GYPE and Parkinson disease: In short words, the shift from healthy to PD conditions can be described as follow: decreasing the maximal M-type potassium conductance in direct and indirect MSN neurons (MSN firing dysfunction) from 2.6 to 1.5 mS/cm2; decreasing the maximal corticostriatal synaptic conductance (reduced sensitivity of direct MSN to cortical inputs) from 0.07 to 0.026 mS/cm2; and increasing the maximal GPe axonal collaterals synaptic conductance from 0.125 to 0.5 mS/cm2 (increase of GPe neuronal firing).