Recent studies suggest that Parkinson's disease (PD) is associated with pathological synchronous oscillatory activity in the basal ganglia. Beta frequency band (beta-FB) oscillations likely contribute to bradykinesia and rigidity in PD; however, details of the relationship between these two phenomena remain unclear. To explore beta-FB oscillatory activity in relation to motor signs of bradykinesia and rigidity, we studied 17 patients with akinetic-rigid type PD who had electrodes implanted into the subthalamic nucleus (STN) for deep brain stimulation therapy. Microelectrode recordings were obtained in the STN during surgery and neuronal activity was analyzed offline. The spectral characteristics were calculated. Of 155 neurons from 30 STN, 56 (36.1%) had beta-FB oscillatory activity. Neurons with oscillatory activity were localized in the dorsal two-thirds of the STN. These data indicate that beta-FB oscillatory activity may be of particular importance in the generation of motor deficits in PD. (C) 2012 Elsevier Ltd. All rights reserved.