L9 Basal Ganglia
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Questions and Answers

What is the primary role of the intrinsic cholinergic interneurons in the caudate?

  • To counteract the activity of nigrostriatal pathways. (correct)
  • To amplify signals from the motor cortex.
  • To stimulate the output nuclei of the basal ganglia.
  • To mediate pain responses in motor control.

    • Which of the following is an output nucleus of the basal ganglia?

  • Medial/Internal Segment Globus Pallidus (correct)
  • Substantia Nigra pars Reticulata (correct)
  • Lateral/External segment of Globus Pallidus
  • Caudate Nucleus

    • How does the basal ganglia influence movement during spontaneous discharge?

  • It remains inactive, preventing movement by default. (correct)
  • It coordinates all muscle activities simultaneously.
  • It initiates involuntary motor activity continually.
  • It enhances voluntary movement across the cortex.

    • What is the role of the basal ganglia in coordinating muscle actions?

    <p>To ensure different muscles and joints are used in a coordinated manner while avoiding conflicting actions. (B)</p> Signup and view all the answers

    What fundamental principle describes the output of the basal ganglia in the absence of external stimulation?

    <p>The output inhibits motor activity in the cortex. (A)</p> Signup and view all the answers

    What is the initial characteristic of the newly disinhibited motor pattern?

    <p>It is uncoordinated. (A)</p> Signup and view all the answers

    Which pathway provides selective inhibition of unwanted actions?

    <p>Indirect Pathway (B)</p> Signup and view all the answers

    What is the role of the GABA neurotransmitter in the Indirect Pathway?

    <p>To inhibit similar unwanted actions. (C)</p> Signup and view all the answers

    Which of the following structures is involved in the Indirect Pathway?

    <p>Medial Globus Pallidus (C)</p> Signup and view all the answers

    Which component is NOT associated with the Indirect Pathway?

    <p>Primary Motor Cortex (B)</p> Signup and view all the answers

    What must the newly disinhibited motor pattern do to become effective?

    <p>It must outcompete similar but unwanted patterns. (A)</p> Signup and view all the answers

    What is the function of the Lateral Globus Pallidus in motor control?

    <p>To inhibit certain motor actions. (C)</p> Signup and view all the answers

    Which of the following describes the relationship between the Direct and Indirect Pathway?

    <p>They work together to regulate motor activity. (A)</p> Signup and view all the answers

    What effect does a high level of basal ganglia activity have on movements?

    <p>It allows for multitasking. (B)</p> Signup and view all the answers

    How do the output nuclei of the basal ganglia function in relation to movements?

    <p>They serve as the 'brake' for self-generated movements. (C)</p> Signup and view all the answers

    What is the primary neurotransmitter released from the indirect pathway of the basal ganglia?

    <p>GABA (B)</p> Signup and view all the answers

    What role does tonic GABAergic activity in the basal ganglia output nuclei play?

    <p>It inhibits the thalamus and cortex most of the time. (D)</p> Signup and view all the answers

    Which structure is part of the basal ganglia and contributes to the output nuclei?

    <p>Caudate/Putamen (C)</p> Signup and view all the answers

    In what way does minimal activity in the basal ganglia affect motor function?

    <p>It restricts all action. (A)</p> Signup and view all the answers

    What could be inferred about the relationship between the basal ganglia and multitasking?

    <p>High basal ganglia activity enhances the ability to manage multiple tasks. (A)</p> Signup and view all the answers

    Which pathway in the basal ganglia is primarily responsible for inhibiting motor activity?

    <p>Indirect Pathway (D)</p> Signup and view all the answers

    What characterizes the indirect pathway in terms of synaptic connections?

    <p>It has an odd number of inhibitory synapses. (A)</p> Signup and view all the answers

    What role does the basal ganglia play when a sudden unexpected stimulus occurs?

    <p>It initiates the Hyperdirect Pathway to prioritize new actions. (B)</p> Signup and view all the answers

    Which neurotransmitter is associated with the default state of doing nothing?

    <p>GABA (A)</p> Signup and view all the answers

    Which of the following neurotransmitters is primarily associated with the output nuclei?

    <p>GABA (B)</p> Signup and view all the answers

    What is the effect of the 'global inhibition' signal sent by the basal ganglia?

    <p>It inhibits all basal ganglia-controlled movements. (B)</p> Signup and view all the answers

    What role does the Subthalamic Fasciculus play in the Basal Ganglia circuit?

    <p>It supports both direct and indirect pathways. (A)</p> Signup and view all the answers

    The pathway responsible for sending the 'global inhibition' signal is known as what?

    <p>The Hyperdirect Pathway (B)</p> Signup and view all the answers

    Which part of the basal ganglia is primarily responsible for initiating motor commands?

    <p>Caudate/Putamen (D)</p> Signup and view all the answers

    What is the primary function of the Medial Globus Pallidus within the Basal Ganglia pathways?

    <p>To inhibit outputs towards the motor cortex. (C)</p> Signup and view all the answers

    In which context does the basal ganglia function when a simple action transitions to a more complex series of movements?

    <p>By sending a global inhibition signal to restart motor planning. (A)</p> Signup and view all the answers

    Which structure provides excitatory input to the motor cortex in the context of the basal ganglia pathways?

    <p>Thalamus (B)</p> Signup and view all the answers

    What combination of actions is described in the passage while undergoing a realization due to an unexpected stimulus?

    <p>Walking and chewing bubble gum, then reprioritizing actions. (D)</p> Signup and view all the answers

    In the context of basal ganglia output pathways, what does the term 'Thalamic Fasciculus' refer to?

    <p>A direct output pathway from the basal ganglia. (D)</p> Signup and view all the answers

    How does glutamate function in relation to the default state of movement?

    <p>It promotes the engagement of motor patterns. (D)</p> Signup and view all the answers

    What is the fundamental role of the thalamus in the context presented?

    <p>It relays information critical for motor control. (B)</p> Signup and view all the answers

    What type of feedback does the entire indirect pathway provide?

    <p>Negative feedback (A)</p> Signup and view all the answers

    What type of neurotransmitter is primarily released by the Indirect Pathway within the Basal Ganglia?

    <p>GABA (D)</p> Signup and view all the answers

    Which structure within the Basal Ganglia is responsible for providing excitatory input to the Motor Cortex?

    <p>Thalamus (D)</p> Signup and view all the answers

    What is a characteristic symptom of Parkinson’s Disease as described?

    <p>Resting tremor (B)</p> Signup and view all the answers

    Which component is associated with the Direct Path within the Basal Ganglia circuitry?

    <p>Striatum (D)</p> Signup and view all the answers

    Which part of the Basal Ganglia is affected by the loss of dopamine in Parkinson’s Disease?

    <p>Substantia Nigra pars Compacta (C)</p> Signup and view all the answers

    What effect does the Indirect Pathway have on motor cortical activity?

    <p>Inhibits movement (D)</p> Signup and view all the answers

    Which neurotransmitter is associated with the excitatory signals in the Basal Ganglia circuit to the Motor Cortex?

    <p>Glutamate (A)</p> Signup and view all the answers

    What type of facial expression is often observed in individuals with Parkinson's Disease?

    <p>Masked faces (D)</p> Signup and view all the answers

    What characterizes akathisia among movement disorders?

    <p>Uncontrollable urges to move. (B)</p> Signup and view all the answers

    Which of the following is true about dystonia?

    <p>It causes sustained multi-muscle contractions that are painless. (C)</p> Signup and view all the answers

    What is the main feature of bradykinesia?

    <p>Diminished motion without muscle weakness. (B)</p> Signup and view all the answers

    Which movement disorder is characterized by large amplitude limb flailing?

    <p>Ballismus/Ballism (C)</p> Signup and view all the answers

    What distinguishes tics from other movement disorders?

    <p>They are repetitive but can be briefly suppressed with effort. (A)</p> Signup and view all the answers

    What is the primary characteristic of paratonia?

    <p>Sustained postural holding of limbs. (B)</p> Signup and view all the answers

    Which of the following best describes the symptom of akinesia?

    <p>Difficulty starting movements. (D)</p> Signup and view all the answers

    What condition can arise from long-term use of dopamine antagonist antipsychotic drugs?

    <p>Tardive Dyskinesia (A)</p> Signup and view all the answers

    How is athetosis typically described?

    <p>Continuous writhing movements that disrupt posture. (D)</p> Signup and view all the answers

    What is the primary consequence of methanol poisoning?

    <p>Blindness and putaminal hemorrhages (C)</p> Signup and view all the answers

    Which gait is characterized by dragging due to hemiplegia or paresis related to upper motor neuron lesions?

    <p>Spastic Gait (A)</p> Signup and view all the answers

    Which behavior describes complex and prolonged purposeless actions resulting from excessive phasic dopamine?

    <p>Punding (C)</p> Signup and view all the answers

    Cerebral palsy primarily results from the dysregulation of which brain region?

    <p>Cerebral Cortex (D)</p> Signup and view all the answers

    What is the primary mechanism responsible for visual impairment following methanol exposure?

    <p>Formaldehyde metabolism (A)</p> Signup and view all the answers

    What is the typical effect of hypoxia during pregnancy related to cerebral palsy?

    <p>Dysregulation of motor function (C)</p> Signup and view all the answers

    Which symptom is characteristic of punding behavior?

    <p>Compulsive organization of objects (A)</p> Signup and view all the answers

    What is the primary function of the Indirect Pathway in the context of motor control?

    <p>Provides selective inhibition of similar but unwanted actions (D)</p> Signup and view all the answers

    Which of the following components is part of the Indirect Pathway?

    <p>Subthalamic Nucleus (C)</p> Signup and view all the answers

    What type of neurotransmitter is predominantly involved in the Indirect Pathway of the Basal Ganglia?

    <p>GABA (A)</p> Signup and view all the answers

    Which statement accurately describes the interaction of the directly and indirectly activated pathways in motor control?

    <p>The Direct Pathway enhances movement while the Indirect Pathway inhibits it. (C)</p> Signup and view all the answers

    What does the indirect pathway primarily utilize among its synapses?

    <p>An odd number of inhibitory synapses (A)</p> Signup and view all the answers

    What occurs as a result of the newly disinhibited motor pattern competing with established patterns?

    <p>The disinhibited pattern remains uncoordinated and ineffective. (A)</p> Signup and view all the answers

    Which neurotransmitter is implicated in the overall function of the output nuclei within the basal ganglia?

    <p>GABA (D)</p> Signup and view all the answers

    In the context of motor control, which area primarily provides input to the motor cortex?

    <p>Thalamus (C)</p> Signup and view all the answers

    What is the consequence of an increase in GABAergic activity within the Indirect Pathway?

    <p>Inhibition of competing movements (D)</p> Signup and view all the answers

    The 'Thalamic Fasciculus' is primarily associated with which function in the basal ganglia pathway?

    <p>Executing basal ganglia output toward the thalamus (D)</p> Signup and view all the answers

    What does the term 'disinhibition' refer to in the context of motor patterns?

    <p>Release of previous motor suppression enabling new patterns (D)</p> Signup and view all the answers

    What type of feedback is provided by the indirect pathway of the basal ganglia?

    <p>Negative feedback (D)</p> Signup and view all the answers

    The role of the Subthalamic Fasciculus in the basal ganglia circuitry is primarily related to which aspect?

    <p>Connecting the direct and indirect pathways (A)</p> Signup and view all the answers

    Which part of the basal ganglia is most directly involved in inhibitory control of the motor cortex?

    <p>Medial Globus Pallidus (B)</p> Signup and view all the answers

    What is the primary role of glutamate in the context of the basal ganglia signaling pathways?

    <p>To provide excitatory input to the motor cortex (D)</p> Signup and view all the answers

    Which structure receives input from the Lateral Globus Pallidus within the basal ganglia pathways?

    <p>Motor thalamus (A)</p> Signup and view all the answers

    What characterizes the axons connecting the motor cortex to the subthalamus in the Hyperdirect Pathway?

    <p>They are large and myelinated. (C)</p> Signup and view all the answers

    What is the primary effect of the Hyperdirect Pathway on the motor thalamus and cortex during the initiation of motor patterns?

    <p>A sudden increase in inhibition. (A)</p> Signup and view all the answers

    Which statement regarding the global inhibition signal in the basal ganglia is accurate?

    <p>It reaches the motor thalamus and cortex before any other signals. (A)</p> Signup and view all the answers

    In the context of the Hyperdirect Pathway, what role do GABA neurotransmitters primarily play?

    <p>To promote inhibition within the motor control pathways. (A)</p> Signup and view all the answers

    What is the functional outcome of the 'phasic' increase in inhibition initiated by the Hyperdirect Pathway?

    <p>It prevents the occurrence of unintended movements. (A)</p> Signup and view all the answers

    What neurotransmitter is primarily associated with the excitatory signals in the basal ganglia circuit to the motor cortex?

    <p>Glutamate (B)</p> Signup and view all the answers

    Which structure provides inhibitory input through GABA in the indirect pathway?

    <p>Medial Globus Pallidus (D)</p> Signup and view all the answers

    Which characteristic best describes the Indirect Pathway in terms of its overall function?

    <p>Inhibits unwanted motor actions (B)</p> Signup and view all the answers

    What is a common symptom associated with Parkinson’s Disease related to emotional expressiveness?

    <p>Masked faces with a loss of emotional expressions (A)</p> Signup and view all the answers

    In the context of the basal ganglia and its pathways, which component is primarily affected by the loss of dopamine in Parkinson’s Disease?

    <p>Substantia nigra pars compacta (D)</p> Signup and view all the answers

    Which pathway is responsible for sending a 'global inhibition' signal to other parts of the brain?

    <p>Indirect Pathway (B)</p> Signup and view all the answers

    What effect does increased activity in the indirect pathway have on the thalamus?

    <p>Inhibits thalamic activity (B)</p> Signup and view all the answers

    Which neurotransmitter is primarily released by the indirect pathway within the basal ganglia?

    <p>GABA (D)</p> Signup and view all the answers

    What is the mechanism of the Hyperdirect Pathway in initiating new motor patterns?

    <p>It causes a phasic increase in inhibition of the motor thalamus and cortex. (B)</p> Signup and view all the answers

    Which statement best describes the axons connecting the motor cortex to the subthalamus in the Hyperdirect Pathway?

    <p>They are large and myelinated. (B)</p> Signup and view all the answers

    What type of signal does the global inhibition from the basal ganglia reach before any other signals?

    <p>A motor thalamus and cortex signal. (A)</p> Signup and view all the answers

    What is the primary function of the direct pathway in the basal ganglia?

    <p>Facilitate disinhibition of motor cortex (D)</p> Signup and view all the answers

    In terms of neurotransmitter activity, what role does GABA play in the Hyperdirect Pathway?

    <p>It increases inhibition of the motor thalamus and cortex. (B)</p> Signup and view all the answers

    Which neurotransmitter is predominantly involved in facilitating action within the context of the basal ganglia?

    <p>Glutamate (B)</p> Signup and view all the answers

    Which aspect of the Hyperdirect Pathway sets it apart from the Direct and Indirect pathways?

    <p>It produces a rapid phasic change in inhibition. (C)</p> Signup and view all the answers

    In the context of basal ganglia circuitry, what is the significance of the output to the thalamus?

    <p>It allows for modulation of motor patterns based on sensory input. (A)</p> Signup and view all the answers

    How does the basal ganglia initiate a newly selected action from a reset initial state?

    <p>Using the direct pathway for disinhibition. (C)</p> Signup and view all the answers

    Which statement accurately describes the role of GABA in the context of the indirect pathway?

    <p>GABA is primarily responsible for inhibiting unwanted actions. (A)</p> Signup and view all the answers

    What is the distinguishing characteristic of akathisia compared to other movement disorders?

    <p>Uncontrollable urges to move without restful state (D)</p> Signup and view all the answers

    Which of the following describes the symptoms of dystonia?

    <p>Sustained postural muscle contractions with twisting movements (B)</p> Signup and view all the answers

    What type of movement disorder involves involuntary, intermittent vocalizations?

    <p>Tics (B)</p> Signup and view all the answers

    Which movement disorder is characterized by slow or fast discrete involuntary movements?

    <p>Chorea (C)</p> Signup and view all the answers

    What movement disorder is typically characterized by excessive muscle movement without intentional control?

    <p>Hyperkinesia (C)</p> Signup and view all the answers

    Bradykinesia is primarily defined by which of the following characteristics?

    <p>Slower than normal movement with starting hesitation (A)</p> Signup and view all the answers

    Which of the following describes ballismus?

    <p>Excessive limb flailing with larger amplitude movements (B)</p> Signup and view all the answers

    What best describes the nature of athetosis as a movement disorder?

    <p>Continuous, slow writhing movements affecting posture (B)</p> Signup and view all the answers

    What is the main function of the Indirect Pathway in movement coordination?

    <p>Enhances motor pattern selectivity by inhibiting unwanted actions (B)</p> Signup and view all the answers

    Which structure primarily interacts with the Indirect Pathway's neurotransmitter?

    <p>Caudate/Putamen (A)</p> Signup and view all the answers

    Which neurotransmitter primarily facilitates the functions of the Indirect Pathway?

    <p>GABA (A)</p> Signup and view all the answers

    What role does the newly disinhibited motor pattern play in movement dynamics?

    <p>It competes with uncoordinated muscle actions to establish control (B)</p> Signup and view all the answers

    Which component is essential in the indirect pathway to modulate motor control effectively?

    <p>Medial Globus Pallidus (D)</p> Signup and view all the answers

    What determines the effectiveness of the Indirect Pathway in suppressing unwanted movements?

    <p>The level of GABAergic influence in the striatum (B)</p> Signup and view all the answers

    In terms of motor coordination, what is the significance of the interaction between the Direct and Indirect Pathways?

    <p>They work in a balanced manner to facilitate smooth motor execution (B)</p> Signup and view all the answers

    What is the nature of the competition faced by newly disinhibited motor patterns?

    <p>They must outcompete pre-existing uncoordinated patterns (D)</p> Signup and view all the answers

    What is a potential consequence of long-term use of dopamine antagonist antipsychotic drugs?

    <p>Punding (C)</p> Signup and view all the answers

    Which condition is described as a non-progressive motor disorder caused by dysfunction in the cerebral cortex?

    <p>Cerebral Palsy (D)</p> Signup and view all the answers

    What is the characteristic symptom of Tardive Dyskinesia?

    <p>Frog-like mouth movements (B)</p> Signup and view all the answers

    What is the primary harmful metabolite produced from methanol?

    <p>Formaldehyde (B)</p> Signup and view all the answers

    Which symptom is associated with bilateral putaminal hemorrhages due to methanol poisoning?

    <p>Motor symptoms (A)</p> Signup and view all the answers

    Which gait is typically characterized by foot-dragging and is often associated with hemiplegia?

    <p>Spastic Gait (A)</p> Signup and view all the answers

    What does the presence of decreased vision within days of methanol exposure indicate?

    <p>Acute toxicity (C)</p> Signup and view all the answers

    What leads to excessive phasic dopamine and subsequent punding behavior?

    <p>Excessive dopamine activity (D)</p> Signup and view all the answers

    What role do the output nuclei of the basal ganglia play in relation to self-generated movements?

    <p>They act as a 'brake' on movements. (C)</p> Signup and view all the answers

    What characterizes the tonic GABAergic activity of the basal ganglia output nuclei?

    <p>It consistently inhibits thalamus and cortex activity. (D)</p> Signup and view all the answers

    How does minimal activity in the basal ganglia affect overall movement control?

    <p>It completely prevents all forms of action. (D)</p> Signup and view all the answers

    What is the main consequence of high levels of activity in the basal ganglia?

    <p>It allows for multitasking without necessarily speeding up movements. (D)</p> Signup and view all the answers

    Which structure predominantly contributes to the inhibition of the motor cortex through the basal ganglia?

    <p>Substantia Nigra pars Reticulata (C)</p> Signup and view all the answers

    Which statement best describes the relationship between the direct and indirect pathways in the basal ganglia?

    <p>The direct pathway promotes movement, whereas the indirect pathway inhibits it. (D)</p> Signup and view all the answers

    What can be concluded about the effects of the indirect pathway in the basal ganglia?

    <p>It allows for selective inhibition of non-essential movements. (A)</p> Signup and view all the answers

    What is the significance of the basal ganglia's 'global inhibition' signal?

    <p>It ensures that unwanted movements are suppressed. (D)</p> Signup and view all the answers

    Study Notes

    Basal Ganglia Overview

    • The basal ganglia are a group of subcortical nuclei involved in motor control, cognition, and emotion.
    • They play a role in initiating and regulating movement, but do not directly control muscles.
    • Direct and indirect pathways are key components of basal ganglia functioning, affecting movement.
    • The basal ganglia receive input from various cortical areas and send output to motor areas, involving the thalamus.

    Lecture Objectives

    • Students should be able to recognize and predict symptoms of major hypokinetic/hyperkinetic movement disorders (Parkinson's, Huntington's, Cerebral Palsy, Tardive Dyskinesia).
    • Students should be able to trace the direct and indirect pathways from cerebral cortex to basal ganglia and thalamus, then back to cerebral cortex.
    • Predict movement disorders from lesions in specific regions of the basal ganglia, tracts, and cortex.
    • Identify basal ganglia structures in cross-sections.

    Moving Words (Motor Deficits)

    • Akathisia: Uncontrollable urges to move
    • Athetosis: Writhing movements, slower and longer than chorea
    • Ballismus (Ballism): Large-amplitude limb flailing
    • Chorea: Discrete involuntary movements (fast or slow)
    • Hyperkinesia: Excessive and abnormal movements
    • Hypokinesia: Diminished movement (not weakness)
    • Bradykinesia: Slow movement, including "start hesitation"
    • Akinesia: Inability to initiate or complete movements
    • Tics: Repeated intermittent movements or vocalizations
    • Cramps: Involuntary painful muscle contractions
    • Dystonia: Painless, sustained, postural contractions that can lead to twisting movements (e.g., Blepharospasm)
    • Paratonia: Involuntary holding positions (e.g., "waxy flexibility")

    Basal Ganglia Anatomy

    • The basal ganglia are comprised of several structures: Caudate nucleus, Putamen, Globus Pallidus, Substantia Nigra, Subthalamic Nucleus.
    • These structures are involved in regulating and initiating voluntary movement

    Inhibitory Interneurons and Logic

    • Neurons have a spontaneous firing rate.
    • Excitation (e.g., glutamate) increases the firing rate.
    • Inhibition (e.g., GABA) decreases the firing rate.
    • Inhibition of an inhibitory neuron causes "disinhibition."
    • Pathways with an odd number of inhibitory synapses are inhibitory, and those with an even number are excitatory.

    Your Brain is a Tortellini

    • The embryonic telencephalon develops as an asymmetrically thick tube.
    • The pallium forms the thin outer layer, and the subpallium forms the thicker basal layer.
    • The pallium becomes the cortex, claustrum, and hippocampus
    • The subpallium is the basal ganglia

    Basal Ganglia - Anatomy and Classification

    • Detailed diagram of basal ganglia structures labels structures and locations.
    • Classification of nuclei: Input nuclei (striatum), Intrinsic Nuclei (substantia nigra pars compacta and externa segment of globus pallidus and medial segment of globus pallidus), and Output nuclei (substantia nigra pars reticulata and internal segment of globus pallidus)

    Inputs to Basal Ganglia

    • Major input to the striatum (caudate and putamen) is excitatory from layer 5 of the cerebral cortex.
    • Different cortical areas send input to the basal ganglia

    Basal Ganglia - Output

    • Output nuclei (e.g., medial globus pallidus, substantia nigra pars reticulata) send GABAergic inhibitory signals to motor thalamus.
    • Thalamus projects to Motor Cortex

    A typical basal ganglia scenario

    • Without outside stimulation, the basal ganglia's output nuclei inhibit the motor cortex and thalamus (default state).
    • Basal Ganglia activation enables the coordination of actions using different muscles and joints, preventing simultaneous actions using the same muscles.
    • Minimally active basal ganglia prevent all action, while high basal ganglia activity allows for multitasking.

    Pathways

    • Direct Pathway, Indirect Pathway, Hyperdirect Pathways
    • The hyperdirect pathway is a rapid pathway that allows for rapid inhibition across the basal ganglia. This pathway is critical when a new task is to be performed.
    • The indirect pathway is used for inhibiting competing actions, allowing for better performance of the main task.
    • The direct pathway is the fastest pathway and is responsible for initiation of action selections.

    Problems in Pathways

    • Hemiballismus/Ballism (unilateral basal ganglia lesion on one side of the body) -Caused by subthalamic lesions
    • Huntington's Chorea (autosomal dominant disease, degeneration of caudate nucleus neurons, less inhibition of the external globus pallidus)

    Huntington's Disease

    • Gross morphology: Small brain with caudate and putamen atrophy.
    • Atrophy of frontal lobe.
    • Intranuclear protein inclusions (containing huntingtin) in striatum and cortex
    • Symptoms: Uncontrolled movements (chorea), slurred speech, difficulty with coordination, cognitive decline, emotional changes

    Dopamine (Substantia Nigra)

    • Dopamine is like "motor oil" for the corticospinal tract.
    • Counteracting the tonic inhibitory output of the medial globus pallidus and sub nigra reticulata
    • Dopamine receptors modulate the balance of direct and indirect pathways (D1 receptors excite, D2 receptors inhibit).

    Parkinson's Disease

    • ~1.5-2% prevalence in individuals over 65.
    • Loss of pars compacta dopaminergic neurons, resulting in disinhibition of the indirect pathway and under-facilitation of the direct pathway.
    • Genetic mutations (e.g., PARK18) and environmental factors are implicated.
    • Presence of Lewy bodies: Aggregates of alpha-synuclein protein.
    • Often is associated with other synucleinopathies (e.g., Lewy Body Dementia).
    • Symptoms include resting tremor, slow movement, rigidity, impaired balance, and masked facial expressions.
    • DaTscan can be used to detect the nigrostriatal dopamine degenerations.

    Differential Diagnosis of Parkinsonism

    Possible causes of Parkinson's-like symptoms, including genetic and environmental factors, drug-induced parkinsonism, vascular parkinsonism, and brain trauma, as well as diseases like Progressive Supranuclear Palsy (PSP), Multiple System Atrophy (MSA), and Corticobasal Ganglionic Degeneration (CBD).

    Warning Signs of Parkinson's Plus Conditions

    • Characteristics of Parkinson's-plus conditions differentiate them from typical Parkinson's disease (e.g., early autonomic dysfunction, rapid progression, etc.)

    Side Effects of Dopamine Replacement Drugs

    • Excessive dopamine can cause psychosis (hallucinations, delusions).
    • Insufficient dopamine can lead to negative symptoms (e.g., alogia, avolition, flat affect)
    • Blocking dopamine in the nigrostriatal pathway can worsen parkinsonian symptoms.
    • Tardive dyskinesia, punding, dopamine dysregulation syndrome (DDS).

    Methanol Poisoning

    • Methanol, often found in windshield washer fluid, is metabolized to formaldehyde.
    • Exposure can cause decreased vision, blindness and bilateral putaminal hemorrhages.
    • Methanol poisoning may present with neurological symptoms and eventually lead to fatality.

    Cerebral Palsy

    • Non-progressive motor disorder from dysregulation of cerebral cortex.
    • Often caused by exposure to hypoxia or toxins during pregnancy.
    • Several types exist, including spastic, dyskinetic, ataxic, and mixed.
    • Symptoms vary in severity and type. Can affect gait, coordination, tone, strength and motor skills and other abilities but is not progressive.

    Practice Questions 1 & 2

    • Details for the practice questions (patient symptoms seen with a particular MRI image, the type of slice, the red structure represented, and affected pathways in the second question are included).

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    L9 MedNeuro2 Sp25 Lec9 Basal Ganglia PDF

    Description

    This quiz covers the essential functions and structures of the basal ganglia, including their role in motor control, cognition, and emotional regulation. Students will explore various movement disorders associated with basal ganglia dysfunction, such as Parkinson's and Huntington's disease. Understand the pathways involved in motor output and the significance of these subcortical nuclei.

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    L9 Fat-Soluble Vitamins Quiz
    42 questions

    L9 Fat-Soluble Vitamins Quiz

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    PamperedNewOrleans
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