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Brain Hemispheres (brain + hemisphere)
Selected AbstractsA Tale of Two Cases: Lessons for Education From the Study of Two Boys Living With Half Their BrainsMIND, BRAIN, AND EDUCATION, Issue 2 2007Mary Helen Immordino-Yang ABSTRACT, In recent years, educators have been looking increasingly to neuroscience to inform their understanding of how children's brain and cognitive development are shaped by their learning experiences. However, while this new interdisciplinary approach presents an unprecedented opportunity to explore and debate the educational implications of neuropsychological research, a good model for this dialogue is lacking. This is in part because relatively little is known about the relationships between cognitive, emotional, and neurological development, in part because of a dearth of research methods designed to rigorously connect issues of learning and development to neuropsychological strengths and weaknesses, and in part because neuropsychological studies are rarely presented in a format that is conducive to meaningful cross-disciplinary dialogue with educators. To begin to address these issues, in this article, I present the complementary cases of Nico and Brooke, two high-functioning adolescents, who have suffered the removal of an entire brain hemisphere (Nico his right and Brooke his left) to control severe epilepsy. Through presenting a neuropsychological study of these rare boys' emotion and affective prosody (vocal intonation) through the developmental lens of an educator, I reinterpret the neuropsychological findings for what they reveal about how the boys leveraged their emotional and cognitive strengths to learn important skills for which they were each missing half of the normally recruited neural hardware. While Nico's and Brooke's results seem on the surface to contradict expectations based on neuropsychological findings with adults, they combine to reveal a compensatory logic that begins to elucidate the active role of the learner as well as the organizing role of emotion in brain development, providing a jumping-off point for discussion between educators and neuroscientists and a model for connecting neuropsychological strengths and weaknesses to learning. [source] MRI-based evaluation of locus and extent of neurotoxic lesions in monkeys ,HIPPOCAMPUS, Issue 4 2001e Málková Abstract To minimize the variability in the extent of lesions made by injections of the excitotoxin ibotenic acid in rhesus monkeys, we developed and validated an MRI-based method to determine the efficacy of the injections soon after surgery. T2-weighted MR images were obtained 6,11 days after surgery from 17 brain hemispheres of monkeys that had received bilateral lesions of either the hippocampal formation (HF), perirhinal cortex, or parahippocampal cortex. The extent of lesion estimated from the hypersignal that appeared in and outside of the targeted area on these MR images was compared with the extent of damage assessed histologically after survival periods ranging from 120,370 days. Highly significant correlations (r values between 0.85,0.99) were found between these two measures for several regions in the medial temporal lobe. Based on this finding, lack of hypersignal in the targeted area of some Ss was followed by successful reinjection of the neurotoxin to create more complete cell loss prior to the postoperative phase of the study. We also assessed the relationship between a postoperative reduction in HF volume, measured from T1-weighted MR images, and the extent of damage determined histologically in 14 hemispheres of monkeys with bilateral excitotoxic HF lesions. The HF volume decreases sharply after surgery until 40,50 days postoperatively, after which there is only a minor further decrease. Based on this finding, we obtained T1-weighted MR images at least 44 days but in most cases close to 1 year after surgery. A highly significant positive correlation (r = 0.95, P < 0.001) was found between neuronal damage and volume reduction, with nearly complete neuronal damage (96,99%) corresponding to a volume reduction of 68,79%. These MRI-based methods thus provide an accurate in vivo evaluation of the locus and extent of neurotoxic lesions. Application of these methods can ensure that each animal in the experiment is used effectively. Hippocampus 2001;11:361,370. Published 2001 Wiley-Liss, Inc. [source] MR tracking of transplanted cells with "positive contrast" using manganese oxide nanoparticlesMAGNETIC RESONANCE IN MEDICINE, Issue 1 2008Assaf A. Gilad Abstract Rat glioma cells were labeled using electroporation with either manganese oxide (MnO) or superparamagnetic iron oxide (SPIO) nanoparticles. The viability and proliferation of SPIO-labeled cells (1.9 mg Fe/ml) or cells electroporated with a low dose of MnO (100 ,g Mn/ml) was not significantly different from unlabeled cells; a higher MnO dose (785 ,g Mn/ml) was found to be toxic. The cellular ion content was 0.1,0.3 pg Mn/cell and 4.4 pg Fe/cell, respectively, with cellular relaxivities of 2.5,4.8 s,1 (R1) and 45,84 s,1 (R2) for MnO-labeled cells. Labeled cells (SPIO and low-dose MnO) were each transplanted in contralateral brain hemispheres of rats and imaged in vivo at 9.4T. While SPIO-labeled cells produced a strong "negative contrast" due to the increase in R2, MnO-labeled cells produced "positive contrast" with an increased R1. Simultaneous imaging of both transplants with opposite contrast offers a method for MR "double labeling" of different cell populations. Magn Reson Med 60:1,7, 2008. © 2008 Wiley-Liss, Inc. [source] Molecular regulation of the developing commissural plateTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 18 2010Randal X. Moldrich Abstract Coordinated transfer of information between the brain hemispheres is essential for function and occurs via three axonal commissures in the telencephalon: the corpus callosum (CC), hippocampal commissure (HC), and anterior commissure (AC). Commissural malformations occur in over 50 human congenital syndromes causing mild to severe cognitive impairment. Disruption of multiple commissures in some syndromes suggests that common mechanisms may underpin their development. Diffusion tensor magnetic resonance imaging revealed that forebrain commissures crossed the midline in a highly specific manner within an oblique plane of tissue, referred to as the commissural plate. This specific anatomical positioning suggests that correct patterning of the commissural plate may influence forebrain commissure formation. No analysis of the molecular specification of the commissural plate has been performed in any species; therefore, we utilized specific transcription factor markers to delineate the commissural plate and identify its various subdomains. We found that the mouse commissural plate consists of four domains and tested the hypothesis that disruption of these domains might affect commissure formation. Disruption of the dorsal domains occurred in strains with commissural defects such as Emx2 and Nfia knockout mice but commissural plate patterning was normal in other acallosal strains such as Satb2,/,. Finally, we demonstrate an essential role for the morphogen Fgf8 in establishing the commissural plate at later developmental stages. The results demonstrate that correct patterning of the commissural plate is an important mechanism in forebrain commissure formation. J. Comp. Neurol. 518:3645,3661, 2010. © 2010 Wiley-Liss, Inc. [source] | ||||||||||