High-frequency Deep Brain Stimulation (DBS) is an effective neurosurgical therapy for patients with Parkinson’s disease (PD) refractory to standard treatments. A typical target for implanting the DBS electrode is the subthalamic nucleus (STN). Despite its wide use, main mechanisms underlying the therapeutic effectiveness are still unclear. It is under debate whether electrical high-frequency stimulation (HFS) yields neuronal inhibitory or excitatory effects. The inhibitory hypothesis proposes a similar effect to surgical ablation. On the other hand, the excitatory hypothesis suggests a HFS-driven activity that interrupts the pathological oscillatory pattern. Based on computer simulations and reported experimental evidence, we addressed some paradoxical inhibitory and excitatory effects of HFS. We presented a functional model of STN-HFS that considers modulatory effects of extracellular potassium concentration on the transition from the Parkinsonian neuronal activity pattern to a multistable state of neuronal activities near a physiological behavior in basal ganglia circuits.