MCQ – 92580

Arrange the following structures in the correct sequence involved in the direct pathway of the basal ganglia:

1. Striatum
2. Globus pallidus
3. Substantia nigra
4. Thalamus
5. Cortex

Correct Answer � C Explanation

The direct pathway in the basal ganglia plays a critical role in facilitating movement by reducing inhibitory signals from the globus pallidus, which results in increased thalamic excitation of the motor cortex.

Here’s the correct sequence:

1. Cortex: The pathway begins when excitatory signals are sent from the motor cortex to the striatum.
2. Striatum: The striatum (caudate and putamen) receives excitatory input from the cortex and sends inhibitory signals to the globus pallidus internus (GPi) and substantia nigra pars reticulata (SNr).
3. Globus pallidus internus : The GPi is inhibited by the striatum, which reduces its inhibitory effect on the thalamus.
4. Substantia nigra pars compacta : The substantia nigra provides dopaminergic input to the striatum, facilitating this pathway.
5. Thalamus: With reduced inhibition from the GPi, the thalamus is free to send excitatory signals back to the motor cortex, enhancing movement.