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Cooper S, Alm KH, Olson IR, Ellman LM. White matter alterations in individuals experiencing attenuated positive psychotic symptoms. Early Interv Psychiatry 2018; 12:372-379. [PMID: 26818412 PMCID: PMC4965329 DOI: 10.1111/eip.12306] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 12/15/2015] [Indexed: 01/08/2023]
Abstract
AIM Diffusion tensor imaging (DTI) studies suggest that reduced fractional anisotropy (FA) in the inferior longitudinal fasciculus (ILF) and superior longitudinal fasciculus (SLF) occurs among schizophrenia patients and those at risk for psychosis. Nevertheless, there is a dearth of knowledge investigating white matter fibre pathways in non-help-seeking individuals who endorse attenuated positive psychotic symptoms (APPS) across a range of mental disorders. The aim of the current study was to determine if alterations in ILF and SLF microstructures were specific to distressing APPS related to risk for psychosis or to APPS symptoms occurring in multiple mental disorders, which would suggest a shared phenotype among disorders. METHOD Twenty-six non-help-seeking young adults were administered the Prodromal Questionnaire. DTI was conducted on participants (n = 13) who endorsed eight or more distressing APPS (D-APPS, a potentially clinically relevant group) and those who endorsed three or fewer distressing APPS (low-APPS; n = 13). Semistructured interviews were administered to determine diagnoses, as well as clinical risk for psychosis status. RESULTS Results indicated that the D-APPS group exhibited decreased FA in the left ILF compared with the low-APPS group, even after removing four D-APPS participants who were considered at risk for psychosis. CONCLUSION Findings suggest that white matter microstructure is altered in individuals experiencing APPS across a range of disorders, independent of clinical high risk for psychosis status. Reduced FA in the left ILF may not be specific to psychosis risk, but rather for APPS that occur in a number of mental disorders.
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Affiliation(s)
- Shanna Cooper
- Department of Psychology, Temple University, Philadelphia, Pennsylvania, USA
| | - Kylie H Alm
- Department of Psychology, Temple University, Philadelphia, Pennsylvania, USA
| | - Ingrid R Olson
- Department of Psychology, Temple University, Philadelphia, Pennsylvania, USA
| | - Lauren M Ellman
- Department of Psychology, Temple University, Philadelphia, Pennsylvania, USA
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Sakurai Y, Furukawa E, Kurihara M, Sugimoto I. Frontal Phonological Agraphia and Acalculia with Impaired Verbal Short-Term Memory due to Left Inferior Precentral Gyrus Lesion. Case Rep Neurol 2018; 10:72-82. [PMID: 29681826 PMCID: PMC5903121 DOI: 10.1159/000487849] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 02/20/2018] [Indexed: 11/19/2022] Open
Abstract
We report a patient with phonological agraphia (selective impairment of kana [Japanese phonetic writing] nonwords) and acalculia (mental arithmetic difficulties) with impaired verbal short-term memory after a cerebral hemorrhage in the opercular part of the left precentral gyrus (Brodmann area 6) and the adjacent postcentral gyrus. The patient showed phonemic paragraphia in five-character kana nonword writing, minimal acalculia, and reduced digit and letter span. Mental arithmetic normalized after 8 months and agraphia recovered to the normal range at 1 year after onset, in parallel with an improvement of the auditory letter span score from 4 to 6 over a period of 14 months and in the digit span score from 6 to 7 over 24 months. These results suggest a close relationship between the recovery of agraphia and acalculia and the improvement of verbal short-term memory. The present case also suggests that the opercular part of the precentral gyrus constitutes the phonological route in writing that conveys phonological information of syllable sequences, and its damage causes phonological agraphia and acalculia with reduced verbal short-term memory.
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Affiliation(s)
| | - Emi Furukawa
- Department of Nephrology, Mitsui Memorial Hospital, Tokyo, Japan
| | - Masanori Kurihara
- Department of Neurology, Mitsui Memorial Hospital, Tokyo, Japan.,Department of Neurology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Izumi Sugimoto
- Department of Neurology, Mitsui Memorial Hospital, Tokyo, Japan
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Fitzgerald J, Leemans A, Kehoe E, O'Hanlon E, Gallagher L, McGrath J. Abnormal fronto-parietal white matter organisation in the superior longitudinal fasciculus branches in autism spectrum disorders. Eur J Neurosci 2017; 47:652-661. [DOI: 10.1111/ejn.13655] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 07/13/2017] [Accepted: 07/13/2017] [Indexed: 11/27/2022]
Affiliation(s)
- Jacqueline Fitzgerald
- Department of Psychiatry; School of Medicine; Trinity College Dublin; Dublin Ireland
- Trinity College Institute of Neuroscience; Trinity College Dublin; Lloyd Building Dublin Ireland
| | - Alexander Leemans
- Image Sciences Institute; University Medical Center Utrecht; Utrecht The Netherlands
| | - Elizabeth Kehoe
- Trinity College Institute of Neuroscience; Trinity College Dublin; Lloyd Building Dublin Ireland
| | - Erik O'Hanlon
- Trinity College Institute of Neuroscience; Trinity College Dublin; Lloyd Building Dublin Ireland
- Department of Psychiatry; Royal College of Surgeons in Ireland; Dublin Ireland
| | - Louise Gallagher
- Department of Psychiatry; School of Medicine; Trinity College Dublin; Dublin Ireland
- Linndara Child and Adolescent Mental Health Service; Dublin Ireland
| | - Jane McGrath
- Department of Psychiatry; School of Medicine; Trinity College Dublin; Dublin Ireland
- Linndara Child and Adolescent Mental Health Service; Dublin Ireland
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An altered scaffold for information processing: Cognitive control development in adolescents with autism. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2017; 2:464-475. [PMID: 28924621 DOI: 10.1016/j.bpsc.2017.06.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We investigated how cognitive neuroscientific studies during the last decade have advanced understanding of cognitive control from adolescence to young adulthood in individuals with autism spectrum disorder (ASD). To do so, we conducted a selective review of the larger structural, resting state, and diffusion imaging studies of brain regions and networks related to cognitive control that have been conducted since 2007 in individuals with ASD and typical development (TYP) ages 10 to 30 years that examined how these regions and networks support behavioral and task-based fMRI performance on tasks assessing cognitive control during this period. Longitudinal structural studies reveal overgrowth of the anterior cingulate (ACC) and slower white matter development in the parietal cortex in adolescents with ASD versus TYP. Cross-sectional studies of the salience, executive control and default mode resting state functional connectivity networks, which mediate cognitive control, demonstrate patterns of connectivity that differ from TYP through adolescence. Finally, white matter tracts underlying these control-related brain regions continue to show reduced diffusion properties compared to TYP. It is thus not surprising that cognitive control tasks performance improves less during adolescence in ASD versus TYP. This review illustrates that a cognitive neuroscientific approach produces insights about the mechanisms of persistent cognitive control deficits in individuals with ASD from adolescence into young adulthood not apparent with neuropsychological methods alone, and draws attention to the great need for longitudinal studies of this period in those with ASD. Further investigation of ACC and fronto-parietal neural circuits may help specify pathophysiology and treatment options.
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55
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Koyama T, Domen K. Diffusion Tensor Fractional Anisotropy in the Superior Longitudinal Fasciculus Correlates with Functional Independence Measure Cognition Scores in Patients with Cerebral Infarction. J Stroke Cerebrovasc Dis 2017; 26:1704-1711. [DOI: 10.1016/j.jstrokecerebrovasdis.2017.03.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 03/22/2017] [Accepted: 03/25/2017] [Indexed: 12/12/2022] Open
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The perisylvian language network and language analytical abilities. Neurobiol Learn Mem 2017; 144:96-101. [PMID: 28710000 DOI: 10.1016/j.nlm.2017.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 07/04/2017] [Accepted: 07/07/2017] [Indexed: 10/19/2022]
Abstract
Aiming at exploring the brain's structural organisation underlying successful second language learning, we investigate the anatomy of the perisylvian language network in a group of healthy adults, consisting of participants with high and average language analytical abilities. Utilising deterministic tractography, six tracts per participant (left and right long direct segment, left and right indirect anterior segment and left and right indirect posterior segment) were virtually dissected and measurements pertaining to their microstructural organisation were collected. Our results obtained by means of linear discriminant analysis pointed to mean diffusivity (MD) values of three tracts (right anterior, left long and left anterior segments) as best discriminating between the two groups. By far the highest coefficient was obtained for the MD values of the right anterior segment, pointing to the role of the right white matter fronto-parietal connectivity for superior language learning abilities. The results imply the importance of attentional processes and reasoning abilities for successful L2 acquisition, and support previous findings concerning right-hemispheric involvement in language learning.
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Relationship Between Perisylvian Essential Language Sites and Arcuate Fasciculus in the Left Hemisphere of Healthy Adults. Neurosci Bull 2017; 33:616-626. [PMID: 28501904 DOI: 10.1007/s12264-017-0137-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 04/11/2017] [Indexed: 10/19/2022] Open
Abstract
Essential language sites and the arcuate fasciculus (AF) have been extensively researched. However, the relationship between them remains insufficiently studied, especially in healthy people. Navigated transcranial magnetic stimulation (nTMS) is increasingly used in language mapping. While enjoying the advantage of non-invasiveness, it is also capable of inducing a virtual lesion in the brain. Thus, it offers the possibility of using the virtual-lesion method to study the healthy brain. This study combined nTMS and diffusion tensor imaging (DTI) tractography to investigate the relationship between essential language sites and the AF in 30 healthy right-handed volunteers. A total of 143 essential language sites were identified using nTMS, and a total of 175 AF terminations were identified using DTI tractography. Sixty-six sites had a direct correlation with the AF, accounting for 46% of the total essential language sites. Forty-seven AF terminations harbored essential language sites, accounting for 27% of the total AF terminations. Upon data rendering to the cortical parcellation system, a region-related heterogeneity of the correlation rate was found. This study provides the first data on the relationship between essential language sites and the AF in healthy adults.
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Young RJ, Tan ET, Peck KK, Jenabi M, Karimi S, Brennan N, Rubel J, Lyo J, Shi W, Zhang Z, Prastawa M, Liu X, Sperl JI, Fatovic R, Marinelli L, Holodny AI. Comparison of compressed sensing diffusion spectrum imaging and diffusion tensor imaging in patients with intracranial masses. Magn Reson Imaging 2016; 36:24-31. [PMID: 27742434 DOI: 10.1016/j.mri.2016.10.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 08/31/2016] [Accepted: 10/05/2016] [Indexed: 10/20/2022]
Abstract
PURPOSE To compare compressed diffusion spectrum imaging (CS-DSI) with diffusion tensor imaging (DTI) in patients with intracranial masses. We hypothesized that CS-DSI would provide superior visualization of the motor and language tracts. MATERIALS AND METHODS We retrospectively analyzed 25 consecutive patients with intracranial masses who underwent DTI and CS-DSI for preoperative planning. Directionally-encoded anisotropy maps, and streamline hand corticospinal motor tracts and arcuate fasciculus language tracts were graded according to a 3-point scale. Tract counts, anisotropy, and lengths were also calculated. Comparisons were made using exact marginal homogeneity, McNemar's and Wilcoxon signed-rank tests. RESULTS Readers preferred the CS-DSI over DTI anisotropy maps in 92% of the cases, and the CS-DSI over DTI tracts in 84%. The motor tracts were graded as excellent in 80% of cases for CS-DSI versus 52% for DTI; 58% of the motor tracts graded as acceptable in DTI were graded as excellent in CS-DSI (p=0.02). The language tracts were graded as excellent in 68% for CS-DSI versus none for DTI; 78% of the language tracts graded as acceptable by DTI were graded as excellent by CS-DSI (p<0.001). CS-DSI demonstrated smaller normalized mean differences than DTI for motor tract counts, anisotropy and language tract counts (p≤0.01). CONCLUSION CS-DSI was preferred over DTI for the evaluation of motor and language white matter tracts in patients with intracranial masses. Results suggest that CS-DSI may be more useful than DTI for preoperative planning purposes.
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Affiliation(s)
- Robert J Young
- Department of Radiology, Memorial Sloan Kettering Cancer Center; Brain Tumor Center, Memorial Sloan Kettering Cancer Center.
| | - Ek T Tan
- Department of Diagnostics, Imaging and Biomedical Technologies, GE Global Research
| | - Kyung K Peck
- Department of Radiology, Memorial Sloan Kettering Cancer Center; Department of Medical Physics, Memorial Sloan Kettering Cancer Center
| | - Mehrnaz Jenabi
- Department of Radiology, Memorial Sloan Kettering Cancer Center
| | - Sasan Karimi
- Department of Radiology, Memorial Sloan Kettering Cancer Center; Brain Tumor Center, Memorial Sloan Kettering Cancer Center
| | - Nicole Brennan
- Department of Radiology, Memorial Sloan Kettering Cancer Center
| | - Jennifer Rubel
- Department of Radiology, Memorial Sloan Kettering Cancer Center
| | - John Lyo
- Department of Radiology, Memorial Sloan Kettering Cancer Center; Brain Tumor Center, Memorial Sloan Kettering Cancer Center
| | - Weiji Shi
- Department of Epidemiology & Biostatistics, Memorial Sloan Kettering Cancer Center
| | - Zhigang Zhang
- Department of Epidemiology & Biostatistics, Memorial Sloan Kettering Cancer Center
| | - Marcel Prastawa
- Department of Diagnostics, Imaging and Biomedical Technologies, GE Global Research
| | - Xiaofeng Liu
- Department of Diagnostics, Imaging and Biomedical Technologies, GE Global Research
| | - Jonathan I Sperl
- Department of Diagnostics, Imaging and Biomedical Technologies, GE Global Research
| | - Robin Fatovic
- Department of Radiology, Memorial Sloan Kettering Cancer Center
| | - Luca Marinelli
- Department of Diagnostics, Imaging and Biomedical Technologies, GE Global Research
| | - Andrei I Holodny
- Department of Radiology, Memorial Sloan Kettering Cancer Center; Brain Tumor Center, Memorial Sloan Kettering Cancer Center
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Clinical considerations and surgical approaches for low-grade gliomas in deep hemispheric locations: insular lesions. Childs Nerv Syst 2016; 32:1875-93. [PMID: 27659830 DOI: 10.1007/s00381-016-3183-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Accepted: 07/06/2016] [Indexed: 12/31/2022]
Abstract
Insula and paralimbic region represent a common location for gliomas in adulthood. However, limbic and paralimbic tumors are rare in children. Reports of pediatric insular tumors are scarce in literature, and most of them are included in adult's series, so their management and outcome can be outlined only after extracting data from these reports. Due to their predominantly low grade, they usually have a benign course for some time, what make them ideal candidates for total resection. However, their intricate location and spread to key areas, including the temporal lobe, make them a surgical challenge. The transsylvian route, with or without resection of the frontal and/or temporal operculae, which requires exposure of part or all of the insula is commonly selected for insular tumor approaches. Intraoperative functional mapping is a standard procedure for resection of central region tumors in adults. In children and young individuals, awake craniotomy is not always possible and surgical planning usually relay on functional and anatomical preoperative studies. The main goal when approaching an insular tumor is to achieve the largest extent of resection to increase overall patient survival while preserving the functional status, minimizing postoperative morbidity and increasing the quality of life. The extent of resection seems to be correlated also with the control of associated (and usually intractable) epilepsy.
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60
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Libero LE, Burge WK, Deshpande HD, Pestilli F, Kana RK. White Matter Diffusion of Major Fiber Tracts Implicated in Autism Spectrum Disorder. Brain Connect 2016; 6:691-699. [PMID: 27555361 DOI: 10.1089/brain.2016.0442] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder found to have widespread alterations in the function and synchrony of brain regions. These differences may underlie alterations in microstructural organization, such as in white matter pathways. To investigate the diffusion of major white matter tracts, the current study examined multiple indices of white matter diffusion in 42 children and adults with ASD and 44 typically developing (TD) age- and IQ-matched peers using diffusion tensor imaging. Diffusivity measures were compared between groups for the following tracts: bilateral cingulum bundle, corpus callosum, inferior longitudinal fasciculus, superior longitudinal fasciculus, and uncinate fasciculus. Results indicate a significant reduction in fractional anisotropy (FA) for the left superior longitudinal fasciculus (LSLF) in ASD children and adults compared with TD peers. A significant increase in radial diffusivity for ASD participants was also found in the same cluster along the LSLF. In addition, a significant positive correlation emerged for all subjects between FA for the LSLF and age, with FA increasing with age. These findings point to a significant alteration in long-distance white matter connectivity in children and adults with ASD, potentially underscoring the relationship between alterations in white matter diffusion and the ASD phenotype. These results also suggest that the white matter alterations in autism may be subtle and related to the developmental trajectory.
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Affiliation(s)
- Lauren E Libero
- 1 UC Davis MIND Institute , Sacramento, California.,2 UC Davis Department of Psychiatry & Behavioral Sciences , Sacramento, California
| | - Wesley K Burge
- 3 Department of Psychology, University of Alabama at Birmingham , Birmingham, Alabama
| | | | - Franco Pestilli
- 5 Department of Psychological and Brain Sciences, Indiana University , Bloomington, Indiana
| | - Rajesh K Kana
- 3 Department of Psychology, University of Alabama at Birmingham , Birmingham, Alabama
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61
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Hsu CCT, Singh D, Watkins TW, Kwan GNC, Skalski M, Hapugoda S, Korah I. Serial magnetic resonance imaging findings of intracerebral spread of listeria utilising subcortical U-fibres and the extreme capsule. Neuroradiol J 2016; 29:425-430. [PMID: 27558992 DOI: 10.1177/1971400916665384] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We present a case of Listeria monocytogenes cerebral abscess with axonal spread via the subcortical U-fibres and extreme capsule on magnetic resonance imaging, with follow-up studies demonstrating serial reduction in oedema and enhancement pattern of the white-matter fibre tracts following antimicrobial treatment. We discuss the microbiological mechanism of bacterial mobility to account for these unique imaging features. Recognition of this distinct pattern of spread of L. monocytogenes cerebral abscess may aid in diagnosis and enable early microbiological culture and treatment.
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Affiliation(s)
| | - Dalveer Singh
- Department of Medical Imaging, Princess Alexandra Hospital, Australia
| | | | - Gigi Nga Chi Kwan
- Department of Medical Imaging, Princess Alexandra Hospital, Australia
| | - Matt Skalski
- Department of Radiology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | | | - Ipeson Korah
- Department of Medical Imaging, Hutt Valley District Health Board, New Zealand
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62
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Pagnozzi AM, Dowson N, Doecke J, Fiori S, Bradley AP, Boyd RN, Rose S. Automated, quantitative measures of grey and white matter lesion burden correlates with motor and cognitive function in children with unilateral cerebral palsy. NEUROIMAGE-CLINICAL 2016; 11:751-759. [PMID: 27330975 PMCID: PMC4908311 DOI: 10.1016/j.nicl.2016.05.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 04/28/2016] [Accepted: 05/27/2016] [Indexed: 11/25/2022]
Abstract
White and grey matter lesions are the most prevalent type of injury observable in the Magnetic Resonance Images (MRIs) of children with cerebral palsy (CP). Previous studies investigating the impact of lesions in children with CP have been qualitative, limited by the lack of automated segmentation approaches in this setting. As a result, the quantitative relationship between lesion burden has yet to be established. In this study, we perform automatic lesion segmentation on a large cohort of data (107 children with unilateral CP and 18 healthy children) with a new, validated method for segmenting both white matter (WM) and grey matter (GM) lesions. The method has better accuracy (94%) than the best current methods (73%), and only requires standard structural MRI sequences. Anatomical lesion burdens most predictive of clinical scores of motor, cognitive, visual and communicative function were identified using the Least Absolute Shrinkage and Selection operator (LASSO). The improved segmentations enabled identification of significant correlations between regional lesion burden and clinical performance, which conform to known structure-function relationships. Model performance was validated in an independent test set, with significant correlations observed for both WM and GM regional lesion burden with motor function (p < 0.008), and between WM and GM lesions alone with cognitive and visual function respectively (p < 0.008). The significant correlation of GM lesions with functional outcome highlights the serious implications GM lesions, in addition to WM lesions, have for prognosis, and the utility of structural MRI alone for quantifying lesion burden and planning therapy interventions.
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Affiliation(s)
- Alex M Pagnozzi
- CSIRO Health and Biosecurity, The Australian e-Health Research Centre, Brisbane, Australia; The University of Queensland, School of Information, Technology and Electrical Engineering, St Lucia, Brisbane, Australia.
| | - Nicholas Dowson
- CSIRO Health and Biosecurity, The Australian e-Health Research Centre, Brisbane, Australia
| | - James Doecke
- CSIRO Health and Biosecurity, The Australian e-Health Research Centre, Brisbane, Australia
| | | | - Andrew P Bradley
- The University of Queensland, School of Information, Technology and Electrical Engineering, St Lucia, Brisbane, Australia
| | - Roslyn N Boyd
- The University of Queensland, Queensland Cerebral Palsy and Rehabilitation Research Centre, Centre for Children's Health Research, Faculty of Medicine and Science, Brisbane, Australia
| | - Stephen Rose
- CSIRO Health and Biosecurity, The Australian e-Health Research Centre, Brisbane, Australia
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63
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Moseley RL, Correia MM, Baron-Cohen S, Shtyrov Y, Pulvermüller F, Mohr B. Reduced Volume of the Arcuate Fasciculus in Adults with High-Functioning Autism Spectrum Conditions. Front Hum Neurosci 2016; 10:214. [PMID: 27242478 PMCID: PMC4867673 DOI: 10.3389/fnhum.2016.00214] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 04/25/2016] [Indexed: 11/17/2022] Open
Abstract
Atypical language is a fundamental feature of autism spectrum conditions (ASC), but few studies have examined the structural integrity of the arcuate fasciculus, the major white matter tract connecting frontal and temporal language regions, which is usually implicated as the main transfer route used in processing linguistic information by the brain. Abnormalities in the arcuate have been reported in young children with ASC, mostly in low-functioning or non-verbal individuals, but little is known regarding the structural properties of the arcuate in adults with ASC or, in particular, in individuals with ASC who have intact language, such as those with high-functioning autism or Asperger syndrome. We used probabilistic tractography of diffusion-weighted imaging to isolate and scrutinize the arcuate in a mixed-gender sample of 18 high-functioning adults with ASC (17 Asperger syndrome) and 14 age- and IQ-matched typically developing controls. Arcuate volume was significantly reduced bilaterally with clearest differences in the right hemisphere. This finding remained significant in an analysis of all male participants alone. Volumetric reduction in the arcuate was significantly correlated with the severity of autistic symptoms as measured by the Autism-Spectrum Quotient. These data reveal that structural differences are present even in high-functioning adults with ASC, who presented with no clinically manifest language deficits and had no reported developmental language delay. Arcuate structural integrity may be useful as an index of ASC severity and thus as a predictor and biomarker for ASC. Implications for future research are discussed.
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Affiliation(s)
- Rachel L Moseley
- Department of Psychology, Bournemouth UniversityDorset, UK; Medical Research Council Cognition and Brain Sciences UnitCambridge, UK; Brain Mapping Unit, Department of Psychiatry, University of CambridgeCambridge, UK; Autism Research Centre, Department of Psychiatry, University of CambridgeCambridge, UK
| | - Marta M Correia
- Medical Research Council Cognition and Brain Sciences Unit Cambridge, UK
| | - Simon Baron-Cohen
- Autism Research Centre, Department of Psychiatry, University of CambridgeCambridge, UK; Cambridge Lifespan Asperger Syndrome Service Clinic, Cambridgeshire and Peterborough National Health Service Foundation TrustCambridge, UK
| | - Yury Shtyrov
- Medical Research Council Cognition and Brain Sciences UnitCambridge, UK; Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical Medicine, Aarhus UniversityAarhus, Denmark; Centre for Cognition and Decision Making, National Research University Higher School of EconomicsMoscow, Russia
| | - Friedemann Pulvermüller
- Medical Research Council Cognition and Brain Sciences UnitCambridge, UK; Brain Language Laboratory, Freie Universität BerlinBerlin, Germany
| | - Bettina Mohr
- Department of Psychiatry, Charité-Universitätsmedizin Berlin Berlin, Germany
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Rodríguez-Aranda C, Waterloo K, Johnsen SH, Eldevik P, Sparr S, Wikran GC, Herder M, Vangberg TR. Neuroanatomical correlates of verbal fluency in early Alzheimer's disease and normal aging. BRAIN AND LANGUAGE 2016; 155-156:24-35. [PMID: 27062691 DOI: 10.1016/j.bandl.2016.03.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 01/22/2016] [Accepted: 03/12/2016] [Indexed: 06/05/2023]
Abstract
Verbal fluency (VF) impairments occur early in Alzheimer's disease (AD) and to a lesser extent also in normal aging. However, the neural underpinnings of these impairments are not fully understood. The present study evaluated whether VF impairments in early AD and normal aging rely upon common or different neuroanatomical correlates. We examined the association between VF performance and brain structure in 18 mild AD patients and 24 healthy elderly. Linear regressions were performed between accuracy and time intervals in VF scores and structural measurements of cerebral gray matter (GM) and white matter (WM) using MRI. Results showed that semantic VF correlated exclusively with GM in cerebellum, left temporal fusiform cortex, and WM in uncinate fasciculus, inferior fronto-occipital fasciculus and corpus callosum. Phonemic VF showed unique associations between intervals and WM in left-hemisphere tracts. The association between GM in hippocampus, subcortical structures and semantic accuracy differentiated patients from controls. Results showed that VF impairments are primarily associated with same structural brain changes in AD as in healthy elderly but at exaggerated levels. However, specific VF deficiencies and their underlying neural correlates exist and these clearly differentiate the initial stages of AD.
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Affiliation(s)
| | - Knut Waterloo
- Department of Psychology, UiT The Artic University of Norway, Tromsø, Norway; Department of Neurology, University Hospital North Norway, Tromsø, Norway
| | - Stein Harald Johnsen
- Department of Neurology, University Hospital North Norway, Tromsø, Norway; Brain and Circulation Research Group, Department of Clinical Medicine, UiT The Artic University of Norway, Tromsø, Norway
| | - Petter Eldevik
- Department of Radiology, University Hospital North Norway, Tromsø, Norway
| | - Sigurd Sparr
- Department of Geriatrics, University Hospital North Norway, Tromsø, Norway
| | - Gry C Wikran
- Department of Radiology, University Hospital North Norway, Tromsø, Norway
| | - Marit Herder
- Department of Radiology, University Hospital North Norway, Tromsø, Norway
| | - Torgil Riise Vangberg
- Department of Radiology, University Hospital North Norway, Tromsø, Norway; Medical Imaging Research Group, Department of Clinical Medicine, UiT The Artic University of Norway, Tromsø, Norway
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Abnormal white matter microstructure in drug-naive first episode schizophrenia patients before and after eight weeks of antipsychotic treatment. Schizophr Res 2016; 172:1-8. [PMID: 26852402 DOI: 10.1016/j.schres.2016.01.051] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 01/21/2016] [Accepted: 01/28/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND Abnormal white matter integrity has been reported among first episode schizophrenia patients. However, findings on whether it can be reversed by short-term antipsychotic medications are inconsistent. METHOD Diffusion tensor imaging (DTI) was obtained from 55 drug-naive first episode schizophrenia patients and 61 healthy controls, and was repeated among 25 patients and 31 controls after 8 weeks during which patients were medicated with antipsychotics. White matter integrity is measured using fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD). These measures showing a group difference by Tract-based spatial statistics (TBSS) at baseline were extracted for longitudinal comparisons. RESULTS At baseline, patients exhibited lower FA, higher MD and higher RD versus controls in forceps, left superior longitudinal fasciculus, inferior fronto-occipital fasciculus, left corticospinal tract, left uncinate fasciculus, left anterior thalamic radiation, and bilateral inferior longitudinal fasciculi. FA values of schizophrenia patients correlated with their negative symptoms (r=-0.412, P=0.002), working memory (r=0.377, P=0.005) and visual learning (r=0.281, P=0.038). The longitudinal changes in DTI indices in these tracts did not differ between patients and controls. However, among the patients the longitudinal changes in FA values in left superior longitudinal fasciculus correlated with the change of positive symptoms (r=-0.560, p=0.004), and the change of processing speed (r=0.469, p=0.018). CONCLUSIONS White matter deficits were validated in the present study by a relatively large sample of medication naïve and first episode schizophrenia patients. They could be associated with negative symptoms and cognitive impairment, whereas improvement in white matter integrity of left superior longitudinal fasciculus correlated with improvement in psychosis and processing speed. Further examination of treatment-related changes in white matter integrity may provide clues to the mechanism of antipsychotic response and provide a biomarker for clinical studies.
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de Pesters A, Taplin AM, Adamo MA, Ritaccio AL, Schalk G. Electrocorticographic mapping of expressive language function without requiring the patient to speak: A report of three cases. EPILEPSY & BEHAVIOR CASE REPORTS 2016; 6:13-8. [PMID: 27408803 PMCID: PMC4925928 DOI: 10.1016/j.ebcr.2016.02.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 02/25/2016] [Accepted: 02/26/2016] [Indexed: 01/24/2023]
Abstract
Objective Patients requiring resective brain surgery often undergo functional brain mapping during perioperative planning to localize expressive language areas. Currently, all established protocols to perform such mapping require substantial time and patient participation during verb generation or similar tasks. These issues can make language mapping impractical in certain clinical circumstances (e.g., during awake craniotomies) or with certain populations (e.g., pediatric patients). Thus, it is important to develop new techniques that reduce mapping time and the requirement for active patient participation. Several neuroscientific studies reported that the mere auditory presentation of speech stimuli can engage not only receptive but also expressive language areas. Here, we tested the hypothesis that submission of electrocorticographic (ECoG) recordings during a short speech listening task to an appropriate analysis procedure can identify eloquent expressive language cortex without requiring the patient to speak. Methods Three patients undergoing temporary placement of subdural electrode grids passively listened to stories while we recorded their ECoG activity. We identified those sites whose activity in the broadband gamma range (70–170 Hz) changed immediately after presentation of the speech stimuli with respect to a prestimulus baseline. Results Our analyses revealed increased broadband gamma activity at distinct locations in the inferior frontal cortex, superior temporal gyrus, and/or perisylvian areas in all three patients and premotor and/or supplementary motor areas in two patients. The sites in the inferior frontal cortex that we identified with our procedure were either on or immediately adjacent to locations identified using electrical cortical stimulation (ECS) mapping. Conclusions The results of this study provide encouraging preliminary evidence that it may be possible that a brief and practical protocol can identify expressive language areas without requiring the patient to speak. This protocol could provide the clinician with a map of expressive language cortex within a few minutes. This may be useful as an adjunct to ECS interrogation or as an alternative to mapping using functional magnetic resonance imaging (fMRI). In conclusion, with further development and validation in more subjects, the approach presented here could help in identifying expressive language areas in situations where patients cannot speak in response to task instructions.
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Affiliation(s)
- Adriana de Pesters
- National Center for Adaptive Neurotechnologies, Wadsworth Center, New York State Department of Health, Albany, NY, USA; Department of Biomedical Sciences, State University of New York at Albany, Albany, NY, USA
| | - AmiLyn M Taplin
- Department of Neurosurgery, Albany Medical College, Albany, NY, USA
| | - Matthew A Adamo
- Department of Neurosurgery, Albany Medical College, Albany, NY, USA
| | | | - Gerwin Schalk
- National Center for Adaptive Neurotechnologies, Wadsworth Center, New York State Department of Health, Albany, NY, USA; Department of Biomedical Sciences, State University of New York at Albany, Albany, NY, USA; Department of Neurology, Albany Medical College, Albany, NY, USA
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67
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Lai CH, Wu YT. The White Matter Microintegrity Alterations of Neocortical and Limbic Association Fibers in Major Depressive Disorder and Panic Disorder: The Comparison. Medicine (Baltimore) 2016; 95:e2982. [PMID: 26945417 PMCID: PMC4782901 DOI: 10.1097/md.0000000000002982] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The studies regarding to the comparisons between major depressive disorder (MDD) and panic disorder (PD) in the microintegrity of white matter (WM) are uncommon. Therefore, we tried to a way to classify the MDD and PD. Fifty-three patients with 1st-episode medication-naive PD, 54 healthy controls, and 53 patients with 1st-episode medication-naive MDD were enrolled in this study. The controls and patients were matched for age, gender, education, and handedness. The diffusion tensor imaging scanning was also performed. The WM microintegrity was analyzed and compared between 3 groups of participants (ANOVA analysis) with age and gender as covariates. The MDD group had lower WM microintegrity than the PD group in the left anterior thalamic radiation, left uncinate fasciculus, left inferior fronto-occipital fasciculus, and bilateral corpus callosum. The MDD group had reductions in the microintegrity when compared to controls in the bilateral superior longitudinal fasciculi, inferior longitudinal fasciculi, inferior fronto-occipital fasciculi, and corpus callosum. The PD group had lower microintegrity in bilateral superior longitudinal fasciculi and left inferior fronto-occipital fasciculus when compared to controls. The widespread pattern of microintegrity alterations in fronto-limbic WM circuit for MDD was different from restrictive pattern of alterations for PD.
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Affiliation(s)
- Chien-Han Lai
- From the Department of Psychiatry, Cheng Hsin General Hospital, Taipei City (C-HL); Department of Biomedical Imaging and Radiological Sciences (C-HL, Y-TW); Brain Research Center (Y-TW); and Institute of Biophotonics, National Yang-Ming University (C-HL, Y-TW), Taipei, Taiwan, ROC
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Hou YC, Yang SH, Wu YT, Lai CH. Alterations of neocortico-limbic association fibers and correlation with diet in prediabetes diagnosed by impaired fasting glucose. J Magn Reson Imaging 2016; 43:1500-6. [PMID: 26756544 DOI: 10.1002/jmri.25127] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/01/2015] [Indexed: 12/13/2022] Open
Abstract
PURPOSE To assess the existence of alterations in the micro-integrity of the fasciculus in prediabetic subjects. The issue of micro-integrity in white matter tracts has not been adequately addressed in prediabetes. MATERIALS AND METHODS Sixty-four prediabetic subjects and 54 controls were enrolled. All participants completed 24-hour diet records and 3-day diet records and received diffusion tensor imaging at 3T. The data for white matter micro-integrity were analyzed and compared between prediabetic subjects and controls with age and gender as covariates. In addition, voxel-wise regression between white matter micro-integrity, diet, and preprandial glucose levels were used to explore the relationship between white matter micro-integrity and diet or serum glucose levels. RESULTS We found that prediabetic subjects had significant reductions in the micro-integrity of bilateral anterior thalamic radiation, left inferior longitudinal fasciculus, and left superior longitudinal fasciculus (corrected P < 0.05). In addition, total carbohydrate intake amount and preprandial serum glucose levels were negatively correlated with the micro-integrity in the left inferior longitudinal fasciculus and left anterior thalamic radiation (r: -0.47, corrected P < 0.05). CONCLUSION Restrictive alterations in the white matter micro-integrity of the anterior thalamic radiation and inferior and superior longitudinal fasciculi might represent the initial "hot spots" for white matter tract alterations, which might play a role in the development of prediabetes. J. Magn. Reson. Imaging 2016;43:1500-1506.
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Affiliation(s)
- Yi-Cheng Hou
- Department of Nutrition, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City, Taiwan, ROC
| | - Shwu-Huey Yang
- School of Nutrition and Health Sciences, College of Public Health and Nutrition, Taipei Medical University, Taipei, Taiwan, ROC
| | - Yu-Te Wu
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan, ROC.,Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan, ROC.,Brain Research Center, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Chien-Han Lai
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan, ROC.,Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan, ROC.,Department of Psychiatry, Cheng Hsin General Hospital, Taipei City, Taiwan, ROC
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Garcia-Zapirain B, Garcia-Chimeno Y, Saralegui I, Fernandez-Ruanova B, Martinez R. Differences in effective connectivity between children with dyslexia, monocular vision and typically developing readers: A DTI study. Biomed Signal Process Control 2016. [DOI: 10.1016/j.bspc.2015.07.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Szatloczki G, Hoffmann I, Vincze V, Kalman J, Pakaski M. Speaking in Alzheimer's Disease, is That an Early Sign? Importance of Changes in Language Abilities in Alzheimer's Disease. Front Aging Neurosci 2015; 7:195. [PMID: 26539107 PMCID: PMC4611852 DOI: 10.3389/fnagi.2015.00195] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 09/28/2015] [Indexed: 12/02/2022] Open
Abstract
It is known that Alzheimer’s disease (AD) influences the temporal characteristics of spontaneous speech. These phonetical changes are present even in mild AD. Based on this, the question arises whether an examination based on language analysis could help the early diagnosis of AD and if so, which language and speech characteristics can identify AD in its early stage. The purpose of this article is to summarize the relation between prodromal and manifest AD and language functions and language domains. Based on our research, we are inclined to claim that AD can be more sensitively detected with the help of a linguistic analysis than with other cognitive examinations. The temporal characteristics of spontaneous speech, such as speech tempo, number of pauses in speech, and their length are sensitive detectors of the early stage of the disease, which enables an early simple linguistic screening for AD. However, knowledge about the unique features of the language problems associated with different dementia variants still has to be improved and refined.
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Affiliation(s)
- Greta Szatloczki
- Research Institute for Linguistics, Hungarian Academy of Sciences , Szeged , Hungary
| | - Ildiko Hoffmann
- Research Institute for Linguistics, Hungarian Academy of Sciences , Budapest , Hungary ; Department of Linguistics, University of Szeged , Szeged , Hungary
| | - Veronika Vincze
- MTA-SZTE Research Group on Artificial Intelligence, University of Szeged , Szeged , Hungary
| | - Janos Kalman
- Research Institute for Linguistics, Hungarian Academy of Sciences , Szeged , Hungary
| | - Magdolna Pakaski
- Research Institute for Linguistics, Hungarian Academy of Sciences , Szeged , Hungary
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71
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Blindness alters the microstructure of the ventral but not the dorsal visual stream. Brain Struct Funct 2015; 221:2891-903. [PMID: 26134685 DOI: 10.1007/s00429-015-1078-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 06/22/2015] [Indexed: 10/23/2022]
Abstract
Visual deprivation from birth leads to reorganisation of the brain through cross-modal plasticity. Although there is a general agreement that the primary afferent visual pathways are altered in congenitally blind individuals, our knowledge about microstructural changes within the higher-order visual streams, and how this is affected by onset of blindness, remains scant. We used diffusion tensor imaging and tractography to investigate microstructural features in the dorsal (superior longitudinal fasciculus) and ventral (inferior longitudinal and inferior fronto-occipital fasciculi) visual pathways in 12 congenitally blind, 15 late blind and 15 normal sighted controls. We also studied six prematurely born individuals with normal vision to control for the effects of prematurity on brain connectivity. Our data revealed a reduction in fractional anisotropy in the ventral but not the dorsal visual stream for both congenitally and late blind individuals. Prematurely born individuals, with normal vision, did not differ from normal sighted controls, born at term. Our data suggest that although the visual streams are structurally developing without normal visual input from the eyes, blindness selectively affects the microstructure of the ventral visual stream regardless of the time of onset. We suggest that the decreased fractional anisotropy of the ventral stream in the two groups of blind subjects is the combined result of both degenerative and cross-modal compensatory processes, affecting normal white matter development.
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72
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Tseng CEJ, Chien YL, Liu CM, Wang HLS, Hwu HG, Tseng WYI. Altered cortical structures and tract integrity of the mirror neuron system in association with symptoms of schizophrenia. Psychiatry Res 2015; 231:286-91. [PMID: 25659475 DOI: 10.1016/j.pscychresns.2015.01.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Revised: 10/17/2014] [Accepted: 01/11/2015] [Indexed: 11/26/2022]
Abstract
The mirror neuron system (MNS) may be implicated in schizophrenia. This study investigated MNS structures, including the pars opercularis (Pop), the supramarginal gyrus (SMg), the third branch of the superior longitudinal fasciculus, and callosal fibers interconnecting bilateral Pop (CC-Pop) and SMg (CC-SMg), and clarified their relationships with positive and negative symptoms of schizophrenia. Participants comprised 32 schizophrenia patients and 32 matched controls who received T1-weighted structural magnetic resonance imaging (MRI, T1WI) and diffusion spectrum imaging (DSI). The cortical measures were computed from the T1WI data. Tract integrity was assessed using a tractography-based analysis of the generalized fractional anisotropy (GFA) derived from the DSI data. Pearson׳s correlations and multiple linear regression analysis were used to investigate the associations between MNS structures and positive and negative symptom scores of schizophrenia. Cortical thickness in bilateral Pop and SMg were significantly thinner and mean GFA of CC-Pop was significantly decreased in patients. Negative symptoms were significantly correlated with left SMg volume, and positive symptoms were significantly correlated with right SMg thickness. Multiple linear regression analysis showed left SMg volume to be the strongest contributor to the negative symptoms. The association between left SMg volume and negative symptoms may reflect the degree of social cognition impairment in schizophrenia.
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Affiliation(s)
- Chieh-En Jane Tseng
- Center for Optoelectronic Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Yi-Ling Chien
- Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan
| | - Chih-Min Liu
- Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan
| | - Hsiao-Lan Sharon Wang
- Center for Optoelectronic Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Hai-Gwo Hwu
- Department of Psychiatry, National Taiwan University Hospital, Taipei, Taiwan; Graduate Institute of Brain and Mind Sciences, National Taiwan University College of Medicine, Taipei, Taiwan.
| | - Wen-Yih Isaac Tseng
- Center for Optoelectronic Medicine, National Taiwan University College of Medicine, Taipei, Taiwan; Graduate Institute of Brain and Mind Sciences, National Taiwan University College of Medicine, Taipei, Taiwan; Department of Medical Imaging, National Taiwan University Hospital, Taipei, Taiwan; Molecular Imaging Center, National Taiwan University, Taipei, Taiwan.
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73
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Eng GK, Sim K, Chen SHA. Meta-analytic investigations of structural grey matter, executive domain-related functional activations, and white matter diffusivity in obsessive compulsive disorder: an integrative review. Neurosci Biobehav Rev 2015; 52:233-57. [PMID: 25766413 DOI: 10.1016/j.neubiorev.2015.03.002] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 02/27/2015] [Accepted: 03/03/2015] [Indexed: 01/04/2023]
Abstract
Obsessive-compulsive disorder (OCD) is a debilitating disorder. However, existing neuroimaging findings involving executive function and structural abnormalities in OCD have been mixed. Here we conducted meta-analyses to investigate differences in OCD samples and controls in: Study 1 - grey matter structure; Study 2 - executive function task-related activations during (i) response inhibition, (ii) interference, and (iii) switching tasks; and Study 3 - white matter diffusivity. Results showed grey matter differences in the frontal, striatal, thalamus, parietal and cerebellar regions; task domain-specific neural differences in similar regions; and abnormal diffusivity in major white matter regions in OCD samples compared to controls. Our results reported concurrence of abnormal white matter diffusivity with corresponding abnormalities in grey matter and task-related functional activations. Our findings suggested the involvement of other brain regions not included in the cortico-striato-thalamo-cortical network, such as the cerebellum and parietal cortex, and questioned the involvement of the orbitofrontal region in OCD pathophysiology. Future research is needed to clarify the roles of these brain regions in the disorder.
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Affiliation(s)
- Goi Khia Eng
- Division of Psychology, School of Humanities and Social Sciences, Nanyang Technological University, 14 Nanyang Drive, Singapore 637332, Singapore
| | - Kang Sim
- Department of General Psychiatry, Institute of Mental Health, 10 Buangkok View, Singapore 539747, Singapore
| | - Shen-Hsing Annabel Chen
- Division of Psychology, School of Humanities and Social Sciences, Nanyang Technological University, 14 Nanyang Drive, Singapore 637332, Singapore; Centre for Research and Development in Learning, 62 Nanyang Drive, Singapore 637459, Singapore.
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74
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Iwabuchi SJ, Kirk IJ. Association between structural and functional connectivity in the verb generation network. Brain Connect 2015; 4:221-9. [PMID: 24575720 DOI: 10.1089/brain.2013.0149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The decade-long endeavor to link brain structure with brain function has met with varying degrees of success. Recent advances in imaging techniques allow a fresh look at the issue, however. In the current investigation, functional magnetic resonance imaging and diffusion tensor imaging (DTI) were employed to directly investigate the link between functional connectivity during a verb generation task and the underlying structural substrate. Nineteen participants performed a verb generation task during functional scanning and also underwent DTI. A psychophysiological interaction analysis was used to map the functional networks recruited during the task and as an index of functional connectivity. The degree to which this correlated with diffusion measures was used to explore the existence of anatomofunctional relationships within the identified connections. A significant correlation was seen for the middle frontal (MFG) to precentral gyrus pathway, where a pattern of low fractional anisotropy and high perpendicular diffusion was associated with low functional connectivity. A second pathway between the MFG and inferior temporal gyrus did not show a significant correlation, which may be attributed to two independent factors that might be influencing the structural properties of this pathway. The variation in structure function relationships within this network may relate to each pathways involvement in different cognitive functions.
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Affiliation(s)
- Sarina Jennifer Iwabuchi
- Research Centre for Cognitive Neuroscience, School of Psychology, University of Auckland , Auckland, New Zealand
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75
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Matejko AA, Ansari D. Drawing connections between white matter and numerical and mathematical cognition: A literature review. Neurosci Biobehav Rev 2015; 48:35-52. [DOI: 10.1016/j.neubiorev.2014.11.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 11/05/2014] [Accepted: 11/08/2014] [Indexed: 10/24/2022]
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Perkins TJ, Stokes MA, McGillivray JA, Mussap AJ, Cox IA, Maller JJ, Bittar RG. Increased left hemisphere impairment in high-functioning autism: a tract based spatial statistics study. Psychiatry Res 2014; 224:119-23. [PMID: 25159311 DOI: 10.1016/j.pscychresns.2014.08.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 06/23/2014] [Accepted: 08/04/2014] [Indexed: 10/24/2022]
Abstract
There is evidence emerging from Diffusion Tensor Imaging (DTI) research that autism spectrum disorders (ASD) are associated with greater impairment in the left hemisphere. Although this has been quantified with volumetric region of interest analyses, it has yet to be tested with white matter integrity analysis. In the present study, tract based spatial statistics was used to contrast white matter integrity of 12 participants with high-functioning autism or Aspergers syndrome (HFA/AS) with 12 typically developing individuals. Fractional Anisotropy (FA) was examined, in addition to axial, radial and mean diffusivity (AD, RD and MD). In the left hemisphere, participants with HFA/AS demonstrated significantly reduced FA in predominantly thalamic and fronto-parietal pathways and increased RD. Symmetry analyses confirmed that in the HFA/AS group, WM disturbance was significantly greater in the left compared to right hemisphere. These findings contribute to a growing body of literature suggestive of reduced FA in ASD, and provide preliminary evidence for RD impairments in the left hemisphere.
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Affiliation(s)
- Thomas John Perkins
- Cognitive Neuroscience Unit, Department of Psychology, School of Psychology, Faculty of Health, Deakin University, 221 Burwood Highway, Victoria, Australia.
| | - Mark Andrew Stokes
- Cognitive Neuroscience Unit, Department of Psychology, School of Psychology, Faculty of Health, Deakin University, 221 Burwood Highway, Victoria, Australia
| | - Jane Anne McGillivray
- Cognitive Neuroscience Unit, Department of Psychology, School of Psychology, Faculty of Health, Deakin University, 221 Burwood Highway, Victoria, Australia
| | - Alexander Julien Mussap
- Cognitive Neuroscience Unit, Department of Psychology, School of Psychology, Faculty of Health, Deakin University, 221 Burwood Highway, Victoria, Australia
| | - Ivanna Anne Cox
- Cognitive Neuroscience Unit, Department of Psychology, School of Psychology, Faculty of Health, Deakin University, 221 Burwood Highway, Victoria, Australia
| | - Jerome Joseph Maller
- Monash Alfred Psychiatry Research Centre, The Alfred and Monash University Central Clinical School, Commercial Rd, Melbourne, Victoria, Australia
| | - Richard Garth Bittar
- Cognitive Neuroscience Unit, Department of Psychology, School of Psychology, Faculty of Health, Deakin University, 221 Burwood Highway, Victoria, Australia; Precision Brain Spine and Pain Centre, Australia; Department of Neurosurgery, Royal Melbourne Hospital, Australia
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Bucheli C, Mato D, Marco de Lucas E, García-Porrero JA, Vázquez-Barquero A, Martino J. Fascículos asociativos ínsulo-operculares: revisión de su anatomía y de las implicaciones para el abordaje transopercular a la ínsula. Neurocirugia (Astur) 2014; 25:268-74. [DOI: 10.1016/j.neucir.2014.07.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 07/05/2014] [Accepted: 07/08/2014] [Indexed: 12/27/2022]
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Teipel S, Ehlers I, Erbe A, Holzmann C, Lau E, Hauenstein K, Berger C. Structural Connectivity Changes Underlying Altered Working Memory Networks in Mild Cognitive Impairment: A Three-Way Image Fusion Analysis. J Neuroimaging 2014; 25:634-42. [PMID: 25354135 DOI: 10.1111/jon.12178] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 05/19/2014] [Accepted: 07/13/2014] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND AND PURPOSE Working memory impairment is among the earliest signs of cognitive decline in Alzheimer's disease (AD) and mild cognitive impairment (MCI). We aimed to study the functional and structural substrate of working memory impairment in early AD dementia and MCI. METHODS We studied a group of 12 MCI and AD subjects compared to 12 age- and gender-matched healthy elderly controls using diffusion tensor imaging (DTI), and functional magnetic resonance imaging (fMRI) during a 2-back versus 1-back letter recognition task. We performed a three-way image fusion analysis with joint independent component analysis of cortical activation during working memory, and DTI derived measures of fractional anisotropy (FA) and the mode of anisotropy. RESULTS We found significant hypoactivation in posterior brain areas and relative hyperactivation in anterior brain areas during working memory in AD/MCI subjects compared to controls. Corresponding independent components from DTI data revealed reduced FA and reduced mode of anisotropy in intracortical projecting fiber tracts with posterior predominance and increased FA and increased mode along the corticospinal tract in AD/MCI compared to controls. CONCLUSIONS Our findings suggest that impairments of structural fiber tract integrity accompany breakdown of posterior and relatively preserved anterior cortical activation during working memory performance in MCI/AD subjects.
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Affiliation(s)
- Stefan Teipel
- Department of Psychosomatic Medicine, University Medicine Rostock, Rostock, Germany.,DZNE, German Center for Neurodegenerative Diseases, Rostock, Germany
| | - Inga Ehlers
- Department of Psychosomatic Medicine, University Medicine Rostock, Rostock, Germany.,DZNE, German Center for Neurodegenerative Diseases, Rostock, Germany
| | - Anna Erbe
- Department of Psychosomatic Medicine, University Medicine Rostock, Rostock, Germany.,DZNE, German Center for Neurodegenerative Diseases, Rostock, Germany
| | - Carsten Holzmann
- Department of Medical Genetics, University Medicine Rostock, Rostock, Germany
| | - Esther Lau
- Department of Psychosomatic Medicine, University Medicine Rostock, Rostock, Germany.,DZNE, German Center for Neurodegenerative Diseases, Rostock, Germany
| | | | - Christoph Berger
- Department of Child and Adolescent Psychiatry, University Medicine Rostock, Rostock, Germany
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Lai CH, Wu YT. Alterations in white matter micro-integrity of the superior longitudinal fasciculus and anterior thalamic radiation of young adult patients with depression. Psychol Med 2014; 44:2825-2832. [PMID: 25065445 DOI: 10.1017/s0033291714000440] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND This study surveyed the characteristics of white matter (WM) micro-integrity in patients who were diagnosed with major depressive disorder (MDD) without co-morbidities. METHOD A total of 44 patients with MDD and 27 normal controls were enrolled in our study. Diffusion tensor imaging images of patients and controls were pre-processed and analysed to estimate differences in WM micro-integrity between patients and controls by performing comparisons of the values obtained from fractional anisotropy (FA). FA outputs of patients and controls were compared by a non-parametric permutation-based method with global brain volume, age and gender as covariates. In addition, the between-group differences of radial diffusivity (RD) and axial diffusivity (AD) were assessed to explain the alterations in FA values. Correlations between clinical variables (such as depression severity, anxiety severity, illness duration) and FA values were also estimated in each group and across both groups. RESULTS The patients with MDD had significantly lower FA values than the controls, for the left superior longitudinal fasciculus (SLF) and the right anterior thalamic radiation (ATR). The reductions in FA values occurred in combination with elevated RD values in the bilateral SLF and decreased AD values in the bilateral ATR. FA values were negatively correlated with depression severity in the SLF and with illness duration in the right SLF and ATR. CONCLUSIONS MDD patients had significant alterations in the WM micro-integrity of the left SLF and the right ATR.
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Affiliation(s)
- C H Lai
- Department of Psychiatry,Cheng Hsin General Hospital,Taipei City,Taiwan, ROC
| | - Y T Wu
- Department of Biomedical Imaging and Radiological Sciences,National Yang-Ming University,Taipei,Taiwan, ROC
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Zakszewski E, Adluru N, Tromp DPM, Kalin N, Alexander AL. A diffusion-tensor-based white matter atlas for rhesus macaques. PLoS One 2014; 9:e107398. [PMID: 25203614 PMCID: PMC4159318 DOI: 10.1371/journal.pone.0107398] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 08/11/2014] [Indexed: 01/20/2023] Open
Abstract
Atlases of key white matter (WM) structures in humans are widely available, and are very useful for region of interest (ROI)-based analyses of WM properties. There are histology-based atlases of cortical areas in the rhesus macaque, but none currently of specific WM structures. Since ROI-based analysis of WM pathways is also useful in studies using rhesus diffusion tensor imaging (DTI) data, we have here created an atlas based on a publicly available DTI-based template of young rhesus macaques. The atlas was constructed to mimic the structure of an existing human atlas that is widely used, making results translatable between species. Parcellations were carefully hand-drawn on a principle-direction color-coded fractional anisotropy image of the population template. The resulting atlas can be used as a reference to which registration of individual rhesus data can be performed for the purpose of white-matter parcellation. Alternatively, specific ROIs from the atlas may be warped into individual space to be used in ROI-based group analyses. This atlas will be made publicly available so that it may be used as a resource for DTI studies of rhesus macaques.
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Affiliation(s)
- Elizabeth Zakszewski
- Waisman Laboratory for Brain Imaging and Behavior, University of Wisconsin - Madison, Madison, Wisconsin, United States of America
- Department of Medical Physics, University of Wisconsin - Madison, Wisconsin Institutes for Medical Research, Madison, Wisconsin, United States of America
| | - Nagesh Adluru
- Waisman Laboratory for Brain Imaging and Behavior, University of Wisconsin - Madison, Madison, Wisconsin, United States of America
| | - Do P. M. Tromp
- Health Emotions Research Institute, University of Wisconsin - Madison, Health Emotions Research Institute Madison, Wisconsin, United States of America
| | - Ned Kalin
- Health Emotions Research Institute, University of Wisconsin - Madison, Health Emotions Research Institute Madison, Wisconsin, United States of America
- Department of Psychiatry, University of Wisconsin - Madison, Wisconsin Psychiatric Institute & Clinics, Madison, Wisconsin, United States of America
| | - Andrew L. Alexander
- Waisman Laboratory for Brain Imaging and Behavior, University of Wisconsin - Madison, Madison, Wisconsin, United States of America
- Department of Psychiatry, University of Wisconsin - Madison, Wisconsin Psychiatric Institute & Clinics, Madison, Wisconsin, United States of America
- Department of Medical Physics, University of Wisconsin - Madison, Wisconsin Institutes for Medical Research, Madison, Wisconsin, United States of America
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81
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Dean DC, O'Muircheartaigh J, Dirks H, Waskiewicz N, Walker L, Doernberg E, Piryatinsky I, Deoni SCL. Characterizing longitudinal white matter development during early childhood. Brain Struct Funct 2014; 220:1921-33. [PMID: 24710623 PMCID: PMC4481335 DOI: 10.1007/s00429-014-0763-3] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 03/19/2014] [Indexed: 12/11/2022]
Abstract
Post-mortem studies have shown the maturation of the brain’s myelinated
white matter, crucial for efficient and coordinated brain communication, follows a nonlinear spatio-temporal pattern that corresponds with the onset and refinement of cognitive functions and behaviors. Unfortunately, investigation of myelination in vivo is challenging and, thus, little is known about the normative pattern of myelination, or its association with functional development. Using a novel quantitative magnetic resonance imaging technique sensitive to myelin we examined longitudinal white matter development in 108 typically developing children ranging in age from 2.5 months to 5.5 years. Using nonlinear mixed effects modeling, we provide the first in vivo longitudinal description of myelin water fraction development. Moreover, we show distinct male and female developmental patterns, and demonstrate significant relationships between myelin content and measures of cognitive function. These findings advance a new understanding of healthy brain development and provide a foundation from which to assess atypical development.
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Affiliation(s)
- Douglas C Dean
- Advanced Baby Imaging Laboratory, School of Engineering, Brown University, Providence, RI, 02912, USA,
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82
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Duffau H, Moritz-Gasser S, Mandonnet E. A re-examination of neural basis of language processing: proposal of a dynamic hodotopical model from data provided by brain stimulation mapping during picture naming. BRAIN AND LANGUAGE 2014; 131:1-10. [PMID: 23866901 DOI: 10.1016/j.bandl.2013.05.011] [Citation(s) in RCA: 240] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 05/18/2013] [Indexed: 05/09/2023]
Abstract
From recent findings provided by brain stimulation mapping during picture naming, we re-examine the neural basis of language. We studied structural-functional relationships by correlating the types of language disturbances generated by stimulation in awake patients, mimicking a transient virtual lesion both at cortical and subcortical levels (white matter and deep grey nuclei), with the anatomical location of the stimulation probe. We propose a hodotopical (delocalized) and dynamic model of language processing, which challenges the traditional modular and serial view. According to this model, following the visual input, the language network is organized in parallel, segregated (even if interconnected) large-scale cortico-subcortical sub-networks underlying semantic, phonological and syntactic processing. Our model offers several advantages (i) it explains double dissociations during stimulation (comprehension versus naming disorders, semantic versus phonemic paraphasias, syntactic versus naming disturbances, plurimodal judgment versus naming disorders); (ii) it takes into account the cortical and subcortical anatomic constraints; (iii) it explains the possible recovery of aphasia following a lesion within the "classical" language areas; (iv) it establishes links with a model executive functions.
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Affiliation(s)
- Hugues Duffau
- Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, 80 Avenue Augustin Fliche, 34295 Montpellier, France; Institut of Neuroscience of Montpellier, INSERM U1051, Team "Plasticity of Central Nervous System, Human Stem Cells and Glial Tumors", Hôpital Saint Eloi, CHU Montpellier, 80 Avenue Augustin Fliche, 34091 Montpellier, France.
| | - Sylvie Moritz-Gasser
- Institut of Neuroscience of Montpellier, INSERM U1051, Team "Plasticity of Central Nervous System, Human Stem Cells and Glial Tumors", Hôpital Saint Eloi, CHU Montpellier, 80 Avenue Augustin Fliche, 34091 Montpellier, France; Department of Neurology, Gui de Chauliac Hospital, Montpellier University Medical Center, 80 Avenue Augustin Fliche, 34295 Montpellier, France
| | - Emmanuel Mandonnet
- Department of Neurosurgery, Hôpital Lariboisière, Paris, France; University Paris Diderot, France; IMNC, UMR 8165, Orsay, France
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83
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Madhavan KM, McQueeny T, Howe SR, Shear P, Szaflarski J. Superior longitudinal fasciculus and language functioning in healthy aging. Brain Res 2014; 1562:11-22. [PMID: 24680744 DOI: 10.1016/j.brainres.2014.03.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 02/11/2014] [Accepted: 03/13/2014] [Indexed: 01/31/2023]
Abstract
Structural deterioration of brain tissue in older adults is thought to be responsible for the majority of age-related cognitive decline. Disruption of widespread cortical networks due to a loss of axonal integrity may also play an important role. Research examining correlations between structural change and functional decline has focused heavily on working memory, processing speed, and executive processes while other aspects of cognition, such as language functioning, have received less attention. The current study aimed to determine whether age-related changes in the superior longitudinal fasciculus (SLF), are responsible for the deterioration in language functioning associated with age. Subjects included 112 right-handed volunteers (ages 19-76). For each subject, the SLF of the left hemisphere was reconstructed from diffusion tensor images (DTI). Mean fractional anisotropy (FA) values were extracted from parietal (SLFp) and temporal (SLFt) bundles. Language functioning was measured using the Peabody Picture Vocabulary Test (PPVT), Boston Naming Test (BNT), Controlled Oral Word Association Test (COWAT), and Semantic Fluency Test (SFT). Regression analyses revealed that males and females showed a different pattern of decline in FA across adulthood. For males, greater SLFt FA was significantly associated with increased COWAT performance, and there was a positive relationship between both age and SLFp FA with BNT scores. In females, greater SLFp FA was related to lower COWAT performance. Taken together, the results suggest that white matter integrity of the SLF follows a different pattern of decline in adulthood for males and females, and this decline differentially affects language functioning.
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Affiliation(s)
- Kiely M Madhavan
- Department of Psychology, University of Cincinnati, Cincinnati, OH, USA; QLI, Omaha, NE, USA.
| | - Tim McQueeny
- Department of Psychology, University of Cincinnati, Cincinnati, OH, USA
| | - Steven R Howe
- Department of Psychology, University of Cincinnati, Cincinnati, OH, USA
| | - Paula Shear
- Department of Psychology, University of Cincinnati, Cincinnati, OH, USA
| | - Jerzy Szaflarski
- Department of Neurology, University of Cincinnati, Cincinnati, OH, USA; Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, USA
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84
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The what, when, where, and how of visual word recognition. Trends Cogn Sci 2014; 18:90-8. [DOI: 10.1016/j.tics.2013.11.005] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 11/24/2013] [Accepted: 11/26/2013] [Indexed: 11/18/2022]
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85
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Martino J, De Lucas EM. Subcortical anatomy of the lateral association fascicles of the brain: A review. Clin Anat 2014; 27:563-9. [PMID: 24453050 DOI: 10.1002/ca.22321] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 08/28/2013] [Indexed: 11/09/2022]
Abstract
Precise knowledge of the connectivities of the different white matter bundles is of great value for neuroscience research. Our knowledge of subcortical anatomy has improved exponentially during recent decades owing to the development of magnetic resonance diffusion tensor imaging tractography (DTI). Although DTI tractography has led to important progress in understanding white matter anatomy, the precise trajectory and cortical connections of the subcortical bundles remain poorly determined. The recent literature was extensively reviewed in order to analyze the trajectories and cortical terminations of the lateral association fibers of the brain.The anatomy of the following tracts is reviewed: superior longitudinal fasciculus, middle longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, uncinate fasciculus, frontal aslant tract, and vertical occipital fasciculus. The functional role of a tract can be inferred from its topography within the brain. Knowing the functional roles of the cortical areas connected by a certain bundle, it is possible to develop new insights into the putative functional properties of such connections.
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Affiliation(s)
- Juan Martino
- Department of Neurological Surgery, Hospital Universitario Marqués de Valdecilla and Instituto de Formación e Investigación Marqués de Valdecilla (IFIMAV), Avda, Valdecilla s/n, Santander, Cantabria, Spain
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86
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Abstract
AbstractThe relevance of anatomical connectivity for understanding of the neural basis of language was recognized in the 19th century, and yet this topic has only recently become the subject of wider research interest. In this paper, I review recent findings on white matter tracts implicated in language: the arcuate fasciculus, superior longitudinal fasciculus, extreme capsule, uncinate fasciculus, middle longitudinal fasciculus, inferior longitudinal fasciculus, and inferior fronto-occipital fasciculus. The reviewed findings on these tracts were reported in studies that used a variety of methods, from post-mortem dissection and diffusion imaging to intraoperative electrostimulation with awake surgery patients. The emerging picture suggests that there is currently no consensus with regard to the exact number and identity of the tracts supporting language, their origins, trajectories, and terminations, as well as their functional interpretation.
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87
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Abstract
The field of the neurobiology of language is experiencing a paradigm shift in which the predominant Broca–Wernicke–Geschwind language model is being revised in favor of models that acknowledge that language is processed within a distributed cortical and subcortical system. While it is important to identify the brain regions that are part of this system, it is equally important to establish the anatomical connectivity supporting their functional interactions. The most promising framework moving forward is one in which language is processed via two interacting “streams”—a dorsal and ventral stream—anchored by long association fiber pathways, namely the superior longitudinal fasciculus/arcuate fasciculus, uncinate fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, and two less well-established pathways, the middle longitudinal fasciculus and extreme capsule. In this article, we review the most up-to-date literature on the anatomical connectivity and function of these pathways. We also review and emphasize the importance of the often overlooked cortico-subcortical connectivity for speech via the “motor stream” and associated fiber systems, including a recently identified cortical association tract, the frontal aslant tract. These pathways anchor the distributed cortical and subcortical systems that implement speech and language in the human brain.
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Affiliation(s)
| | - Byron Bernal
- Department of Radiology, Miami Children’s Hospital, Miami, FL, USA
| | - Pascale Tremblay
- Université Laval and Centre de Recherche de l’Institut Universitaire en Santé mentale de Québec, Quebec, Canada
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88
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Kinoshita M, Nakada M, Okita H, Hamada JI, Hayashi Y. Predictive value of fractional anisotropy of the arcuate fasciculus for the functional recovery of language after brain tumor resection: a preliminary study. Clin Neurol Neurosurg 2013; 117:45-50. [PMID: 24438804 DOI: 10.1016/j.clineuro.2013.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 11/29/2013] [Accepted: 12/02/2013] [Indexed: 11/19/2022]
Abstract
OBJECTIVE The arcuate fasciculus has been recognized as an important pathway for language processing. Brain tumors located in proximity to the fasciculus frequently cause preoperative language impairment, and in some cases, no language recovery occurs after tumor resection. No predictive value has been presented for possible postoperative language recovery after tumor resection. The aim of this study is to analyze the preoperative state of the arcuate fasciculus in the patients with brain tumor from the perspective of its usefulness as a predictive factor for postoperative recovery of language functions. METHODS For 12 right-handed patients with brain tumors in the left hemisphere, preoperative arcuate fasciculi were analyzed with fractional anisotropy (FA) of the diffusion tensor imaging (DTI) tractography. Language functions were evaluated pre- and postoperatively by using the Western Aphasia Battery (WAB). The preoperative value of the FA of the arcuate fasciculus on the lesion side was examined in relation with the language recovery. RESULTS There was a positive relationship between preoperative increasing values of the FA of the left arcuate fasciculus and improvement of the postoperative total WAB score (p=0.0056), and the scores of the naming (p=0.018), reading (p=0.029), and writing subcategories (p=0.012) CONCLUSION: The preoperative increasing value of the FA of the arcuate fasciculus in the dominant hemisphere could be a predictor for postoperative language recovery following tumor resection. Meticulous procedure should be performed especially in the cases with higher FA of the arcuate fasciculus harboring high possibility of language recovery.
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Affiliation(s)
| | | | - Hirokazu Okita
- Department of Physical Medicine and Rehabilitation, Kanazawa University, Kanazawa, Japan
| | | | - Yutaka Hayashi
- Department of Neurosurgery, Kanazawa University, Kanazawa, Japan.
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89
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Investigating the ventral-lexical, dorsal-sublexical model of basic reading processes using diffusion tensor imaging. Brain Struct Funct 2013; 220:445-55. [PMID: 24189777 DOI: 10.1007/s00429-013-0666-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 10/21/2013] [Indexed: 01/18/2023]
Abstract
Recent results from diffusion tensor imaging (DTI) studies provide evidence of a ventral-lexical stream and a dorsal-sublexical stream associated with reading processing. We investigated the relationship between behavioural reading speed for stimuli thought to rely on either the ventral-lexical, dorsal-sublexical, or both streams and white matter via fractional anisotropy (FA) and mean diffusivity (MD) using DTI tractography. Participants (N = 32) overtly named exception words (e.g., 'one', ventral-lexical), regular words (e.g., 'won', both streams), nonwords ('wum', dorsal-sublexical) and pseudohomophones ('wun', dorsal-sublexical) in a behavioural lab. Each participant then underwent a brain scan that included a 30-directional DTI sequence. Tractography was used to extract FA and MD values from four tracts of interest: inferior longitudinal fasciculus, uncinate fasciculus, arcuate fasciculus, and inferior fronto-occipital fasciculus. Median reaction times (RTs) for reading exception words and regular words both showed a significant correlation with the FA of the uncinate fasciculus thought to underlie the ventral processing stream, such that response time decreased as FA increased. In addition, RT for exception and regular words showed a relationship with MD of the uncinate fasciculus, such that response time increased as MD increased. Multiple regression analyses revealed that exception word RT accounted for unique variability in FA of the uncinate over and above regular words. There were no robust relationships found between pseudohomophones, or nonwords, and tracts thought to underlie the dorsal processing stream. These results support the notion that word recognition, in general, and exception word reading in particular, rely on ventral-lexical brain regions.
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90
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Gierhan SME. Connections for auditory language in the human brain. BRAIN AND LANGUAGE 2013; 127:205-221. [PMID: 23290461 DOI: 10.1016/j.bandl.2012.11.002] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 10/29/2012] [Accepted: 11/05/2012] [Indexed: 06/01/2023]
Abstract
The white matter bundles that underlie comprehension and production of language have been investigated for a number of years. Several studies have examined which fiber bundles (or tracts) are involved in auditory language processing, and which kind of language information is transmitted by which fiber tract. However, there is much debate about exactly which fiber tracts are involved, their precise course in the brain, how they should be named, and which functions they fulfill. Therefore, the present article reviews the available language-related literature, and educes a neurocognitive model of the pathways for auditory language processing. Besides providing an overview of the current methods used for relating fiber anatomy to function, this article details the precise anatomy of the fiber tracts and their roles in phonological, semantic and syntactic processing, articulation, and repetition.
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Affiliation(s)
- Sarah M E Gierhan
- Max Planck Institute for Human Cognitive and Brain Sciences, Department of Neuropsychology, Leipzig, Germany; Berlin School of Mind and Brain, Humboldt University of Berlin, Berlin, Germany.
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91
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Brown EC, Jeong JW, Muzik O, Rothermel R, Matsuzaki N, Juhász C, Sood S, Asano E. Evaluating the arcuate fasciculus with combined diffusion-weighted MRI tractography and electrocorticography. Hum Brain Mapp 2013; 35:2333-47. [PMID: 23982893 DOI: 10.1002/hbm.22331] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 04/23/2013] [Accepted: 04/25/2013] [Indexed: 11/08/2022] Open
Abstract
The conventional model of language-related brain structure describing the arcuate fasciculus as a key white matter tract providing a direct connection between Wernicke's region and Broca's area has been called into question. Specifically, the inferior precentral gyrus, possessing both primary motor (Brodmann Area [BA] 4) and premotor cortex (BA 6), has been identified as a potential alternative termination. The authors initially localized cortical sites involved in language using measurement of event-related gamma-activity on electrocorticography (ECoG). The authors then determined whether language-related sites of the temporal lobe were connected, via white matter structures, to the inferior frontal gyrus more tightly than to the precentral gyrus. The authors found that language-related sites of the temporal lobe were far more likely to be directly connected to the inferior precentral gyrus through the arcuate fasciculus. Furthermore, tractography was a significant predictor of frontal language-related ECoG findings. Analysis of an interaction between anatomy and tractography in this model revealed tractrography to have the highest predictive value for language-related ECoG findings of the precentral gyrus. This study failed to support the conventional model of language-related brain structure. More feasible models should include the inferior precentral gyrus as a termination of the arcuate fasciculus. The exact functional significance of direct connectivity between temporal language-related sites and the precentral gyrus requires further study.
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Affiliation(s)
- Erik C Brown
- MD/PhD Program, School of Medicine, Wayne State University, Detroit, Michigan; Department of Psychiatry and Behavioral Neurosciences, School of Medicine, Wayne State University, Detroit, Michigan
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92
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Magro E, Moreau T, Seizeur R, Zemmoura I, Gibaud B, Morandi X. Connectivity within the primary motor cortex: a DTI tractography study. Surg Radiol Anat 2013; 36:125-35. [PMID: 23820893 DOI: 10.1007/s00276-013-1160-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 06/21/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE Because of the motor function of the precentral area, the connections of the primary motor cortex by white matter fiber bundles have been widely studied in diffusion tensor imaging (DTI). Nevertheless, the connections within the primary motor cortex have yet to be explored. We have studied the connectivity between the different regions of the precentral gyrus in a population of subjects. METHODS Based on T1 magnetic resonance imaging (MRI) and on individual sulco-gyral anatomy, we defined a parcellation of the right and the left precentral gyri in 20 healthy subjects (10 right-handers; 10 left-handers). This parcellation gave us the opportunity to study MRI tracks reconstructed by tractography within the precentral gyrus and to compare these connections across subjects. We also performed a classical dissection of post-mortem brain tissue to isolate this pattern of connectivity. RESULTS We showed MRI tracks connecting the different parts of the same precentral gyrus. This result was reproducible and was found in the left and right hemispheres of the 20 subjects. A quantitative description of the bilateral distribution of the MRI tracks was performed, based on statistical analysis and asymmetry indices, to compare asymmetry and handedness. CONCLUSIONS To the best of our knowledge, this pattern of connectivity has never before been detailed in the literature. Its functional meaning remains to be determined, which requires further study.
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Affiliation(s)
- Elsa Magro
- Service de Neurochirurgie, CHRU Cavale Blanche, 29200, Brest, France,
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93
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Conventional and advanced MRI features of pediatric intracranial tumors: supratentorial tumors. AJR Am J Roentgenol 2013; 200:W483-503. [PMID: 23617516 DOI: 10.2214/ajr.12.9724] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE. Our objective is to review the imaging characteristics and applications of conventional and advanced neuroimaging techniques of supratentorial intracranial masses in the pediatric population. Specifically, we review astrocytomas, oligodendrogliomas, primary neuroectodermal tumors, dysembryoplastic neuroepithelial tumors, gangliogliomas, arachnoid cysts, and choroid plexus and pineal region masses. CONCLUSION. Advanced imaging methods, such as MR spectroscopy, perfusion MRI, functional MRI, diffusion-tensor imaging, and tractography, help develop a more accurate differential diagnosis and aid in planning tumor treatment.
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94
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Perlaki G, Horvath R, Orsi G, Aradi M, Auer T, Varga E, Kantor G, Altbäcker A, John F, Doczi T, Komoly S, Kovacs N, Schwarcz A, Janszky J. White-matter microstructure and language lateralization in left-handers: a whole-brain MRI analysis. Brain Cogn 2013; 82:319-28. [PMID: 23792788 DOI: 10.1016/j.bandc.2013.05.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 05/17/2013] [Accepted: 05/20/2013] [Indexed: 01/19/2023]
Abstract
Most people are left-hemisphere dominant for language. However the neuroanatomy of language lateralization is not fully understood. By combining functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI), we studied whether language lateralization is associated with cerebral white-matter (WM) microstructure. Sixteen healthy, left-handed women aged 20-25 were included in the study. Left-handers were targeted in order to increase the chances of involving subjects with atypical language lateralization. Language lateralization was determined by fMRI using a verbal fluency paradigm. Tract-based spatial statistics analysis of DTI data was applied to test for WM microstructural correlates of language lateralization across the whole brain. Fractional anisotropy and mean diffusivity were used as indicators of WM microstructural organization. Right-hemispheric language dominance was associated with reduced microstructural integrity of the left superior longitudinal fasciculus and left-sided parietal lobe WM. In left-handed women, reduced integrity of the left-sided language related tracts may be closely linked to the development of right hemispheric language dominance. Our results may offer new insights into language lateralization and structure-function relationships in human language system.
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Affiliation(s)
- Gabor Perlaki
- Department of Neurology, University of Pecs, Ret U. 2, 7623 Pecs, Hungary
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95
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Molinaro N, Barraza P, Carreiras M. Long-range neural synchronization supports fast and efficient reading: EEG correlates of processing expected words in sentences. Neuroimage 2013; 72:120-32. [PMID: 23357072 PMCID: PMC3817365 DOI: 10.1016/j.neuroimage.2013.01.031] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 01/05/2013] [Accepted: 01/20/2013] [Indexed: 02/08/2023] Open
Abstract
Word reading is heavily influenced by the information provided by previous context. In this study, we analyzed the neurophysiological bases of sentence reading through the EEG activity elicited during reading the same word embedded in differently constraining contexts: a) a low-constraining context; b) a high-constraining semantic compositional context; c) a high-constraining collocational context in which the item was in final position of a multi-word fixed-order expression. Cloze-probability of the two high-constraining contexts was equated. Before reading the target word we observed increased EEG gamma phase synchronization for the high-constraining compositional context and increased EEG theta synchronization for the collocational context (both compared to the low-constraining condition). After reading the target word we observed increased frontal positive EEG evoked activity (~220ms) for the high-constraining compositional context but an even earlier (~120ms) effect for the high-constraining collocational condition that was distributed over the scalp. A positive correlation was found only between the increased theta synchronization and the early EEG effect for the high-constraining collocational condition. Results indicate that long-range frontal-occipital interactions in the theta band - indexing working memory operations - support early visual-orthographic analysis of an incoming stimulus (such as the expected word); gamma-phase synchronization better represents binding operations between feed-forward activation and matching feedback. These data suggest that internal linguistic knowledge stored in long-term memory - if unambiguously pre-activated - supports the low-level perceptual processes involved in reading.
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Affiliation(s)
- Nicola Molinaro
- BCBL, Basque center on Cognition, Brain and Language, Donostia/San Sebastian, Spain.
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96
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Kristo G, Leemans A, Raemaekers M, Rutten GJ, de Gelder B, Ramsey NF. Reliability of two clinically relevant fiber pathways reconstructed with constrained spherical deconvolution. Magn Reson Med 2013; 70:1544-56. [PMID: 23359402 DOI: 10.1002/mrm.24602] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 11/05/2012] [Accepted: 11/27/2012] [Indexed: 11/07/2022]
Abstract
The single diffusion tensor model is inadequate for the reconstruction of fiber pathways in brain regions with multiple fiber orientations. To overcome this limitation, constrained spherical deconvolution has been proposed. A high reliability of constrained spherical deconvolution is, however, a pre-requisite for its use in clinical applications. Reliability of reconstructed fiber pathways can be assessed in terms of architectural (addressing their spatial configuration) and microstructural (addressing diffusion-derived measures along the fibers) reproducibility. We assess the reliability for two clinically relevant fiber pathways: the corticospinal tract and arcuate fasciculus. The fiber pathways were reconstructed using constrained spherical deconvolution in 11 healthy subjects who were scanned on three occasions. Coefficients of variations of diffusion-derived measures were used to assess the microstructural reproducibility. Image correlation and fiber overlap were used to assess the architectural reproducibility. The mean correlation between sessions was 72% for both the corticospinal tract and arcuate fasciculus. The mean overlap between sessions was 63% for the corticospinal tract and 58% for the arcuate fasciculus. Coefficients of variations of diffusion-derived measures showed very low variation (all measures <3.1%). These results are comparable with reliability results based on the diffusion tensor model, which is commonly used in clinical settings. The reliability results found here are, therefore, promising to further investigate the use of constrained spherical deconvolution in clinical practice.
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Affiliation(s)
- Gert Kristo
- Department of Medical Psychology and Neuropsychology, University of Tilburg, Tilburg, The Netherlands; Department of Neurosurgery, St. Elisabeth Hospital, Tilburg, The Netherlands; Department of Neurology and Neurosurgery, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Utrecht, The Netherlands
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97
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Tracing superior longitudinal fasciculus connectivity in the human brain using high resolution diffusion tensor tractography. Brain Struct Funct 2013; 219:269-81. [PMID: 23288254 DOI: 10.1007/s00429-012-0498-y] [Citation(s) in RCA: 213] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Accepted: 12/17/2012] [Indexed: 10/27/2022]
Abstract
The major language pathways such as superior longitudinal fasciculus (SLF) pathways have been outlined by experimental and diffusion tensor imaging (DTI) studies. The SLF I and some of the superior parietal lobule connections of the SLF pathways have not been depicted by prior DTI studies due to the lack of imaging sensitivity and adequate spatial resolution. In the current study, the trajectory of the SLF fibers has been delineated on five healthy human subjects using diffusion tensor tractography on a 3.0-T scanner at high spatial resolution. We also demonstrate for the first time the trajectory and connectivity of the SLF fibers in relation to other language pathways as well as the superior parietal lobule connections of the language circuit using high spatial resolution DTI in the healthy adult human brain.
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98
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Häberling IS, Badzakova-Trajkov G, Corballis MC. Asymmetries of the arcuate fasciculus in monozygotic twins: genetic and nongenetic influences. PLoS One 2013; 8:e52315. [PMID: 23300971 PMCID: PMC3534675 DOI: 10.1371/journal.pone.0052315] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 11/16/2012] [Indexed: 12/02/2022] Open
Abstract
We assessed cerebral asymmetry for language in 35 monozygotic twin pairs. Using DTI, we reconstructed the arcuate fasciculus in each twin. Among the male twins, right-handed pairs showed greater left-sided asymmetry of connectivity in the arcuate fasciculus than did those with discordant handedness, and within the discordant group the right-handers had greater left-sided volume asymmetry of the arcuate fasciculus than did their left-handed co-twins. There were no such effects in the female twins. Cerebral asymmetry for language showed more consistent results, with the more left-cerebrally dominant twins also showing more leftward asymmetry of high anisotropic fibers in the arcuate fasciculus, a result applying equally to female as to male twins. Reversals of arcuate fasciculus asymmetry were restricted to pairs discordant for language dominance, with the left-cerebrally dominant twins showing leftward and the right-cerebrally dominant twins rightward asymmetry of anisotropic diffusion in the arcuate fasciculus. Because monozygotic twin pairs share the same genotype, our results indicate a strong nongenetic component in arcuate fasciculus asymmetry, particularly in those discordant for cerebral asymmetry.
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Affiliation(s)
- Isabelle S Häberling
- Research Centre for Cognitive Neuroscience and Department of Psychology, The University of Auckland, Auckland, New Zealand.
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99
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Li Z, Peck KK, Brennan NP, Jenabi M, Hsu M, Zhang Z, Holodny AI, Young RJ. Diffusion tensor tractography of the arcuate fasciculus in patients with brain tumors: Comparison between deterministic and probabilistic models. ACTA ACUST UNITED AC 2013; 6:192-200. [PMID: 25328583 DOI: 10.4236/jbise.2013.62023] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE The purpose of this study was to compare the deterministic and probabilistic tracking methods of diffusion tensor white matter fiber tractography in patients with brain tumors. MATERIALS AND METHODS We identified 29 patients with left brain tumors <2 cm from the arcuate fasciculus who underwent pre-operative language fMRI and DTI. The arcuate fasciculus was reconstructed using a deterministic Fiber Assignment by Continuous Tracking (FACT) algorithm and a probabilistic method based on an extended Monte Carlo Random Walk algorithm. Tracking was controlled using two ROIs corresponding to Broca's and Wernicke's areas. Tracts in tumoraffected hemispheres were examined for extension between Broca's and Wernicke's areas, anterior-posterior length and volume, and compared with the normal contralateral tracts. RESULTS Probabilistic tracts displayed more complete anterior extension to Broca's area than did FACT tracts on the tumor-affected and normal sides (p < 0.0001). The median length ratio for tumor: normal sides was greater for probabilistic tracts than FACT tracts (p < 0.0001). The median tract volume ratio for tumor: normal sides was also greater for probabilistic tracts than FACT tracts (p = 0.01). CONCLUSION Probabilistic tractography reconstructs the arcuate fasciculus more completely and performs better through areas of tumor and/or edema. The FACT algorithm tends to underestimate the anterior-most fibers of the arcuate fasciculus, which are crossed by primary motor fibers.
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Affiliation(s)
- Zhixi Li
- Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, USA
| | - Kyung K Peck
- Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, USA ; Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, USA
| | - Nicole P Brennan
- Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, USA
| | - Mehrnaz Jenabi
- Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, USA
| | - Meier Hsu
- Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, USA
| | - Zhigang Zhang
- Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, USA
| | - Andrei I Holodny
- Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, USA ; Brain Tumor Center, Memorial Sloan-Kettering Cancer Center, New York, USA
| | - Robert J Young
- Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, USA ; Brain Tumor Center, Memorial Sloan-Kettering Cancer Center, New York, USA
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100
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Information-theoretic approach for automated white matter fiber tracts reconstruction. Neuroinformatics 2012; 10:305-18. [PMID: 22467471 DOI: 10.1007/s12021-012-9148-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Fiber tracking is the most popular technique for creating white matter connectivity maps from diffusion tensor imaging (DTI). This approach requires a seeding process which is challenging because it is not clear how and where the seeds have to be placed. On the other hand, to enhance the interpretation of fiber maps, segmentation and clustering techniques are applied to organize fibers into anatomical structures. In this paper, we propose a new approach to automatically obtain bundles of fibers grouped into anatomical regions. This method applies an information-theoretic split-and-merge algorithm that considers fractional anisotropy and fiber orientation information to automatically segment white matter into volumes of interest (VOIs) of similar FA and eigenvector orientation. For each VOI, a number of planes and seeds is automatically placed in order to create the fiber bundles. The proposed approach avoids the need for the user to define seeding or selection regions. The whole process requires less than a minute and minimal user interaction. The agreement between the automated and manual approaches has been measured for 10 tracts in a DTI brain atlas and found to be almost perfect (kappa > 0.8) and substantial (kappa > 0.6). This method has also been evaluated on real DTI data considering 5 tracts. Agreement was substantial (kappa > 0.6) in most of the cases.
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