401
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Seghier ML, Lazeyras F, Pegna AJ, Annoni J, Zimine I, Mayer E, Michel CM, Khateb A. Variability of fMRI activation during a phonological and semantic language task in healthy subjects. Hum Brain Mapp 2004; 23:140-55. [PMID: 15449358 PMCID: PMC6871802 DOI: 10.1002/hbm.20053] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Assessing inter-individual variability of functional activations is of practical importance in the use of functional magnetic resonance imaging (fMRI) in a clinical context. In this fMRI study we addressed this issue in 30 right-handed, healthy subjects using rhyme detection (phonologic) and semantic categorization tasks. Significant activations, found mainly in the left hemisphere, concerned the inferior frontal gyrus, the superior/middle temporal gyri, the prefrontal cortex, the inferior parietal lobe, the superior parietal lobule/superior occipital gyrus, the pre-central gyrus, and the supplementary motor area. Intensity/spatial analysis comparing activations in both tasks revealed an increased involvement of frontal regions in the semantic task and of temporo-parietal regions in the phonologic task. The frequency of activation analyzed in nine regional subdivisions revealed a high inter-subject variability but showed that the most frequently activated regions were the inferior frontal gyrus and the prefrontal cortex. Laterality indices, strongly lateralizing in both tasks, were slightly higher in the semantic (0.76 +/- 0.19) than the phonologic task (0.66 +/- 0.27). Frontal dominance indices (a measure of frontal vs. posterior left hemisphere dominance) indicated more robust frontal activations in the semantic than the phonologic task. Our study allowed the characterization of the most frequently involved foci in two language tasks and showed that the combination of these tasks constitutes a suitable tool for determining language lateralization and for mapping major language areas.
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Affiliation(s)
- Mohamed L. Seghier
- Department of Radiology, Geneva University Hospital, Geneva, Switzerland
- Plurifaculty Program of Cognitive Neuroscience, University of Geneva, Geneva, Switzerland
| | - François Lazeyras
- Department of Radiology, Geneva University Hospital, Geneva, Switzerland
| | - Alan J. Pegna
- Neuropsychology Unit, Department of Neurology, Geneva University Hospital, Geneva, Switzerland
- Functional Brain Mapping Laboratory, Department of Neurology, Geneva University Hospital, Geneva, Switzerland
| | - Jean‐Marie Annoni
- Neuropsychology Unit, Department of Neurology, Geneva University Hospital, Geneva, Switzerland
| | - Ivan Zimine
- Department of Radiology, Geneva University Hospital, Geneva, Switzerland
| | - Eugène Mayer
- Neuropsychology Unit, Department of Neurology, Geneva University Hospital, Geneva, Switzerland
| | - Christoph M. Michel
- Functional Brain Mapping Laboratory, Department of Neurology, Geneva University Hospital, Geneva, Switzerland
| | - Asaid Khateb
- Neuropsychology Unit, Department of Neurology, Geneva University Hospital, Geneva, Switzerland
- Functional Brain Mapping Laboratory, Department of Neurology, Geneva University Hospital, Geneva, Switzerland
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402
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Baciu M, Juphard A, Cousin E, Bas JFL. Evaluating fMRI methods for assessing hemispheric language dominance in healthy subjects. Eur J Radiol 2004; 55:209-18. [PMID: 16036149 DOI: 10.1016/j.ejrad.2004.11.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Revised: 10/10/2004] [Accepted: 11/15/2004] [Indexed: 10/26/2022]
Abstract
We evaluated two methods for quantifying the hemispheric language dominance in healthy subjects, by using a rhyme detection (deciding whether couple of words rhyme) and a word fluency (generating words starting with a given letter) task. One of methods called "flip method" (FM) was based on the direct statistical comparison between hemispheres' activity. The second one, the classical lateralization indices method (LIM), was based on calculating lateralization indices by taking into account the number of activated pixels within hemispheres. The main difference between methods is the statistical assessment of the inter-hemispheric difference: while FM shows if the difference between hemispheres' activity is statistically significant, LIM shows only that if there is a difference between hemispheres. The robustness of LIM and FM was assessed by calculating correlation coefficients between LIs obtained with each of these methods and manual lateralization indices MLI obtained with Edinburgh inventory. Our results showed significant correlation between LIs provided by each method and the MIL, suggesting that both methods are robust for quantifying hemispheric dominance for language in healthy subjects. In the present study we also evaluated the effect of spatial normalization, smoothing and "clustering" (NSC) on the intra-hemispheric location of activated regions and inter-hemispheric asymmetry of the activation. Our results have shown that NSC did not affect the hemispheric specialization but increased the value of the inter-hemispheric difference.
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Affiliation(s)
- Monica Baciu
- Laboratoire de Psychologie et NeuroCognition, UMR 5105 CNRS, Université Pierre Mendès-France, F38040 Grenoble Cedex 09, France.
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403
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Abstract
Using previously published functional magnetic resonance imaging work studying object recall as a framework, we describe the spatial and temporal properties of brain activation as one plausible model of visually triggered access to semantic memory. We suggest that interactions between the dorsomedial thalamus and Brodmann area 6 facilitate the setting of object search criteria and perhaps drive the search. The pulvinar nucleus of the thalamus, in concert with ventral temporal and occipital cortical regions, become active later, perhaps when the criteria are met or the target object is identified.
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Affiliation(s)
- Michael A Kraut
- Department of Radiology, Division of Neuroradiology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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404
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Billingsley-Marshall RL, Simos PG, Papanicolaou AC. Reliability and validity of functional neuroimaging techniques for identifying language-critical areas in children and adults. Dev Neuropsychol 2004; 26:541-63. [PMID: 15456683 DOI: 10.1207/s15326942dn2602_1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Advances in neuroimaging technologies over the last 15 years have prompted their relatively widespread use in the study of brain mechanisms supporting language function in children and adults. We reviewed reliability and external validity studies of 3 of the most common functional imaging methods, functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), and positron emission tomography (PET). Although reliability and validity reports for fMRI are generally quite favorable, significant variability was found across studies with respect to methodology, preventing in some cases either the assessment of the reliability of individual datasets, or cross-study comparisons. Reliability and validity reports of MEG are strong, yet methodological questions regarding optimal modeling techniques remain. PET investigators report good concordance of language maps with data from more invasive brain mapping techniques, but its use of radioactive tracers and poorer spatial and temporal resolution make it the least optimal of the 3 methods for language mapping. Investigations of the cortical networks supporting language function during development and into adulthood should be viewed in the context of the validity and reliability of the methods used, with careful attention to details regarding the methodologies employed in the acquisition and analysis of statistical maps.
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Affiliation(s)
- Rebecca L Billingsley-Marshall
- Vivian L. Smith Center for Neurologic Research, Department of Neurosurgery, Division of Clinical Neurosciences, University of Texas-Houston Medical School, 77030, USA.
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405
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Thivard L, Hombrouck J, du Montcel ST, Delmaire C, Cohen L, Samson S, Dupont S, Chiras J, Baulac M, Lehéricy S. Productive and perceptive language reorganization in temporal lobe epilepsy. Neuroimage 2004; 24:841-51. [PMID: 15652319 DOI: 10.1016/j.neuroimage.2004.10.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2004] [Revised: 09/13/2004] [Accepted: 10/01/2004] [Indexed: 10/26/2022] Open
Abstract
The aim of this work was to determine whether productive and perceptive language functions are differentially affected in homogeneous groups of epilepsy patients with right and left temporal lobe epilepsy (TLE). Eighteen patients with left TLE, 18 with right TLE, and 17 healthy volunteers were studied using fMRI during performance of three tasks assessing the productive and perceptive aspects of language (covert semantic verbal fluency, covert sentence repetition, and story listening). Hemispheric dominance for language was calculated in the frontal and temporal regions using laterality indices (LI). Atypical lateralization was defined as a right-sided LI (LI<-0.20) in the frontal lobes during the verbal fluency task or in the temporal lobes during the story listening task. Control subjects and right TLE patients demonstrated a strong left lateralization for language in the frontal lobes during the fluency task, whereas activation was less lateralized to the left hemisphere in left TLE patients, although the difference did not reach significance. In the story listening and the repetition tasks, activation was significantly more right sided in the temporal lobes of patients with left TLE. Atypical language representation was found in 19% of TLE patients (five left and two right TLE). The shift toward the right hemisphere was significantly larger in the temporal than the frontal lobes in patients with atypical language lateralization compared to TLE patients with a typical language lateralization. Neuropsychological performances of patients with atypical language patterns were better than those of patients with typical patterns, suggesting that this reorganization may represent a compensatory mechanism.
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Affiliation(s)
- Lionel Thivard
- Department of Neurology, Hôpital de la Salpêtrière, 75013 Paris, France
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406
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Jansen A, Flöel A, Deppe M, van Randenborgh J, Dräger B, Kanowski M, Knecht S. Determining the hemispheric dominance of spatial attention: a comparison between fTCD and fMRI. Hum Brain Mapp 2004; 23:168-80. [PMID: 15449360 PMCID: PMC6871950 DOI: 10.1002/hbm.20055] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2003] [Accepted: 04/02/2004] [Indexed: 11/06/2022] Open
Abstract
Human brain mapping allows the systematic assessment of interindividual differences in functional brain anatomy. Functional transcranial Doppler sonography (fTCD) is an imaging tool that allows for fast and mobile assessment of hemispheric lateralization of task-related brain activation. It is ideal to screen large cohorts of subjects. The goal of the present study was to investigate whether fTCD and functional magnetic resonance imaging (fMRI) determine hemispheric lateralization of brain activation related to visuospatial attention concordantly. Used together, fMRI and fTCD may then open up a wide range of potential applications in neuroscience. Fifteen subjects were examined both with fTCD and fMRI while they judged accuracy of line bisections (Landmark task). For fTCD, the maximal mean difference in stimulus-related relative cerebral blood flow velocity changes in the left and right middle cerebral arteries was assessed as the lateralization index LI(fTCD). For fMRI, two approaches were used to determine hemispheric dominance. First, we measured brain activity as the extent of the activated region, i.e., the number of activated voxels above a statistical threshold. Second, we calculated the magnitude of the fMRI signal change between the activation and the control task within a region of interest. Results of fTCD and fMRI were concordant in every single case. Therefore, scanning large cohorts with fTCD for hemispheric dominance during Landmark task will provide results consistent with fMRI. FMRI can then be used for in depth assessment of the specific patterns of activation.
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Affiliation(s)
- Andreas Jansen
- Department of Neurology, University of Münster, D-4829 Münster, Germany.
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407
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Hirata M, Kato A, Taniguchi M, Saitoh Y, Ninomiya H, Ihara A, Kishima H, Oshino S, Baba T, Yorifuji S, Yoshimine T. Determination of language dominance with synthetic aperture magnetometry: comparison with the Wada test. Neuroimage 2004; 23:46-53. [PMID: 15325351 DOI: 10.1016/j.neuroimage.2004.05.009] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2003] [Revised: 05/07/2004] [Accepted: 05/11/2004] [Indexed: 11/19/2022] Open
Abstract
Cerebral dominance for language function was investigated with synthetic aperture magnetometry (SAM). The results were compared with those of the Wada test. SAM is a spatial filtering technique that enables demonstration of the spatiotemporal distribution of oscillatory changes (synchronization and desynchronization) in magnetoencephalography (MEG) signals elicited by specific brain activation. MEG was conducted during a silent reading task in 20 consecutive preoperative neurosurgical patients who also underwent a Wada test. The spatial distribution of oscillatory changes related to silent reading was shown tomographically with SAM as statistical images. Language dominance was estimated by the laterality index, which scales the lateralization of the beta (13-25 Hz) and low gamma (25-50 Hz) band desynchronizations in the inferior frontal gyrus (IFG) or middle frontal gyrus (MFG). Oscillatory changes were distributed multifocally and bilaterally in the occipital cortex, IFG or MFG, and temporo-parieto-occipital border regions. In 19 patients (95%), language lateralization estimated by the laterality index was congruent with the result of the Wada test. In left-handed patients, SAM analysis clearly differentiated language dominance (left, right, or bilateral), and the findings were confirmed by the Wada test. Lateralization of beta or low gamma band desynchronizations in the IFG or MFG is a good indicator of the side of language dominance. Reliability of MEG imaging with SAM is sufficient to evaluate language dominance preoperatively in neurosurgical patients.
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Affiliation(s)
- Masayuki Hirata
- Department of Neurosurgery, Osaka University Graduate School of Medicine, Osaka, Japan.
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408
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Abstract
Functional MRI (fMRI) methods use currently standard MRI scanning hardware to detect changes in regional blood flow and metabolism that accompany regional brain activation. Major applications of fMRI in epilepsy include the localization of task-correlated language and memory function, and the localization of ictal and paroxysmal phenomena. Language lateralization by fMRI provides comparable results to intracarotid amobarbital testing, and memory lateralization by fMRI also shows promise. The recent development of methodologies to allow interpretable electroencephalographic data to be recorded during MRI scanning has opened up new opportunities for combining the spatial resolution of imaging with the temporal resolution of electrophysiology in seizure localization.
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Affiliation(s)
- John A Detre
- Center for Functional Neuroimaging, Departments of Neurology and Radiology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
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409
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Constable RT, Pugh KR, Berroya E, Mencl WE, Westerveld M, Ni W, Shankweiler D. Sentence complexity and input modality effects in sentence comprehension: an fMRI study. Neuroimage 2004; 22:11-21. [PMID: 15109993 DOI: 10.1016/j.neuroimage.2004.01.001] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2003] [Revised: 12/03/2003] [Accepted: 01/05/2004] [Indexed: 10/26/2022] Open
Abstract
Cortical regions engaged by sentence processing were mapped using functional MRI. The influence of input modality (spoken word vs. print input) and parsing difficulty (sentences containing subject-relative vs. object-relative clauses) was assessed. Auditory presentation was associated with pronounced activity at primary auditory cortex and across the superior temporal gyrus bilaterally. Printed sentences by contrast evoked major activity at several posterior sites in the left hemisphere, including the angular gyrus, supramarginal gyrus, and the fusiform gyrus in the occipitotemporal region. In addition, modality-independent regions were isolated, with greatest overlap seen in the inferior frontal gyrus (IFG). With respect to sentence complexity, object-relative sentences evoked heightened responses in comparison to subject-relative sentences at several left hemisphere sites, including IFG, the middle/superior temporal gyrus, and the angular gyrus. These sites showing modulation of activity as a function of sentence type, independent of input mode, arguably form the core of a cortical system essential to sentence parsing.
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Affiliation(s)
- R Todd Constable
- Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, CT 06520-8042, USA.
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410
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Chirurgie de l’épilepsie chez l’enfant : critères d’éligibilité. Revue de la littérature. Rev Neurol (Paris) 2004. [DOI: 10.1016/s0035-3787(04)71203-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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411
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Deppe M, Ringelstein EB, Knecht S. The investigation of functional brain lateralization by transcranial Doppler sonography. Neuroimage 2004; 21:1124-46. [PMID: 15006680 DOI: 10.1016/j.neuroimage.2003.10.016] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2003] [Revised: 09/30/2003] [Accepted: 10/06/2003] [Indexed: 11/24/2022] Open
Abstract
Functional transcranial Doppler sonography (fTCD) adds to the techniques of functional imaging. fTCD measures cerebral perfusion changes related to neural activation in a way comparable to functional magnetic resonance tomography. fTCD contends itself with comparison of averaged, event-related blood flow velocity changes within the territories of two cerebral arteries, for example the left versus the right middle cerebral artery. It can thus serve to evaluate the functional lateralization of higher cognitive functions like hemispheric language dominance (HLD). We present typical applications of fTCD by summarizing studies employing the technique. Then, the physical and physiological underpinnings of fTCD are reviewed. After a brief description of a prototype paradigm for assessing HLD, a detailed outline of the fTCD data analysis is presented. Caveats for fTCD, like other functional imaging techniques, are that the validity of results depends on adequate control of the task parameters, particularly cooperation and reference conditions. We complete the review with examinations of the reliability and validity of the fTCD technique. We conclude that fTCD can be employed to substitute the invasive amobarbital procedure to determine language lateralization in individual patients before undergoing brain surgery. Because of its easy applicability, robustness and mobility, fTCD can also be used to examine many subjects (including children) to obtain representative data on the variability of lateralization of higher cognitive functions, or to scan for atypical patterns of lateralization.
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Affiliation(s)
- Michael Deppe
- Department of Neurology, University of Münster, D-48129 Münster, Germany.
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412
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Deblaere K, Boon PA, Vandemaele P, Tieleman A, Vonck K, Vingerhoets G, Backes W, Defreyne L, Achten E. MRI language dominance assessment in epilepsy patients at 1.0 T: region of interest analysis and comparison with intracarotid amytal testing. Neuroradiology 2004; 46:413-20. [PMID: 15127167 DOI: 10.1007/s00234-004-1196-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2003] [Accepted: 03/09/2004] [Indexed: 10/26/2022]
Abstract
The primary goal of this study was to test the reliability of presurgical language lateralization in epilepsy patients with functional magnetic resonance imaging (fMRI) with a 1.0-T MR scanner using a simple word generation paradigm and conventional equipment. In addition, hemispherical fMRI language lateralization analysis and region of interest (ROI) analysis in the frontal and temporo-parietal regions were compared with the intracarotid amytal test (IAT). Twenty epilepsy patients under presurgical evaluation were prospectively examined by both fMRI and IAT. The fMRI experiment consisted of a word chain task (WCT) using the conventional headphone set and a sparse sequence. In 17 of the 20 patients, data were available for comparison between the two procedures. Fifteen of these 17 patients were categorized as left hemispheric dominant, and 2 patients demonstrated bilateral language representation by both fMRI and IAT. The highest reliability for lateralization was obtained using frontal ROI analysis. Hemispherical analysis was less powerful and reliable in all cases but one, while temporo-parietal ROI analysis was unreliable as a stand-alone analysis when compared with IAT. The effect of statistical threshold on language lateralization prompted for the use of t-value-dependent lateralization index plots. This study illustrates that fMRI-determined language lateralization can be performed reliably in a clinical MR setting operating at a low field strength of 1 T without expensive stimulus presentation systems.
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Affiliation(s)
- K Deblaere
- Department of Neuroradiology, Ghent University Hospital, De Pintelaan 185, 9000, Ghent, Belgium.
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413
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Meneses MS, Rocha SFB, Blood MRY, Trentin A, Benites Filho PR, Kowacs PA, Oliveira NDA, Simão CA, Awamura Y, Vítola MLA. [Functional magnetic resonance imaging in the determination of dominant language cerebral area]. ARQUIVOS DE NEURO-PSIQUIATRIA 2004; 62:61-7. [PMID: 15122435 DOI: 10.1590/s0004-282x2004000100011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Functional magnetic resonance imaging (fMRI) is a technique for detecting minimal changes in brain perfusion and oxygenation secondary to neuronal activation. Its application in the pre-surgical evaluation of epileptic patients with temporal mesial sclerosis is currently being under investigation in several centers. This study aims to describe an activation paradigm for the evaluation of language and memory functions, as an alternative to the worldwide used Wada test, which is an invasive procedure. In order to propose a paradigm adapted to the Portuguese language, we report our experience in determining the dominant cerebral area for language through fMRI with a verbal fluency task. The results of the fMRI from 19 patients studied in Curitiba in a period of approximately two years were studied. Sixteen of them presented with left hemispheric cerebral language dominance. In five patients, results from fMRI and Wada test could be compared and agreed in localization. Our results reinforce the view that fMRI may become an essential tool for medical practice, perhaps for the determination of eloquent areas in the evaluation of candidates for epilepsy surgery.
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Affiliation(s)
- Murilo S Meneses
- Neurocirurgião do Instituto de Neurologia de Curitiba, Departmento de Anatomia, Universidade Federal Paraná, Curitiba, PR, Brazil.
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414
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Josse G, Mazoyer B, Crivello F, Tzourio-Mazoyer N. Left planum temporale: an anatomical marker of left hemispheric specialization for language comprehension. ACTA ACUST UNITED AC 2004; 18:1-14. [PMID: 14659492 DOI: 10.1016/j.cogbrainres.2003.08.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We report on a study aimed at investigating the relationships between handedness, anatomical data and functional data related to speech processing. Twenty subjects with variable handedness (Edinburgh score ranging from -100 to 100) underwent both anatomical magnetic resonance imaging (MRI) and Positron Emission Tomography (PET) during story listening and rest. The surface areas of the left and right planum temporale (PT) were measured on each subject's MRI scan. A multiple regression analysis of PET data was conducted using these PT surface areas as well as handedness scores as predictors. The surface of the left PT explained a significant part of the functional variability. We observed that subjects who had the larger left PT were likely to show a larger leftward functional asymmetry of several perisylvian areas, namely the inferior parietal lobule outside the supra-marginal gyrus (the angular gyrus and the cortex above), Heschl's gyrus, the rolandic operculum, and the temporal pole. The size of the right PT explained only a little part of functional variability and we found no evidence that the anatomical asymmetry of the PT explained functional variability. In addition, we could not evidence any relationship between handedness and functional data. These results, which confirm previous work, argue for a perceptive origin of hemispheric specialization for language comprehension as has been suggested by others.
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Affiliation(s)
- Goulven Josse
- Groupe d'Imagerie Neurofonctionnelle, UMR 6095, CNRS, CEA, Université de Caen and Université Paris V, GIP Cyceron, Bd Becquerel BP 5229, 14074 Caen Cedex, France
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415
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Abstract
Hemispheric specialization for language is one of the most robust findings of cognitive neuroscience. In this review, we first present the main hypotheses about the origins of this important aspect of brain organization. These theories are based in part on the main approaches to hemispheric specialization: studies of aphasia, anatomical asymmetries and, nowadays, neuroimaging. All these approaches uncovered a large inter-individual variability which became the bulk of research on hemispheric specialization. This is why, in a second part of the review, we present the main facts about inter-individual variability, trying to relate findings to the theories presented in the first part. This review focuses on neuroimaging as it has recently given important results, thanks to investigations of both anatomical and functional asymmetries in healthy subjects. Such investigations have confirmed that left-handers, especially "familial left-handers", are more likely to have an atypical pattern of hemispheric specialization for language. Differences between men and women seem less evident although a less marked hemispheric specialization for language was depicted in women. As for the supposed relationship between anatomical and functional asymmetries, it has been shown that the size of the left (not the right) planum temporale could explain part of the variability of left hemispheric specialization for language comprehension. Taken as a whole, findings seem to vary with language tasks and brain regions, therefore showing that hemispheric specialization for language is multi-dimensional. This is not accounted for in the existing models of hemispheric specialization.
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Affiliation(s)
- Goulven Josse
- Groupe d'Imagerie Neurofonctionnelle, UMR 6095, CNRS, CEA, Université de Caen and Université Paris V., France
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416
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Moritz C, Haughton V. Functional MR imaging: paradigms for clinical preoperative mapping. Magn Reson Imaging Clin N Am 2004; 11:529-42, v. [PMID: 15018109 DOI: 10.1016/s1064-9689(03)00062-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Clinical applications of functional MR imaging include mapping of brain functions in relationship to intracranial tumors, seizure foci, or vascular malformations to determine the risk for performing surgical excision, the need for intraoperative mapping during excision, and selecting the optimal surgical approach to a lesion. A variety of paradigms are used to produce a blood-oxygen-level-dependent response in various brain regions, which can be identified with functional MR imaging. The paradigms used include active motor, language, or cognitive tasks, and passive tactile, auditory, or visual stimuli. Activation usually indicates the location of eloquent cortex. Lack of function in a region cannot be assumed when functional MR imaging shows absence of activation within the region.
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Affiliation(s)
- Chad Moritz
- Department of Radiology, University Hospitals and Clinics, University of Wisconsin, 600 Highland Avenue, E3/311 CSC, Madison, WI 53792, USA
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417
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Abstract
PURPOSE OF REVIEW The rapid expansion of novel applications and the development of new techniques in structural and functional imaging modalities present a troubling challenge to keep up with and harness potential valuable information created in this critical field of epilepsy localization and non-invasive in-vivo research. RECENT FINDINGS Recent advances in epilepsy imaging have centered on: (1) improving the localization of epileptogenic tissue beyond that of state-of-the-art structural magnetic resonance imaging; (2) monitoring the development and progression of epileptogenic pathology, particularly mesial temporal sclerosis; and (3) an investigation of the in-vivo structural and functional disturbances underlying and revealing mechanisms of partial epilepsy pathophysiology. SUMMARY The main impact of the progress in epilepsy localization with multimodality imaging is to allow more effective presurgical evaluation and the selection of patients with intractable seizures. By combining serial imaging findings and genetic studies, the major questions surrounding the development and progression of mesial temporal sclerosis with regard to the cause and consequence of epilepsy will soon be answered. Long-standing questions concerning in-vivo metabolic and neurotransmitter disturbances associated with partial epilepsy, detected and depicted (but not understood) with magnetic resonance spectroscopy and positron emission tomography, are finally being addressed.
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Affiliation(s)
- Robert C Knowlton
- UAB Epilepsy Center, Department of Neurology, University of Alabama at Birmingham School of Medicine, Birmingham, Alabama, USA.
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418
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Driessen M, Beblo T, Mertens M, Piefke M, Rullkoetter N, Silva-Saavedra A, Reddemann L, Rau H, Markowitsch HJ, Wulff H, Lange W, Woermann FG. Posttraumatic stress disorder and fMRI activation patterns of traumatic memory in patients with borderline personality disorder. Biol Psychiatry 2004; 55:603-11. [PMID: 15013829 DOI: 10.1016/j.biopsych.2003.08.018] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2003] [Revised: 07/29/2003] [Accepted: 08/26/2003] [Indexed: 01/18/2023]
Abstract
BACKGROUND Early traumatization and additional posttraumatic stress disorder are frequent in patients with borderline personality disorder (BPD). The purpose of this study was to investigate neural correlates of traumatic memory in BPD with and without posttraumatic stress disorder (PTSD) using functional magnetic resonance imaging (fMRI). METHODS We studied 12 traumatized female patients BPD, 6 of them with and 6 without PTSD. According to an autobiographical interview key words (cues) were defined for traumatic and for negative but nontraumatic episodes. In a block-designed fMRI task patients recalled these episodes. Contrasts between trauma condition and nontrauma condition were analyzed. RESULTS Analyses for all subjects revealed activation of orbitofrontal cortex areas in both hemispheres, anterior temporal lobes, and occipital areas. In the subgroup without PTSD, activation of orbitofrontal cortex on both sides and Broca's area predominated. In the subgroup with additional PTSD, we observed right more than left activation of anterior temporal lobes, mesiotemporal areas, amygdala, posterior cingulate gyrus, occipital areas, and cerebellum. CONCLUSIONS Dependent on absence or presence of additional PTSD different neural networks seem to be involved in the traumatic memory of patients with BPD.
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Affiliation(s)
- Martin Driessen
- Center of Psychiatry and Psychological Medicine, Gilead Hospital Bethel, Bielefeld, Germany, Bielefeld
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419
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Briellmann RS, Mitchell LA, Waites AB, Abbott DF, Pell GS, Saling MM, Jackson GD. Correlation between language organization and diffusion tensor abnormalities in refractory partial epilepsy. Epilepsia 2004; 44:1541-5. [PMID: 14636325 DOI: 10.1111/j.0013-9580.2003.19403.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE Atypical language organization is more frequently found in patients with refractory partial epilepsy than in healthy controls; however, the reasons for this are not well known. Here we assess the relation between language laterality index (LI) and white-matter tract changes. METHODS Nine patients with refractory partial epilepsy were assessed with a 3-T GE scanner. Functional magnetic resonance imaging (fMRI) of language and diffusion tensor imaging (DTI) were acquired. For the fMRI, a noun-verb generation task was performed, all images were motion corrected, and activated pixels in classic language areas were counted. The DTI images were acquired in six standard directions with an initial non-diffusion-weighted scan. The "average anisotropy" was determined in a region of interest in the frontal lobe, temporal lobe, and parietal lobe white matter. An asymmetry index (AI) was calculated for language and DTI. Atypical language lateralization was diagnosed if the lateralization index (LI)-language was smaller than 0.4. RESULTS Two of the nine patients had atypical language localization (LI-language, -0.6, and 0.3); both had left temporal DTI asymmetry (LI-DTI, -0.3 and -0.2). The remaining seven patients had typical language localization, and no marked DTI abnormalities. Asymmetry in temporal lobe DTI correlated with LI-language (r= 0.8; p = 0.006). CONCLUSIONS Atypical language lateralization in patients with partial epilepsy may be associated with white-matter tract abnormalities.
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Affiliation(s)
- Regula S Briellmann
- Brain Research Institute, University of Melbourne, Austin and Repatriation Medical Centre, Repatriation Campus, Heidelberg West 3081, Victoria, Australia
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420
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Lohmann H, Deppe M, Jansen A, Schwindt W, Knecht S. Task repetition can affect functional magnetic resonance imaging-based measures of language lateralization and lead to pseudoincreases in bilaterality. J Cereb Blood Flow Metab 2004; 24:179-87. [PMID: 14747744 DOI: 10.1097/01.wcb.0000100066.36077.91] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Repeated functional magnetic resonance imaging (fMRI) during learning and recovery can inform us about functional reorganization in the brain. We examined how, in the absence of reorganization, simple task repetition affects measures of fMRI activation. We studied fMRI activation over 10 consecutive sessions of silent word generation in a healthy subject. Additionally, we performed functional transcranial Doppler sonography (fTCD) to learn about the temporal pattern of corresponding changes in cerebral blood flow velocity (CBFV) and pulsatility. With repetition, word generation-associated increases in heart rate diminished steadily. Task repetition also led to a net increase in CBFV bilaterally and to a bilateral increase in the number of activated voxels on fMRI. As a result, whereas the absolute interhemispheric difference of activated voxels remained constant, there was a decrease in the standard fMRI index for language lateralization [LIfMRI = 100 (activated voxels in left hemisphere - voxels in right)/(voxels in left + voxels in right)]. Thus task repetition can lead to changes in task-related autonomic drive and an augmentation of bihemispheric blood flow. This can mimic increasing bilaterality of brain activation.
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421
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Sommer IEC, Ramsey NF, Mandl RCW, van Oel CJ, Kahn RS. Language activation in monozygotic twins discordant for schizophrenia. Br J Psychiatry 2004; 184:128-35. [PMID: 14754824 DOI: 10.1192/bjp.184.2.128] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND In previous functional magnetic resonance imaging (fMRI) studies, participants with schizophrenia showed decreased language lateralisation, resulting from increased activation of the right hemisphere compared with controls. AIM To determine whether decreased lateralisation and increased right cerebral language activation constitute genetic predispositions for schizophrenia. METHOD Language activation was measured using fMRI in 12 right-handed monozygotic twin pairs discordant for schizophrenia and 12 healthy right-handed monozygotic twin pairs who were twin pairs who were matched for gender, age and education. RESULTS Language lateralisation was decreased in discordant twin pairs compared with the healthy twin pairs. The groups did not differ in activation of the language-related areas of the left hemisphere, but language-related activation in the right hemisphere was activation in the significantly higher in the discordant twin pairs than in the healthy pairs. Within the discordant twin pairs, language lateralisation was not significantly different between patients with schizophrenia and their co-twins. CONCLUSIONS Decreased language lateralisation may constitute a genetic predisposition for schizophrenia.
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Affiliation(s)
- Iris E C Sommer
- Rudolf Magnus Institute of Neuroscience Psychiatry Department, University Medical Center, Utrecht, The Netherlands.
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422
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Vingerhoets G, Deblaere K, Backes WH, Achten E, Boon P, Boon PJ, Hofman P, Vermeulen J, Vonck K, Wilmink J, Aldenkamp AP. Lessons for neuropsychology from functional MRI in patients with epilepsy. Epilepsy Behav 2004; 5 Suppl 1:S81-9. [PMID: 14725851 DOI: 10.1016/j.yebeh.2003.11.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This contribution aims to review the major findings of pre- and postsurgical functional magnetic resonance imaging (fMRI) in patients with refractory epilepsy from a neuropsychological perspective. We compared the contribution of fMRI with the intracarotid amytal procedure (IAP) with respect to functional mapping of language and memory in patients with therapy-resistant epilepsy. We conclude that using comprehensive language paradigms, fMRI has been able (1) to provide estimates of the degree of language lateralization including the degree of involvement of the nondominant hemisphere, (2) to provide information on the location of its activated network during expressive and receptive language, and (3) to help delineate eloquent language regions in the vicinity of the surgical target, thus preventing postoperative complications. The contribution of the frequently observed nondominant hemisphere activation to language should be explored and its clinical relevance determined. Evidence from fMRI studies is accumulating that reorganization of cognitive and motor function favors the activation of contralateral homotopic areas, although this process is far from understood. The exact functional contribution of atypical areas of activation should be investigated critically. In the presurgical evaluation process, detailed and reliable localization of language and memory functions of the individual patient is mandatory and should be the ultimate goal in the development of comprehensive clinical fMRI protocols.
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Affiliation(s)
- Guy Vingerhoets
- Laboratory for Neuropsychology, Ghent University, De Pintelaan 185, B-9000 Ghent, Belgium.
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423
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Abstract
PURPOSE To determine if children with speech delay who have been sedated have patterns of activation to passive language paradigms that are different than those of children with normal speech. MATERIALS AND METHODS Seventeen children with speech delay (age range, 2-7 years; mean, 4.0 years) and 35 age-matched children with normal speech (age range, 2-8 years; mean, 4.2 years) were evaluated. The subjects in the control group were selected from patients referred for conventional magnetic resonance (MR) imaging. All children had absence of auditory impairment or mental retardation, and MR findings indicated that brain structure was normal. Sedation was achieved with pentobarbital (3-5 mg/kg) or chloral hydrate (75 mg/kg). Functional MR imaging was performed with a single-shot echo-planar blood oxygen-level-dependent technique and a passive block paradigm, in which the child listened to his or her mother's prerecorded voice. Statistical postprocessing of functional MR images was performed with the t test and cluster detection methods. Comparison between groups was performed depending on the type of data with a nonparametrical Mann-Whitney test, parametrical t test, or Fisher exact test. RESULTS Five (83%) of the six children older than 3 years with speech delay had lateralized activation of functional MR imaging signal in the right hemisphere. Ten (71%) of 14 age-matched patients with normal speech had activation in the left hemisphere when exposed to the same passive listening tasks. When these groups were compared, this difference was statistically significant. (P =.036). No statistically significant lateralization was seen across all age groups in children with activation. CONCLUSION Children older than 3 years with speech delay have activation in the right hemisphere more frequently than children older than 3 years with normal speech, who often have the expected finding of activation in the left hemisphere.
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Affiliation(s)
- Byron Bernal
- Department of Radiology, Miami Childrens' Hospital, 3100 SW 62nd Ave, Miami, FL 33155, USA
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424
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Hoshi Y, Tsou BH, Billock VA, Tanosaki M, Iguchi Y, Shimada M, Shinba T, Yamada Y, Oda I. Spatiotemporal characteristics of hemodynamic changes in the human lateral prefrontal cortex during working memory tasks. Neuroimage 2004; 20:1493-504. [PMID: 14642462 DOI: 10.1016/s1053-8119(03)00412-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The prefrontal cortex (PFC) is widely believed to subserve mental manipulation and monitoring processes ascribed to the central executive (CE) of working memory (WM). We attempted to examine and localize the CE by functional imaging of the frontal cortex during tasks designed to require the CE. Using near-infrared spectroscopy, we studied the spatiotemporal dynamics of oxygenated hemoglobin (oxy-Hb), an indicator of changes in regional cerebral blood flow, in both sides of lateral PFC during WM intensive tasks. In most participants, increases in oxy-Hb were localized within one subdivison during performance of the n-back task, whereas oxy-Hb increased more diffusely during the random number generation (RNG) task. Activation of the ventrolateral PFC (VLPFC) was prominent in the n-back task; both sustained and transient dynamics were observed. Transient dynamics means that oxy-Hb first increases but then decreases to less than 50% of the peak value or below the baseline level before the end of the task. For the RNG task sustained activity was also observed in the dorsolateral PFC (DLPFC), especially in the right hemisphere. However, details of patterns of activation varied across participants: subdivisions commonly activated during performance of the two tasks were the bilateral VLPFCs, either side of the VLPFC, and either side of the DLPFC in 4, 2, and 4 of the 12 participants, respectively. The remaining 2 of the 12 participants had no regions commonly activated by these tasks. These results suggest that although the PFC is implicated in the CE, there is no stereotyped anatomical PFC substrate for the CE.
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Affiliation(s)
- Yoko Hoshi
- Department of Integrated Neuroscience, Tokyo Institute of Psychiatry, Kamikitazawa-2-1-8, Setagaya-ku, Tokyo 156-8585, Japan.
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425
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Ries ML, Boop FA, Griebel ML, Zou P, Phillips NS, Johnson SC, Williams JP, Helton KJ, Ogg RJ. Functional MRI and Wada Determination of Language Lateralization: A Case of Crossed Dominance. Epilepsia 2004; 45:85-9. [PMID: 14692913 DOI: 10.1111/j.0013-9580.2004.04403.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The Wada test has historically been the conventional procedure for determining language lateralization before neurosurgery. However, functional magnetic resonance imaging (fMRI) offers a less invasive alternative to the Wada procedure. Research indicates that the two techniques used together may provide comparable, and sometimes complementary, information that results in improved prediction of postsurgical language ability. We present a case in which use of fMRI in conjunction with Wada testing provided complementary information about language lateralization before neurosurgical resection of a mesial temporal subependymoma for seizure control in a patient with schizencephaly.
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Affiliation(s)
- Michele L Ries
- St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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426
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Tzourio-Mazoyer N, Josse G, Crivello F, Mazoyer B. Interindividual variability in the hemispheric organization for speech. Neuroimage 2004; 21:422-35. [PMID: 14741679 DOI: 10.1016/j.neuroimage.2003.08.032] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A PET activation study was designed to investigate hemispheric specialization during speech comprehension and production in right- and left-handed subjects. Normalized regional cerebral blood flow (NrCBF) was repeatedly monitored while subjects either listened to factual stories (Story) or covertly generated verbs semantically related to heard nouns (Gener), using silent resting (Rest) as a common control condition. NrCBF variations in each task, as compared to Rest, as well as functional asymmetry indices (FAI = right minus left NrCBF variations), were computed in anatomical regions of interest (AROIs) defined on the single-subject MNI template. FAIs were predominantly leftward in all regions during both tasks, although larger FAIs were observed during Gener. Subjects were declared "typical" for language hemispheric specialization based on the presence of significant leftward asymmetries (FAI < 0) in the pars triangularis and opercularis of the inferior frontal gyrus during Gener, and in the middle and inferior temporal AROIs during Story. Six subjects (including five LH) showed an atypical language representation. Among them, one presented a right hemisphere specialization during both tasks, another a shift in hemispheric specialization from production to comprehension (left during Gener, right during Story). The group of 14 typical subjects showed significant positive correlation between homologous left and right AROIs NrCBF variations in temporal areas during Story, and in temporal and inferior frontal areas during Gener, almost all regions presenting a leftward FAI. Such correlations were also present in deactivated areas with strong leftward asymmetry (supramarginalis gyrus, inferior parietal region). These results suggest that entry into a language task translates into a hemispheric reconfiguration of lateral cortical areas with global NrCBF increase in the dominant hemisphere and decrease in the minor hemisphere. This can be considered as the setting up of a "language mode", under the control of a mechanism that operates at a perisylvian level. On top of this global organization, regional variations carry on the performance of the cognitive operations specific to the language task to be performed. Hemispheric relationships could be different in atypical subjects, with either between task hemispheric regulation differences or differences in regional specialization.
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Affiliation(s)
- N Tzourio-Mazoyer
- Groupe d'Imagerie Neurofonctionnelle (GIN), UMR 6095 CNRS, CEA, Universités de Caen et Paris 5, 14074 Cedex, Caen, France.
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427
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Neuloh G, Schramm J. Motor Evoked Potential Monitoring for the Surgery of Brain Tumours and Vascular Malformations. Adv Tech Stand Neurosurg 2004; 29:171-228. [PMID: 15035339 DOI: 10.1007/978-3-7091-0558-0_5] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Brain surgery incurs a significant risk of a new motor deficit in lesions within or adjacent to the motor areas and pathways which, for the patient, presents one of the most disabling complications of such operations. It is a major concern of intracranial procedures to delineate and monitor motor regions in order to preserve their structural and functional integrity, while still achieving maximal cytoreduction. The technique of motor evoked potential recording has had to be adapted to intraoperative recording conditions under general anaesthesia, but has been available for clinical use now for almost ten years. This contribution summarizes the current technique and related methods, as well as our clinical experience in some 400 cases of MEP monitoring in supratentorial tumors, lesions in and around the brainstem, and aneurysm surgery. Intraoperative MEP recordings have been shown to reliably reflect an impending new motor deficit. Irreversible MEP deterioration heralds new paresis, and unaltered recordings predict preserved motor function. This is also true in aneurysm surgery where conventional SEP monitoring may yield false-negative results with regard to development of a new motor deficit. Moreover, if MEP deterioration can be reversed, or halted by early surgical intervention, the presence of only a transient motor deficit, or even the lack of a new postoperative deficit, indicates the success of the MEP monitoring method in the prevention of a significant motor impairment. Certain complicated lesions can only be operated on at all because MEP monitoring is available. In conclusion, intraoperative MEP monitoring is a useful aid in brain surgery with which to avoid a new motor deficit without compromise to the surgical result. Controlled prospective studies will be required to verify the clinical value of the method.
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Affiliation(s)
- G Neuloh
- Department of Neurosurgery, University of Bonn, Germany
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428
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Medina LS, Aguirre E, Bernal B, Altman NR. Functional MR Imaging versus Wada Test for Evaluation of Language Lateralization: Cost Analysis. Radiology 2004; 230:49-54. [PMID: 14695386 DOI: 10.1148/radiol.2301021122] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To compare the total direct costs (fixed and variable costs) of functional magnetic resonance (MR) imaging and of the Wada test for evaluation of language lateralization. MATERIALS AND METHODS The direct fixed and variable costs of functional MR imaging (performed in 21 patients with mean age +/- SD of 15.5 years +/- 8.9) and of the Wada test (performed in 18 patients aged 19.2 years +/- 5.4) were determined prospectively with time and motion analyses. The labor of all personnel involved in evaluations of language lateralization was tracked, and involvement times were recorded to the nearest minute. All material items used in the studies were recorded. Costs of labor and of materials were determined from personnel reimbursement data and from vendor pricing, respectively. Direct fixed costs were determined from hospital accounting department records. Means (+/- SDs) were calculated for all direct fixed and variable costs. Total direct costs were determined for each procedure and compared by using the Student t test. RESULTS The total direct costs of the Wada test (US dollars 1130.01 +/- US dollars 138.40) and of functional MR imaging (US dollars 301.82 +/- US dollars 10.65) were significantly different (P <.001). The cost of the Wada test was 3.7 times higher than that of functional MR imaging. CONCLUSION Substantial savings are achievable with the use of functional MR imaging instead of the Wada test to evaluate language lateralization.
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Affiliation(s)
- L Santiago Medina
- Division of Neuroradiology and Health Outcomes, Policy and Economics Center, Department of Radiology, Miami Children's Hospital, 3100 SW 62 Ave, Miami, FL 33155, USA.
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429
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Baciu MV, Watson JM, McDermott KB, Wetzel RD, Attarian H, Moran CJ, Ojemann JG. Functional MRI reveals an interhemispheric dissociation of frontal and temporal language regions in a patient with focal epilepsy. Epilepsy Behav 2003; 4:776-80. [PMID: 14698719 DOI: 10.1016/j.yebeh.2003.08.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We report the case of a patient with frontal lobe epilepsy in whom the Wada test failed to lateralize representation of language (fluent speech was observed after amobarbital injection on both the right and left side). Functional magnetic resonance imaging (fMRI) during a lexical processing task revealed an atypical organization of language represented by an interhemispheric dissociation of language regions with a right frontal dominance and a left temporal dominance. Consistent with the fMRI results, the patient's ability to name pictures was not reliably impaired by electrocortical stimulation (ECS) of left frontal cortex. The findings from Wada, fMRI, and ECS were confirmed by a lack of language impairment after left frontal lobectomy for seizures. This case illustrates that fMRI can precisely map cortical language networks in epileptic patients and that fMRI may be used to help interpret laterality results provided by the Wada procedure.
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Affiliation(s)
- M V Baciu
- Department of Psychology, Pierre Mendes-France University, Grenoble, France
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430
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Kraut MA, Calhoun V, Pitcock JA, Cusick C, Hart J. Neural hybrid model of semantic object memory: implications from event-related timing using fMRI. J Int Neuropsychol Soc 2003; 9:1031-40. [PMID: 14738284 DOI: 10.1017/s135561770397007x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Revised: 04/14/2003] [Indexed: 11/07/2022]
Abstract
Previous studies by our group have demonstrated fMRI signal changes and synchronized gamma rhythm EEG oscillations between thalamus and cortical regions as subjects recall objects from visually presented features. Here, we extend this work by estimating the time course of fMRI signal changes in the cortical and subcortical regions found to exhibit evidence for task-related activation. Our results indicate that there are separate loci of signal changes in the thalamus (dorsomedial and pulvinar) that exhibit notable differences in times of onset, peak and return to baseline of signal changes. The signal changes in the pulvinar demonstrate the slowest transients of all the cortical and subcortical regions we examined. Evaluation of cortical regions demonstrated salient differences as well, with the signal changes in Brodmann area 6 (BA6) rising, peaking, and returning to baseline earlier than those detected in other regions. We conclude that BA6 mediates early designation or refinement of search criteria, and that the pulvinar may be involved in the binding of feature stimuli for an integrated object memory.
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Affiliation(s)
- Michael A Kraut
- Dept. of Radiology, Division of Neuroradiology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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431
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Borbély K, Gjedde A, Nyáry I, Czirják S, Donauer N, Buck A. Speech activation of language dominant hemisphere:. Neuroimage 2003; 20:987-94. [PMID: 14568468 DOI: 10.1016/s1053-8119(03)00382-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2003] [Revised: 05/27/2003] [Accepted: 06/26/2003] [Indexed: 11/21/2022] Open
Abstract
We tested the prediction that single photon emission computed tomography (SPECT) of the blood flow distribution in speech-activated brain identifies the language-dominant hemisphere. We based the prediction on the hypothesis that language activation leads to focally increased regional cerebral blood flow (rCBF), which is reflected in the uptake of a flow tracer recorded by SPECT. We compared the results of speech activation to the results of functional transcranial Doppler (fTCD) monitoring in the same subjects. Preoperatively, 17 patients (10 women and 7 men with a mean age of 36 +/- 15 years) with diagnoses of epilepsy (n = 14) or arteriovenous malformation (AVM) (n = 3) had two SPECT and two stereo-TCD monitoring studies in each case, one at rest, and one during 3 min of speech activation. Except for two left-handed patients with right-hemisphere dominance, the subjects had the highest changes of rCBF from baseline to activation in the left posterior inferior frontal cortex and in contralateral cerebellum. The results show that changes of the level of neuronal activity reflected by the measurement of rCBF variations might be detected by SPECT. Additionally, the evaluation of hemispheric language dominance based on SPECT showed a complete agreement with the evaluation based on fTCD results (yielding a kappa coefficient equal to 1), and therefore, speech-activation SPECT mapping might be helpful in the evaluation of hemispheric language dominance, especially when fMRI and PET are not available or they are contraindicated for some reason.
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432
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Abstract
The intracarotid amytal procedure (IAP) was used twice to assess the suitability of three male patients for two successive neurosurgical procedures to relieve intractable temporal lobe epilepsy. First an amygdalohippocampectomy was performed, then further tissue was removed in a temporal lobe resection because their seizures had failed to remit. Repetition of the IAP following amygdalohippocampectomy when there was a known excision allowed inferences to be made regarding its validity in assessing lateralization of language functioning, memory functioning, and lateralization of seizure focus. The procedure was found to be reliable in assessing both language dominance and adequacy of memory functioning of the hemisphere contralateral to the lesion site. The procedure's third function of lesion lateralization was valid for identifying the known neurosurgical lesion. However, it was less successful in corroborating the lateralization of seizure focus before amygdalohippocampectomy. Differences in cognitive outcome between the two neurosurgical procedures are discussed.
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Affiliation(s)
- Jessica Bramham
- Neuropsychology Unit, Department of Psychology, Henry Wellcome Building, Institute of Psychiatry, De Crespigny Park, London SE5 8AF,
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433
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Akanuma N, Koutroumanidis M, Adachi N, Alarcón G, Binnie CD. Presurgical assessment of memory-related brain structures: the Wada test and functional neuroimaging. Seizure 2003; 12:346-58. [PMID: 12915080 DOI: 10.1016/s1059-1311(02)00323-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Medial temporal lobe structures are known to play a major role in memory processing. Recent work has revealed that extratemporal structures (e.g. the frontal lobe and thalamus) may also be important in memory function. In candidates for epilepsy surgery, particularly in those with temporal lobe seizures, presurgical evaluation of memory function is essential, since seizures may originate in the neural substrate that is critical for memory. In this article, we review the tools used for presurgical evaluation and their contribution to the understanding of memory function, focusing on the Wada test, [18F]fluorodeoxy-glucose positron emission tomography ([18F]FDG-PET) and functional magnetic resonance imaging (fMRI). We also explore perspectives on future studies that may elucidate the role of the temporal and extratemporal structures in memory function and the mechanisms of cerebral plasticity.
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Affiliation(s)
- Nozomi Akanuma
- Department of Clinical Neuroscience, Guy's, King's and St. Thomas' School of Medicine, King's College London, London, UK.
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434
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Aldenkamp AP, Boon PA, Deblaere K, Achten E, Backes WH, Boon P, Hofman P, Troost J, Vandemaele P, Vermeulen J, Vonck K, Wilmink J. Usefulness of language and memory testing during intracarotid amobarbital testing: observations from an fMRI study. Acta Neurol Scand 2003; 108:147-52. [PMID: 12911455 DOI: 10.1034/j.1600-0404.2003.00116.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND Several procedures for testing language lateralization and memory function exist during the intracarotid amobarbital test (IAT). The use of functional magnetic resonance imaging (fMRI) gives the opportunity to assess the validity of some of these procedures, or at least to inspect the neuronal correlates. A comprehensive fMRI protocol was tested, aimed at addressing aspects of lateralization of language, as well as testing memory in relation to activation of mesiotemporal regions. Here we report observations with possible consequences for the current IAT procedures. MATERIALS AND METHODS The protocol consisted of three language tasks (overt naming, semantic decision and silent word generation) and two memory tasks (encoding and retrieving visual scenes). The paradigms used a block-related procedure in nine right-handed normal volunteers. During the procedure dynamic weighted full brain images were acquired which are sensitive to the blood oxygenation activation effect. RESULTS Encoding showed symmetrical bilateral activation in the mesiotemporal regions, specifically the hippocampus, parahippocampal gyrus and fusiform gyrus. With a retrieval task activation of the mesiotemporal areas was restricted to the posterior hippocampal area. Overt object naming showed results, similar to encoding tasks with bilateral activation of hippocampal areas. Silent word generation showed much stronger ability to lateralize than the other two language-related tasks and especially object naming. CONCLUSION Activation revealed by fMRI activation shows that IAT procedures, using active semantic language processing or comprehensive procedures with multiple language tasks have the highest guarantee for individual activation lateralization. Simple object naming does not guarantee a lateralized language fMRI activation pattern. Of the different memory procedures during IAT, the procedures (Interview and the Montreal) demanding encoding processing will be related to larger areas of bilateral hippocampal activation than procedures (Seattle) exclusively requiring retrieval. Moreover, tasks using recognition of previously presented language items (naming objects) are equally effective for assessing hippocampal activation compared with presenting separate memory items.
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Affiliation(s)
- A P Aldenkamp
- Epilepsy Centre 'Kempenhaeghe', Ghent University Hospital, Belgium.
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435
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Stippich C, Mohammed J, Kress B, Hähnel S, Günther J, Konrad F, Sartor K. Robust localization and lateralization of human language function: an optimized clinical functional magnetic resonance imaging protocol. Neurosci Lett 2003; 346:109-13. [PMID: 12850560 DOI: 10.1016/s0304-3940(03)00561-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
An optimized clinical functional magnetic resonance imaging (fMRI) protocol with a total scanning time of 8 min is presented that localizes Broca's and Wernicke's areas robustly and determines hemispheric dominance. Language function was visualized using two different sentence generation (SG) and word generation (WG) tasks. Block designed blood oxygenation level dependent (BOLD) fMRI was applied in 14 right-handed volunteers at 1.5 T during visual stimulation. BOLD-clusters were assessed individually for anatomical localization. Reference data are provided for the maximum correlation of the measured BOLD-signal time course to the applied reference function (r(max)), for the maximum relative signal change (dS%), cluster size and Euklidian coordinates of Broca and Wernicke activation and of the anatomical homologues in the right hemispheres. Statistical means and a lateralization index (LI) were calculated. Broca activation focussed on the inferior frontal gyrus, and Wernicke activation on the superior temporal, supramarginal or middle temporal gyri. Mean BOLD-signals for Broca ranged from 1.53% (SG) to 2.56% (WG), and for Wernicke from 1.47% (SG) to 1.80% (WG). LI indicated left language dominance. The data provided further evidence for the high anatomical variability of language areas, which underlined the relevance of an individual language localization and lateralization prior to brain surgery.
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Affiliation(s)
- Christoph Stippich
- Department of Neurology, University of Heidelberg Medical Center, Im Neuenheimer Feld 400, D-69120 Heidelberg, Germany.
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436
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Specht K, Holtel C, Zahn R, Herzog H, Krause BJ, Mottaghy FM, Radermacher I, Schmidt D, Tellmann L, Weis S, Willmes K, Huber W. Lexical decision of nonwords and pseudowords in humans: a positron emission tomography study. Neurosci Lett 2003; 345:177-81. [PMID: 12842285 DOI: 10.1016/s0304-3940(03)00494-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In this functional positron emission tomography study brain activations during an auditory lexical decision task with two experimental conditions were investigated. First, the subjects had to discriminate between real words and nonwords; second, real words varied with pseudowords. Comparing each of these tasks to an auditory control condition we found bilateral activation of the superior temporal and inferior frontal gyrus, lateralized to the left in the pseudoword condition. The comparison of the lexical decision tasks revealed higher rCBF during the pseudo-/real word decisions within BA 47, adjacent to Broca's area, and the anterior cingulate. The data support the notion that the lexical decision during a nonword task is mainly based on a phonological discrimination process, whereas a pseudoword task more strongly requires lexical access resulting in activation of BA 47.
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Affiliation(s)
- Karsten Specht
- Division of Neurolinguistics, Neurology Department, University Hospital Aachen, Aachen, Germany.
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437
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Abstract
One of the most pertinent applications of the principle primum non nocere (first do no harm) is in the optimization of neurosurgical procedures for patients with resectable lesions. The gold standard for identifying eloquent areas of the brain to be avoided in resections is direct cortical stimulation and somatosensory evoked potential monitoring, which is itself an invasive, cumbersome and difficult technique for mapping these areas. Functional magnetic resonance imaging shows great promise as a viable noninvasive alternative to invasive mapping as well as significant current clinical utility in cases in which it cannot yet fully supplant cortical stimulation methods. Ongoing work is directed toward overcoming technical limitations, improved mapping of complex functions such as language and memory, and mapping of white matter tracts.
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Affiliation(s)
- Paul E Kim
- Department of Neuroradiology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
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438
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Bartha L, Brenneis C, Schocke M, Trinka E, Köylü B, Trieb T, Kremser C, Jaschke W, Bauer G, Poewe W, Benke T. Medial temporal lobe activation during semantic language processing: fMRI findings in healthy left- and right-handers. BRAIN RESEARCH. COGNITIVE BRAIN RESEARCH 2003; 17:339-46. [PMID: 12880904 DOI: 10.1016/s0926-6410(03)00135-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Medial temporal lobe (MTL) areas are well known to serve episodic memory functions; their contribution to semantic memory has been occasionally noticed but not studied in detail. In the present fMRI study, 35 right-handed and 35 left-handed healthy subjects performed a semantic decision paradigm during which subjects heard spoken concrete nouns designating objects and had to decide on whether these objects were available in the supermarket and cost lest then a certain amount of money. The control paradigm consisted of sequences of low and high tones where subjects had to decide whether a sequence contained two high tones. The resulting contrast activation of semantic decision versus tone decision involved neocortical temporal, parietal, and prefrontal areas. Additional significant, bilateral activations in the MTL, the hippocampal formation, and adjacent areas were found. The exact incidence and location of activation was studied in a single-subject analysis for all 70 subjects. At the chosen threshold of P<0.001, 94% of subjects showed activations in the MTL and inferior temporal lobe (ITL). Activations were found along the longitudinal axis of the MTL, including the hippocampal formation and the parahippocampal gyrus. In the ITL, parts of the fusiform and lingual gyri were activated. Activations were similar in right- and left-handers. We conclude from this study that the MTL and parts of the ITL can be added to the areas activated by semantic verbal memory processing.
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Affiliation(s)
- Lisa Bartha
- Clinic for Neurology, University of Innsbruck, Innsbruck, Austria
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439
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Knake S, Haag A, Hamer HM, Dittmer C, Bien S, Oertel WH, Rosenow F. Language lateralization in patients with temporal lobe epilepsy: a comparison of functional transcranial Doppler sonography and the Wada test. Neuroimage 2003; 19:1228-32. [PMID: 12880847 DOI: 10.1016/s1053-8119(03)00174-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study prospectively investigates whether noninvasive functional transcranial Doppler sonography (fTCD) is a useful tool to determine hemispheric language lateralization in the presurgical evaluation of patients with medically intractable temporal lobe epilepsy (TLE). fTCD results were compared with the Wada test as the gold standard. Wada test and fTCD were performed in 13 patients suffering from TLE. fTCD continuously measured blood flow velocities in both middle cerebral arteries, while the patient was performing a cued word generation task. During the Wada test, spontaneous speech, comprehension, reading, naming, and repetition were investigated. A laterality index (LI) was obtained by both procedures. Due to a lack of an acoustic temporal bone window, fTCD could not be performed in two patients (15%). In 9 of the remaining 11 patients hemispheric language dominance was found on the left side, in 1 patient on the right side, and 1 patient showed bihemispheric language representation. In all patients fTCD and the Wada test were in good agreement regarding hemispheric language lateralization, and the LI of both techniques were highly correlated (r = 0.776, P = 0.005). fTCD gives predictions of hemispheric language dominance consistent with the Wada test results even in children, patients with low IQ, and nonnative speakers. It is an alternative to the Wada test in determining language lateralization in patients with temporal lobe epilepsy.
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Affiliation(s)
- Susanne Knake
- Department of Neurology, Interdisciplinary Epilepsy Center, Philipps-University, Marburg, Germany.
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440
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Knecht S, Jansen A, Frank A, van Randenborgh J, Sommer J, Kanowski M, Heinze HJ. How atypical is atypical language dominance? Neuroimage 2003; 18:917-27. [PMID: 12725767 DOI: 10.1016/s1053-8119(03)00039-9] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Atypical, right-hemisphere language dominance is poorly understood. It is often observed in patients with brain reorganization due to lesions early in life. It can also be encountered in seemingly normal individuals. We compared the patterns of neural language activation in 7 individuals with left- and 7 with right-hemisphere language dominance, none of whom had any evidence of brain lesions. We speculated that incongruencies in the activation patterns in atypical, right-hemisphere language dominance could indicate a reorganized neural language system after undetected early brain damage. Functional magnetic resonance imaging analysis of brain activation during phonetic word generation demonstrated (1). no increased activation in the subdominant hemisphere in right compared to left language dominance, (2). a similar variability in the pattern of activation in both groups, and (3). a mirror reverse pattern of activation in right- compared to left-hemisphere dominant subjects. These findings support the view that in individuals with an unrevealing medical history right-hemispheric dominance constitutes a natural rather than an abortive variant of language lateralization.
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Affiliation(s)
- S Knecht
- Department of Neurology, University of Münster, Münster, Germany.
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441
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Liu HL, Wu CT, Chen JC, Hsu YY, Wai YY, Wan YL. Implementations of clinical functional magnetic resonance imaging using character-based paradigms for the prediction of Chinese language dominance. J Comput Assist Tomogr 2003; 27:207-12. [PMID: 12703013 DOI: 10.1097/00004728-200303000-00017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE Recently, functional MRI (fMRI) using word generation (WG) tasks has been shown to be effective for mapping the Chinese language-related brain areas. In clinical applications, however, patients' performance cannot be easily monitored during WG tasks. In this study, we evaluated the feasibility of a word choice (WC) paradigm in the clinical setting and compared the results with those from WG tasks. METHOD Intrasubject comparisons of fMRI with both WG and WC paradigms were performed on six normal human subjects and two tumor patients. Subject responses in the WC paradigm, based on semantic judgments, were recorded. Activation strength, extent, and laterality were evaluated and compared. RESULTS Our results showed that fMRI with the WC paradigm evoked weaker neuronal activation than that with the WG paradigm in Chinese language-related brain areas. It was sufficient to reveal language laterality for clinical use, however. In addition, it resulted in less nonlanguage-specific brain activation. CONCLUSION Results from the patient data demonstrated strong evidence for the necessity of incorporating response monitoring during fMRI studies, which suggested that fMRI with the WC paradigm is more appropriate to be implemented for the prediction of Chinese language dominance in clinical environments.
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Affiliation(s)
- Ho-Ling Liu
- Department of Diagnostic Radiology, Chang Gung Memorial Hospital, Taiwan.
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442
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Gaillard WD, Sachs BC, Whitnah JR, Ahmad Z, Balsamo LM, Petrella JR, Braniecki SH, McKinney CM, Hunter K, Xu B, Grandin CB. Developmental aspects of language processing: fMRI of verbal fluency in children and adults. Hum Brain Mapp 2003; 18:176-85. [PMID: 12599275 PMCID: PMC6871939 DOI: 10.1002/hbm.10091] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2002] [Accepted: 10/11/2002] [Indexed: 11/10/2022] Open
Abstract
We examined developmental differences, in location and extent of fMRI language activation maps, between adults and children while performing a semantic fluency task. We studied 29 adults and 16 children with echo planar imaging BOLD fMRI at 1.5 T using covert semantic verbal fluency (generation of words to categories compared to rest) using a block design. Post task testing was administered to assess performance. Individual data were analyzed with an a priori region of interest approach from t maps (t = 4) and asymmetry indices (AI). Group studies were analyzed using SPM 99 (Wellcome, UK; fixed effect, corrected P < 0.0001). We found no significant differences in location or laterality of activation between adults and children for a semantic verbal fluency task. Adults activated more pixels than children in left inferior frontal gyrus and left middle frontal gyrus, but AIs were the similar across ages (r(2) < 0.09). Extent or laterality of activation was not affected by performance (r(2) < 0.15). The brain areas that process semantic verbal fluency are similar in children and adults. The laterality of activation does not change appreciably with age and appears to be strongly lateralized by age 7 years.
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Affiliation(s)
- William D Gaillard
- Department of Neurology, Children's National Medical Center, George Washington University School of Medicine, Washington, DC 20010, USA.
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443
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Matthews PM, Adcock J, Chen Y, Fu S, Devlin JT, Rushworth MFS, Smith S, Beckmann C, Iversen S. Towards understanding language organisation in the brain using fMRI. Hum Brain Mapp 2003; 18:239-47. [PMID: 12599283 PMCID: PMC6871892 DOI: 10.1002/hbm.10099] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2002] [Accepted: 10/06/2002] [Indexed: 12/28/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI), which allows non-invasive mapping of human cognitive functions, has become an important tool for understanding language function. An understanding of component processes and sources of noise in the images is contributing to increased confidence in the reproductability of studies. This allows clinical applications, e.g., for pre-surgical lateralisation of language functions in patients with temporal lobe epilepsy. fMRI is a sensitive method for mapping regions involved in language functions. We recently have applied it to study the effect of word surface form on reading with a comparison of responses to Chinese characters or alphabetical Pinyin. Interpretation of fMRI activations must be made with caution; fMRI suggests task-associated activation, but does not independently confirm that such activity is necessary. However, complementary studies can be performed using transcranial magnetic stimulation (TMS), which can be used to interfere with brain activity in a specific region transiently for characterisation of the behavioural effects. We describe how TMS combined with fMRI has confirmed a role for the left inferior frontal cortex in semantic processing.
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Affiliation(s)
- P M Matthews
- Centre for Functional Magnetic Resonance Imaging of the Brain, Department of Clinical Neurology, John Radcliffe Hospital, Oxford, United Kingdom.
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444
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Krainik A, Lehéricy S, Duffau H, Capelle L, Chainay H, Cornu P, Cohen L, Boch AL, Mangin JF, Le Bihan D, Marsault C. Postoperative speech disorder after medial frontal surgery: role of the supplementary motor area. Neurology 2003; 60:587-94. [PMID: 12601097 DOI: 10.1212/01.wnl.0000048206.07837.59] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Patients undergoing surgical resection of medial frontal lesions may present transient postoperative speech disorders that remain largely unpredictable. OBJECTIVE To relate the occurrence of this speech deficit to the specific surgical lesion of the supplementary motor area (SMA) involved during language tasks using fMRI. METHODS Twelve patients were studied using a verbal fluency task before resection of a low-grade glioma of the medial frontal lobe and compared with six healthy subjects. Pre- and postoperative MR variables including the hemispheric dominance for language, the extent of SMA removal, and the volume of resection were compared to the clinical outcome. RESULTS Following surgery, 6 of 12 patients presented speech disorders. The deficit was similar across patients, consisting of a global reduction in spontaneous speech, ranging from a complete mutism to a less severe speech reduction, which recovered within a few weeks or months. The occurrence of the deficit was related to the resection of the activation in the SMA of the dominant hemisphere for language (p < 0.01). Increased activation in the SMA of the healthy hemisphere on the preoperative fMRI was observed in patients with postoperative speech deficit. CONCLUSIONS fMRI is able to identify the area at risk in the SMA, of which resection is related to the occurrence of characteristic transient postoperative speech disorders. Increased SMA activation in the healthy hemisphere suggested that a plastic change of SMA function occurred in these patients.
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Affiliation(s)
- A Krainik
- Department of Neuroradiology, Hôpital de la Salpêtrière, Paris, France
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445
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Chee MWL, Lee HL, Soon CS, Westphal C, Venkatraman V. Reproducibility of the word frequency effect: comparison of signal change and voxel counting. Neuroimage 2003; 18:468-82. [PMID: 12595200 DOI: 10.1016/s1053-8119(02)00019-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
We determined the reproducibility of both the direction and the effect size of the word frequency effect (WFE) as it relates to associative semantic judgments. Sixteen volunteers were scanned twice. At the group level of analysis, signal change and voxel counting could both reproducibly detect the existence of a WFE. However, signal change data showed less intersession variation, particularly in the left inferior frontal gyrus. The effect size of WFE was well reproduced only with signal change measurements. In consideration of the signal change data, statistical threshold did not have a major effect on the detection or determination of the effect size. In general, while the direction of the WFE was reasonably reproducible at the individual level, the effect size was far less well reproduced. These findings suggest that with existing techniques, fMRI may be used to track changes in brain activation stemming from improvement in language proficiency at the group level but not at the individual level.
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Affiliation(s)
- Michael W L Chee
- Cognitive Neuroscience Laboratory, SingHealth Research Laboratories, c/o Singapore General Hospital, 7 Hospital Drive #01-11, Singapore 169856.
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446
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Adcock JE, Wise RG, Oxbury JM, Oxbury SM, Matthews PM. Quantitative fMRI assessment of the differences in lateralization of language-related brain activation in patients with temporal lobe epilepsy. Neuroimage 2003; 18:423-38. [PMID: 12595196 DOI: 10.1016/s1053-8119(02)00013-7] [Citation(s) in RCA: 237] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Defining language lateralization is important to minimize morbidity in patients treated surgically for temporal lobe epilepsy (TLE). Functional magnetic resonance imaging (fMRI) offers a promising, noninvasive, alternative strategy to the Wada test. Here we have used fMRI to study healthy controls and patients with TLE in order to (i) define language-related activation patterns and their reproducibility; (ii) compare lateralization determined by fMRI with those from of the Wada test; and (iii) contrast different methods of assessing fMRI lateralization. Twelve healthy right-handed controls and 19 right-handed preoperative patients with TLE (12 left- and seven right-TLE) were studied at 3T using fMRI and a verbal fluency paradigm. A Wada test also was performed on each of the patients. Greater activation was found in several areas in the right hemisphere for the left-TLE group relative to controls or right-TLE patients. Relative hemispheric activations calculated based on either the extent or the mean signal change gave consistent results showing a more bihemispheric language representation in the left-TLE patients. There was good agreement between the Wada and fMRI results, although the latter were more sensitive to involvement of the nondominant right hemisphere. The reproducibility of the fMRI values was lowest for the more bihemispherically represented left-TLE patients. Overall, our results further demonstrate that noninvasive fMRI measures of language-related lateralization may provide a practical and reliable alternative to invasive testing for presurgical language lateralization in patients with TLE. The high proportion (33%) of left-TLE patients showing bilateral or right hemispheric language-related lateralization suggests that there is considerable plasticity of language representation in the brains of patients with intractable TLE.
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Affiliation(s)
- J E Adcock
- Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB), Department of Clinical Neurology, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK.
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447
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Abstract
The 1990s were dubbed the "Decade of the Brain." During this time there was a marked increase in the amount of neuroimaging work observing how the brain accomplishes many tasks, including the processing of language. In this chapter we review the past 15 years of neuroimaging research on language production and comprehension. The findings of these studies indicate that the processing involved in language use occurs in diffuse brain regions. These regions include Broca's and Wernicke's areas, primary auditory and visual cortex, and frontal regions in the left hemisphere, as well as in the right hemisphere homologues to these regions. We conclude the chapter by discussing the future of neuroimaging research into language production and comprehension.
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448
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Abstract
Drug treatment resistant epilepsy is an important public health problem. Patients with epilepsy of focal origin may have an excellent outcome following surgery that removes the source of seizures. Identification of the precise cortical region producing seizures is crucial to a good outcome; additionally, identification of eloquent cortical areas near the region to be resected is essential to prevent postoperative neurological deficit. A wide range of imaging techniques is valuable for imaging the epileptogenic zone, including high-resolution T1 MRI, T2 signal quantitation, MR spectroscopy, diffusion imaging, PET, SPECT and simultaneous EEG-fMRI. Eloquent cortex has in the past been mapped using highly invasive techniques; fMRI of motor and cognitive tasks holds great promise for future non-invasive mapping strategies.
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Affiliation(s)
- Mark P Richardson
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, UK
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449
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Desmond JE, Annabel Chen SH. Ethical issues in the clinical application of fMRI: factors affecting the validity and interpretation of activations. Brain Cogn 2002; 50:482-97. [PMID: 12480492 DOI: 10.1016/s0278-2626(02)00531-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ability of functional magnetic resonance imaging (fMRI) to localize activations in a single patient, along with the safety and widespread availability of this methodology, has lead to an increasing use of fMRI for clinical purposes such as pre-surgical planning. As methodology continues to improve and more experience with fMRI in the clinical setting is acquired, clinical functional neuroimaging will likely have an increasing influence over patient care. Therefore, ethical use of fMRI, as with other medical techniques, requires understanding the factors impacting the interpretation of the methodology. Issues affecting the validity and interpretation of clinical functional neuroimaging, including effects of altered hemodynamic response function, head motion, and structural changes in the brain, are reviewed. The distinction between correlated and necessary activation in a clinical context is discussed. Different types of statistical errors in fMRI analysis are described, along with their consequences to the patient. Finally, for the future of clinical fMRI development, the need for normative patient data, as well as standardized tasks, scan protocols, and data analyses, is discussed.
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Affiliation(s)
- John E Desmond
- Department of Radiology, Lucas MRS Center, MC: 5488, Stanford University, Stanford, CA 94305-5488, USA.
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450
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Loring DW, Meador KJ, Allison JD, Pillai JJ, Lavin T, Lee GP, Balan A, Dave V. Now you see it, now you don't: statistical and methodological considerations in fMRI. Epilepsy Behav 2002; 3:539-547. [PMID: 12609249 DOI: 10.1016/s1525-5050(02)00558-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We illustrate the effects of statistical threshold, spatial clustering, voxel size, and two approaches to multiple comparison correction on fMRI results. We first analyzed fMRI images obtained from a single subject during a noun-verb matching task. Data were analyzed with Statistical Parametric Mapping (SPM) using two different voxel sizes, and results were displayed at three different levels of statistical significance. At each statistical threshold, results were first uncorrected for multiple comparisons and spatial extent and then presented using a spatial extent cluster of 20 voxels. We then statistically controlled the Type I error rate associated with multiple comparisons by using the false discovery rate and by the random field adjustment for false-positive rate used by SPM. We also examined group results from language and graphesthesia paradigms at three levels of statistical significance. In all circumstances, apparent random activations decreased as more conservative statistical approaches were employed, but activation in areas considered to be functionally significant was also reduced. These issues are important in the choice of analytic approach and interpretation of fMRI results, with clear implications for the surgical management of individual patients when fMRI results are used to delineate specific areas of eloquent cortex.
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Affiliation(s)
- D W. Loring
- Department of Neurology, Medical College of Georgia, 30912-3275, Augusta, GA, USA
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