Basal Nuclei
Biology
Level
pending
If the nigrostriatal supply undergoes deterioration, what will cause hypokinesia?
The over-inhibition of the indirect pathway by choline and glutamate.
The over-stimulation of the striatopallidal neurons of the direct pathway by choline and glutamate.
The loss of the cholinergic stimulation to the GABAergic neurons of the putamen.
The inhibition of the direct pathway's motor output as there is no dopamine to begin motor output.
The loss of the only pathway necessary for the initiation of motor output of the indirect pathway.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
1 solution
Dopaminergic (nigrostriatal) fibres initiate movement through both the direct & indirect pathway. They act on GABAergic (striatopallidal)* fibres as follows:
I. Direct pathway: D1 (stimulatory) receptors which stimulate the neurons* and initiate movement.
II. Indirect pathway: D2 (inhibitory) receptors which inhibit the neurons* but initiate movement.
The summary is: Dopaminergic system initiates movement through both the pathways and is the only initiator of the indirect pathway.
Cholinergic system terminates movement through both the pathways and is the only terminator of the direct pathway. It is antagonistic to dopaminergic system.
Glutaminergic system works within the pathways and stimulates the successive neurons. It also initiates movement through the direct pathway but terminates it through the indirect pathway.
GABAergic system works within the pathways and is inhibitory to the successive neurons.
Now, the analysis of choices:
When dopaminergic system is absent, the only initiator of the indirect pathway is lost as cholinergic and glutaminergic systems continue to terminate the movement. This is the correct one.
Though the direct pathway is less stimulated for it has lost one of its initiators, the glutaminergic system is still there to support it.
Cholinergic & glutaminergic systems are untouched and continue their function as before.