I am studying the direct and indirect pathways of Parkinson’s Disease. Is it safe to say the GPI and GPE’s neurotransmitter is GABA, which is inhibitory, the subthamlamic/thalamic neurotransmitter is Glutamate, which is excitatory, and the substantia nigra’s neurotransmitter is Dopamine (which is excitatory in the direct pathway and inhibtory in the indirect pathway?
I think you’ve got it! Dopamine can be excitatory or inhibitory depending on its receptor. In the direct pathway, dopamine binds to D1 receptors, which are excitatory. In the indirect pathway, it binds to D2 receptors, which are inhibitory.
If you want some more information and/or a different presentation of the pathways, the below website does a nice job of summarizing the direct and indirect pathways. Be careful not to get too “in the weeds” here for exam prep purposes – a basic understanding of the pathways and their impact on movement will likely be sufficient for the NCS exam!