This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pain Physiology, Subject name: Physiology
[{'content': 'Stimulation of which of the following areas of brain is experimentally used to control intractable pain: \nSelect and explain. \nA. Periaqueductal grey matter, B. Mesencephalon, C. Subthalamic nucleus, D. Medial forebrain bundle', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. a. Periaqueductal grey matter (Ref: Ganong 22/e p260, 261) Stimulation of Periaqueductal grey matter (PAG) is an established experimental therapy reserved for intractable somatogenic and/or noceceptive pain that remains poorly controlled despite all conservative measures. Deep Brain Stimulation for Intractable Pain Periaqueductal Grey Matter (PAG)/ Periventricular Grey Matter (PVG) Deep Brain Stimulation Sensory Thalamic Deep Brain Stimulation * PAG/PVG deep brain stimulation has shown to maximally benefit patients with intractable somatogenic and nociceptive painQ * Sensory thalamic deep brain stimulation has shown to maximally benefit patients with intractable neuropathic painQ Scientific evidence demonstrating safety and efficacy is however, not robust to support widespread use of Deep brain Stimulation for the treatment of intractable pain.', 'role': 'assistant'}]