The subthalamic nucleus (STN) has generally been considered as a rely station within frontal-subcortical motor control circuitry. The function of the STN in the current model of the basal ganglia organization was developed from animal model and neurodegenerative diseases with hypo- and hyperkinetic movement disorders: therefore, the STN represents a relay in the so-called "indirect" pathway of the parallel basal ganglia-thalamocortical circuits. STN excitatory efferents reinforce the inhibition of basal ganglia output nuclei, the internal globus pallidus (GPi) and the reticular substantia nigra (SNr) on thalamo-frontal neurons. A "direct" striato-pallidal pathway opposes the STN by normally inhibiting basal ganglia outflow, facilitating thalamo-frontal drive. Starting from the clinical observations to motor improvement after deep brain stimulation of the STN, we extend the discussion to the possible cognitive and attention role of the DBS-STN technique.
