The lateral globus pallidus, also known as GPe, where e stands for "external," in combination with the subthalamic nucleus, constitutes a specific system called a coupled pacemaker. This dorsal "pale globe" is primarily connected with the midbrain and the hypothalamus. However, it is also co-extensive in certain ways and seems to join with the putamen, providing the overall structure the look of a camera lens. The GPe, along with the medial globus pallidus, are also closely connected with the amgydala. They receive large inputs from the amgydala, but do not give back much in return. The GPe axons also reach out to various other parts of the basal ganglia, apart from their primary connection with the subthalamic nucleus. A high level of activity of the lateral globus pallidus may also lead to involuntary ballistic and hyperkinetic movements and tremors in the limbs. The GPe's role as a key regulator of the basal ganglia system also makes it a target in the treatment for Parkinson's disease.