Complex sentence: In this line of thinking, a large body of empirical evidence for a close relationship between brain activity and mind activity has led most neuroscientists to be materialists or physicalists, believing that mental phenomena are ultimately reducible to physical phenomena.
Split into simpler sentences: In this line of thinking, a large body of empirical evidence for a close relationship between brain activity and mind activity has led most neuroscientists to be physicalists. Physicalists believe that mental phenomena are ultimately reducible to physical phenomena.