Flashcards in Basal Ganglia Deck (54):
What are the basal nuclei?
1. Caudate nucleus
3. Globus pallidus
4. Subthalamic nucleus
5. Substantia nigra
What are the two parts of the substantia nigra?
Putamen + caudate nucleus = ?
Review Spoctor's basal ganglia lecture
Main afferents to the basal ganglia are to where?
Main efferents from the basal ganglia are from where?
What is the function of the VA/VL complex in the thalamus on the frontal cortex?
What is the function of the basal ganglia on the thalamus?
What are the four major loops of the basal ganglia?
What is the pathway of the basal ganglia innervation?
AND BACK TO CORTEX!
True or false: The basal ganglia does not get input from the spinal cord directly.
What is the direct path through the basal ganglia?
Striatum to the GP/SN
What does the globus pallidus do to the thalamus?
Tonically inhibits it
Where does the substantia nigra fit into the basal ganglia motor loops?
Stimulates the caudate/putamen
What is the effect of the cortex on the striatum? What does the striatum do?
Cortex will stimulate the putamen, which inhibits the pallidum, which inhibits the excitatory thalamus
What is the indirect pathway through the basal ganglia?
GP to subthalamic nucleus, or to GP/SN
STN to GP/SNr
What neurotransmitter does the cerebral cortex release that has an effect on the striatum?
What neurotransmitter does the striatum release that has an effect on the globus pallidus?
GABA (inhibitory) and something else
What are the two parts of the BG loops that release E?
What neurotransmitter do most parts of the BG release, except for the cortex and subthalamic nucleus?
Where does the body movement loop start in the cortex? (3)
Primary motor, premotor and supplementary motor
How can the body movement loop be specific?
might selectively activate some movements and suppress others
What part of the cortex does the oculomotor loop start in?
FEF and supplementary eye field
What is the function of the oculomotor loop?
Involved in the control of saccadic eye movements
Where does the prefrontal loop start in the cortex?
Dorsolateral prefrontal cortex
What is the function of the prefrontal cortex?
regulate the initiation and termination of cognitive processes such as planning, attention and working memory
What part of the cortex does the limbic loop start in?
Anterior cingulate gyrus
What is the function of the limbic loop?
regulate emotional behavior and motivation
What are the symptoms of parkinsonism? (3)
-Rhythmic tremor at rest
-Bradykinesia (or akinesia)
-Postural flexion and instability
What is the incidence of parkinson's disease in patients over the age of 60?
When does parkinson's usually appear?
What is the gait like in parkinson's?
Small, shuffling steps and the absence of arm swing that normally accompanies or walking
What is the handwriting like in parkinson's?
What is the frozen gait syndrome seen in Parkinson's?
Sudden inability to start walking
What is the pathophysiology of Parkinson's?
Degeneration of dopaminergic projection to striatum from the substantia nigra
What is the protein that is accumulated in Parkinson's?
What are the facies seen in parkinson's?
Mask like (cannot initiate movements)
What are the cells that are lost in Parkinson's? How many do you have to lose to show symptoms?
What is the effect on the basal ganglia circuitry when the substantia nigra is removed?
Increased inhibition to the globus pallidus, leading to less inhibition of the subthalamic nucleus
More tonic inhibition of the thalamus
What are the two pharmacologic treatments for parkinson's?
What is the MOA of deep brain stimulation for Parkinson's?
Stimulate the dopaminergic neurons
What are the symptoms of Huntington's?
What is the pathophysiology of Huntington's? (3)
a. First selective loss of GABA/enkephalin projection from striatum to GPe
b. Later more widespread degeneration of striatal neurons
c. Also loss of cortical neurons
What is the genetic basis for Huntington's disease? How is it inherited?
Triplet CAG repeat in Huntingtin gene.
Inherited in an AD fashion
After how many CAG repeats does Huntington's become symptomatic? What is the relationship between age of onset, and number of repeats?
40 or more
More = earlier onset
What is hemiballismus?
involuntary, violent, flinging movements of a limb while the patient is awake
What is tardive dyskinesia?
iatrogenic disorder due to long-term treatment with drugs that affect dopamine systems
What is athetosis?
Slow, writhing movements
What are chorea?
brief, sudden, random, twitch-like movements of limbs or facial muscles. They resemble fragments of normal voluntary movement.
What is the effect on the basal ganglia in Huntingtons?
Loss of striatum inhibition to the external segment of the globus pallidus,
Thus increased inhibition of the internal segment of the GP, resulting in greater inhibition of the thalamus
Draw out the basal ganglia pathway.
Hemiballismus is often associated with a lesion where?
What is the pathophysiology of Tardive dyskinesia?
Antipsychotic drugs cause denervation hypersensitivity since they block dopamine receptors