sentences:  Studies show that ocular microtremors have some promise as a tool for determining the level of consciousness in an individual, as well as the progression of some degenerative diseases including Parkinson's disease and multiple sclerosis.Although originally thought to stem from spontaneous firing of motor units, the origin of ocular microtremors is now believed to be in the oculomotor nuclei in the reticular formation of the brainstem.This new insight opened the possibility of using ocular tremors as a gauge for neuronal activity in that region of the central nervous system.