• Globus pallidus internus;
  • Parkinson's disease;
  • Pallidotomy


We studied tremor-related activity in globus pallidus internus (GPi) neurons and the effects of pallidotomy on tremor in patients with Parkinson's disease. By using micro-electrode recording, we identified GPi neurons with rhythmic firing at the frequency of contralateral tremor. There was a strong correlation between the tremor-related neuronal activity and limb tremor (r = 0.73). The majority of tremor-related neurons were located in the ventral one half of the caudal GPi, the area that is the target for pallidotomy. We found that pallidotomy produced striking improvements in off-period contralateral tremor. These effects were immediate and were maintained for ≥ 2 years. This benefit is obtained despite the progressive nature of the illness and the often reduced dose of medications after surgery.