Question

When a decision is made to move, the striatum receives excitatory glutamatergic input from virtually all regions of the cerebral cortex. In addition to the cortical input, the striatum also receives input from dopaminergic neurons of the SNpc (pars compacta). The dopamine input, however, serves mainly as a modulator of transmission from the cortex to the striatum.

Options:
a) D1 receptors are found in the direct (Go) pathway of the striatum.
b) D2 receptors are found in the indirect (Stop) pathway.

Answer 1

The striatum receives excitatory input from the cerebral cortex and modulatory dopaminergic input from the SNpc. D1 receptors are involved in the direct pathway that facilitates movement, while D2 receptors participate in the indirect pathway that inhibits movement. These pathways and their receptors play critical roles in motor control.

Step-by-step explanation:

In the neuroscience of motor control, the striatum of the brain receives excitatory glutamatergic input from the cerebral cortex and is also influenced by dopaminergic neurons from the substantia nigra pars compacta (SNpc). The dopaminergic input modulates the corticostriatal transmission primarily through two types of dopamine receptors: D1 and D2 receptors. D1 receptors are predominantly found in the direct pathway (also known as the 'Go' pathway), which facilitates movement. Conversely, D2 receptors are mainly located in the indirect pathway (referred to as the 'Stop' pathway), which inhibits movement. The switch between these pathways plays a crucial role in the regulation of motor activity. For example, when the SNpc is active, movement is facilitated through the direct pathway activation, which triggers disinhibition of the thalamus and consequently excites the cortex. In contrast, when the SNpc is silent, the indirect pathway reinforces thalamic inhibition, resulting in reduced motor activity, as seen in diseases such as Parkinson's.