Jurgen Germann¹, D. Vousden¹, P Steadman¹, J. Dazai¹, C. Laliberte¹, S. Spring¹, L. Cahill¹, R. M. Henkelman¹, and Jason P Lerch^1
1The Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada

Brain shape is influenced by experience. The time course of the changes, however, remains unknown. In our study we longitudinally imaged mice undergoing spatial navigation training. Our results show that learning is associated with definite local brain changes detectable using live-imaging. These changes, found as early as on the second day of training, occur in specific brain regions depending on the experimental setup. The time course of local remodeling varies between regions. Whole brain live MRI is capable of detecting and characterizing these brain changes and is instrumental studying local changes within the brain as a learning system.

Jurgen Germann¹, P. Steadman¹, D. Vousden¹, J. Dazai¹, S. Spring¹, C. Laliberte¹, L. Cahill¹, R. M. Henkelman¹, and J. P. Lerch^1
1The Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Ontario, Canada

The famous London taxi driver study demonstrated that some hippocampal regions are larger in taxi drivers compared to matched controls. These anatomical differences are likely related to extensive experience. What, however, is the influence of preexisting anatomical differences on subsequent learning performance. In our study we imaged mice prior to spatial navigation training. Our results show that local variance in brain shape predicts subsequent learning performance. The relevant regions differ depending on the learning condition. Whole brain live MRI is capable of detecting and characterizing preexisting anatomical differences and instrumental in studying brain behavior relationship.

Fernando Calamante^1,2, Jacques-Donald Tournier^1,2, Nyoman D Kurniawan³, Zhengyi Yang³, Erika Gyengesi⁴, Graham J Galloway³, David C Reutens³, and Alan Connelly^1,2
1Brain Research Institute, Florey Neuroscience Institutes, Heidelberg West, Victoria, Australia, ²Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia, ³Centre for Advanced Imaging, The University of Queensland, Brisbane, Queensland, Australia, ⁴Neuroscience Research Australia, Randwick, New South Wales, Australia

The recently introduced super-resolution track-density imaging (TDI) is able to increase the spatial resolution of the reconstructed images beyond the acquired MRI resolution by incorporating information contained in whole-brain fibre-track modelling results. The TDI technique not only provides a means to achieve super-resolution, but it also provides very high anatomical contrast with a new MRI contrast mechanism. However, the anatomical information-content of this novel contrast mechanism has not been validated yet. We perform such a study using ex vivo mouse brains acquired at 16.4T, and comparing the results of the super-resolution TDI technique to histological staining.

Yen-Yu Ian Shih¹, You-Yin Chen², Hsin-Yi Lai², and Timothy Q Duong^1
1Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States, ²Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan

This study employed very high resolution CBV fMRI (40x40 ìm in-plane resolution) and multichannel field potential recording to investigate the neurovascular coupling within cortical laminae. This MRI resolution was achieved by using a small surface coil and an 11.7 T scanner. Graded forepaw electrical stimulation was employed to modulate layer-specific neuronal activities. Our results indicate that CBV responses and field potential changes at laminar resolution are not completely coupled.

Jeremy Joseph Flint^1,2, Brian Hansen³, Sharon Portnoy^1,2, Choong H Lee^2,4, Michael A King⁵, Michael Fey⁶, Franck Vincent⁶, Peter Vestergaard-Poulsen³, and Stephen J. Blackband^2,7
1Neuroscience, University of Florida, Gainesville, Fl, United States, ²McKnight Brain Institute, University of Florida, Gainesville, Fl, United States, ³Center for Functionally Integrative Neuroscience, University of Aarhus, Aarhus, Denmark, ⁴Electrical Engineering, University of Florida, Gainesville, Fl, United States, ⁵Pharmacology and Therapeutics, University of Florida, Gainesville, Fl, United States, ⁶Bruker Biospin, ⁷National High Magnetic Field Laboratory, Talahassee, Fl, United States

The ability to resolve microstructural details of biological tissues has been a long sought-after goal in the field of MR imaging. Magnetic resonance microscopy (MRM) has evolved to reveal ever-finer details of the cellular organization which makes up tissue parenchyma. Such techniques are needed so that we may understand the primary structural origins underlying MR signal changes resultant from pathology. In the current study, we report what we believe to be the first instances of cellular imaging in humans and neural process imaging in humans and pigs using magnetic resonance microscopy techniques.

Federico De Martino¹, Jan Zimmermann¹, Gregor Adriany², Pierre-Francois van de Moortele², David A Feinberg³, Kamil Ugurbil², Rainer Goebel¹, and Essa Yacoub^2
1Cognitive Neuroscience, Maastricht University, Maastricht, Netherlands, ²CMRR, Radiology, University of Minnesota, Minneapolis, Minnesota, United States, ³Advanced MRI Technologies, Sebastopol, California, United States

We provide direct evidence of columnar organization of direction selective features (DSF) in human area MT using spin echo BOLD based fMRI at ultra high fields (7 tesla). We demonstrate that the functional selectivity and sensitivity of high field high resolution SE BOLD fMRI is sufficient to resolve the fine grained organization of feature representations within higher level folded cortical areas.

Rosa M Sanchez Panchuelo¹, Julien Besle², Richard Bowtell¹, Denis Schluppeck², and Susan Francis^1
1Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, United Kingdom, ²School of Psychology, University of Nottingham, Nottingham, United Kingdom

The increased BOLD contrast-to-noise ratio at 7T has been exploited to measure fine topographic organisation in individual subjects within the index finger representation (base-to-tip) in human somatosensory cortex (S1) at 1.5mm isotropic resolution using a travelling wave paradigm. Subjects were scanned twice to assess reproducibility, and data displayed on a flattened representation of the cortex. An organized somatotopy within the cortical area corresponding to the index finger was found for two subjects, with phase reversals in the map which are consistent with mirrored representations in adjacent sub-regions 3a/3b/1/2 of S1. The results were reproducible across sessions for all subjects.

Jaco J.M. Zwanenburg^1,2, Maarten J Versluis³, Peter R Luijten¹, and Natalia Petridou^1,4
1Radiology, Universiy Medical Center Utrecht, Utrecht, Netherlands, ²Image Sciences Institute, Universiy Medical Center Utrecht, Utrecht, Netherlands, ³Radiology, Leiden University Medical Center, Leiden, Netherlands, ⁴Rudolf Magnus Institute, University Medical Center Utrecht, Utrecht, Netherlands

This work shows that high resolution (0.5 mm isotropic) T2* weighted images of the whole brain can be obtained in less than 6 minutes by utilizing the high SNR efficiency of echo planar imaging (EPI). The image SNR is increased by a factor of 2, and the coverage by a factor of approx. 5, compared to conventional gradient echo imaging (GRE) with the same scan duration. The contrast for both magnitude and phase is equivalent between EPI and GRE imaging.

Masaki Fukunaga^1,2, Peter van Gelderen¹, Jongho Lee¹, Tie-Qiang Li¹, Jacco A de Zwart¹, Hellmut Merkle¹, Kant M Matsuda³, Eiji Matsuura⁴, and Jeff H Duyn^1
1Advanced MRI section, LFMI, NINDS, National Institutes of Health, Bethesda, MD, United States, ²Biofunctional Imaging, Immunology Frontier Research Center, Osaka University, Suita, Osaka, Japan, ³Laboratory of Pathology, NCI, National Institutes of Health, Bethesda, MD, United States, ⁴Laboratory of Neuroimmunology, NINDS, National Institutes of Health, Bethesda, MD, United States

Variations of magnetic susceptibility have been demonstrated in primary visual cortex and shown to relate to tissue iron content. Here we extend this finding to cortical regions in the parietal lobe of human brain. Comparison of 7T MRI data with iron and myelin histology suggests that iron dominates the contrast across many cortical areas including sensory-motor cortex, cingulate and precuneus. Interestingly, myelin and iron differentially contribute to susceptibility contrast in subcortical white matter versus the optic radiation.

Graham Wiggins¹, Chris Wiggins², Bei Zhang¹, Ryan Brown¹, Bernd Stoeckel³, and Daniel K Sodickson^1
1Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY10016, United States, ²CEA/NeuroSpin, Saclay, France,³Siemens Medical Solutions USA Inc, New York, NY, United States

At 7T, T2* weighted gradient echo imaging reveals unexpected contrast variation in white matter which appears to be associated with specific fiber bundles. The mechanism behind this variation has been debated, and it has been proposed that it may be caused by intrinsic properties of the fiber bundle such as degree of myelination or iron content, or that it depends on the orientation of the fiber bundles in relation to the main B0 field. With a novel coil system we obtain T2* maps in orientations 90 degrees apart and demonstrate that T2* depends strongly on orientation.