This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous System, Subject name: Physiology
Which cerebellar component would be abnormal in a degenerative disease that affected spinal sensory neurons? 
Select and explain. 
A. Purkinje cells, B. Mossy fibers, C. Parallel fibers, D. Climbing fibers
B: Mossy fibers
Answer: B: Mossy fibers 
Explanation: Ans. B. Mossy fibersSpinal input, such as from the spinocerebellar tracts, enters the cerebellum on the mossy fibers. The climbing fibers originate from the inferior olivary nucleus of the medulla (the olivo-cerebellar tract). The other components are intrinsic to the cerebellum.Diagram of neural connections in the cerebellum. Plus (+) and minus (-) signs indicate whether endings are excitatory or inhibitory. BC, basket cell; GC, Golgi cell; GR, granule cell; NC, cell in deep nucleus; PC, Purkinje cell.