Which area of the basal ganglia is considered inhibitory in the direct pathway?

The internal globus pallidus is regarded as an inhibitory component in the direct pathway of the basal ganglia circuitry. The direct pathway functions to facilitate movement by promoting the activity of the motor cortex. When the striatum (composed of the caudate and putamen) receives excitatory input from the cortex and other brain structures, it becomes activated and subsequently inhibits the internal globus pallidus.

This inhibition means that the internal globus pallidus, which normally sends inhibitory signals to the thalamus (and thereby inhibits movement), is less active. As a result, reduced inhibitory output from the internal globus pallidus allows the thalamus to become more active and send excitatory signals back to the motor cortex, promoting movement. This pathway highlights how the basal ganglia regulate movement by balancing excitatory and inhibitory influences.

In contrast, the other areas mentioned, such as the putamen and the external globus pallidus, have different roles in the basal ganglia circuitry. The putamen plays a role in receiving and processing information, while the external globus pallidus acts as a relay within the indirect pathway rather than contributing to the inhibitory aspect of the direct pathway. The nucleus accumbens is primarily involved in the reward circuitry and