DOCSLIB.ORG

Anterior Peri-Insular Quadrantotomy: a Cadaveric White Matter Dissection Study

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Anterior Peri-Insular Quadrantotomy: a Cadaveric White Matter Dissection Study LABORATORY INVESTIGATION J Neurosurg Pediatr 25:331–339, 2020 Anterior peri-insular quadrantotomy: a cadaveric white matter dissection study *Pablo Gonzalez-Lopez, MD, PhD,1 Giulia Cossu, MD,2 Etienne Pralong, MD,2 Matias Baldoncini, MD,3 Mahmoud Messerer, MD, MSc,2,4 and Roy Thomas Daniel, MD, MCh2,4 1Department of Neurosurgery, Hospital General Universitario Alicante, Spain; 2Department of Neurosurgery, University Hospital of Lausanne, Switzerland; 3Department of Neurological Surgery, San Fernando Hospital, Buenos Aires, Argentina; and 4Faculty of Medicine and Biology, University of Lausanne, Switzerland OBJECTIVE Anterior quadrant disconnection represents a safe surgical option in well-selected pediatric patients with a large frontal lobe lesion anterior to the motor cortex. The understanding of the anatomy of the white matter tracts con- necting the frontal lobe with the rest of the cerebrum forms the basis of a safe and successful disconnective surgery. The authors explored and illustrated the relevant white matter tracts sectioned during each surgical step using fiber dissection techniques. METHODS Five human cadaveric hemispheres were dissected to illustrate the frontal connections in the 3 planes. The dissections were performed from lateral to medial, medial to lateral, and ventral to dorsal to describe the various tracts sectioned during the 4 steps of this surgery, namely the anterior suprainsular window, intrafrontal disconnection, anterior callosotomy, and frontobasal disconnection. RESULTS At the beginning of each surgical step, the U fibers were cut. During the anterior suprainsular window, the superior longitudinal fasciculus (SLF), the uncinate fasciculus, and the inferior fronto-occipital fasciculus (IFOF) were vi- sualized and sectioned, followed by sectioning of the anterior limb of the internal capsule. During the intrafrontal discon- nection, the SLF was cut, along with the corona radiata. At the medial surface the cingulum was sectioned. The anterior callosotomy disconnected the anterior third of the body of the callosum, the genu, and the rostrum. The frontobasal disconnection addressed the last remaining fibers connecting the frontal lobe with the rest of the hemisphere, namely the anterior limb of the anterior commissure. CONCLUSIONS The anterior peri-insular quadrantotomy aims at effectively treating children with large lesions of the frontal lobe anterior to the motor cortex. A precise understanding of the gyral anatomy of this lobe along with the several white matter connections is crucial to avoid motor complications and to ensure complete disconnection. https://thejns.org/doi/abs/10.3171/2019.10.PEDS19472 KEYWORDS epilepsy surgery; anterior quadrantotomy; disconnective surgery; frontal lobe OCAL epilepsies restricted to the frontal lobe account frontal lobe anterior to the precentral gyrus and is com- for 20% of patients with refractory epilepsy, and posed of the superior, middle, and inferior frontal gyri on they represent the second most common cause for the lateral surface of the cerebrum, the cingulate gyrus Ffocal epilepsy syndromes after temporal lobe epilepsy.10,11 and the anterior part of the callosum on the medial sur- Small lesions are treated by simple lesionectomy, while face, and the orbital gyri and gyrus rectus on the basal larger lesions have been traditionally treated by frontal lo- surface. Patients with well-defined epileptogenic lesions bectomy. 3,8 Disconnective surgery, such as hemispheroto- of the frontal lobe and with sparing of the perirolandic my or anterior and/or posterior quadrantotomy, has gained cortex and preserved motor functions are ideal candidates increasing acceptance for treating the large hemispheric for an anterior peri-insular quadrantotomy that keeps the and/or subhemispheric lesions that are frequently seen in motor cortex and the posterior quadrant and their projec- the pediatric population.3–6 tions intact, thereby maintaining neurological functions. The anterior quadrant is defined as the portion of the Disconnective surgery avoids the classical complications ABBREVIATIONS IFOF = inferior fronto-occipital fasciculus; SLF = superior longitudinal fasciculus. SUBMITTED August 12, 2019. ACCEPTED October 21, 2019. INCLUDE WHEN CITING Published online December 20, 2019; DOI: 10.3171/2019.10.PEDS19472. * P.G.L. and G.C. contributed equally to this work. ©AANS 2020, except where prohibited by US copyright law J Neurosurg Pediatr Volume 25 • April 2020 331 Unauthenticated | Downloaded 10/09/21 10:40 AM UTC Gonzalez-Lopez et al. associated with large brain resections.3,11 We recently pub- lished the technical details of this surgery along with a case description of a 9-year-old child.2 Due to the rarity of these cases, reports from the literature on this group of patients are scarce. We performed a cadaveric study that details the anato- my of the white matter fibers that are disconnected during the isolation of the frontal lobe from the rest of the cere- brum during the different surgical steps of this procedure. Methods Five human brain specimens were prepared accord- ing to Klingler’s technique for white matter dissection.10 Thus, the brains were extracted when they were as fresh as possible, during the first 12 hours postmortem. The specimens were cleaned under running water and fixed for 8 weeks in a 10% formaldehyde solution. Each piece underwent fixation while hanging upside down by a suture in the basilar artery to avoid morphological disruptions of its shape and size. After the 8-week fixation, the specimens were cleaned under running water again and then frozen to −15°C for 2 weeks. The brains were then thawed and the arachnoid tissue and vessels were carefully dissected and detached from the cortical surface. After this 10-week period, the specimens were ready for the dissection. All the speci- mens were dissected from the lateral, medial, and basal aspects of each frontal lobe, with special attention paid to the sequential removal of underlying white matter tracts. The target in all 3 areas was reaching the frontal horn of the ipsilateral lateral ventricle. Each step of the dissection was photographed to pro- duce high-definition white matter dissection images to show the different tracts exposed, which are those discon- nected during the anterior peri-insular quadrantotomy. Special attention was given to the different connections of all these tracts to determine whether this original surgical procedure allows a complete anterior quadrant disconnec- tion. Results Anatomically, the anterior quadrant is limited posteri- orly by the precentral sulcus on the lateral surface and by the paracentral ascending branch of the cingulate sulcus on the medial surface (Fig. 1A). Below the surface, the anterior quadrant is limited by the anterior part of the cir- cular sulcus and by the anterior perforated substance. As already detailed in our previous report,2 the peri-in- FIG. 1. High-definition white matter dissection images of a right- sular anterior quandrantotomy can be divided into 4 surgi- hemisphere brain specimen in which the 4 sequential corticotomies are cal steps: 1) the anterior suprainsular window, 2) the ante- represented. A: Lateral view of the right hemisphere. The first corticoto- my (1) runs parallel and anterior to the precentral sulcus, disrupting the rior callosotomy, 3) the intrafrontal disconnection, and 4) cerebral cortex of the posterior aspects of F1, F2, and F3. The second the frontobasal disconnection. The details of these discon- corticotomy (2) represents the laterobasal disconnection parallel to the nections are illustrated in Fig. 1. The following paragraphs floor of the anterior fossa through the basal aspect of F3. B: Mediobasal detail the procedure as performed in the cadaver dissec- view of the right cerebral hemisphere showing the medial (3) and basal tion to illustrate the white matter tracts encountered and disconnections (4). The third corticotomy (3) disrupts the cortex of the sectioned during this disconnective procedure. medial gyrus of the frontal lobe as well as the cingulum and corpus cal- losum. FIG. 1. (continued)→ Lateral Dissection Lateral to medial dissection was used to progressively 332 J Neurosurg Pediatr Volume 25 • April 2020 Unauthenticated | Downloaded 10/09/21 10:40 AM UTC Gonzalez-Lopez et al. FIG. 1. C: Basal aspect of the cerebral hemisphere, where the basal corticotomy is represented, disrupting the cortical aspect of the lateral, posterior, and medial fronto-orbital gyri and gyrus rectus: 1, anterior fronto-orbital gyrus; 2, posterior fronto-orbital gyrus; 3, medial fronto-orbital gyrus; 4, lateral fronto-orbital gyrus. For the surgical procedure in patients, the skin incision per- formed is a barn door–type incision, placed in the frontotemporal region, that allows access to perform a frontotemporoparietal craniotomy. This allows adequate exposure of the anterior sylvian point, superior temporal gyrus, inferior and middle frontal gyri, and precentral gyrus (shown in panel A). The cortical incision is placed in the frontal operculum parallel to the sylvian fissure, and this incision is turned superiorly at its posterior end to perform the intrafrontal disconnection. These incisions are deepened to the ventricle, where the anterior callosotomy is performed. The intrafrontal disconnection is then continued medially to reach the interhemispheric fissure by disruption of the frontal cortices at its medial surface (shown in panel B). AC = anterior commissure; aps = anterior perforated substance;
Load more

Recommended publications
  • Combined Structural and Diffusion Tensor Imaging Detection of Ischemic Injury in Moyamoya Disease: Relation to Disease Advancement and Cerebral Hypoperfusion
    CLINICAL ARTICLE Combined structural and diffusion tensor imaging detection of ischemic injury in moyamoya disease: relation to disease advancement and cerebral hypoperfusion Ken Kazumata, MD, PhD,1 Kikutaro Tokairin, MD,1 Masaki Ito, MD, PhD,1 Haruto Uchino, MD, PhD,1 Taku Sugiyama, MD, PhD,1 Masahito Kawabori, MD, PhD,1 Toshiya Osanai, MD, PhD,1 Khin Khin Tha, MD, PhD,2 and Kiyohiro Houkin, MD, PhD1 1Department of Neurosurgery, Hokkaido University Graduate School of Medicine; and 2Clinical Research and Medical Innovation Center, Hokkaido University Hospital, Sapporo, Japan OBJECTIVE The microstructural integrity of gray and white matter is decreased in adult moyamoya disease, suggesting covert ischemic injury as a mechanism of cognitive dysfunction. Establishing a microstructural brain imaging marker is critical for monitoring cognitive outcomes following surgical interventions. The authors of the present study determined the pathophysiological basis of altered microstructural brain injury in relation to advanced arterial occlusion, cerebral hypoperfusion, and cognitive function. METHODS The authors examined 58 patients without apparent brain lesions and 30 healthy controls by using structural MRI, as well as diffusion tensor imaging (DTI). Arterial occlusion in each hemisphere was classified as early or ad- vanced stage based on MRA and posterior cerebral artery (PCA) involvement. Regional cerebral blood flow (rCBF) was measured with N-isopropyl-p-[123I]-iodoamphetamine SPECT. Furthermore, cognitive performance was examined using the Wechsler Adult Intelligence Scale, Third Edition and the Trail Making Test (TMT). Both voxel- and region of inter- est–based analyses were performed for groupwise comparisons, as well as correlation analysis, using parameters such as cognitive test scores; gray matter volume; fractional anisotropy (FA) of association fiber tracts, including the inferior frontooccipital fasciculus (IFOF) and superior longitudinal fasciculus (SLF); PCA involvement; and rCBF.
    [Show full text]
  • Primary Lateral Sclerosis, Upper Motor Neuron Dominant Amyotrophic Lateral Sclerosis, and Hereditary Spastic Paraplegia
    brain sciences Review Upper Motor Neuron Disorders: Primary Lateral Sclerosis, Upper Motor Neuron Dominant Amyotrophic Lateral Sclerosis, and Hereditary Spastic Paraplegia Timothy Fullam and Jeffrey Statland * Department of Neurology, University of Kansas Medical Center, Kansas, KS 66160, USA; [email protected] * Correspondence: [email protected] Abstract: Following the exclusion of potentially reversible causes, the differential for those patients presenting with a predominant upper motor neuron syndrome includes primary lateral sclerosis (PLS), hereditary spastic paraplegia (HSP), or upper motor neuron dominant ALS (UMNdALS). Differentiation of these disorders in the early phases of disease remains challenging. While no single clinical or diagnostic tests is specific, there are several developing biomarkers and neuroimaging technologies which may help distinguish PLS from HSP and UMNdALS. Recent consensus diagnostic criteria and use of evolving technologies will allow more precise delineation of PLS from other upper motor neuron disorders and aid in the targeting of potentially disease-modifying therapeutics. Keywords: primary lateral sclerosis; amyotrophic lateral sclerosis; hereditary spastic paraplegia Citation: Fullam, T.; Statland, J. Upper Motor Neuron Disorders: Primary Lateral Sclerosis, Upper 1. Introduction Motor Neuron Dominant Jean-Martin Charcot (1825–1893) and Wilhelm Erb (1840–1921) are credited with first Amyotrophic Lateral Sclerosis, and describing a distinct clinical syndrome of upper motor neuron (UMN) tract degeneration in Hereditary Spastic Paraplegia. Brain isolation with symptoms including spasticity, hyperreflexia, and mild weakness [1,2]. Many Sci. 2021, 11, 611. https:// of the earliest described cases included cases of hereditary spastic paraplegia, amyotrophic doi.org/10.3390/brainsci11050611 lateral sclerosis, and underrecognized structural, infectious, or inflammatory etiologies for upper motor neuron dysfunction which have since become routinely diagnosed with the Academic Editors: P.
    [Show full text]
  • Long-Term Microstructure and Cerebral Blood Flow Changes in Patients Recovered from COVID-19 Without Neurological Manifestations
    The Journal of Clinical Investigation CLINICAL MEDICINE Long-term microstructure and cerebral blood flow changes in patients recovered from COVID-19 without neurological manifestations Yuanyuan Qin,1 Jinfeng Wu,2 Tao Chen,3 Jia Li,1 Guiling Zhang,1 Di Wu,1 Yiran Zhou,1 Ning Zheng,2 Aoling Cai,2 Qin Ning,3 Anne Manyande,4 Fuqiang Xu,2,5 Jie Wang,2,5 and Wenzhen Zhu1 1Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China. 2State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological Systems, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan, Hubei, China. 3Institute and Department of Infectious Disease, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China. 4School of Human and Social Sciences, University of West London, Middlesex, United Kingdom. 5University of Chinese Academy of Sciences, Beijing, China. BACKGROUND. The coronavirus disease 2019 (COVID-19) rapidly progressed to a global pandemic. Although some patients totally recover from COVID-19 pneumonia, the disease’s long-term effects on the brain still need to be explored. METHODS. We recruited 51 patients with 2 subtypes of COVID-19 (19 mild and 32 severe) with no specific neurological manifestations at the acute stage and no obvious lesions on the conventional MRI 3 months after discharge. Changes in gray matter morphometry, cerebral blood flow (CBF), and white matter (WM) microstructure were investigated using MRI. The relationship between brain imaging measurements and inflammation markers was further analyzed.
    [Show full text]
  • Connectivity and Neurochemistry of the Commissura Anterior of the Pigeon (Columba Livia)
    RESEARCH ARTICLE Connectivity and Neurochemistry of the Commissura Anterior of the Pigeon (Columba livia) Sara Letzner,* Annika Simon, and Onur Gunt€ urk€ un€ Department of Biopsychology, Institute of Cognitive Neuroscience, Faculty of Psychology, Ruhr-University Bochum, Bochum, Germany ABSTRACT pallial and amygdaloid projections were reciprocally The anterior commissure (AC) and the much smaller organized, and all AC projections originated within a hippocampal commissure constitute the only interhemi- rather small area of the arcopallium and the PoA. The spheric pathways at the telencephalic level in birds. commissural neurons were not GABA-positive, and thus Since the degeneration study from Zeier and Karten possibly not of an inhibitory nature. In sum, our neuroa- (1973), no detailed description of the topographic orga- natomical study demonstrates that a small group of nization of the AC has been performed. This information arcopallial and amygdaloid neurons constitute a wide is not only necessary for a better understanding of range of contralateral projections to sensorimotor and interhemispheric transfer in birds, but also for a com- limbic structures. Different from mammals, in birds the parative analysis of the evolution of commissural sys- neurons that project via the AC constitute mostly heter- tems in the vertebrate classes. We therefore examined otopically organized and unidirectional connections. In the fiber connections of the AC by using choleratoxin addition, the great majority of pallial areas do not par- subunit B (CTB) and biotinylated dextran amine (BDA). ticipate by themselves in interhemispheric exchange in Injections into subareas of the arcopallium and poste- birds. Instead, commissural exchange rests on a rather rior amygdala (PoA) demonstrated contralateral projec- small arcopallial and amygdaloid cluster of neurons.
    [Show full text]
  • Handbook on White Matter: Structure, Function and Changes
    Neuroanatomy Research at the Leading Edge HANDBOOK ON WHITE MATTER: STRUCTURE, FUNCTION AND CHANGES No part of this digital document may be reproduced, stored in a retrieval system or transmitted in any form or by any means. The publisher has taken reasonable care in the preparation of this digital document, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained herein. This digital document is sold with the clear understanding that the publisher is not engaged in rendering legal, medical or any other professional services. NEUROANATOMY RESEARCH AT THE LEADING EDGE Handbook on White Matter: Structure, Function and Changes Timothy B. Westland and Robert N. Calton 2009 ISBN: 978-1-60692-375-7 Neuroanatomy Research at the Leading Edge HANDBOOK ON WHITE MATTER: STRUCTURE, FUNCTION AND CHANGES TIMOTHY B. WESTLAND AND ROBERT N. CALTON EDITORS Nova Science Publishers, Inc. New York Copyright © 2009 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. For permission to use material from this book please contact us: Telephone 631-231-7269; Fax 631-231-8175 Web Site: http://www.novapublishers.com NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions.
    [Show full text]
  • Glutamate Transporter Mrna Expression in Proliferative Zones of the Developing and Adult Murine CNS
    The Journal of Neuroscience, April 1, 1996, 76(7):2191-2207 Glutamate Transporter mRNA Expression in Proliferative Zones of the Developing and Adult Murine CNS Margaret L. Sutherland,is2 Tracy A. Delaney,’ and Jeffrey L. Noebels’s2 1Division of Neuroscience, “Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, Houston, Texas 77030 Neuronal migration, differentiation, and synapse formation are transcript expression continued in the subventricular zone developmental processes within the CNS significantly influ- postnatally and persisted in this proliferative zone in the adult enced by ionotropic and metabotropic glutamate receptor ac- brain. From PO onward, mEAAT1 mRNA was present predom- tivity. Extracellular glutamate concentrations mediating this ac- inantly in the cerebellar Purkinje cell layer and at a much lower tivity are regulated by transport proteins localized in neuronal abundance in the cortex, hippocampus, basal nuclei, and sep- and glial cell membranes. We have used in situ hybridization tum, whereas from P7 onward, mEAAT2 mRNA expression analysis with subtype-specific antisense-oligonucleotides to increased throughout most of the neuraxis. Postnatally, tran- study the distribution of glia-specific excitatory amino acid scripts for mEAAT1 and mEAAT2 were found in cell bodies, transporter (mEAAT1 and mEAAT2) mRNAs during the later processes, and commissural white matter tracts of the CNS. stages of embryogenesis and postnatal CNS development. The divergent temporal and spatial expression
    [Show full text]
  • Quantitative Analysis of Axon Collaterals of Single Pyramidal Cells
    Yang et al. BMC Neurosci (2017) 18:25 DOI 10.1186/s12868-017-0342-7 BMC Neuroscience RESEARCH ARTICLE Open Access Quantitative analysis of axon collaterals of single pyramidal cells of the anterior piriform cortex of the guinea pig Junli Yang1,2*, Gerhard Litscher1,3* , Zhongren Sun1*, Qiang Tang1, Kiyoshi Kishi2, Satoko Oda2, Masaaki Takayanagi2, Zemin Sheng1,4, Yang Liu1, Wenhai Guo1, Ting Zhang1, Lu Wang1,3, Ingrid Gaischek3, Daniela Litscher3, Irmgard Th. Lippe5 and Masaru Kuroda2 Abstract Background: The role of the piriform cortex (PC) in olfactory information processing remains largely unknown. The anterior part of the piriform cortex (APC) has been the focus of cortical-level studies of olfactory coding, and asso- ciative processes have attracted considerable attention as an important part in odor discrimination and olfactory information processing. Associational connections of pyramidal cells in the guinea pig APC were studied by direct visualization of axons stained and quantitatively analyzed by intracellular biocytin injection in vivo. Results: The observations illustrated that axon collaterals of the individual cells were widely and spatially distrib- uted within the PC, and sometimes also showed a long associational projection to the olfactory bulb (OB). The data showed that long associational axons were both rostrally and caudally directed throughout the PC, and the intrinsic associational fibers of pyramidal cells in the APC are omnidirectional connections in the PC. Within the PC, associa- tional axons typically followed rather linear trajectories and irregular bouton distributions. Quantitative data of the axon collaterals of two pyramidal cells in the APC showed that the average length of axonal collaterals was 101 mm, out of which 79 mm (78% of total length) were distributed in the PC.
    [Show full text]
  • Toward a Common Terminology for the Gyri and Sulci of the Human Cerebral Cortex Hans Ten Donkelaar, Nathalie Tzourio-Mazoyer, Jürgen Mai
    Toward a Common Terminology for the Gyri and Sulci of the Human Cerebral Cortex Hans ten Donkelaar, Nathalie Tzourio-Mazoyer, Jürgen Mai To cite this version: Hans ten Donkelaar, Nathalie Tzourio-Mazoyer, Jürgen Mai. Toward a Common Terminology for the Gyri and Sulci of the Human Cerebral Cortex. Frontiers in Neuroanatomy, Frontiers, 2018, 12, pp.93. 10.3389/fnana.2018.00093. hal-01929541 HAL Id: hal-01929541 https://hal.archives-ouvertes.fr/hal-01929541 Submitted on 21 Nov 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. REVIEW published: 19 November 2018 doi: 10.3389/fnana.2018.00093 Toward a Common Terminology for the Gyri and Sulci of the Human Cerebral Cortex Hans J. ten Donkelaar 1*†, Nathalie Tzourio-Mazoyer 2† and Jürgen K. Mai 3† 1 Department of Neurology, Donders Center for Medical Neuroscience, Radboud University Medical Center, Nijmegen, Netherlands, 2 IMN Institut des Maladies Neurodégénératives UMR 5293, Université de Bordeaux, Bordeaux, France, 3 Institute for Anatomy, Heinrich Heine University, Düsseldorf, Germany The gyri and sulci of the human brain were defined by pioneers such as Louis-Pierre Gratiolet and Alexander Ecker, and extensified by, among others, Dejerine (1895) and von Economo and Koskinas (1925).
    [Show full text]
  • 01 05 Lateral Surface of the Brain-NOTES.Pdf
    Lateral Surface of the Brain Medical Neuroscience | Tutorial Notes Lateral Surface of the Brain 1 MAP TO NEUROSCIENCE CORE CONCEPTS NCC1. The brain is the body's most complex organ. LEARNING OBJECTIVES After study of the assigned learning materials, the student will: 1. Demonstrate the four paired lobes of the cerebral cortex and describe the boundaries of each. 2. Sketch the major features of each cerebral lobe, as seen from the lateral view, identifying major gyri and sulci that characterize each lobe. NARRATIVE by Leonard E. WHITE and Nell B. CANT Duke Institute for Brain Sciences Department of Neurobiology Duke University School of Medicine Overview When you view the lateral aspect of a human brain specimen (see Figures A3A and A102), three structures are usually visible: the cerebral hemispheres, the cerebellum, and part of the brainstem (although the brainstem is not visible in the specimen photographed in lateral view for Fig. 1 below). The spinal cord has usually been severed (but we’ll consider the spinal cord later), and the rest of the subdivisions are hidden from lateral view by the hemispheres. The diencephalon and the rest of the brainstem are visible on the medial surface of a brain that has been cut in the midsagittal plane. Parts of all of the subdivisions are also visible from the ventral surface of the whole brain. Over the next several tutorials, you will find video demonstrations (from the brain anatomy lab) and photographs (in the tutorial notes) of these brain surfaces, and sufficient detail in the narrative to appreciate the overall organization of the parts of the brain that are visible from each perspective.
    [Show full text]
  • A Fiber, 9, 10, 66, 67 Abdomen, 221 Visceral Afferent, 222 Absolute
    INDEX A fiber, 9, 10, 66, 67 all-or-none law, 62 Abdomen, 221 current during propagation, 62, 63 visceral afferent, 222 current loop, 64 Absolute temperature, 26 definition, 40 Acceleration depolarization phase, 38 angular, 183 duration, 38 linear, 183, 184 effect on contraction, 144 negative, 184 frequency, 50 positive, 184 generation, 88, 89 Accommodation, excitability, 60 inactivation, 48 Acetic acid, 74, 78 inhibition, 96 Acetylenoline ion current, 42, 43 cycle, 78 ion shift, 40, 42, 43 end plate, 74, 75 kinetics, 44-52 fate, 77, 78 mechanism of propagation, 62 intestinal muscle, 237 membrane conductance, 49 membrane receptor, 77-79 muscle, 129 muscarinergic transmission, 223, 225 overshoot, 38 nicotinergic transmission, 223, 225 peak, 38 quanta, 82 phase, 38 receptor, 78, 79 potassium conductance, 41 Renshaw cell, 100 propagation, 61-68 smooth muscle, 230, 231 refractory period, 50 transmitter function, 100, 101 refractory phase, 49, 50 Acetylcholinesterase, 101 repolarization, 38 ACh, 74, 75, s.a. acetylcholine rising phase, 38 Acid, fatty, 225 saltatory conduction, 64-66 Actin, 131-133, 139, 147 smooth muscle, 230, 231 Actinomycin, '312 sodium conductance, 41, 42 Action potential, 37-43 sodium deficiency, 43 Action potential tetrodotoxin, 52 after-potential, 39 threshold, 39 327 328 Index Action potential (cont.) Anion, 21 time course, 37, 38 Anococcygeal muscle, 233 trigger, 39 Anoce,58 triphasic current, 64 Antagonist inhibition, 109, 212 upstroke, 38 Anterior pens, micturition center, 241 velocity of conduction, 61 Anticholinergic substance, 313 Active transport Antidiuretic hormone, 259 membrane, 32 Aphagia, 264 sodium, 35 Aphasia Activity clock, 288 motor, 305 Adaptation, hormonal, 259 sensory, 305 Adenohypophysis Apoplexy, 196, 310 feedback system, 259 ARAS,295 hormone control, 257-259 Areflexia, 170 hypothalamus, 254 Arousal, 295 Adenosine triphosphate, 132-134, 147, 226 Arterial pressure, 247, s.a.
    [Show full text]
  • Morphological Evidence for the Sprouting of Inhibitory Commissural Fibers in Response to the Lesion of the Excitatory Entorhinal Input to the Rat Dentate Gyrus
    The Journal of Neuroscience, October 1995, 75(10): 6868-6878 Morphological Evidence for the Sprouting of Inhibitory Commissural Fibers in Response to the Lesion of the Excitatory Entorhinal Input to the Rat Dentate Gyrus T. Deller,’ M. Frotscher,’ and R. Nitsch2 ‘Institute of Anatomy, University of Freiburg, D-79001 Freiburg, Germany and ‘Institute of Anatomy, Humboldt University Berlin (Charitb), D-l 0098 Berlin, Germany Recently a commissural fiber projection that terminates in missural and associational fibers to the inner molecular layer the outer molecular layer of the fascia dentata was de- expand their termination zone (e.g., Lynch et al., 1973, 1976; scribed in normal rats (Deller et al., 1995). In the present Zimmer et al., 1973; Goldowitz and Cotman, 1980; Lynch et article, Phaseolus vu/g&s leucoagglutinin (PHAL) tracing al., 1982; West et al., 1984); (2) septohippocampal fibers, known was used to analyze the contribution of this previously un- to terminate throughout the molecular layer of the dentate gyms, known projection to the commissural sprouting response form a dense fiber plexus in the denervated zone (Lynch et al., after entorhinal cortex lesion. Rats 4-9 weeks after unilat- 1972; Nadler et al., 1977; Nyakas et al., 1988); and (3) axons eral entorhinal lesion received a single PHAL deposit into of the crossed temporo-dentate pathway participate in the rein- the hilus of the fascia dentata contralateral to the lesion nervation of the denervated septal portion of the hippocampal side. Unlesioned control animals received a similar PHAL formation (Steward et al., 1974; Goldowitz et al., 1975; Deller deposit. The degree of axonal arborization and the bouton et al., 1995b).
    [Show full text]
  • Features of the Cerebral Vascular Pattern That Predict Vulnerability to Perfusion Or Oxygenation Deficiency: an Anatomic Study
    431 Features of the Cerebral Vascular Pattern That Predict Vulnerability to Perfusion or Oxygenation Deficiency: An Anatomic Study D. M. Moody1 In an ongoing study of brain microvasculature in humans at autopsy, we had the 1 2 M.A. Bell · opportunity to analyze the overall scheme of this vascular supply. The native endothelial V. R. Challa3 membrane enzyme, alkaline phosphatase, is used to precipitate black lead sulfide salt in the vessel wall, rendering the brain microvasculature visible by both light microscopy and microradiography. There are six distinct patterns of intraparenchymal afferent blood supply to the supratentorial brain: short arterioles from a single source (e.g., those in the cortex); short- to intermediate-length arterioles, single source (anterior two-thirds of the corpus callosum); short- to intermediate-length arterioles and arteries, dual source (subcortical U fibers); intermediate-length arterioles and arteries, triple source (extreme/ external capsule and claustrum); long arteries and arterioles, single source (centrum semiovale); and large, long muscular arteries, single source (thalamus and basal ganglia). The nature of this arrangement offers some protection to certain regions of the cerebrum from circulatory challenges such as hypotension, while leaving other areas vulnerable. The distal arterioles supplying two of these protected regions, the U-fiber area and the extreme/external capsule and claustrum area, also exhibit the feature of interdigitation, which can offer additional collateral potential from one arteriolar territory to the next. Aging, hypertension, diabetes mellitus, and atherosclerosis can have a significant impact on brain microcirculation. The way in which vascular patterns dictate the distribution of these effects is discussed. The ability to stain the cerebral microvessels and demonstrate the finer points of their patterns in sections and microradiographs has enabled us to resolve some long-standing questions about vascular connections and directions.
    [Show full text]