Basal Ganglia Flashcards
What are the various structures related to the basal ganglia?
- Caudate
- Putamen
- Globus pallidus
- Substantia nigra
- Subthalamus
T/F: The putamen is a large nucleus with a head, body, and tail.
FALSE
Caudate
T/F: Of the basal ganglia components, the caudate is the most involved with cognitive functions.
TRUE
Which basal ganglia structure travels just lateral to the lateral ventricle?
Caudate
In a coronal section, put these in order from lateral to medial: putamen, globus pallidus, insula, thalamus.
- Insula
- Putamen
- Globus pallidus
- Thalamus
What are the two parts of the substantia nigra?
- Compact
2. Reticular
The ______ part of the substantia nigra is a basal ganglia output nucleus.
Reticular
The _______ part of the SN contains densely packed, pigmented neurons.
Compact
A 50 year old man presents with chorea, muscle rigidity, and cognitive disturbances. A brain scan shows degeneration of the striatum. What is the disease?
Huntington’s Disease
What are the four basic loops of the basal ganglia?
- Motor loop: learned movements
- Cognitive loop: motor intentions
- Limbic loop: emotional aspects of movement
- Oculomoter loop: voluntary saccades
Which nucleus of the BG does the motor loop utilize?
Putamen
Which nucleus of the BG does the cognitive loop use?
Caudate
While learning a movement the _______ loop is used, once it is learned the _____ loop is used.
Cognitive; motor
What parts of the BG are important in the oculomotor loop?
Caudate and Substantia nigra
What is the major excitatory neuron in the direct pathway?
Glutamate (cerebral cortex and thalamus)
What is the major inhibitory neuron in the direct pathway?
GABA (striatum and GPi)
Describe the direct pathway of the motor loop in the BG.
Cerebral cortex excites striatum -> striatum inhibits GPi -> inhibited GPi now sends less inhibition to thalamus -> thalamus is more active in exciting cerebral cortex -> more movement
What two pathways come together to form the thalamic fasciculus on the way to the thalamus?
Lenticular fasciculus and ansa lenticularis
T/F: The direct pathway is used to move.
TRUE
What are the added steps in the indirect pathway?
Striatum inhibits GPe -> inhibited GPe sends less inhibition to subthalamus -> subthalamus excites GPi -> GPi inhibits thalamus -> thalamus sends less excitation to cerebral cortex -> suppressed movement
In the direct and indirect pathways, which structures are excitatory?
- Cerebral cortex
2. Subthalamus 3. Thalamus
In the direct and indirect pathways, which structures are inhibitory?
- Striatum
2. GPi and GPe
In the indirect pathway the ___ is inhibited, causing the ______ to excite the ___.
GPe; subthalamus; GPi
Results in more inhibition of thalamus and less movement
What would damage to the subthalamus result in?
More unsuppressed cortical output
What is the role of the subthalamus?
Uses disinhibition to suppress unwanted movement
T/F: The direct and indirect pathways work simultaneously.
TRUE
What causes parkinson’s disease?
Degeneration of nigrostriatal fibers
In a patient with parkinson’s disease, _________ will be seen in the compact part of the substantia nigra.
Lewy bodies
What are the three cardinal features of Parkinson’s?
- Bradykinesia (slow movement)
- Resting tremor
- Rigidity
Which pathway is favored in a Parkinson’s disease patient?
Indirect
How does levadopa treat Parkinson’s?
Replaces dopamine
What is a pallidotomy?
Selectively damage the GPi so there is less inhibition on the thalamus
