10 Basal Ganglia II Flashcards
what are the main inputs to the basal ganglia? what about outputs?
inputs: striatum
outputs: globus pallidus, SNR
in the resting state, what does the basal ganglia do the the thalamus?
The basal ganglia suppress movement by inhibiting the thalamus and ultimately the cortex
What is the function of the internal basal ganglia circuits?
to connect the input side (striatum) to the output sides (GPi and SNR)
what are the two basic circuits called in the basal ganglia?
direct and indirect (This is what allows the striatum to work on the GPi and SNR)
In general, the direct pathway of the basal ganglia is to? and the indirect pathway is to what?
direct pathway= bringing about wanted movements
indirect pathway= suppressing unwanted movements
Describe the pattern of the direct pathway of the basal ganglia?
1) striatum (caudate nucleus and putamen)
2) D1 receptors on MSN (substance P and dynorphin)
3) GPi/SNR
4) Thalamus
5) cerebral cortex
6) Motor action
which two areas have a major effect on the D1 and D2 receptors of the MSN’s?
Cortex (directly from brain)
SNC (releasing dopamine)
what are the differences between MSN’s that are activated by the D1 vs D2 receptors?
MSN’s start in the striatum and go to the GPi (direct) or to the GPe (indirect). Those going to the GPi contain substance P and dynorphin (D1 receptors), and those going to the GPe contain enkephalin (D2 receptors).
What activates the D1 and D2 receptors? where does this stuff come from?
1) dopamine
2) SNC
MSN’s projecting to the GPe are inhibitory/excitatory?
inhibitory. They prevent the inhibition of the of the STN by inhibiting the inhibitor.
what is the indirect pathway of the basal ganglia?
1) striatum
2) D2 receptor on MSN (enkephalin)
3) GPe
4) Subthalamic nuclei (STN)
5) GPi
6) Thalamus (VA)
7) Cerebral cortex
8) motor action
What is the key monoaminergic transmitter in basal ganglia function?
Dopamine
note that seratonin and norepinephrine also have a small affect
when mentioned in the notes as the striatum, what is generally being referred to?
putamen and caudate nucleus
what is the nigrostriatal pathway?
the pathway of dopamine release from the SNC to the caudate nuclei and putamen.
where do most axon terminals end of the dopaminergic axons coming from the SNC?
on the dendrites of the MSN in the striatum. (some end on interneurons)
T/F the globus pallidus, subthalmic nucleus, and SNR have dopamine input?
True (clarification needed here) page 3 basal ganglia 2
dopamine released into the striatum promotes what?
movement!
what does dopamine do to the D1 receptors? D2 receptors?
dopamine is excitatory to the D1 receptors, and inhibitory to the D2 receptors.
If I have an idea to move, how do I get to the point where I release dopamine?
1) Idea in frontal cortex
2) striosomal pathway (striatum to SNC)
3) SNC to striatum through dopamine releasing neurons.
4) release of dopamine on MSN neurons in desired loop (direct and indirect)
what is a hypokinetic disorder?
akinesia or the inability to move like normal
Is Parkinsons disease hypo or hyper kinetic?
hypokinetic
what causes parkinsons disease?
the loss of dopaminergic neurons in the SNC
The loss of dopaminergic neurons releasing dopamine causes a decrease in dopamine being released in the striatum. What are the down stream affect of this on the direct pathway?
1) no dopamine=no activation of D1
2) no inhibition GPi/SNR
3) GPi/SNR can now inhibit thalamus.
4) No stimulation of cortex by thalamus
what if you have a stroke that affects the basal ganglia? SNC?
This can cause parkinsons
