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Fernando Calamante, Ben Jeurissen, Robert E Smith, Jacques-Donald Tournier, Alan Connelly
PURPOSE: To investigate whether diffusion MRI can be used to study cortical segregation based on a contrast related to neurite density, thus providing a complementary tool to myelin-based MRI techniques used for myeloarchitecture. METHODS: Several myelin-sensitive MRI methods (e.g., based on T1 , T2 , and T2*) have been proposed to parcellate cortical areas based on their myeloarchitecture. Recent improvements in hardware, acquisition, and analysis methods have opened the possibility of achieving a more robust characterization of cortical microstructure using diffusion MRI...
September 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Eunjung Min, Sungbea Ban, Yanyan Wang, Sung Chul Bae, Gabriel Popescu, Catherine Best-Popescu, Woonggyu Jung
We present the scattering properties of mouse brain using multispectral diffraction phase microscopy. Typical diffraction phase microscopy was incorporated with the broadband light source which offers the measurement of the scattering coefficient and anisotropy in the spectral range of 550-900 nm. The regional analysis was performed for both the myeloarchitecture and cytoarchitecture of the brain tissue. Our results clearly evaluate the multispectral scattering properties in the olfactory bulb and corpus callosum...
March 1, 2017: Biomedical Optics Express
Zhiwei Ma, Nanyin Zhang
Cross-population covariance of brain morphometric quantities provides a measure of interareal connectivity, as it is believed to be determined by the coordinated neurodevelopment of connected brain regions. Although useful, structural covariance analysis predominantly employed bulky morphological measures with mixed compartments, whereas studies of the structural covariance of any specific subdivisions such as myelin are rare. Characterizing myelination covariance is of interest, as it will reveal connectivity patterns determined by coordinated development of myeloarchitecture between brain regions...
September 2017: Human Brain Mapping
Boris C Bernhardt, Fatemeh Fadaie, Reinder Vos De Wael, Seok-Jun Hong, Min Liu, Marie C Guiot, David A Rudko, Andrea Bernasconi, Neda Bernasconi
The majority of MRI studies in temporal lobe epilepsy (TLE) have utilized morphometry to map widespread cortical alterations. Morphological markers, such as cortical thickness or grey matter density, reflect combinations of biological events largely driven by overall cortical geometry rather than intracortical tissue properties. Because of its sensitivity to intracortical myelin, quantitative measurement of longitudinal relaxation time (qT1) provides and an in vivo proxy for cortical microstructure. Here, we mapped the regional distribution of qT1 in a consecutive cohort of 24 TLE patients and 20 healthy controls...
June 3, 2017: NeuroImage
Micah Allen, Darya Frank, James C Glen, Francesca Fardo, Martina F Callaghan, Geraint Rees
Empathy is a key component of our ability to engage and interact with others. In recent years, the neural mechanisms underlying affective and cognitive empathy have garnered intense interest. This work demonstrates that empathy for others depends upon a distributed network of regions such as the insula, parietal cortex, and somatosensory areas, which are also activated when we ourselves experience an empathized-with emotion (e.g., pain). Individuals vary markedly in their ability to empathize with others, which predicts the tendency to help others and relates to individual differences in the neuroanatomy of these areas...
March 3, 2017: Scientific Reports
Roberto Viviani, Tony Stöcker, Julia C Stingl
The MR signal from gray matter has been long known to present small differences in intensity that have been attributed to variations in cortical myelin content. Previous studies have shown that the T1-, T2-weighted signal and their ratio are sensitive to these variations. Here, we investigated different combinations of signal from MPRAGE and FLAIR images in multimodal segmentation with parametric models of signal intensity to identify a procedure for the identification of contrast in cortical gray matter and the segmentation of different cortical components at 3T...
February 28, 2017: NeuroImage
Micah Allen, James C Glen, Daniel Müllensiefen, Dietrich Samuel Schwarzkopf, Francesca Fardo, Darya Frank, Martina F Callaghan, Geraint Rees
The ability to introspectively evaluate our experiences to form accurate metacognitive beliefs, or insight, is an essential component of decision-making. Previous research suggests individuals vary substantially in their level of insight, and that this variation is related to brain volume and function, particularly in the anterior prefrontal cortex (aPFC). However, the neurobiological mechanisms underlying these effects are unclear, as qualitative, macroscopic measures such as brain volume can be related to a variety of microstructural features...
April 1, 2017: NeuroImage
José P Marques, Diana Khabipova, Rolf Gruetter
In this manuscript, the use of quantitative imaging at ultra-high field is evaluated as a mean to study cyto and myelo-architecture of the cortex. The quantitative contrasts used are the longitudinal relaxation rate (R1), apparent transverse relaxation rate (R2(*)) and quantitative susceptibility mapping (QSM). The quantitative contrasts were computed using high resolution in-vivo (0.65mm isotropic) brain data acquired at 7T. The performance of the different quantitative approaches was evaluated by visualizing the contrast between known highly myelinated primary sensory cortex regions and the neighbouring cortex...
February 15, 2017: NeuroImage
Benjamin A E Hunt, Prejaas K Tewarie, Olivier E Mougin, Nicolas Geades, Derek K Jones, Krish D Singh, Peter G Morris, Penny A Gowland, Matthew J Brookes
The human brain relies upon the dynamic formation and dissolution of a hierarchy of functional networks to support ongoing cognition. However, how functional connectivities underlying such networks are supported by cortical microstructure remains poorly understood. Recent animal work has demonstrated that electrical activity promotes myelination. Inspired by this, we test a hypothesis that gray-matter myelin is related to electrophysiological connectivity. Using ultra-high field MRI and the principle of structural covariance, we derive a structural network showing how myelin density differs across cortical regions and how separate regions can exhibit similar myeloarchitecture...
November 22, 2016: Proceedings of the National Academy of Sciences of the United States of America
Robert Turner
When blood oxygenation level-dependent (BOLD) contrast functional magnetic resonance imaging (fMRI) was discovered in the early 1990s, it provoked an explosion of interest in exploring human cognition, using brain mapping techniques based on MRI. Standards for data acquisition and analysis were rapidly put in place, in order to assist comparison of results across laboratories. Recently, MRI data acquisition capabilities have improved dramatically, inviting a rethink of strategies for relating functional brain activity at the systems level with its neuronal substrates and functional connections...
October 5, 2016: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Emmanuel Márquez-Legorreta, José de Anchieta C Horta-Júnior, Albert S Berrebi, Enrique Saldaña
The zone of transition between the pretectum, derived from prosomere 1, and the thalamus, derived from prosomere 2, is structurally complex and its understanding has been hampered by cytoarchitectural and terminological confusion. Herein, using a battery of complementary morphological approaches, including cytoarchitecture, myeloarchitecture and the expression of molecular markers, we pinpoint the features or combination of features that best characterize each nucleus of the pretectothalamic transitional zone of the rat...
2016: Frontiers in Neuroanatomy
I Large, H Bridge, B Ahmed, S Clare, J Kolasinski, W W Lam, K L Miller, T B Dyrby, A J Parker, J E T Smith, G Daubney, J Sallet, A H Bell, K Krug
Extrastriate visual area V5/MT in primates is defined both structurally by myeloarchitecture and functionally by distinct responses to visual motion. Myelination is directly identifiable from postmortem histology but also indirectly by image contrast with structural magnetic resonance imaging (sMRI). First, we compared the identification of V5/MT using both sMRI and histology in Rhesus macaques. A section-by-section comparison of histological slices with in vivo and postmortem sMRI for the same block of cortical tissue showed precise correspondence in localizing heavy myelination for V5/MT and neighboring MST...
October 2016: Cerebral Cortex
Seung-Goo Kim, Thomas R Knösche
Absolute pitch (AP) is known as the ability to recognize and label the pitch chroma of a given tone without external reference. Known brain structures and functions related to AP are mainly of macroscopic aspects. To shed light on the underlying neural mechanism of AP, we investigated the intracortical myeloarchitecture in musicians with and without AP using the quantitative mapping of the longitudinal relaxation rates with ultra-high-field magnetic resonance imaging at 7 T. We found greater intracortical myelination for AP musicians in the anterior region of the supratemporal plane, particularly the medial region of the right planum polare (PP)...
October 2016: Human Brain Mapping
Miwa Horiuchi-Hirose, Kazuhiko Sawada
The purpose of this study was to quantitatively clarify differences in laminar structure and myeloarchitecture of sulcal and gyral regions of the cerebral cortex of ferrets. Histological sections of cerebrum from male and female ferrets at postnatal day 90 were made at the coronal plane, and were immunostained with anti-NeuN or anti-myelin basic protein (MBP). Thickness was estimated in the entire depth or three strata, that is, layer I, outer (layers II-III) and inner (layers IV-VI) strata of the neocortex in representative five sulcal and seven gyral regions...
August 2016: Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology
Christopher D Rowley, Pierre-Louis Bazin, Christine L Tardif, Manpreet Sehmbi, Eyesha Hashim, Nadejda Zaharieva, Luciano Minuzzi, Benicio N Frey, Nicholas A Bock
Alterations in the myelination of the cerebral cortex may underlie abnormal cortical function in a variety of brain diseases. Here, we describe a technique for investigating changes in intracortical myelin in clinical populations on the basis of cortical thickness measurements with magnetic resonance imaging (MRI) at 3 Tesla. For this, we separately compute the thickness of the shallower, lightly myelinated portion of the cortex and its deeper, heavily myelinated portion (referred to herein as unmyelinated and myelinated cortex, respectively)...
2015: Frontiers in Neuroscience
Miriam D Waehnert, Juliane Dinse, Andreas Schäfer, Stefan Geyer, Pierre-Louis Bazin, Robert Turner, Christine Lucas Tardif
Structural magnetic resonance imaging can now resolve laminar features within the cerebral cortex in vivo. A variety of intracortical contrasts have been used to study the cortical myeloarchitecture with the purpose of mapping cortical areas in individual subjects. In this article, we first briefly review recent advances in MRI analysis of cortical microstructure to portray the potential and limitations of the current state-of-the-art. We then present an integrated framework for the analysis of intracortical structure, composed of novel image processing tools designed for high resolution cortical images...
January 15, 2016: NeuroImage
Adrian K Andelin, David J Bruning, Daniel J Felleman, Jaime F Olavarria
Previous studies in rabbits identified an array of extrastriate cortical areas anatomically connected with V1 but did not describe their internal topography. To address this issue, we injected multiple anatomical tracers into different regions in V1 of the same animal and analyzed the topography of resulting extrastriate labeled fields with reference to the patterns of callosal connections and myeloarchitecture revealed in tangential sections of the flattened cortex. Our results extend previous studies and provide further evidence that rabbit extrastriate areas resemble the visual areas in rats and mice not only in their general location with respect to V1 but also in their internal topography...
2015: Neurology Research International
G Mangeat, S T Govindarajan, C Mainero, J Cohen-Adad
Recently, T2* imaging at 7Tesla (T) MRI was shown to reveal microstructural features of the cortical myeloarchitecture thanks to an increase in contrast-to-noise ratio. However, several confounds hamper the specificity of T2* measures (iron content, blood vessels, tissues orientation). Another metric, magnetization transfer ratio (MTR), is known to also be sensitive to myelin content and thus would be an excellent complementary measure because its underlying contrast mechanisms are different than that from T2*...
October 1, 2015: NeuroImage
Eyesha Hashim, Christopher D Rowley, Sharon Grad, Nicholas A Bock
Functional studies of cortical plasticity in humans suggest that the motor cortex reorganizes when the descending motor output pathway is disrupted as a result of limb amputation. The question thus arises if the underlying anatomical organization of the motor cortex is also altered in limb amputation. Owing to challenges involved in imaging the thin cerebral cortex in vivo, there is limited data available on the anatomical or morphological plasticity of the motor cortex in amputation. In this paper, we study the morphology of the primary motor cortex in four lower limb amputees with 37 or more years of amputation and four age and gender-matched controls using 0...
2015: Frontiers in Neuroscience
Christine Lucas Tardif, Andreas Schäfer, Miriam Waehnert, Juliane Dinse, Robert Turner, Pierre-Louis Bazin
The position of cortical areas can be approximately predicted from cortical surface folding patterns. However, there is extensive inter-subject variability in cortical folding patterns, prohibiting a one-to-one mapping of cortical folds in certain areas. In addition, the relationship between cortical area boundaries and the shape of the cortex is variable, and weaker for higher-order cortical areas. Current surface registration techniques align cortical folding patterns using sulcal landmarks or cortical curvature, for instance...
May 1, 2015: NeuroImage
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