Areas of the cortex located just behind the temples containing the neurons responsible for the sense of hearing and meaningful speech. Frontal Lobes Areas of the cortex located in the front and top of the brain, responsible for higher mental processes and decision making as well as the production of fluent speech.
As a practical matter, some might argue, if a filibuster is threatened and it takes 60 votes to end debate in the Senate, then it does take 60 votes to pass a bill. Nothing in the Constitution says that a three-fifths majority is necessary to pass ordinary legislation.
It's not that a piece of legislation requires 60 votes to be passed, 51 will do. It's that the Senate's Rules Of Order allow for two things: 1. Any Senator has an absolute right to be heard to speak on the floor regarding any measure being considered.