why nor-adrenaline which is released from substantia nigra has excitatory effect on works of basal nuclei while dopamine has inhibitory effect

Answer 1

I'm sorry, but that statement is not accurate. Norepinephrine (nor-adrenaline) is not released from the substantia nigra, but rather from neurons in the locus coeruleus, which is located in the brainstem. The substantia nigra, on the other hand, releases dopamine.

Dopamine released from the substantia nigra has an excitatory effect on the basal ganglia, particularly the direct pathway. It helps facilitate movement by promoting the activation of the motor cortex and inhibiting unwanted movement.

Norepinephrine, on the other hand, has a modulatory effect in the brain that varies depending on the receptor type it binds to. In general, it can have both excitatory and inhibitory effects depending on the specific brain region and receptors involved.

It's important to note that the functioning of the basal ganglia is a complex process involving interactions between various neurotransmitters, including dopamine, GABA, and glutamate. The exact mechanisms and effects of these neurotransmitters on the basal ganglia are still being studied and understood.