Normal Brain Anatomy

Monday 12 May 2014

Michel Thiebaut de Schotten^1,2, Laurent Cohen¹, Eduardo Amemiya³, Lucia Braga³, and Stanislas Dehaene^4
1Brain and Spine Institute, Paris, France, ²Natbrainlab - Institute of Psychiatry, London, United Kingdom, ³SARAH Network–International Center for Neurosciences and Rehabilitation, Brasilia, Brazil, ⁴Collège de France, Paris, France

The acquisition of literacy results from an effortful learning process that leads to functional changes in several cortical regions. We explored whether learning to read also leads to anatomical changes within the left intrahemispheric white matter pathways that interconnect these regions. We revealed that the acquisition of literacy is associated with a reinforcement of left temporo-parietal connections whose microstructure predicts overall reading performance and the functional specialization of the Visual Word Form Area. This anatomical magnetic resonance imaging marker may be useful to predict developmental reading disorders.

Evan Calabrese¹, Christine Hulette², and G. Allan Johnson^3
1Biomedical Engineering, Duke University, Durham, North Carolina, United States, ²Pathology, Duke University, Durham, North Carolina, United States,³Radiology, Duke University, Durham, North Carolina, United States

Deep brain stimulation (DBS) provides symptomatic relief from a number of otherwise refractory neurologic conditions through stimulation of small structures in the brainstem and diencephalon. As researchers and clinicians continue to investigate new DBS targets, there is a need for accurate 3D maps of brainstem anatomy and structural connectivity. Diffusion MRI can provide important insight, but clinical studies lack the spatial and/or angular (diffusion) resolution needed for detailed mapping. We present a high spatial- and high angular-resolution diffusion MRI atlas of the postmortem human brainstem and thalamus with an emphasis on structural mapping of DBS targets.

Fulvia Palesi^1,2, Donald Tournier^3,4, Fernando Calamante^3,4, Nils Muhlert^5,6, Gloria Castellazzi^2,7, Declan Chard^5,8, Egidio D'Angelo^2,9, and Claudia A. M. Wheeler-Kingshott^5
1Department of Physics, University of Pavia, Pavia, Pavia, Italy, ²Brain Connectivity Center, National Neurological Institute C. Mondino, Pavia, Pavia, Italy, ³The Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, Heidelberg, Australia, ⁴Department of Medicine, Austin Health and Northern Health, University of Melbourne, Heidelberg, Australia, ⁵NMR Research Unit, Department of Neuroinflammation, Queen Square MS Centre, UCL Institute of Neurology, London, United Kingdom, ⁶Department of Psychology, Cardiff University, Cardiff, United Kingdom, ⁷Department of Industrial and Information Engineering, University of Pavia, Pavia, Italy, ⁸National Institute for Health Research, UCLH Biomedical Research Centre, London, United Kingdom, ⁹Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy

In addition to motor functions, growing evidence indicates that in humans the cerebellum plays a significant role in cognition. This is occurs through connections with cerebral associative areas via synapsis in the thalamus. While recognizing that tractography provides an indirect evidence of anatomical connectivity between regions, using advanced diffusion MRI tractography we aimed to characterise the cerebello-thalamo-cortical pathway in terms of functional and anatomical areas touched by streamlines. Almost 80% of the streamlines reached the cerebellar hemispheres on one side and the associative cerebral cortex on the other, suggesting a prominent connectivity and supporting the coevolution of the two structures.

Andre J. W. van der Kouwe¹, M. Dylan Tisdall¹, Himanshu Bhat², Bruce Fischl¹, and Jonathan R. Polimeni^1
1Radiology, Massachusetts General Hospital, Charlestown, MA, United States, ²Siemens Healthcare USA, Charlestown, MA, United States

Conventional MPRAGE suffers from blurring in the inner phase encoding direction (between inversions) and readout direction, due to T1 and T2* decay that broadens the point spread functions in these directions, respectively. This can be mitigated by combining multiple GRAPPA accelerated phase encoding blocks and multiple higher bandwidth echoes (shorter readouts that also reduce susceptibility distortion), respectively. This also enables estimation of absolute T1 and T2* times for each voxel. To minimize blurring, real-time prospective motion tracking with EPI volume navigators is included. The resulting generalized MPRAGE sequence provides high quality images for brain morphometry without affecting total acquisition time.

Ana-Maria Oros-Peusquens¹ and N. Jon Shah^1,2
1INM-4, Research Centre Jülich, Jülich, Germany, ²Department of Neurology, RWTH Aachen University, Aachen, Germany

MRI of fixed tissue is increasingly used to investigate the brain. However, properties of tissue change with fixation. This study investigates post mortem formalin-fixed brains quantitatively in order to provide a baseline for MR parameters characteristic of healthy brain tissue. The variability of several quantitative MRI parameters is characterized in fixed brain tissue obtained from donors unaffected by neurological conditions. Among other parameters, quantitative water content determined non-invasively with MRI is reported on whole human post mortem brains for the first time to our knowledge. Correlations between different parameters were investigated and compared to the same quantities measured in vivo.

Allen Newton^1,2, Benoit Dawant³, and Pierre D'Haese^3
1Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States, ²Institute of Imaging Science, Vandebrilt University, Nashville, TN, United States, ³Electrical Engineering and Computer Science, Vanderbilt University, Nashville, TN, United States

Visualizing intrathalamic structures anatomically is important for guidance of surgical interventions, as well as validating existing thalamic parcellations from functional connectivity or DTI tractography, though it has proven quite difficult. Recent reports have begun to identify methods capable of identifying these structures via susceptibility weighted imaging, or by visualizing white matter boundaries between these structures using optimized MPRAGE acquisitions. We present evidence of the potential for the combined use of these techniques to increase the structures that can identified on an individual level. Furthermore, we demonstrate the utility of imaging with MPRAGE imaging with shorter inerversion delays for intrathalamic parcellation.

Manisha Aggarwal¹, Olga Pletnikova², Juan Troncoso², and Susumu Mori^1
1Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ²Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, United States

We demonstrate high angular resolution diffusion MR microimaging to resolve the region-specific microstructure of cortical areas in the fixed human brain. Diffusion MRI of cortical tissue microstructure is challenged by both the low anisotropy in gray matter microenvironments and the level of resolution necessary to delineate the layered architecture. Here, using 3D gradient and spin echo based acquisition, HARDI data of cortical specimens were acquired with 30 diffusion directions at 90 µm isotropic resolution. The diffusion micro-imaging data of the prefrontal, primary motor, and primary visual areas revealed the region-specific laminar microstructure of cortical gray matter with unprecedented detail.

Tae-Hoon Kim¹ and Gwang-Woo Jeong^2
1Research Institute of Medical Imaging, Chonnam National University Medical School, Gwangju, Korea, ²Radiology, Chonnam National University Medical School, Gwangju, Korea

During the past two decades, several studies in females of animal models and human have been performed to unveil the reproductive system changes and the complex interactions with the ovaries. However, morphologic variations in the central nerve system following menopause have not yet been studied. Therefore, this study utilized voxel-based morphormetry (VBM) to evaluate the age-related changes and the effects of menopause on the brain volumes in postmenopausal women.

Jan Scholz¹, Yosuke Niibori², Paul Frankland^2,3, and Jason Lerch^1,4
1Mouse Imaging Centre, Hospital for Sick Children, Toronto, ON, Canada, ²Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, ON, Canada, ³Department of Psychology & Physiology, University of Toronto, Toronto, ON, Canada, ⁴Medical Biophysics, University of Toronto, Toronto, ON, Canada

Here we investigate how rotarod training affects brain volume and microstrucure using ex-vivo MRI in mice. The rotarod is a standard test that taxes motor coordination and balance. Volume of motor and balance-related regions increases after rotarod training. Volume of the motor cortex is positively correlated with rotarod performace. Diffusion imaging indicates that trained mice have higher FA in the hippocampus. Time spent on the rotarod is associated with higher FA in the hippocampus and lower FA in V1. By using complementary measures of microstructure and volume this study reveals the substantial structural reorganization of the adult mouse brain following a brief period of motor training.

Yi Gao¹ and Lawrence Ver Hoef^1
1University of Alabama at Birmingham, Birmingham, AL, United States

We present a segmentation scheme utilizing sub-voxel precision for the hippocampal dentation structure extraction from 3T MR images. This reveals the degree of dentation varies between normal individuals from prominently dentated to minimally dentated.