Complex sentence: However, when a significant percentage of the motor neurons die (about% 50 -% 60), this decreases up to% 80 of the dopamine levels which inhibits the ability for neurons to generate and transmit a signal.
Split into simpler sentences: However, when a significant percentage of the motor neurons die (about 50-60%), this decreases dopamine levels by up to 80%. This inhibits the ability for neurons to generate and transmit a signal.