumb as soon as they detected a change in the sensory signal. The regional cerebral blood flow (rCBF) was measured quantitatively with (15)O-butanol and positron emission tomography (PET) in nine normal male subjects. Cytoarchitectural areas were delimited in 10 post mortem brains by objective and quantitative methods. The images of the post mortem brains subsequently were transformed into standard anatomic format. One PET scanning for each of the sensory modalities was done. The control condition was rest with the subjects having their eyes closed. The rCBF images were anatomically standardized, and clusters of significant changes in rCBF were identified. These were localized to motor areas delimited on a preliminary basis, such as supplementary motor area (SMA), dorsal premotor zone (PMD), rostral cingulate motor area (CMAr), and within areas delimited by using microstructural i.e., cytoarchitectonic criteria, such as areas 4a, 4p, 3a, 3b, and 1. Fields of activation observed as a main effect for all three modalities were located bilaterally in the SMA, CMAr, contralateral PMD, primary motor (M1), and primary somatosensory cortex (SI). The activation in M1 engaged areas 4a and 4p and expanded into area 6. The activation in SI engaged areas 3b, 1, and extended into somatosensory association areas and the supramarginal gyrus posteriorly. We identified significant activations that were specific for each modality in the respective sensory association cortices, though no modality specific regions were found in the motor areas. Fields in the anterior cingulate cortex, rostral to the CMAr, consistently showed significant negative correlation with mean reaction time (RT) in all three tasks. These results show that simple reaction time tasks activate many subdivisions of the motor cortices. The information from different sensory modalities converge onto the common structures: the contralateral areas 4a, 4p, 3b, 1, the PMD, and bilaterally on the SMA and the CMAr. The anterior cingulate cortex might be a key structure which determine the speed of reaction in simple RT tasks.
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Affiliation(s)
- E Naito
- Department of Neuroscience, Division of Human Brain Research, The Karolinska Institute, 171 77 Stockholm, Sweden
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Lancaster JL, Woldorff MG, Parsons LM, Liotti M, Freitas CS, Rainey L, Kochunov PV, Nickerson D, Mikiten SA, Fox PT. Automated Talairach Atlas labels for functional brain mapping. Hum Brain Mapp 2000. [DOI: 10.1002/1097-0193(200007)10:3%3c120::aid-hbm30%3e3.0.co;2-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Abstract
Vibration at approximately 70 Hz on the biceps tendon elicits a vivid illusory arm extension. Nobody has examined which areas in the brain are activated when subjects perceive this kinesthetic illusion. The illusion was hypothesized to originate from activations of somatosensory areas normally engaged in kinesthesia. The locations of the microstructurally defined cytoarchitectonic areas of the primary motor (4a and 4p) and primary somatosensory cortex (3a, 3b, and 1) were obtained from population maps of these areas in standard anatomical format. The regional cerebral blood flow (rCBF) was measured with (15)O-butanol and positron emission tomography in nine subjects. The left biceps tendon was vibrated at 10 Hz (LOW), at 70 or 80 Hz (ILLUSION), or at 220 or 240 Hz (HIGH). A REST condition with eyes closed was included in addition. Only the 70 and 80 Hz vibrations elicited strong illusory arm extensions in all subjects without any electromyographic activity in the arm muscles. When the rCBF of the ILLUSION condition was contrasted to the LOW and HIGH conditions, we found two clusters of activations, one in the supplementary motor area (SMA) extending into the caudal cingulate motor area (CMAc) and the other in area 4a extending into the dorsal premotor cortex (PMd) and area 4p. When LOW, HIGH, and ILLUSION were contrasted to REST, giving the main effect of vibration, areas 4p, 3b, and 1, the frontal and parietal operculum, and the insular cortex were activated. Thus, with the exception of area 4p, the effects of vibration and illusion were associated with disparate cortical areas. This indicates that the SMA, CMAc, PMd, and area 4a were activated associated with the kinesthetic illusion. Thus, against our expectations, motor areas rather than somatosensory areas seem to convey the illusion of limb movement.
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