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Movement Disorders
Basal Nuclei review
Question | Answer |
---|---|
How does the basal ganglia influence descending motor pathways? | Through complex feedback loops that project information to the motor cortex |
Where does cortical input to the Basal Ganglia arise from? | Prefrontal, motor cortex (M1,premotor area, supplementary motor area) and parietal cortex |
Besides general motor functions, the basal ganglia also influences what functions? | eye movements frontal executive / cognitive fxns (DLPFC) Limbic pathways (emotions/memory) |
What are the players in the major loop that influences the motor cortex? | cortex > striatum > pallidum > thalamus > cortex |
What is the primary receptor region for input to the Basal Ganglia? | putamen |
What are the 2 main types of movement disorders in the Basal Ganglia? | Hypokinetic Hyperkinetic |
How are the hyperkinetic movement disorders further subdivided? | jerky non-jerky |
What is the difference between the globus pallidus interna and the thalamus? | GPi - neurons are spontaneously active and inhibit the thalamus Thalamus - neurons are excitatory to the SMA of the cortex. |
What is the net result of the direct pathway? | excitation of SMA, increased motor activity |
What is the net result of the indirect pathway? | inhibition of SMA, decreased motor activity |
What are the main components of the Basal Ganglia? | Caudate Nucleus Putamen Globus Pallidus Substantia Nigra Subthalamic Nucleus |
What are the basal ganglia components that comprise the striatum? | Caudate Nucleus Putamen |
What are the basal ganglia components that comprise the lentiform nucleus? | Putamen Globus Pallidus |
What is the anatomical relationship of the caudate nucleus to the internal capsule? | Caudate is always medial |
What is the anatomical relationship of the putamen and globus pallidus to the internal capsule? | Putamen and globus pallidus are always lateral |
What part of the substantia nigra is pigmented? | the dorsal part, the Substantia Nigra pars compacta |
What is the term for the ventral Substantia Nigra? | Pars Reticulata |
What is the nature of the input to the basal ganglia? | excitatory, glutamatergic to striatum |
What is the nature of the neurons of the putamen? | inhibitory, gaba-ergic fibers |
What is the nature of the neurons of the Globus Pallidus interna? | inhibitory, gaba-ergic fibers |
What is the state of the GPi at rest? | inhibitory to the thalamus (via pallidothalamic gaba-ergic fibers) |
Parkinson's disease is what type of movement disorder? | hypokinetic |
Classic features of parkinson's disease? | bradykinesia resting tremor hypomimia freezing festinating gait cogwheel rigidity decrease arm swing postural instability |
Huntington's disease is what type of movement disorder? | hyperkinetic |
Classic features of Huntington's disease? | choreoathetosis slowed saccades fatal 20 yrs after sx appear autosomal dominant gene |
Explain/diagram direct pathway? | cortex and Sub nigra (D1) activates putamen, which inhibits GPi, which inhibits thalamus, which excites Cortex causing net excitation |
Explain/diagram indirect pathway? | cortex and Sub nigra inhibits (D2) striatum, which inhibits GPe, which inhibits Subthalamic nucleus which activates GPi, which inhibits thalamus, which excites Cortex causing net inhibition of movement |