DOCSLIB.ORG

Anatomy of the Subthalamic Nucleus, with Correlation of Deep Brain Stimulation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Anatomy of the Subthalamic Nucleus, with Correlation of Deep Brain Stimulation » See the corresponding retraction notice, DOI: 10.3171/2015.10.JNS145r, for full details. « LABORATORY INVESTIGATION Anatomy of the subthalamic nucleus, with correlation of deep brain stimulation Akın Akakın, MD,1 Baran Yılmaz, MD,1 Türker Kılıç, MD,1 PhD, and Albert L. Rhoton Jr., MD2 1Department of Neurosurgery, School of Medicine, Bahcesehir University, Istanbul, Turkey; and 2Department of Neurosurgery, School of Medicine, University of Florida, Gainesville, Florida O BJECT The goal in this study was to examine the cadaveric anatomy of the subthalamic nucleus (STN) and to analyze the implications of the findings for deep brain stimulation (DBS) surgery. METHODS Five formalin-fixed human cerebrums were dissected using the Klingler fiber dissection technique. Digital photographs of the dissections were fused to obtain an anaglyphic image. RESULTS The STN was located posteroinferior to the anterior corticospinal fibers, posterosuperior to the substantia nigra, and anteromedial to the red nucleus, lenticular fasciculus, and thalamic fasciculus. The subthalamic region is ven- tral to the thalamus, medial to the internal capsule, and lateral and caudal to the hypothalamus. The nuclei found within the subthalamic region include the STN. The relationship between the STN and surrounding structures, which are not delineated sharply, is described. CONCLUSIONS The fiber dissection technique supports the presence of the subthalamic region as an integrative net- work in humans and offers the potential to aid in understanding the impacts of DBS surgery of the STN in patients with Parkinson disease. Further research is needed to define the exact role of the STN in the integrative process. http://thejns.org/doi/abs/10.3171/2014.10.JNS145 KEY WORDS neuroanatomy; subthalamic nucleus; fiber dissection; anatomy HE subthalamic nucleus (STN) is an important part of the STN and movement. In this study we describe the of the brain related to Parkinson disease (PD) and anatomical relationship between the STN and surrounding other involuntary movements. The STN contains structures. Tsome fibers that travel to the cortical area and basal gan- glia.2 The STN is located just superomedial to the red Methods nucleus and substantia nigra. Widely acknowledged as an important modulator of basal ganglia output, the STN re- Anatomical Study ceives its major afferents from the cerebral cortex, thala- The cerebral hemispheres and cerebrums of 5 human mus, globus pallidus externus (GPe), and brainstem. The cadavers were fixed in a 10% formalin solution for at least STN projects mainly to both segments of the GP, sub- 3 weeks. The first step in the preparation of the specimens stantia nigra, striatum, and brainstem and is essentially was the removal of the arachnoidal and vascular structures composed of glutamatergic neurons. Lesions of the STN with the aid of a surgical microscope (magnification range induce choreiform abnormal movements and ballism on ×6 to ×40). The hemispheres were frozen at -16°C for 2–4 the contralateral side of the body.2,3 Despite current inter- weeks. Twenty-four hours after completion of the freezing est, little is knownRetracted about the relation between function process, the white fiber dissection was done with fine and ABBREVIATIONS DBS = deep brain stimulation; GPe, GPi = globus pallidus externus, globus pallidus internus; PD = Parkinson disease; STN = subthalamic nucleus. SUBMITTED January 16, 2014. ACCEPTED October 15, 2014. INCLUDE WHEN CITING Published online April 24, 2015; DOI: 10.3171/2014.10.JNS145. DISCLOSURE The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. ©AANS, 2015 J Neurosurg April 24, 2015 1 A. Akakın et al. self-shaped wooden spatulas. We took numerous digital tween the claustrum and the putamen. By removing the photographs during dissections and, using a specific soft- fibers of the dorsal extreme capsule, we can see the fibers ware program (Anamaker 3D; available free from www. of the dorsal external capsule at the periphery of the dorsal stereoeye.com), we fused the images to obtain an ana- claustrum. At the level of the limen insula, the uncinate glyphic image. fasciculus and inferior frontooccipital fasciculus can be observed (Fig. 1). Results After dissection of the crus cerebri, we first observe the Anatomical Dissection substantia nigra, which is located superolateral to the red nucleus. When the red nucleus is dissected, fibers of the The dissection of the brain is started from the gray mat- ansa lenticularis can be observed. The STN is located pos- ter of the cortex, and U-fibers are observed under the gray teroinferior to the anterior corticospinal fibers, posterosu- matter. After the removal of U-fibers, the cortical fibers perior to the substantia nigra, and anteromedial to the red are seen. To expose the superior longitudinal fasciculus, nucleus, lenticular fasciculus, and thalamic fasciculus. The we remove the cortical gray matter; adjacent superficial STN had a café-au-lait color in cadaver sections (Fig. 2). short fibers of the frontal, temporal, and parietal oper- cula; the middle, frontal, superior, and middle temporal Identification of the STN gyri; and the inferior parietal lobule. The first identified fasciculus in dissection, which begins on the lateral hemi- The STN is a small, lens-shaped nucleus in the brain. spheric surface, is the superior longitudinal (arcuate) fas- The STN is a part of the basal ganglia system and is lo- ciculus. Traditionally, this fasciculus can be described as cated ventral to the thalamus, dorsal to the substantia nig- a reversed C-shaped structure, which surrounds the insula ra, and medial to the internal capsule (Fig. 3). Anterior and interconnects the frontal and temporal lobes (Fig. 1). and lateral borders of the STN are enveloped by fibers of At a deeper level in the temporoparietal area, a group the internal capsule, which separates this nucleus laterally of fibers arching around the posterosuperior insular bor- from the GP. Posteromedially, the STN is very close to der is seen to be traveling between the posterior temporal the red nucleus. The ventral borders of the STN are the region and the prefrontal area. These fibers form the fron- cerebral peduncle and the substantia nigra. Dorsally, the totemporal or arcuate segment of the superior longitudi- STN has a border with the fasciculus lenticularis, which nal fasciculus. By dissecting the inferolateral hemispheric separates the STN from the ventral thalamus. surface, we can see a group of fibers deep to the tempo- Several fiber tracts course near the borders of the STN. roparietal segment of the superior longitudinal fasciculus The subthalamic fasciculus consists of fibers that inter- (Fig. 1). connect the STN and GP. This fiber bundle arises from Progressive dissection of the fibers of the superior lon- the inferolateral border of the STN (Fig. 2). gitudinal fasciculus reveals the insular cortex. After re- The ansa lenticularis consists of fibers from the globus moval of the insular subcortex, we can see the white fibers pallidus internus (GPi) that project toward the thalamus. of the extreme capsule; and at the level of the limen in- It originates mainly from the lateral portion of the GPi, sula, the fibers of the uncinate and inferior occipitofrontal coursing in a medial, ventral, and rostral direction and fascicles can be distinguished. The extreme capsule is a sweeping anteriorly around the posterior limb of the in- group of fibers situated between the insular cortex and the ternal capsule. This tract arises from the medial aspect claustrum (Fig. 1). of the GPi, perforates the internal capsule, and forms a The external capsule is composed of fibers situated be- bundle ventral to the zona incerta. Although some fibers FIG. 1. A: Gray matter has been dissected, and fibers have been uncovered. The gyri and sulci have been identified. B: Fibers haveRetracted been dissected; the claustrum can be seen. Internal capsules have been dissected. The inferior frontal fasciculus and uncinate fasciculus are identified. The optic radiation can be followed inferiorly. C: The claustrum has been dissected, and the putamen is identified. The sagittal stratum can be followed, radiating posteriorly. Fasc. = fasciculus; Front. = frontal; gyr. = gyrus; i.c. = internal capsule; Inf. = inferior; Int. = internal; Lat. Gen. bod = lateral geniculate body; long. = longitudinal; Midd. = middle; Occ. = occipital; rad. = radiation; Sup. = superior; Temp. = temporal. Figure is available in color online only. 2 J Neurosurg April 24, 2015 Subthalamic nucleus anatomy FIG. 2. Left: View from the medial aspect of the cerebrum. The red nucleus can be viewed medial to the substantia nigra. The thalamus is located posterolateral to the substantia nigra. The optic nerve and the stalk can be observed medially. Right: Subtha- lamic nucleus and ansa lenticularis fibers are seen. Association fibers between basal ganglia and the STN can be viewed. The red nucleus is located medially and inferiorly. The ansa lenticularis and substantia nigra can be seen on the inferior and lateral side of the STN, respectively. Pit. = pituitary. Figure is available in color online only. from the lenticular fasciculus are dorsal to the STN, most nuclei found within the subthalamic region include the of this tract courses rostral to the nucleus. Fiber tracts ly- STN and zona incerta. The STN has a very close relation- ing posterior to the STN include the medial lemniscus, ship with the substantia nigra and the red nucleus (Fig. 5). spinothalamic tract, and trigeminothalamic tract (Fig. 2). In particular, the dorsal aspects of the lateral portion of Discussion the rostral two-thirds and the caudal one-third of the nu- cleus are anatomically related to the motor circuits. Sub- The STN is a small, lens-shaped nucleus in the brain. thalamic afferent fibers, corticosubthalamic projections, The STN is part of the basal ganglia system and is located and most of the cortical afferents to the STN arise from ventral to the thalamus, dorsal to the substantia nigra, and the primary motor cortex, supplementary motor area, pre– medial to the internal capsule.
Load more

Recommended publications
  • Basal Ganglia & Cerebellum
    1/2/2019 This power point is made available as an educational resource or study aid for your use only. This presentation may not be duplicated for others and should not be redistributed or posted anywhere on the internet or on any personal websites. Your use of this resource is with the acknowledgment and acceptance of those restrictions. Basal Ganglia & Cerebellum – a quick overview MHD-Neuroanatomy – Neuroscience Block Gregory Gruener, MD, MBA, MHPE Vice Dean for Education, SSOM Professor, Department of Neurology LUHS a member of Trinity Health Outcomes you want to accomplish Basal ganglia review Define and identify the major divisions of the basal ganglia List the major basal ganglia functional loops and roles List the components of the basal ganglia functional “circuitry” and associated neurotransmitters Describe the direct and indirect motor pathways and relevance/role of the substantia nigra compacta 1 1/2/2019 Basal Ganglia Terminology Striatum Caudate nucleus Nucleus accumbens Putamen Globus pallidus (pallidum) internal segment (GPi) external segment (GPe) Subthalamic nucleus Substantia nigra compact part (SNc) reticular part (SNr) Basal ganglia “circuitry” • BG have no major outputs to LMNs – Influence LMNs via the cerebral cortex • Input to striatum from cortex is excitatory – Glutamate is the neurotransmitter • Principal output from BG is via GPi + SNr – Output to thalamus, GABA is the neurotransmitter • Thalamocortical projections are excitatory – Concerned with motor “intention” • Balance of excitatory & inhibitory inputs to striatum, determine whether thalamus is suppressed BG circuits are parallel loops • Motor loop – Concerned with learned movements • Cognitive loop – Concerned with motor “intention” • Limbic loop – Emotional aspects of movements • Oculomotor loop – Concerned with voluntary saccades (fast eye-movements) 2 1/2/2019 Basal ganglia “circuitry” Cortex Striatum Thalamus GPi + SNr Nolte.
    [Show full text]
  • Imaging of the Confused Patient: Toxic Metabolic Disorders Dara G
    Imaging of the Confused Patient: Toxic Metabolic Disorders Dara G. Jamieson, M.D. Weill Cornell Medicine, New York, NY The patient who presents with either acute or subacute confusion, in the absence of a clearly defined speech disorder and focality on neurological examination that would indicate an underlying mass lesion, needs to be evaluated for a multitude of neurological conditions. Many of the conditions that produce the recent onset of alteration in mental status, that ranges from mild confusion to florid delirium, may be due to infectious or inflammatory conditions that warrant acute intervention such as antimicrobial drugs, steroids or plasma exchange. However, some patients with recent onset of confusion have an underlying toxic-metabolic disorders indicating a specific diagnosis with need for appropriate treatment. The clinical presentations of some patients may indicate the diagnosis (e.g. hypoglycemia, chronic alcoholism) while the imaging patterns must be recognized to make the diagnosis in other patients. Toxic-metabolic disorders constitute a group of diseases and syndromes with diverse causes and clinical presentations. Many toxic-metabolic disorders have no specific neuroimaging correlates, either at early clinical stages or when florid symptoms develop. However, some toxic-metabolic disorders have characteristic abnormalities on neuroimaging, as certain areas of the central nervous system appear particularly vulnerable to specific toxins and metabolic perturbations. Areas of particular vulnerability in the brain include: 1) areas of high-oxygen demand (e.g. basal ganglia, cerebellum, hippocampus), 2) the cerebral white matter and 3) the mid-brain. Brain areas of high-oxygen demand are particularly vulnerable to toxins that interfere with cellular respiratory metabolism.
    [Show full text]
  • Neuron Numbers Increase in the Human Amygdala from Birth to Adulthood, but Not in Autism
    Neuron numbers increase in the human amygdala from birth to adulthood, but not in autism Thomas A. Avinoa, Nicole Bargera, Martha V. Vargasa, Erin L. Carlsona, David G. Amarala,b,c, Melissa D. Baumana,b, and Cynthia M. Schumanna,1 aDepartment of Psychiatry and Behavioral Sciences, UC Davis MIND Institute, School of Medicine, University of California, Davis, Sacramento, CA 95817; bCalifornia National Primate Research Center, University of California, Davis, CA 95616; and cCenter for Neuroscience, University of California, Davis, CA 95618 Edited by Joseph E. LeDoux, New York University, New York, NY, and approved March 1, 2018 (received for review February 12, 2018) Remarkably little is known about the postnatal cellular develop- process, however, may also make the amygdala more susceptible ment of the human amygdala. It plays a central role in mediating to developmental or environmental insults. emotional behavior and has an unusually protracted development ASD is characterized by impairments in social communication well into adulthood, increasing in size by 40% from youth to combined with restricted interests and behaviors. Alterations in adulthood. Variation from this typical neurodevelopmental trajec- amygdala growth can be detected as early as 2 y of age (23–26) tory could have profound implications on normal emotional devel- and persist into late childhood (5, 27). The severity of the indi- vidual’s social and communicative symptoms positively correlates opment. We report the results of a stereological analysis of the – number of neurons in amygdala nuclei of 52 human brains ranging with amygdala enlargement, suggesting a potential structure from 2 to 48 years of age [24 neurotypical and 28 autism spectrum function relationship (23).
    [Show full text]
  • Auditory and Vestibular Systems Objective • to Learn the Functional
    Auditory and Vestibular Systems Objective • To learn the functional organization of the auditory and vestibular systems • To understand how one can use changes in auditory function following injury to localize the site of a lesion • To begin to learn the vestibular pathways, as a prelude to studying motor pathways controlling balance in a later lab. Ch 7 Key Figs: 7-1; 7-2; 7-4; 7-5 Clinical Case #2 Hearing loss and dizziness; CC4-1 Self evaluation • Be able to identify all structures listed in key terms and describe briefly their principal functions • Use neuroanatomy on the web to test your understanding ************************************************************************************** List of media F-5 Vestibular efferent connections The first order neurons of the vestibular system are bipolar cells whose cell bodies are located in the vestibular ganglion in the internal ear (NTA Fig. 7-3). The distal processes of these cells contact the receptor hair cells located within the ampulae of the semicircular canals and the utricle and saccule. The central processes of the bipolar cells constitute the vestibular portion of the vestibulocochlear (VIIIth cranial) nerve. Most of these primary vestibular afferents enter the ipsilateral brain stem inferior to the inferior cerebellar peduncle to terminate in the vestibular nuclear complex, which is located in the medulla and caudal pons. The vestibular nuclear complex (NTA Figs, 7-2, 7-3), which lies in the floor of the fourth ventricle, contains four nuclei: 1) the superior vestibular nucleus; 2) the inferior vestibular nucleus; 3) the lateral vestibular nucleus; and 4) the medial vestibular nucleus. Vestibular nuclei give rise to secondary fibers that project to the cerebellum, certain motor cranial nerve nuclei, the reticular formation, all spinal levels, and the thalamus.
    [Show full text]
  • Digital Neuroanatomy
    DIGITAL NEUROANATOMY LM NEUROHISTOLOGY George R. Leichnetz, Ph.D. Professor, Department of Anatomy & Neurobiology Virginia Commonwealth University 2004 Press the Å and Æ keys on your keyboard to navigate through this lecture There are three morphological types of neurons in the nervous system: unipolar, bipolar, and multipolar. While all three types can be found in the PNS, the CNS only contains multipolar neurons. CNS multipolar neurons vary greatly in morphology: eg. spinal cord motor neurons, pyramidal cells of cerebral cortex, Purkinje cells of cerebellar cortex. The supportive cells of the CNS are neuroglia: astrocytes, oligodendrocytes, and microglia. Oligodendrocytes myelinate CNS axons, while Schwann cells myelinate PNS axons. Protoplasmic astrocytes predominate in CNS gray matter, while fibrous astrocytes predominate in CNS white matter. The ventral horn of the spinal cord Lumbar Spinal Cord contains multipolar motor neurons. Dorsal White Horn Matter Gray Matter Ventral Kluver- Horn Barrera Stain (LFB & CV) Cell bodies of motor neurons Dendrite Gray Matter Dendrite Perineuronal H & E oligodendrocyte Stain Nucleus, nucleolus Abundant Nissl substance Dorsal root Dorsal root ganglion Ventral root Gray Matter: contains White Matter: cell bodies of neurons contains x-sections of myelinated axons Multipolar motor neurons Silver Stain of the ventral horn Large multipolar motor neurons of the spinal cord ventral horn: see nucleus, nucleolus, abundant Nissl substance, multiple tapering processes (dendrites). The axon hillock (origin of axon from cell body) lacks Nissl. Nucleus Axon hillock dendrites Nucleolus Nissl substance (RER) Kluver-Barrera Stain (Luxol Fast Blue and Cresyl Violet) Thoracic Spinal Cord The nucleus dorsalis of Clarke, located in the base of the dorsal horn of the thoracic spinal cord, contains multipolar neurons whose nucleus is eccentric and Nissl around the periphery of the cell body (as if it were chromatolytic).
    [Show full text]
  • Review of Spinal Cord Basics of Neuroanatomy Brain Meninges
    Review of Spinal Cord with Basics of Neuroanatomy Brain Meninges Prof. D.H. Pauža Parts of Nervous System Review of Spinal Cord with Basics of Neuroanatomy Brain Meninges Prof. D.H. Pauža Neurons and Neuroglia Neuron Human brain contains per 1011-12 (trillions) neurons Body (soma) Perikaryon Nissl substance or Tigroid Dendrites Axon Myelin Terminals Synapses Neuronal types Unipolar, pseudounipolar, bipolar, multipolar Afferent (sensory, centripetal) Efferent (motor, centrifugal, effector) Associate (interneurons) Synapse Presynaptic membrane Postsynaptic membrane, receptors Synaptic cleft Synaptic vesicles, neuromediator Mitochondria In human brain – neurons 1011 (100 trillions) Synapses – 1015 (quadrillions) Neuromediators •Acetylcholine •Noradrenaline •Serotonin •GABA •Endorphin •Encephalin •P substance •Neuronal nitric oxide Adrenergic nerve ending. There are many 50-nm-diameter vesicles (arrow) with dark, electron-dense cores containing norepinephrine. x40,000. Cell Types of Neuroglia Astrocytes - Oligodendrocytes – Ependimocytes - Microglia Astrocytes – a part of hemoencephalic barrier Oligodendrocytes Ependimocytes and microglial cells Microglia represent the endogenous brain defense and immune system, which is responsible for CNS protection against various types of pathogenic factors. After invading the CNS, microglial precursors disseminate relatively homogeneously throughout the neural tissue and acquire a specific phenotype, which clearly distinguish them from their precursors, the blood-derived monocytes. The ´resting´ microglia
    [Show full text]
  • Nucleus Laminaris
    OUP UNCORRECTED PROOF – FIRST-PROOF, 26/03/2010, GLYPH 1 2 2 2 Nucleus Laminaris 3 Yuan Wang Jason Tait Sanchez , and Edwin W Rubel 4 Our ability to detect subtle acoustic cues in noisy environments, like a con- 5 versation in a crowded restaurant, is one benefi t of binaural hearing. Binaural 6 hearing is also essential for sound localization. The ability to localize the 7 source of a sound is dependent on time disparities in the arrival of low- 8 frequency signals between the two ears, referred to as interaural time differ- 9 ence (ITD). In all vertebrates, ITDs are encoded by distinct neural circuits in 10 the central auditory nervous system specialized for the temporal processing 11 of sound at the network, synaptic, and cellular levels. Coding of ITDs is fi rst 12 performed by the medial superior olive (MSO) of mammals and by the 13 nucleus laminaris (NL) in birds and some reptiles. 14 This chapter will focus on the microcircuitry of the chicken NL, which is 15 an excellent example of neural architecture exquisitely tailored for its special- 16 ized function in sound localization. Neurons in NL are coincidence detectors, 17 encoding temporal information of sound arriving at the two ears by respond- 18 ing maximally when resulting action potentials (APs) arrive simultaneously, 19 a unique feature responsible for the coding of ITDs in the microsecond range. 20 We will discuss the important structural and functional specializations of NL 21 that optimize this specialized ability, fundamental for binaural hearing in 22 most birds and mammals.
    [Show full text]
  • Different Projections of the Central Amygdaloid Nucleus Mediate Autonomic and Behavioral Correlates of Conditioned Fear
    The Journal of Neuroscience, July 1988, 8(7): 2517-2529 Different Projections of the Central Amygdaloid Nucleus Mediate Autonomic and Behavioral Correlates of Conditioned Fear Joseph E. LeDoux, Jiro Iwata, Piera Cicchetti, and Donald J. Reis Division of Neurobiology, Cornell University Medical College, New York, New York 10021 The purpose of the present study was to determine whether Iwata et al., 1986a).The critical amygdaloid regionsare located lesions of areas projected to by the central amygdaloid nu- in the dorsal part of this structure, and include the lateral and cleus (ACE) would disrupt the classical conditioning of auto- central nuclei and the amygdalostriatal transition zone (Iwata nomic and/or behavioral emotional responses. The areas et al., 1986a; LeDoux et al., 1986a). Since the major projection studied included 3 projection targets of the ACE: the lateral from the acoustic thalamus terminates in the lateral nucleusand hypothalamic area (LH), midbrain central gray (CG) region, the amygdalostriatal zone (LeDoux et al., 1985), one of these and bed nucleus of the stria terminalis (BNST). Lesions were regionsprobably servesas the sensoryinterface of the amygdala made either electrolytically or by microinjection of ibotenic during conditioning (Cicchetti et al., 1987). In contrast, the acid, which destroys local neurons without interrupting fibers amygdaloid output pathway is likely to involve the central nu- of passage. Two weeks later, the animals were classically cleus, a structure implicated in the expressionof the autonomic
    [Show full text]
  • Multistable Properties of Human Subthalamic Nucleus Neurons in Parkinson’S Disease
    Multistable properties of human subthalamic nucleus neurons in Parkinson’s disease Jeremy W. Chopeka,1, Hans Hultbornb, and Robert M. Brownstonea,2 aDepartment of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, WC1N 3BG London, United Kingdom; and bDepartment of Neuroscience, University of Copenhagen, 2200 Copenhagen N, Denmark Edited by Peter L. Strick, University of Pittsburgh, Pittsburgh, PA, and approved October 15, 2019 (received for review July 18, 2019) To understand the function and dysfunction of neural circuits, it is thorough characterization of complex neuronal properties is necessary to understand the properties of the neurons participating critical for understanding the modus operandi of neural circuits. in the behavior, the connectivity between these neurons, and the The connectivity of the excitatory subthalamic nucleus (STN) neuromodulatory status of the circuits at the time they are producing of the basal ganglia is well understood: it receives inputs from the the behavior. Such knowledge of human neural circuits is difficult, globus pallidus externa (GPe), motor cortex, and substantia nigra at best, to obtain. Here, we study firing properties of human pars compacta, and projects to the GPe, globus pallidus interna, subthalamic neurons, using microelectrode recordings and microstim- and substantia nigra pars reticulata. Furthermore, the basic ulation during awake surgery for Parkinson’s disease. We dem- electrophysiological properties of these neurons is reasonably onstrate that low-amplitude, brief trains of microstimulation can lead well understood, with resurgent and persistent sodium- and to persistent changes in neuronal firing behavior including switching calcium-dependent potassium conductances playing key roles for between firing rates, entering silent periods, or firing several bursts repetitive firing, and low-threshold calcium currents playing a then entering a silent period.
    [Show full text]
  • Cerebellar Histology & Circuitry
    Cerebellar Histology & Circuitry Histology > Neurological System > Neurological System CEREBELLAR HISTOLOGY & CIRCUITRY SUMMARY OVERVIEW Gross Anatomy • The folding of the cerebellum into lobes, lobules, and folia allows it to assume a tightly packed, inconspicuous appearance in the posterior fossa. • The cerebellum has a vast surface area, however, and when stretched, it has a rostrocaudal expanse of roughly 120 centimeters, which allows it to hold an estimated one hundred billion granule cells — more cells than exist within the entire cerebral cortex. - It is presumed that the cerebellum's extraordinary cell count plays an important role in the remarkable rehabilitation commonly observed in cerebellar stroke. Histology Two main classes of cerebellar nuclei • Cerebellar cortical neurons • Deep cerebellar nuclei CEREBELLAR CORTICAL CELL LAYERS Internal to external: Subcortical white matter Granule layer (highly cellular) • Contains granule cells, Golgi cells, and unipolar brush cells. Purkinje layer 1 / 9 • Single layer of large Purkinje cell bodies. • Purkinje cells project a fine axon through the granule cell layer. - Purkinje cells possess a large dendritic system that arborizes (branches) extensively and a single fine axon. Molecular layer • Primarily comprises cell processes but also contains stellate and basket cells. DEEP CEREBELLAR NUCLEI From medial to lateral: Fastigial Globose Emboliform Dentate The globose and emboliform nuclei are also known as the interposed nuclei • A classic acronym for the lateral to medial organization of the deep nuclei is "Don't Eat Greasy Food," for dentate, emboliform, globose, and fastigial. NEURONS/FUNCTIONAL MODULES • Fastigial nucleus plays a role in the vestibulo- and spinocerebellum. • Interposed nuclei are part of the spinocerebellum. • Dentate nucleus is part of the pontocerebellum.
    [Show full text]
  • Motor Systems Basal Ganglia
    Motor systems 409 Basal Ganglia You have just read about the different motor-related cortical areas. Premotor areas are involved in planning, while MI is involved in execution. What you don’t know is that the cortical areas involved in movement control need “help” from other brain circuits in order to smoothly orchestrate motor behaviors. One of these circuits involves a group of structures deep in the brain called the basal ganglia. While their exact motor function is still debated, the basal ganglia clearly regulate movement. Without information from the basal ganglia, the cortex is unable to properly direct motor control, and the deficits seen in Parkinson’s and Huntington’s disease and related movement disorders become apparent. Let’s start with the anatomy of the basal ganglia. The important “players” are identified in the adjacent figure. The caudate and putamen have similar functions, and we will consider them as one in this discussion. Together the caudate and putamen are called the neostriatum or simply striatum. All input to the basal ganglia circuit comes via the striatum. This input comes mainly from motor cortical areas. Notice that the caudate (L. tail) appears twice in many frontal brain sections. This is because the caudate curves around with the lateral ventricle. The head of the caudate is most anterior. It gives rise to a body whose “tail” extends with the ventricle into the temporal lobe (the “ball” at the end of the tail is the amygdala, whose limbic functions you will learn about later). Medial to the putamen is the globus pallidus (GP).
    [Show full text]
  • Thalamus.Pdf
    Thalamus 583 THALAMUS This lecture will focus on the thalamus, a subdivision of the diencephalon. The diencephalon can be divided into four areas, which are interposed between the brain stem and cerebral hemispheres. The four subdivisions include the hypothalamus to be discussed in a separate lecture, the ventral thalamus containing the subthalamic nucleus already discussed, the epithalamus which is made up mostly of the pineal body, and the dorsal thalamus (henceforth referred to as the thalamus) which is the focus of this lecture. Although we will not spend any time in lecture on the pineal body, part of the epithalamus, it does have some interesting features as well as some clinical relevance. The pineal is a small midline mass of glandular tissue that secretes the hormone melatonin. In lower mammals, melatonin plays a central role in control of diurnal rhythms (cycles in body states and hormone levels that follow the day- night cycle). In humans, at least a portion of the control of diurnal rhythms has been taken over by the hypothalamus, but there is increasing evidence that the pineal and melatonin play at least a limited role. Recent investigations have demonstrated a role for melatonin in sleep, tumor reduction and aging. Additionally, based on the observation that tumors of the pineal can induce a precocious puberty in males it has been suggested that the pineal is also involved in timing the onset of puberty. In many individuals the pineal is partially calcified and can serve as a marker for the midline of the brain on x- rays. Pathological processes can sometimes be detected by a shift in its position.
    [Show full text]