Short-term depression and temporal summation allow different baseline frequencies to underlie different modes of action in the globus pallidus. Upper panel: schematic illustration of the basal ganglia indirect pathway in the rat brain. Neurons in the GP project to the EP and fire at a wide range of frequencies. Lower panel: different modes of action are enabled by the different baseline frequencies. Low baseline firing rate in the GP allows GP neurons to induce prolonged inhibition in the EP, medium baseline frequencies allow GP neurons to induce brief inhibition or excitation in the EP, high baseline frequencies allow GP neurons to induce prolonged excitation in the EP.