Basal Ganglia

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Basal Ganglia

    • consists of subcortical nuclei (gray matter) within the cerebral hemispheres.
    • Components
      • Caudate nucleus
      • Putamen
      • Globus pallidus
      • Amygdala (amygdaloid nuclear complex)
      • Claustrum
    • Groupings of the basal ganglia
      • Striatum (neostriatum)
        • consists of the caudate nucleus and the putamen
        • have a common embryologic origin.
      • Lentiform nucleus
        • consists of the putamen and the globuspallidus.
      • Corpus striatum
        • consists of the lentiform nucleus and the caudate nucleus.
      • Striatal Motor System
        • is also called the extrapyramidal motor system.
        • plays a role in the initiation and execution of somatic motor activity, especially willed movement.
        • is involved in automatic stereotyped motor activity of a postural and reflex nature.
        • exerts its influences on motor activities via the thalamus, motor cortex, and corticobulbar and corticospinal systems.
    • Components of the striatal system
      • Striatum (caudatoputamen or neostriatum)
        • Caudate nucleus (caudatum)
        • Putamen
      • Globus pallidus (pallidum or paleostriatum)
        • Medial (internal) segment
          • is adjacent to the internal capsule.
        • Lateral (external) segment
          • is adjacent to the putamen.
      • Subthalamic nucleus
      • Thalamus
        • Ventral anterior nucleus
        • Ventral lateral nucleus
        • Centromedian nucleus
      • Substantianigra
        • Pars compacta
          • containsdopaminergic neurons, which contain the pigment melanin.
        • Pars reticularis
          • containsgamma-aminobutyric acid (GABA) –ergic neurons.
      • Pedunculopontine nucleus
        • lies in the lateral tegmentum of the caudal midbrain.
    • Major connections of the striatal system
      • Striatum (caudate nucleus and putamen)
        • receivesinput from
          • largest input from the neocortex, from virtually all neocortical areas.
          • thalamus (centromedian nucleus
          • substantianigra.
        • projects fibers to two major nuclei
          • the globuspallidus
          • substantianigra (parsreticularis).
      • Globus pallidus
        • receives input from two major nuclei
          • the striatum
          • subthalamic nucleus.
        • projects fibers to three major nuclei
          • thesubthalamic nucleus
          • the thalamus (ventral anterior, ventral lateral, and centromedian nuclei),
          • pedunculopontine nucleus
      • Subthalamic nucleus
        • receives input from the globuspallidusand from the motor cortex.
        • projects fibers to the globuspallidus.
      • Thalamus
        • Input to the thalamus
          • Globus pallidus
            • projects to the ventral anterior, ventral lateral, and centromedian nuclei.
          • Substantianigra
          • projects from the pars reticularis to the ventral anterior, ventral lateral, and themediodorsal nuclei of the thalamus
        • Projections from the thalamus
          • Motor cortex (area 4)
            • from the ventral lateral and centromedian nuclei
          • Premotor cortex (area 6)
            • from the ventral anterior and ventral lateral nuclei
          • Supplementary motor cortex (area 6)
            • from the ventral lateral and ventral anterior nuclei
          • Striatum
            • from the centromedian nucleus
          • Substantianigra
            • receives major input from the striatum.
            • projects fibers to the striatum and the thalamus (ventral anterior, ventral lateral, andmediodorsal nuclei).
          • Pedunculopontine nucleus
            • receivesGABA-ergic input from the globuspallidus.
            • projectsglutaminergic fibers to the globuspallidus and to the substantianigra.
    • Major neurotransmitters of the neurons of the striatal system
      • Glutamate-containing neurons
        • project from the cerebral cortex to the striatum.
        • project from thesubthalamic nucleus to the globuspallidus.
        • excite striatal GABA-ergic and cholinergic neurons.
      • GABA-containing neurons
        • are the predominant neurons of the striatal system.
        • are found in the striatum, globuspallidus, and substantianigra (pars reticularis).
        • give rise to GABA-ergic projections:
          • striatopallidalprojections
          • striatonigralprojections
          • pallidothalamicprojections
          • nigrothalamic projections.
        • degenerate in Huntington disease.
      • Dopamine-containing neurons
        • are found in the pars compacta of the substantianigra
        • give rise to the dopaminergic nigrostriatal projection.
        • are thought to regulate the production of striatal peptides and peptide mRNA.
        • degenerate in Parkinson disease.
      • Neurons containing acetylcholine (ACh)
        • are local circuit neurons found in the striatum.
      • Neuropeptide-containing neurons
        • includeenkephalin, dynorphin, substance P, somatostatin, neurotensin, neuropeptide Y, and cholecystokinin.
        • are also found in the basal ganglia.
        • coexist with the major neurotransmitters (e.g., GABA and/or enkephalin and GABAand/or substance P).
    • Ventral striatopallidal complex and its connections
      • play a role in initiating movements in response to motivational and emotional activity (e.g., limbic functions).
      • Ventral striatum
        • consists of the nucleus accumbens and the olfactory tubercle.
        • receives input from the olfactory, prefrontal, and hippocampal cortices
        • projects to the ventral pallidum.
      • Ventral pallidum
        • consists of the substantiainnominata.
        • receives input from the ventral striatum.
        • projects to the medial dorsal nucleus of the thalamus.
    • Clinical correlations
      • Parkinson disease
        • associated with degeneration and depigmentation of neurons in the substantianigra.
        • results in the depletion of dopamine in the caudate nucleus and putamen.
      • Progressive supranuclear palsy
        • is associated with Parkinson disease.
        • together withParkinson disease is called the Parkinson-plus syndrome.
        • is characterized by
          • supranuclearophthalmoplegia, primarily downgaze paresis
          • followed by paresis of other eye movements
          • result in the clinical picture of pseudobulbar palsy
        • is characterized by neuronal cell loss in the globuspallidus, red nucleus, substantianigra, periaqueductal gray, and dentate nucleus.
        • spares the cerebral and the cerebellar cortices.
        • results in neurofibrillary tangles in the surviving neurons.
      • Huntington disease (chorea major)
        • is an inherited autosomal dominant movement disorder
        • associated with severe degeneration of the cholinergic and GABA-ergic neurons, which are located in the caudate nucleus and putamen.
        • is usually accompanied by gyral atrophy in the frontal and temporal lobes.
        • can be traced to a single gene defect on chromosome 4.
        • is characterized by impaired initiation and slowness of saccadic eye movements
        • patientscannot make a volitional saccade without moving the head.
        • results in clinical manifestations of choreiform movements and progressive dementia.
        • results in hydrocephalus ex vacuodue to the loss of neurons located in the head of the caudate nucleus
      • Sydenham chorea (St. Vitus dance)
        • is the most common cause of chorea overall.
        • occurs mainly in girls as a sequela to rheumatic fever.
      • Chorea gravidarum
        • occurs usually during the second trimester of pregnancy.
      • Ballism and hemiballism
        • are extrapyramidal motor disorders most often resulting from a vascular lesion (infarct) of the subthalamic nucleus.
        • are characterized by violent flinging (ballistic) movements of one or both extremities
        • symptoms appear on the contralateral side.
        • may be treated with dopamine-blocking drugs or with GABA-mimetic agents.
        • may be treated surgically by ventrolateralthalamotomy.
      • Hepatolenticular degeneration (Wilson disease)
        • is an autosomal recessive disorder
        • due to a defect in the metabolism of copper (ceruloplasmin).
        • has its gene locus on chromosome 13.
        • results in clinical manifestations of tremor, rigidity, and choreiform or athetoticmovements
        • Tremor is the most common neurologic sign.
        • haspsychiatric symptoms, including psychosis, personality disorders, and dementia.
        • results in a corneal Kayser-Fleischer ring, which is pathognomonic.
        • is marked by lesions in the liver (cirrhosis) and in the lentiform nuclei (necrosis and cavitation of the putamen).
        • is diagnosed by low serum ceruloplasmin, elevated urinary excretion of copper, andincreased copper concentration in liver biopsy.
        • is treated with the copper-chelating agent D-penicillamine and pyridoxine for anemia.
      • Tardive dyskinesia
        • is a syndrome of repetitive choreic movements affecting the face, limbs, and trunk.
        • results from treatment with antipsychotic drugs (e.g., phenothiazines, butyrophenones, or metoclopramide).


        The Basal Ganglia – UBC Flexible Learning
        Neuroanatomy – Basal Ganglia
        Basal Ganglia Motor Circuit – Function & Dysfunction
        The Basal Ganglia – Direct and Indirect Pathway.
        Basic Parts of the Brain – Part 2 – 3D Anatomy Tutoria
        Basal Ganglia Demonstration by Dr Sanjoy Sanyal MUA Neuroscience Lab – Part 1
        Serial 1cm axial slices of human brain to show cortex, subcortical white matter, till the basal ganglia – thalamus level, with running commentary. Performed on 20 June 2011 in MUA Neuroscience Lab.
        Dissection and commentary by Dr Sanjoy Sanyal, Associate Professor and Course Director of Neuroscience in Medical University of the Americas, Nevis, St.Kitts-Nevis, WI
        Camera and assistance by Sonja Langley, Med 3 Neuroscience student and Class President in MUA
        Video editing by Chris Robinson, Med 4 student in MUA
        Anatomy and Diseases of the Basal Ganglia
        Animation describing the anatomy of the basal ganglia and listing some relevant diseases.