Brain Layers versus Brain Parts

I’ve heard you talk about three brain layers but recently I read an article that talked about three brain parts. Which is which?

In the early 20^th Century, neuroscientist and physician, Paul D. MacLean, proposed the Triune Brain Model in an attempt to help people understand more about how the brain functions. He believed that the human brain was really three brains in one: the neocortex (consisting of two cerebral hemispheres), the limbic system (often referred to as the mammalian brain and consisting of a collection of small brain organs such as the hippocampus and hypothalamus), and the reptilian brain (consisting of the two cerebellums and the brain stem). Nowadays some refer to this model as three functional brain layers. Brain parts tomorrow.