Complex sentence: Neural oscillations were observed by researchers as early as Hans Berger in 1924, more than 50 years later, intrinsic oscillatory behavior in vertebrate neurons was encountered, but their functional role is still not fully understood.
Split into simpler sentences: Neural oscillations were observed by researchers as early as 1924 (by Hans Berger). More than 50 years later, intrinsic oscillatory behavior was encountered in vertebrate neurons, but its functional role is still not fully understood.