Targeting the caudal intralaminar nuclei for functional neurosurgery of movement disorders

The caudal intralaminar nuclei, in particular the Centrum-Medianum Parafascicularis (CM-Pf) nucleus complex, are involved in various functions, particularly in pain processing and in motor control, through their projections to the subthalamic nucleus and their afferents from the pallidum internus (GPi) (or entopeduncular nucleus in the rat). The nociceptive inputs received by the CM-Pf are modulated by the somato-sensory thalamus. The lateral habenula (HbL) receives noxious inputs and has an inhibitory influence on the nigral dopaminergic neurons. CM-Pf and the HbL share comparable response characteristics to noxious inputs and might play comparable, and perhaps complementary, roles in conveying the nociceptive information to the basal ganglia system, thereby modulating motor responses, such as freezing and dyskinesias. The interaction between CM-Pf, HbL, GPi, STN and SNC might provide a new template for high frequency stimulation strategies in the treatment of movement disorders.