Corticostriate Projections and Motor Activity
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Corticostriate Projections and Motor Activity

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Questions and Answers

What type of neurotransmitter is primarily used for output from the striatum to the globus pallidus in the direct pathway?

  • Serotonin
  • GABA (correct)
  • Glutamate
  • Dopamine

    • Which structure provides excitatory input to the striatum in the direct pathway?

  • Cortex (correct)
  • Substantia nigra
  • Thalamus
  • Globus pallidus

    • In the indirect pathway, which neurotransmitter is involved in the excitatory input to the striatum from the cortex?

  • Glutamate (correct)
  • GABA
  • Dopamine
  • Serotonin

    • What is the final effect of the output from the GPi/SNr nuclei to the thalamus in the context of the pathways discussed?

    <p>Inhibitory</p> Signup and view all the answers

    Which of the following pathways is utilized by the pallidothalamic fibers from the GPi?

    <p>Lenticular fasciculus</p> Signup and view all the answers

    What is the outcome of decreased motor activity associated with corticostriate projections?

    <p>Hypokinesia</p> Signup and view all the answers

    Which structure is primarily involved in the dorsolateral prefrontal loop pathway?

    <p>Caudate nucleus</p> Signup and view all the answers

    Which projection pathway does the direct corticostriate projection utilize to reach the neostriatum?

    <p>Subcallosal fasciculus</p> Signup and view all the answers

    What is the primary role of the basal ganglia in motor control?

    <p>Automatic execution of learned motor plans</p> Signup and view all the answers

    Which neurotransmitter is involved in mesencephalostriate projections originating from the substantia nigra pars compacta?

    <p>Dopamine</p> Signup and view all the answers

    What occurs as a result of a lesion to the basal ganglia?

    <p>Slower and less automatic cortical control</p> Signup and view all the answers

    What effect does dopamine have on D1 striatal neurons in the mesencephalostriate projections?

    <p>Excitatory</p> Signup and view all the answers

    In the context of the motor loop, what do the discharges relate to?

    <p>Target location in space and limb movement</p> Signup and view all the answers

    In relation to striatal output, which neuromodulator is noted to have no effect when directed towards the GPe?

    <p>GABA</p> Signup and view all the answers

    What characteristic best describes corticostriate pathways during childhood?

    <p>Functionally immature</p> Signup and view all the answers

    What function does the oculomotor loop serve?

    <p>Facilitating the reward-based control of visual attention</p> Signup and view all the answers

    Which type of input does the striatum receive in its gating function?

    <p>Dopaminergic inhibitory and cortical sensorimotor excitatory inputs</p> Signup and view all the answers

    Which area does not project to the GPe based on the neuromodulator information provided?

    <p>Substance P</p> Signup and view all the answers

    Which structure is involved in regulating sensorimotor access?

    <p>Pallidum</p> Signup and view all the answers

    Which of the following neurotransmitters has an inhibitory effect on D2 striatal neurons that project to the GPe?

    <p>Dopamine</p> Signup and view all the answers

    What type of control does the oculomotor loop primarily engage with?

    <p>Automatic visual attention and saccadic eye movement</p> Signup and view all the answers

    Which neurotransmitters are contained in Spiny Neurons of the Neostriatum?

    <p>GABA, Taurine, Neuropeptides</p> Signup and view all the answers

    What characterizes the Matrix Compartment of the Neostriatum?

    <p>Sensorimotor cortex input</p> Signup and view all the answers

    Which of the following statements about the Substantia Nigra Pars Reticulata (SNpr) is true?

    <p>The SNpr is similar morphologically and chemically to the Globus Pallidus interna.</p> Signup and view all the answers

    What happens to Spiny and Aspiny Interneurons in Huntington’s Chorea?

    <p>They are lost.</p> Signup and view all the answers

    Which of the following is NOT a feature of the Striosomes in the Neostriatum?

    <p>Characterized by heavy substances</p> Signup and view all the answers

    Which of the following neuropeptides is NOT mentioned as being contained in Spiny Neurons?

    <p>Endorphins</p> Signup and view all the answers

    Which area is primarily responsible for initiating outputs from the Striosomes?

    <p>Substantia Nigra Pars Compacta</p> Signup and view all the answers

    In what condition are Spiny Neurons typically silent?

    <p>At rest</p> Signup and view all the answers

    What characterizes hemiballismus?

    <p>Uncontrolled flinging movements of a limb on one side</p> Signup and view all the answers

    In which area of the brain do vascular lesions commonly associated with hemiballismus occur?

    <p>Contralateral subthalamic nucleus</p> Signup and view all the answers

    Which neurotransmitter is primarily associated with the output from the globus pallidus externa to the subthalamic nucleus?

    <p>GABA</p> Signup and view all the answers

    What role does the nucleus accumbens septi play in the basal ganglia systems?

    <p>Mediating reward and motivation</p> Signup and view all the answers

    Which statement is true regarding deep brain stimulation (DBS) for Parkinson’s disease?

    <p>It is most effective in the subthalamic nucleus.</p> Signup and view all the answers

    Which of the following types of regulators is NOT part of the basal ganglia and its neural systems?

    <p>Cerebellar regulators</p> Signup and view all the answers

    What aspect of motor control is affected by hemiballismus?

    <p>Uncontrolled ballistic movements</p> Signup and view all the answers

    What is the primary characteristic of the output from the subthalamic nucleus?

    <p>It is excitatory and mediated by glutamate.</p> Signup and view all the answers

    Study Notes

    Dorsolateral Prefrontal Loop Pathway

    • Striatum integrates and transmits information primarily from the caudate nucleus to globus pallidus and substantia nigra.
    • Originates from the dorsolateral prefrontal cortex.

    Basal Ganglia Functions

    • Basal ganglia facilitate automatic execution of learned motor plans.
    • Motor skills shift from cortical control to basal ganglia as they are learned.
    • Lesions in basal ganglia can lead to slower, less accurate motor responses, reducing automatism.

    Motor Roles of Basal Ganglia

    • Prepares and executes movements through motor and oculomotor loops.
    • Motor loop involves discharge linked to target location, limb direction, and muscle pattern.
    • Oculomotor loop is associated with visual fixation and saccadic movements, also influencing visual attention based on reward.
    • Gating function allows modulation of sensory input for motor control, balancing inhibitory and excitatory signals.

    Neuronal Composition of Neostriatum

    • Spiny neurons constitute 96% of neostriatal projections, with GABA, taurine, and various neuropeptides involved in neurotransmission.
    • The striatum consists of striosomes (patches) and matrix compartments, having distinct inputs and outputs.

    Inputs and Outputs of Neostriatum

    • Striosomes: receive input from medial frontal cortex and limbic regions; output to SNpc.
    • Matrix: receives input from sensorimotor cortex; output goes to SNpr and GP.
    • Direct and indirect cortical inputs reach neostriatum through internal and external capsules and subcallosal fasciculus.

    Striatal Pathways

    • Direct pathway: facilitates movement by stimulating the striatum through glutamate and dopamine, using GABA for inhibitory feedback to GPi/SNr and thalamus.
    • Indirect pathway: inhibits movement, involves glutamate and dopamine, and incorporates a more complex feedback mechanism through GPi to thalamus.

    Dopaminergic Projections

    • Originates from substantia nigra pars compacta, affecting D1 and D2 striatal neurons differently, influencing excitatory or inhibitory signals.
    • Projects to striatum via areas like the ventral tegmental area and retrorubral nucleus.

    Ballismus and Deep Brain Stimulation (DBS)

    • Ballismus often presents as hemiballismus, characterized by uncontrolled flinging limb movements, commonly linked to lesions in the contralateral subthalamic nucleus.
    • Deep brain stimulation is a therapeutic method effective for Parkinson’s disease, targeting favorable sites like the subthalamic nucleus.

    Ventral (Limbic) Striatum

    • Involved in the limbic system, with outputs primarily directed to the ventral pallidum.
    • The nucleus accumbens septi plays a crucial role in reward processing and motivation, influencing behaviors such as drug addiction.

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    Description

    Explore the relationships between corticostriate projections and motor activity, focusing on how inputs from the cerebral cortex affect movement. Discover the implications of hypokinesia, particularly in conditions like Parkinson's disease, and the roles of direct and indirect pathways in motor control.

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