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.
The rules haven't changed in a few decades, but the customs have. In both houses of Congress, you still need a majority (50%+1) to pass a bill. In the House of Representatives, that's the only consideration. In the Senate, the rules are a bit more complex. If the bill makes it to a vote, it needs only 51 votes. But you need to debate before it gets to a vote.