The oscillatory nature of basal ganglia activity is highly tied with some movement disorders.We study, through bifurcation analysis and computer simulations, the appearance of abnormal oscillations in an already proposed reduced neural circuit model of the subthalamic nucleus and globus pallidus loop.The results show that the model exhibits stable steady states associated to normal activity and oscillatory activity corresponding to the often termed "tremor frequency" oscillations due to their coherence with parkinsonian tremor observed in patients with Parkinson's disease.