Memory Loss from a Subcortical White Matter Infarct

Total Page:16

File Type:pdf, Size:1020Kb

Memory Loss from a Subcortical White Matter Infarct J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.51.6.866 on 1 June 1988. Downloaded from Journal of Neurology, Neurosurgery, and Psychiatry 1988;51:866-869 Short report Memory loss from a subcortical white matter infarct CAROL A KOOISTRA, KENNETH M HEILMAN From the Department ofNeurology, College ofMedicine, University ofFlorida, and the Research Service, Veterans Administration Medical Center, Gainesville, FL, USA SUMMARY Clinical disorders of memory are believed to occur from the dysfunction of either the mesial temporal lobe, the mesial thalamus, or the basal forebrain. Fibre tract damage at the level of the fornix has only inconsistently produced amnesia. A patient is reported who suffered a cerebro- vascular accident involving the posterior limb of the left internal capsule that resulted in a persistent and severe disorder of verbal memory. The inferior extent of the lesion effectively disconnected the mesial thalamus from the amygdala and the frontal cortex by disrupting the ventral amygdalofugal and thalamic-frontal pathways as they course through the diencephalon. This case demonstrates that an isolated lesion may cause memory loss without involvement of traditional structures associated with memory and may explain memory disturbances in other white matter disease such as multiple sclerosis and lacunar state. Protected by copyright. Memory loss is currently believed to reflect grey day of his illness the patient was transferred to Shands matter damage of either the mesial temporal lobe,' -4 Teaching Hospital at the University of Florida for further the mesial or the basal forebrain.'0 l evaluation. thalamus,5-9 Examination at that time showed the patient to be awake, Cerebrovascular accidents resulting in memory dys- alert, attentive and fully oriented. He was able to repeat four function may occur in any of these three numbers forward, could not recall any of three objects after regions.3 79 12 13 In contrast, amnesia from white 3 minutes, but was able to remember recent presidents. matter damage is unusual and when present is usually Spontaneous speech was grammatically correct with mild related to fornix lesions. 14 - 19 hesitancy on initiation of sentences and a tendency towards We observed a patient, however, who developed a echolalia. Repetition, naming, reading and writing were all severe verbal amnesia from an infarct of the posterior preserved. Verbal comprehension was mildly impaired only limb of the internal capsule. Aside from its obvious when dependent upon understanding complex syntactic structures involved in relationships. Finger naming, right/left orientation and sparing of the usual memory, calculations were normal. Visual-spatial testing of spontane- the lesion was also atypical by its apparent limitation ously drawn and copied figures was normal. There was no http://jnnp.bmj.com/ to the white matter pathways of the diencephalon. neglect and no difficulty with either graphaesthesia or stereo- gnosia. The remainder of his neurological examination dem- Case report onstrated a moderate right hemiparesis in a pyramidal distri- bution with concomitant hyperreflexia and extensor plantar A 69 year old, right-handed, high school educated gas sta- response. Neuropsychological assessment included Form I tion supervisor was in good health until the acute onset of a of the Wechsler Memory Scale. Despite scoring nearly right hemiparesis associated with dysarthria and mild flawlessly on the personal information (6/6) and orientation expressive difficulties. His symptoms improved after 2 hours, (4/5) subtests, the patient only recalled 4/24 and 2/22 memo- only to recur 30 minutes later, at which time continuous ries from the logical memory subtest (about 2 SD below that on September 24, 2021 by guest. intravenous heparin was begun. His deficits fluctuated over expected for his intelligence and age).20 Paired associate the next 36 hours before becoming permanent. On the 10th testing yielded a score of 4/21 (all easy associations), which falls more than 3 SD below the mean.20 In contrast, non- Address for reprint requests: Carol A. Kooistra, M.D., 145 Dillon verbal memory function was less affected, as shown by his Drive, Spartanburg, S.C. 29302, USA visual reproduction subtest score (4/14), only 1 SD below mean. His memory quotient was calculated as 79. Received 20 February 1987 and in revised form 21 September 1987. A computed tomography (CT) scan of the head 14 days Accepted 22 September 1987 after onset of symptoms revealed an area of lucency 866 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.51.6.866 on 1 June 1988. Downloaded from Memory loss from a subcortical white matter infarct 867 _ w~~oo ML,&v t I ...F.. i N Fig (a) CT scan showing lucency in left posterior internal capsule. (b) coronal CT scan, reconstructed, showing lucency in internal capsule. Protected by copyright. occupying the posterior limb and genu of the left internal projects to the cingulate gyrus through the lateral capsule (fig). Coronal reconstruction demonstrated the in- thalamic radiations and post-commissural ferior aspect of the lesion to extend within the white matter fornix.22 24 to just above the suprasellar cistern (fig). The arterial distri- The amygdaloid system was delineated by bution of the presumed thrombotic infarct was felt to best fit and brought to prominence by Horel's that of the anterior choroidal artery.21 Yakovlev23 Over the following weeks, the patient demonstrated mild temporal stem theory of amnesia.24 This system's improvement in motor deficits; however, two years after targets again lie within the diencephalon and are discharge he remains significantly amnestic, incapable of reached by either the stria terminalis or ventral recalling any of three objects after three minutes. amygdalofugal pathways. The stria terminalis lies in the lateral wall of the temporal horn and body of the lateral ventricle, arching superiorly and anteriorly to Discussion cross the anterior limb of the internal capsule and anterior commissure and connecting with the hypo- Amnesia has not been previously recognised as a thamalus, nucleus accumbens and anterior pole of the http://jnnp.bmj.com/ sequela of damage to the internal capsule. Therefore, thalamus.25 26 the presence of severe memory deficits in this case The ventral amygdalofugal pathway consists of may be related to damage to some additional two components. Both originate from the basolateral diencephalic structure(s), with sparing of the dorsal amygdala and travel anteriorly and medially through medial thalamus, hippocampal formation, and basal the albal stalk of the temporal lobe to enter the forebrain. inferior diencephalon. One component continues Recent experimental work in memory has empha- rostrally to the septal region as the diagonal band of sised two separate but parallel anatomic systems: the Broca, additionally sending some fibres to the dorsal on September 24, 2021 by guest. hippocampal and the amygdaloid. The former is medial thalamus via the inferior thalamic peduncle.25 essentially composed of those pathways described by The second component forms the ansa peduncularis, Papez22 in which hippocampal efferents travel which courses medially, lying ventral to the ansa len- through the fornix to reach directly (post- ticularis and posterior limb of the internal capsule, commissurally)23 and indirectly (via the mammillary and ultimately reaches the hypothalamus, whereupon bodies and mammillothalamic tract) the anterior the fibres turn superiorly and posteriorly to terminate nucleus of the thalamus, which then subsequently in the magnocellular portion of the dorsal medial J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.51.6.866 on 1 June 1988. Downloaded from 868 Kooistra, Heitman nucleus, again entering by way of the inferior the ventral amygdalofugal pathways and the dorsal thalamic peduncle. medial thalamus-frontal fibres as they course in the The principal dorsal medial nucleus' efferent path- vicinity of the genu and the posterior limb of the ways project to the prefrontal cortex, exiting through internal capsule, thereby effectively disconnecting the inferior thalamic peduncle to head rostrally in the dorsal medial thalamus from prefrontal and lateral anterior internal capsule.27 28 Thus, the amyg- amygdaloid areas. Additionally, the medial forebrain daloid system interconnects the anterior inferior tem- bundle, portions of the basal nucleus of Meynert, and poral cortex, the basolateral amygdala, the dorsal anterior thalamic nucleus efferents may be affected. medial nucleus and the prefrontal cortex with the var- The severity of the patient's memory loss would sug- ious diencephalic pathways travelling in the region of gest that more than one structure or system is both the anterior and posterior limbs of the internal involved. Despite the problems inherent in defining capsule and either entering or exiting the thalamus via the extent of ischaemia by CT scanning, there appears the inferior thalamic peduncle. to be no radiological involvement of the mammillary Mishkin demonstrated the parallel nature of bodies, the medial thalamus, the fornix, or the hippo- the hippocampal and amygdaloid systems through campus. The possibility of diaschisis initially causing selective cortical and subcortical lesions. His animals functional disturbances in areas remote from the demonstrated a more severe recognition memory infarct seems unlikely owing to the persistence of the deficit with combined destruction of amygdala and memory
Recommended publications
  • Resting State Connectivity of the Human Habenula at Ultra-High Field
    Author’s Accepted Manuscript Resting State Connectivity of the Human Habenula at Ultra-High Field Salvatore Torrisi, Camilla L. Nord, Nicholas L. Balderston, Jonathan P. Roiser, Christian Grillon, Monique Ernst www.elsevier.com PII: S1053-8119(16)30587-0 DOI: http://dx.doi.org/10.1016/j.neuroimage.2016.10.034 Reference: YNIMG13531 To appear in: NeuroImage Received date: 26 August 2016 Accepted date: 20 October 2016 Cite this article as: Salvatore Torrisi, Camilla L. Nord, Nicholas L. Balderston, Jonathan P. Roiser, Christian Grillon and Monique Ernst, Resting State Connectivity of the Human Habenula at Ultra-High Field, NeuroImage, http://dx.doi.org/10.1016/j.neuroimage.2016.10.034 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 1 Resting State Connectivity of the Human Habenula at Ultra-High Field Salvatore Torrisi1, Camilla L. Nord2, Nicholas L. Balderston1, Jonathan P. Roiser2, Christian Grillon1, Monique Ernst1 Affiliations 1 Section on the Neurobiology of Fear and Anxiety, National Institute of Mental Health, Bethesda, MD 2 Neuroscience and Cognitive Neuropsychiatry group, University of College, London, UK Abstract The habenula, a portion of the epithalamus, is implicated in the pathophysiology of depression, anxiety and addiction disorders.
    [Show full text]
  • Lesions in the Bed Nucleus of the Stria Terminalis Disrupt
    Neuroscience 128 (2004) 7–14 LESIONS IN THE BED NUCLEUS OF THE STRIA TERMINALIS DISRUPT CORTICOSTERONE AND FREEZING RESPONSES ELICITED BY A CONTEXTUAL BUT NOT BY A SPECIFIC CUE-CONDITIONED FEAR STIMULUS G. M. SULLIVAN,a* J. APERGIS,b D. E. A. BUSH,b Activation of the hypothalamic–pituitary–adrenal (HPA) L. R. JOHNSON,b M. HOUb AND J. E. LEDOUXb axis, including release of glucocorticoids, is a central com- aDepartment of Psychiatry, Columbia University College of Physicians ponent of the adaptive response to real or anticipated and Surgeons, 1051 Riverside Drive, Unit #41, New York, NY 10032, aversive physical or psychological challenge. Surprisingly USA little is known about the neural circuits by which environ- bCenter for Neural Science, New York University, 4 Washington Place, mental stimuli come to elicit HPA responses. Fear condi- New York, NY 10003, USA tioning, a behavioral model of emotional stress, is poten- tially useful for exploring this issue since the neural path- Abstract —The bed nucleus of the stria terminalis (BNST) is ways by which stimuli initiate fear behaviors and believed to be a critical relay between the central nucleus of associated autonomic responses have been characterized the amygdala (CE) and the paraventricular nucleus of the in detail (LeDoux, 2000; Davis and Whalen, 2001; Maren, hypothalamus in the control of hypothalamic–pituitary– 2001). adrenal (HPA) responses elicited by conditioned fear stimuli. Through fear conditioning an organism learns that a If correct, lesions of CE or BNST should block expression of simple sensory stimulus (a cue), or more complex environ- HPA responses elicited by either a specific conditioned fear mental representation (a context), predicts imminent ad- cue or a conditioned context.
    [Show full text]
  • The Connexions of the Amygdala
    J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.28.2.137 on 1 April 1965. Downloaded from J. Neurol. Neurosurg. Psychiat., 1965, 28, 137 The connexions of the amygdala W. M. COWAN, G. RAISMAN, AND T. P. S. POWELL From the Department of Human Anatomy, University of Oxford The amygdaloid nuclei have been the subject of con- to what is known of the efferent connexions of the siderable interest in recent years and have been amygdala. studied with a variety of experimental techniques (cf. Gloor, 1960). From the anatomical point of view MATERIAL AND METHODS attention has been paid mainly to the efferent connexions of these nuclei (Adey and Meyer, 1952; The brains of 26 rats in which a variety of stereotactic or Lammers and Lohman, 1957; Hall, 1960; Nauta, surgical lesions had been placed in the diencephalon and and it is now that there basal forebrain areas were used in this study. Following 1961), generally accepted survival periods of five to seven days the animals were are two main efferent pathways from the amygdala, perfused with 10 % formol-saline and after further the well-known stria terminalis and a more diffuse fixation the brains were either embedded in paraffin wax ventral pathway, a component of the longitudinal or sectioned on a freezing microtome. All the brains were association bundle of the amygdala. It has not cut in the coronal plane, and from each a regularly spaced generally been recognized, however, that in studying series was stained, the paraffin sections according to the Protected by copyright. the efferent connexions of the amygdala it is essential original Nauta and Gygax (1951) technique and the frozen first to exclude a contribution to these pathways sections with the conventional Nauta (1957) method.
    [Show full text]
  • Fos Activation of Selective Afferents to Ventral Tegmental Area During Cue-Induced Reinstatement of Cocaine Seeking in Rats
    The Journal of Neuroscience, September 19, 2012 • 32(38):13309–13325 • 13309 Behavioral/Systems/Cognitive Fos Activation of Selective Afferents to Ventral Tegmental Area during Cue-Induced Reinstatement of Cocaine Seeking in Rats Stephen V. Mahler and Gary S. Aston-Jones Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425 Ventral tegmental area (VTA) dopamine neurons are crucial for appetitive responses to Pavlovian cues, including cue-induced reinstate- ment of drug seeking. However, it is unknown which VTA inputs help activate these neurons, transducing stimuli into salient cues that drive drug-seeking behavior. Here we examined 56 VTA afferents from forebrain and midbrain that are Fos activated during cue-induced reinstatement. We injected the retrograde tracer cholera toxin ␤ subunit (CTb) unilaterally into rostral or caudal VTA of male rats. All animalsweretrainedtoself-administercocaine,thenextinguishedofthisbehavior.Onafinaltestday,animalswereexposedtoresponse- contingent cocaine-associated cues, extinction conditions, a non-cocaine-predictive CSϪ, or a novel environment, and brains were processed to visualize CTb and Fos immunoreactivity to identify VTA afferents activated in relation to behaviors. VTA-projecting neurons in subregions of medial accumbens shell, ventral pallidum, elements of extended amygdala, and lateral septum (but not pre- frontal cortex) were activated specifically during cue-induced cocaine seeking, and some of these were also activated proportionately to the degree of cocaine seeking. Surprisingly, though efferents from the lateral hypothalamic orexin field were also Fos activated during reinstatement, these were largely non-orexinergic. Also, VTA afferents from the rostromedial tegmental nucleus and lateral habenula were specifically activated during extinction and CSϪ tests, when cocaine was not expected.
    [Show full text]
  • Interruption of the Connections of the Mammillary Bodies Protects Against Generalized Pentylenetetrazol Seizures in Guinea Pigs
    The Journal of Neuroscience, March 1987, 7(3): 662-670 Interruption of the Connections of the Mammillary Bodies Protects Against Generalized Pentylenetetrazol Seizures in Guinea Pigs Marek A. Mirski and James A. Ferrendelli Division of Clinical Neuropharmacology, Department of Pharmacology and Department of Neurology and Neurological Surgery, Washington University School of Medicine, St. Louis, Missouri 63110 Electrolytic lesions in the anterior and mid-diencephalon and Morin, 1953; Gellhorn et al., 1959) fields of Fore1(Jinnai, 1966; ventral midbrain in guinea pigs were produced to examine Jinnai et al., 1969; Jinnai and Mukawa, 1970), substantianigra the effects of interruption of the fornix (FX), mammillothal- (Iadarola and Gale, 1982; Garant and Gale, 1983; Gonzalez and amic tracts (MT), and mammillary peduncles (MP), respec- Hettinger, 1984; McNamara et al., 1983, 1984), and several tively, on the expression of pentylenetetrazol (PTZ) sei- thalamic nuclei (Mullen et al., 1967; Jinnai et al., 1969; Feeney zures. As a group, all mid-diencephalic lesioned animals and Gullotta, 1972; Kusske et al., 1972; Van Straaten, 1975; had some degree of protection from the electroencephalo- Quesney et al., 1977). graphic and behavioral convulsant and lethal effects of the Recently we observed the selective metabolic activation of drug. Through a composite volume analysis of protected the mammillary bodies (MB) and their immediate connections versus unprotected animals, as well as a retrospective com- during a threshold convulsive stimulus induced by the co-in- parison between MT and non-MT lesioned animals, it was fusion of pentylenetetrazol (PTZ) and ethosuximide (ESM) demonstrated that small mid-diencephalic lesions incorpo- (Mirski and Ferrendelli, 1983).
    [Show full text]
  • Gene Expression of Prohormone and Proprotein Convertases in the Rat CNS: a Comparative in Situ Hybridization Analysis
    The Journal of Neuroscience, March 1993. 73(3): 1258-1279 Gene Expression of Prohormone and Proprotein Convertases in the Rat CNS: A Comparative in situ Hybridization Analysis Martin K.-H. Schafer,i-a Robert Day,* William E. Cullinan,’ Michel Chri?tien,3 Nabil G. Seidah,* and Stanley J. Watson’ ‘Mental Health Research Institute, University of Michigan, Ann Arbor, Michigan 48109-0720 and J. A. DeSeve Laboratory of *Biochemical and 3Molecular Neuroendocrinology, Clinical Research Institute of Montreal, Montreal, Quebec, Canada H2W lR7 Posttranslational processing of proproteins and prohor- The participation of neuropeptides in the modulation of a va- mones is an essential step in the formation of bioactive riety of CNS functions is well established. Many neuropeptides peptides, which is of particular importance in the nervous are synthesized as inactive precursor proteins, which undergo system. Following a long search for the enzymes responsible an enzymatic cascade of posttranslational processing and mod- for protein precursor cleavage, a family of Kexin/subtilisin- ification events during their intracellular transport before the like convertases known as PCl, PC2, and furin have recently final bioactive products are secreted and act at either pre- or been characterized in mammalian species. Their presence postsynaptic receptors. Initial endoproteolytic cleavage occurs in endocrine and neuroendocrine tissues has been dem- C-terminal to pairs of basic amino acids such as lysine-arginine onstrated. This study examines the mRNA distribution of (Docherty and Steiner, 1982) and is followed by the removal these convertases in the rat CNS and compares their ex- of the basic residues by exopeptidases. Further modifications pression with the previously characterized processing en- can occur in the form of N-terminal acetylation or C-terminal zymes carboxypeptidase E (CPE) and peptidylglycine a-am- amidation, which is essential for the bioactivity of many neu- idating monooxygenase (PAM) using in situ hybridization ropeptides.
    [Show full text]
  • Functional Heterogeneity in the Bed Nucleus of the Stria Terminalis
    8038 • The Journal of Neuroscience, August 3, 2016 • 36(31):8038–8049 Dual Perspectives Dual Perspectives Companion Paper: Contributions of the Central Extended Amygdala to Fear and Anxiety, by Alexander J. Shackman and Andrew S. Fox Functional Heterogeneity in the Bed Nucleus of the Stria Terminalis Nur Zeynep Gungor and Denis Pare´ Center for Molecular and Behavioral Neuroscience, Rutgers State University, Newark, New Jersey 07102 Early work stressed the differing involvement of the central amygdala (CeA) and bed nucleus of the stria terminalis (BNST) in the genesis of fear versus anxiety, respectively. In 2009, Walker, Miles, and Davis proposed a model of amygdala-BNST interactions to explain these functional differences. This model became extremely influential and now guides a new wave of studies on the role of BNST in humans. Here, we consider evidence for and against this model, in the process highlighting central principles of BNST organization. This analysis leads us to conclude that BNST’s influence is not limited to the generation of anxiety-like responses to diffuse threats, but that it also shapes the impact of discrete threatening stimuli. It is likely that BNST-CeA interactions are involved in modulating responses to such threats. In addition, whereas current views emphasize the contributions of the anterolateral BNST region in anxiety, accumulating data indicate that the anteromedial and anteroventral regions also play a critical role. The presence of multiple functional subregions within the small volume of BNST raises significant technical obstacles for functional imaging studies in humans. Key words: amygdala; anxiety; BNST; fear Introduction et al., 2003; Xu et al., 2012), and alarm pheromones (Breitfeld In 2009, Walker et al.
    [Show full text]
  • Spinal Cord Organization
    Lecture 4 Spinal Cord Organization The spinal cord . Afferent tract • connects with spinal nerves, through afferent BRAIN neuron & efferent axons in spinal roots; reflex receptor interneuron • communicates with the brain, by means of cell ascending and descending pathways that body form tracts in spinal white matter; and white matter muscle • gives rise to spinal reflexes, pre-determined gray matter Efferent neuron by interneuronal circuits. Spinal Cord Section Gross anatomy of the spinal cord: The spinal cord is a cylinder of CNS. The spinal cord exhibits subtle cervical and lumbar (lumbosacral) enlargements produced by extra neurons in segments that innervate limbs. The region of spinal cord caudal to the lumbar enlargement is conus medullaris. Caudal to this, a terminal filament of (nonfunctional) glial tissue extends into the tail. terminal filament lumbar enlargement conus medullaris cervical enlargement A spinal cord segment = a portion of spinal cord that spinal ganglion gives rise to a pair (right & left) of spinal nerves. Each spinal dorsal nerve is attached to the spinal cord by means of dorsal and spinal ventral roots composed of rootlets. Spinal segments, spinal root (rootlets) nerve roots, and spinal nerves are all identified numerically by th region, e.g., 6 cervical (C6) spinal segment. ventral Sacral and caudal spinal roots (surrounding the conus root medullaris and terminal filament and streaming caudally to (rootlets) reach corresponding intervertebral foramina) collectively constitute the cauda equina. Both the spinal cord (CNS) and spinal roots (PNS) are enveloped by meninges within the vertebral canal. Spinal nerves (which are formed in intervertebral foramina) are covered by connective tissue (epineurium, perineurium, & endoneurium) rather than meninges.
    [Show full text]
  • White Matter Tracts - Brain A143 (1)
    WHITE MATTER TRACTS - BRAIN A143 (1) White Matter Tracts Last updated: August 8, 2020 CORTICOSPINAL TRACT .......................................................................................................................... 1 ANATOMY .............................................................................................................................................. 1 FUNCTION ............................................................................................................................................. 1 UNCINATE FASCICULUS ........................................................................................................................... 1 ANATOMY .............................................................................................................................................. 1 DTI PROTOCOL ...................................................................................................................................... 4 FUNCTION .............................................................................................................................................. 4 DEVELOPMENT ....................................................................................................................................... 4 CLINICAL SIGNIFICANCE ........................................................................................................................ 4 ARTICLES ..............................................................................................................................................
    [Show full text]
  • White Matter Dissection and Structural Connectivity of the Human Vertical
    www.nature.com/scientificreports OPEN White matter dissection and structural connectivity of the human vertical occipital fasciculus to link vision-associated brain cortex Tatsuya Jitsuishi1, Seiichiro Hirono2, Tatsuya Yamamoto1,3, Keiko Kitajo1, Yasuo Iwadate2 & Atsushi Yamaguchi1* The vertical occipital fasciculus (VOF) is an association fber tract coursing vertically at the posterolateral corner of the brain. It is re-evaluated as a major fber tract to link the dorsal and ventral visual stream. Although previous tractography studies showed the VOF’s cortical projections fall in the dorsal and ventral visual areas, the post-mortem dissection study for the validation remains limited. First, to validate the previous tractography data, we here performed the white matter dissection in post-mortem brains and demonstrated the VOF’s fber bundles coursing between the V3A/B areas and the posterior fusiform gyrus. Secondly, we analyzed the VOF’s structural connectivity with difusion tractography to link vision-associated cortical areas of the HCP MMP1.0 atlas, an updated map of the human cerebral cortex. Based on the criteria the VOF courses laterally to the inferior longitudinal fasciculus (ILF) and craniocaudally at the posterolateral corner of the brain, we reconstructed the VOF’s fber tracts and found the widespread projections to the visual cortex. These fndings could suggest a crucial role of VOF in integrating visual information to link the broad visual cortex as well as in connecting the dual visual stream. Te VOF is the fber tract that courses vertically at the posterolateral corner of the brain. Te VOF was histori- cally described in monkey by Wernicke1 and then in human by Obersteiner2.
    [Show full text]
  • 1. 2. A) Explain the Compositions of White Matter and Gray
    Tfy-99.2710 Introduction to the Structure and Operation of the Human Brain, fall 2015 Exercise 1 1. 2. a) Explain the compositions of white matter and gray matter. White matter consists of glial cells and myelinated axons. It does not contain the cell bodies of neurons and acts as a signal pathway for the gray matter regions of the central nervous system. Gray matter consists of glial cells and unmyelinated axons. It contains neuronal cell bodies. b) Explain shortly the structure of a neuron. Neurons can be divided into three main parts: the cell body or the soma, the dendrites and the axon. The dendrites act as neuronal antennas in that they receive incoming signals. The cell body functions as the information processing unit of the neuron, and is responsible for sending signals forward. The axon is the signal pathway of the neuron; the signals sent by the cell body are transmitted along the axon to the axon terminals located away from the cell body. Signal transfer is along the axon is aided by the myelin sheath that covers the axon. c) Explain: Tfy-99.2710 Introduction to the Structure and Operation of the Human Brain, fall 2015 Exercise 1 i) myelin Membrane that wraps around axons. Formed from glial support cells: oligodendrogolia in the central nervous system and Schwann cells in the peripheral nervous system. Myelin facilitates signal transfer along axons by allowing action potentials to skip between the nodes of Ranvier (saltatory conduction). ii) receptor Molecule specialized in receiving a chemical signal by binding a specific neurotransmitter.
    [Show full text]
  • Two Fiber Pathways Connecting Amygdala and Prefrontal Cortex in Humans and Monkeys
    bioRxiv preprint doi: https://doi.org/10.1101/561811; this version posted March 20, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Two fiber pathways connecting amygdala and prefrontal cortex in humans and monkeys Davide Folloni1,2*, Jérôme Sallet1,2, Alexandre A. Khrapitchev3, Nicola R. Sibson3, Lennart Verhagen1,2†, Rogier B. Mars2,4† 1Wellcome Integrative Neuroimaging (WIN), Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom 2Wellcome Integrative Neuroimaging (WIN), Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom 3Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom 4Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands †Authors contributed equally to the work *To whom correspondence should be addressed: Address: Davide Folloni, Department of Experimental Psychology, University of Oxford, Tinsley Building, Mansfield Road, Oxford, OX1 3SR, UK E-mail: [email protected] 1 bioRxiv preprint doi: https://doi.org/10.1101/561811; this version posted March 20, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Abstract The interactions between amygdala and prefrontal cortex are pivotal to many neural processes involved in learning, decision-making, emotion, and social regulation.
    [Show full text]