How does the thalamus relay information from the midbrain to the dorsal striatum?

The dorsal striatum—comprising the caudate nucleus and putamen—receives information from subcortical regions, including the midbrain, via the thalamus.1

Specifically, the intralaminar nuclei of the thalamus serve as a key relay for this connectivity. The caudal intralaminar group, which includes the centromedian (CM) and parafascicular (Pf) nuclei, maintains reciprocal connections with the basal ganglia and provides predominant output to the striatum. These nuclei receive input from various brainstem and midbrain structures, such as the superior colliculus and brainstem sensory nuclei, allowing them to modulate movement and arousal by relaying this information to the dorsal striatum. Additionally, the rostral intralaminar nuclei receive input from distributed subcortical arousal structures and target the association and limbic striatum.1