This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Physiology
[{'content': 'Lesion of which hypothalamic nuclei leads to loss of circadian rhythm \nSelect and explain. \nA. Dorsomedial, B. Ventromedial, C. Supraoptic, D. Suprachiasmatic', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The suprachiasmatic nucleus or nuclei, abbreted SCN, is a tiny region on the brain&;s midline, situated directly above the optic chiasm. It is responsible for controlling circadian rhythms. The neuronal and hormonal activities it generates regulate many different body functions in a 24-hour cycle, using around 20,000 neurons.Ref: Ganong&;s review of medical physiology; 24th edition; page no:-278', 'role': 'assistant'}]