Brainstem and Cranial Nerve
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A Network of Genetic Repression and Derepression Specifies Projection
A network of genetic repression and derepression INAUGURAL ARTICLE specifies projection fates in the developing neocortex Karpagam Srinivasana,1, Dino P. Leonea, Rosalie K. Batesona, Gergana Dobrevab, Yoshinori Kohwic, Terumi Kohwi-Shigematsuc, Rudolf Grosschedlb, and Susan K. McConnella,2 aDepartment of Biology, Stanford University, Stanford, CA 94305; bMax-Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg, Germany; and cLawrence Berkeley National Laboratory, Berkeley, CA 94720 This contribution is part of the special series of Inaugural Articles by members of the National Academy of Sciences elected in 2011. Contributed by Susan K. McConnell, September 28, 2012 (sent for review August 24, 2012) Neurons within each layer in the mammalian cortex have stereotypic which results in a suppression of corticothalamic and callosal projections. Four genes—Fezf2, Ctip2, Tbr1, and Satb2—regulate fates, respectively, and axon extension along the corticospinal these projection identities. These genes also interact with each tract (CST). Fezf2 mutant neurons fail to repress Satb2 and Tbr1, other, and it is unclear how these interactions shape the final pro- thus their axons cross the CC and/or innervate the thalamus jection identity. Here we show, by generating double mutants of inappropriately. Fezf2, Ctip2, and Satb2, that cortical neurons deploy a complex In callosal projection neurons, Satb2 represses the expression Ctip2 Bhlhb5 genetic switch that uses mutual repression to produce subcortical of and , leading to a repression of subcerebral fates. Satb2 Tbr1 or callosal projections. We discovered that Tbr1, EphA4, and Unc5H3 Interestingly, we found that promotes expression in fi upper layer callosal neurons, and Tbr1 expression in these neu- are critical downstream targets of Satb2 in callosal fate speci ca- fi tion. -
The Superior and Inferior Colliculi of the Mole (Scalopus Aquaticus Machxinus)
THE SUPERIOR AND INFERIOR COLLICULI OF THE MOLE (SCALOPUS AQUATICUS MACHXINUS) THOMAS N. JOHNSON' Laboratory of Comparative Neurology, Departmmt of Amtomy, Un&versity of hfiehigan, Ann Arbor INTRODUCTION This investigation is a study of the afferent and efferent connections of the tectum of the midbrain in the mole (Scalo- pus aquaticus machrinus). An attempt is made to correlate these findings with the known habits of the animal. A subterranean animal of the middle western portion of the United States, Scalopus aquaticus machrinus is the largest of the genus Scalopus and its habits have been more thor- oughly studied than those of others of this genus according to Jackson ('15) and Hamilton ('43). This animal prefers a well-drained, loose soil. It usually frequents open fields and pastures but also is found in thin woods and meadows. Following a rain, new superficial burrows just below the surface of the ground are pushed in all directions to facili- tate the capture of worms and other soil life. Ten inches or more below the surface the regular permanent highway is constructed; the mole retreats here during long periods of dry weather or when frost is in the ground. The principal food is earthworms although, under some circumstances, larvae and adult insects are the more usual fare. It has been demonstrated conclusively that, under normal conditions, moles will eat vegetable matter. It seems not improbable that they may take considerable quantities of it at times. A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the University of Michigan. -
ON-LINE FIG 1. Selected Images of the Caudal Midbrain (Upper Row
ON-LINE FIG 1. Selected images of the caudal midbrain (upper row) and middle pons (lower row) from 4 of 13 total postmortem brains illustrate excellent anatomic contrast reproducibility across individual datasets. Subtle variations are present. Note differences in the shape of cerebral peduncles (24), decussation of superior cerebellar peduncles (25), and spinothalamic tract (12) in the midbrain of subject D (top right). These can be attributed to individual anatomic variation, some mild distortion of the brain stem during procurement at postmortem examination, and/or differences in the axial imaging plane not easily discernable during its prescription parallel to the anterior/posterior commissure plane. The numbers in parentheses in the on-line legends refer to structures in the On-line Table. AJNR Am J Neuroradiol ●:●●2019 www.ajnr.org E1 ON-LINE FIG 3. Demonstration of the dentatorubrothalamic tract within the superior cerebellar peduncle (asterisk) and rostral brain stem. A, Axial caudal midbrain image angled 10° anterosuperior to posteroinferior relative to the ACPC plane demonstrates the tract traveling the midbrain to reach the decussation (25). B, Coronal oblique image that is perpendicular to the long axis of the hippocam- pus (structure not shown) at the level of the ventral superior cerebel- lar decussation shows a component of the dentatorubrothalamic tract arising from the cerebellar dentate nucleus (63), ascending via the superior cerebellar peduncle to the decussation (25), and then enveloping the contralateral red nucleus (3). C, Parasagittal image shows the relatively long anteroposterior dimension of this tract, which becomes less compact and distinct as it ascends toward the thalamus. ON-LINE FIG 2. -
Brain Anatomy
BRAIN ANATOMY Adapted from Human Anatomy & Physiology by Marieb and Hoehn (9th ed.) The anatomy of the brain is often discussed in terms of either the embryonic scheme or the medical scheme. The embryonic scheme focuses on developmental pathways and names regions based on embryonic origins. The medical scheme focuses on the layout of the adult brain and names regions based on location and functionality. For this laboratory, we will consider the brain in terms of the medical scheme (Figure 1): Figure 1: General anatomy of the human brain Marieb & Hoehn (Human Anatomy and Physiology, 9th ed.) – Figure 12.2 CEREBRUM: Divided into two hemispheres, the cerebrum is the largest region of the human brain – the two hemispheres together account for ~ 85% of total brain mass. The cerebrum forms the superior part of the brain, covering and obscuring the diencephalon and brain stem similar to the way a mushroom cap covers the top of its stalk. Elevated ridges of tissue, called gyri (singular: gyrus), separated by shallow groves called sulci (singular: sulcus) mark nearly the entire surface of the cerebral hemispheres. Deeper groves, called fissures, separate large regions of the brain. Much of the cerebrum is involved in the processing of somatic sensory and motor information as well as all conscious thoughts and intellectual functions. The outer cortex of the cerebrum is composed of gray matter – billions of neuron cell bodies and unmyelinated axons arranged in six discrete layers. Although only 2 – 4 mm thick, this region accounts for ~ 40% of total brain mass. The inner region is composed of white matter – tracts of myelinated axons. -
Midbrain Tegmental Lesions Affecting Or Sparing the Pupillary Fibres
J7ournal ofNeurology, Neurosurgery, and Psychiatry 1996;61:401-402 401 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.61.4.401 on 1 October 1996. Downloaded from SHORT REPORT Midbrain tegmental lesions affecting or sparing the pupillary fibres Naokatsu Saeki, Naohisa Murai, Kenro Sunami Abstract lesion in the upper midbrain and close to the Two patients with oculomotor palsy third ventricle (fig 1). caused by midbrain infarction are Three months later the oculomotor palsy reported. In the first, pupillary reaction improved. The patient returned to his previ- was affected and in the second this reac- ous work after a further three months. tion was spared. Because the lesions in the anterior part of the tegmentum were CASE 2 in the upper midbrain in the first patient A 68 year old woman with hypertension for and in the lower midbrain in the second, eight years suddenly developed vertigo and it is suggested that the pupillary compo- nents of the oculomotor nerve are located in the upper midbrain. (7 Neurol Neurosurg Psychiatry 1996;61:401-402) Keywords: midbrain; oculomotor nerve; pupil sparing We report the details of two patients with a small midbrain infarction, the first with impairment of pupillary reaction to light and the second in which this reaction was pre- served. The aim of this study was to elucidate the topography of oculomotor pupillary fibres in the midbrain tegmentum based on findings using MRI. http://jnnp.bmj.com/ Case studies CASE 1 A 67 year old man with a 10 year history of hypertension presented with difficulty in open- ing his left eye on waking up in the morning. -
White Matter Anatomy: What the Radiologist Needs to Know
White Matter Anatomy What the Radiologist Needs to Know Victor Wycoco, MBBS, FRANZCRa, Manohar Shroff, MD, DABR, FRCPCa,*, Sniya Sudhakar, MBBS, DNB, MDb, Wayne Lee, MSca KEYWORDS Diffusion tensor imaging (DTI) White matter tracts Projection fibers Association Fibers Commissural fibers KEY POINTS Diffusion tensor imaging (DTI) has emerged as an excellent tool for in vivo demonstration of white matter microstructure and has revolutionized our understanding of the same. Information on normal connectivity and relations of different white matter networks and their role in different disease conditions is still evolving. Evidence is mounting on causal relations of abnormal white matter microstructure and connectivity in a wide range of pediatric neurocognitive and white matter diseases. Hence there is a pressing need for every neuroradiologist to acquire a strong basic knowledge of white matter anatomy and to make an effort to apply this knowledge in routine reporting. INTRODUCTION (Fig. 1). However, the use of specific DTI sequences provides far more detailed and clini- DTI has allowed in vivo demonstration of axonal cally useful information. architecture and connectivity. This technique has set the stage for numerous studies on normal and abnormal connectivity and their role in devel- DIFFUSION TENSOR IMAGING: THE BASICS opmental and acquired disorders. Referencing established white matter anatomy, DTI atlases, Using appropriate magnetic field gradients, and neuroanatomical descriptions, this article diffusion-weighted sequences can be used to summarizes the major white matter anatomy and detect the motion of the water molecules to and related structures relevant to the clinical neurora- from cells. This free movement of the water mole- diologist in daily practice. -
Corticospinal Tract (CST) Reconstruction Based on Fiber
Corticospinal Tract (CST) reconstruction based on fiber orientation distributions (FODs) tractography Youshan Zhang Computer Science and Engineering Department Lehigh University Bethlehem, PA [email protected] Abstract—The Corticospinal Tract (CST) is a part of pyra- About 75%-90% of the CST fibers descend to the lateral midal tract (PT) and it can innervate the voluntary movement corticospinal tract by decussation of the pyramid, but a few of skeletal muscle through spinal interneurons (the 4th layer of fibers form the anterior corticospinal tract by not crossing the Rexed gray board layers), and anterior horn motorneurons (which control trunk and proximal limb muscles). Spinal cord the pyramid [9], [10]. The fibers, which first passed through injury (SCI) is a highly disabling disease often caused by the medial posterior spinocerebellar tract then went into traffic accidents. The recovery of CST and the functional the lumbosacral spinocerebellar tract, were not yet appeared reconstruction of spinal anterior horn motor neurons play an [11], [12]. The main function of the CST is innervating essential role in the treatment of SCI. However, the localization the voluntary movement of skeletal muscle through spinal and reconstruction of CST are still challenging issues, the accuracy of the geometric reconstruction can directly affect interneurons (the 4th layer of the Rexed gray board layers), the results of the surgery. The main contribution of this paper and anterior horn motorneurons (which control trunk and is the reconstruction of the CST based on the fiber orientation proximal limb muscles), then the CST terminates in the spinal distributions (FODs) tractography. Differing from tensor-based motor cells (which control the fine motor of small muscle tractography in which the primary direction is a determined in extremities) [13]. -
The Nuclear Pattern of the Non-Tectal Portions of the Midbrain and Isthmus in Ungtjlates
THE NUCLEAR PATTERN OF THE NON-TECTAL PORTIONS OF THE MIDBRAIN AND ISTHMUS IN UNGTJLATES LOIS A. GILLILAN Dr. Louis Merwin Gelston Fellow, Mrdical School, Universzty of Mickigan, Ann Arbor Department of Anatomy, University of Ptttsburgh, Pennsylvania TWENTY-SIX PLATES (TWENTY-SIX FIGURES) INTRODUCTION The material used for this study of the midbrain of the 16 cin pig (Sus scrofa), the adult sheep (Ovis aries) and the old horse (Equus caballus) consists of serially cut, transverse, toluidin blue sections. For the generous grant which made possible this research the writer wishes to express grateful acknowlcdgmeiit to the Horace H. Rackham School of Graduate Studies of the University of Michigan. Very little literature dealing with the ungulate midbrain has come to our attention. Papers by Solnitzsky ( '38 and '39) deal with the dorsal thalamic, subthalamic, and hypothalamic regions of the pig brain; they contain accounts of the pre- tectal regions, substantia nigra and the rostra1 tip of the red nucleus. Rose ('42 b) has found that the pretectal nucleus in the sheep is represented by two groups of cells. Le Gros Clark ( '26) observed that the Edinger-Westphal nucleus in the sheep was little differentiated, and in the pig th'e cells were only slightly different from the small medial raphe cells with which they become continuous anteriorly. The Edinger-Westphal nucleus in the pig is mostly a midline structure with only occasional bilateral clumping. Tsuchida ( '06) found no Edinger-Westphal nucleus in the sheep and in the horse a few scattered cells only. He observed no nucleus medianns anterior and no true nucleus of Perlia; in the horse no nucleus of 289 290 G. -
Destruction of the "Pyramidal Tract" in Man*
Destruction of the "Pyramidal Tract" in Man* PAUL C. BucY, M.D., JAMES E. KEPLINGER, M.D., AND EDIR B. SIQUEIRA,M.D. Department of Surgery, Northwestern University Medical School and Section on Neurological Surgery, Chicago Wesley Memorial Hospital, Chicago, Illinois PPORTUNITIES to observe the results cal "pyramidal tract") occupy the central of the isolated destruction of the portion of the cerebral peduncle (Fig. 1) as O "pyramidal tract" in man are rare. Levin ls,19 has shown, while the corticospinal There are but few places in the nervous sys- fibers from the postcentral region lie immedi- tem where the corticospinal fibers are sepa- ately lateral to these (Fig. ~).1 In the most rated sufficiently from other systems to per- medial part of the peduncle are found the mit of their isolated destruction, either surgi- frontopontine fibers, ls,19 The exact nature of cally or by disease. Extirpation of the the fibers in the most lateral part of the cere- pre- and postcentral cerebral cortex results in bral peduncle is less well known. Marin a destruction of the "pyramidal tract" but et al., 2~ from a study of human material con- also destroys other fibers, both ascending and cluded that the lateral segment of the pe- descending, thus producing a complex pic- duncle is composed of corticopontine fibers ture. Lesions of the internal capsule fre- from the parietal, occipital and temporal quently destroy the corticospinal system but lobes. However, their evidence as to occipito- they also destroy descending pathways to the pontine fibers is not conclusive, and that basal ganglia, the thalamus, the brain stem, dealing with a temporopontine component the cerebellum, etc., as well as many ascend- indicates only a very few such fibers. -
Anatomy & Function of the BRAINSTEM & CEREBELLUM
Anatomy & Function of the BRAINSTEM & CEREBELLUM Prof. Dr. Cem Çallı EDiNR, EDiPNR, EDER Chief of Neuroradiology Section, Ege University Medical Faculty, Dept of Radiology Izmir, TURKEY Embryology 5w of gestation http://thebrain.mcgill.ca/flash/a/a_09/a_09_cr/a_09_cr_dev/a_09_cr_dev.html Embryology Cerebellum Medulla Oblongata Langman’s Medical Embryology Embryology Cerebellum forms at 7 months of gestation http://www.kidsintransitiontoschool.org/meet-your-cerebellum-the-link-between-movement-and-learning/ CEREBELLUM Cerebellum ‘’Little brain’’ Up to 10% of brain volume More than 50% of brain neurons Anterior brainstem and 4. ventricle Surrounded by tentorium Connects to brainstem CEREBELLUM Cerebellar cortex has 3 layers (vs 6 layers of cerebral cortex) Cerebellar white matter is called ‘’Arbor Vitae’’ ‘’Tree of life’’ Cerebellar Cortex Cerebellar cortex has 3 layers 1. Molecular layer Stellate cells Basket cells 2. Purkinje Cell layer 3. Granular layer Granule cells Unipolar brush cells Golgi cells Cerebellar Vermis Cerebellar Lobules Larsell’s classification Cerebellum has 10 lobules Lobules are expressed I-X Extensions from vermis http://www.edoctoronline.com/medical-atlas.asp?c=4&id=21803 Cerebellar Lobules Larsell’s classification Voogd L et al, Trends Neurosci, 1998 Cerebellum: Gross Morphological Divisions Anterior Lobe Posterior lobe Flocculonodular lobe http://http://www.slideshare.net/ananthatiger/anatomy-of-cerebellum Cerebellum: Gross Morphological Divisions Anterior Lobe Posterior lobe Flocculonodular -
Imaging of Neuromodulation and Surgical Interventions for Epilepsy
Published August 5, 2021 as 10.3174/ajnr.A7222 REVIEW ARTICLE Imaging of Neuromodulation and Surgical Interventions for Epilepsy M.E. Adin, D.D. Spencer, E. Damisah, A. Herlopian, J.L. Gerrard, and R.A. Bronen ABSTRACT SUMMARY: About one-third of epilepsy cases are refractory to medical therapy. During the past decades, the availability of surgi- cal epilepsy interventions has substantially increased as therapeutic options for this group of patients. A wide range of surgical interventions and electrophysiologic neuromodulation techniques are available, including lesional resection, lobar resection, ther- moablation, disconnection, multiple subpial transections, vagus nerve stimulation, responsive neurostimulation, and deep brain stim- ulation. The indications and imaging features of potential complications of the newer surgical interventions may not be widely appreciated, particularly if practitioners are not associated with comprehensive epilepsy centers. In this article, we review a wide range of invasive epilepsy treatment modalities with a particular focus on their postoperative imaging findings and complications. A state-of-the-art treatment algorithm provides context for imaging findings by helping the reader understand how a particular invasive treatment decision is made. ABBREVIATIONS: ANT ¼ anterior thalamic nucleus; ATL ¼ anterior temporal lobectomy; DBS ¼ deep brain stimulation; EEG ¼ electroencephalogram; FGATIR ¼ fast gray matter acquisition T1 inversion recovery; LITT ¼ laser interstitial thermal therapy; MST ¼ multiple subpial transection; MTS ¼ mesial tempo- ral sclerosis; RNS ¼ responsive neurostimulation; VNS ¼ vagus nerve stimulation pilepsy, a recurrent spontaneous seizure disorder, is the third decade, the availability of epilepsy interventions has increased Eleading cause of neurologic symptoms, with a prevalence of substantially beyond the traditional resective surgical treatments. approximately 1%. -
Differential Diagnosis of T2 Hyperintense Brainstem Lesions: Part 1
Differential Diagnosis of T2 Hyperintense Brainstem Lesions: Part 1. Focal Lesions Juan A. Guzmán-De-Villoria, MD,* Pilar Fernández-García, MD,† and Concepción Ferreiro-Argüelles, MD‡ Brainstem lesions can be classified as focal or diffuse. Magnetic resonance imaging is the most suitable imaging modality for evaluating these lesions. As a rule, focal lesions are not large and have well-defined margins. Causes include tumors, vascular malformations, demyelinating diseases, brain abscesses, hypertrophic olivary degeneration, and dilated Virchow–Robin spaces. Differential diagnoses of these numerous entities mandates a review of magnetic resonance imaging findings in conjunction with epidemiologic aspects, clinical features, and other medical test results. Semin Ultrasound CT MRI 31:246-259 © 2010 Elsevier Inc. All rights reserved. agnetic resonance imaging (MRI) is the most sensi- atively nonspecific, hence as a result each group encom- Mtive and specific technique for diagnosing disorders passes a range of different disorders. of the posterior fossa and the brainstem (BS) in particular. The list of pathologic entities set forth in this and the follow- Visualization of this area of the body by computed tomog- ing discussion is not intended to be exhaustive but rather to be raphy (CT) is difficult because of the presence of bone- sufficiently ample to cover most of the lesions likely to affect the hardening artifacts.1 Entities visible in the BS are highly BS (Table 1 and Fig. 1). Additionally, classification as a focal or diverse in their natures as well as treatment and progno- diffuse lesion is determined on the basis of MRI findings, and sis,1 and they can often pose a challenge for radiologists.