Final answer:
The striatum, consisting of the putamen and caudate nucleus, is part of the basal nuclei and processes motor control information by sending signals through the direct and indirect pathways involving the globus pallidus and substantia nigra, which in turn modulate activity in the thalamus.
Step-by-step explanation:
The striatum is a subcortical part of the forebrain that consists of the putamen and the caudate nucleus. As part of the basal nuclei (also known as basal ganglia), the striatum is pivotal in the processing of information related to motor control and movement. All input to the basal nuclei is from the cortex into the striatum, which is an excitatory connection releasing glutamate. The striatum is involved in two main pathways within the basal nuclei: the direct pathway, where the striatum sends inhibitory signals through the internal segment of the globus pallidus (GPi) and the substantia nigra pars reticulate (SNr) to the thalamus, resulting in increased movement; and the indirect pathway, involving the external segment of the globus pallidus (GPe), subthalamic nucleus (STN), and GPI/SNr, which leads to decreased movement control by the cortex. Dopamine from the substantia nigra pars compacta influences these pathways by either activating the direct pathway through D1-type receptors or inhibiting the indirect pathway through D2-type receptors.