Is the brain really a reptilian core wrapped in a limbic layer and a rational neocortex? · Grey Matter

That picture is the triune brain model, proposed by Paul MacLean from the 1960s and popularised by his 1990 book, and it remains a common teaching map.

Is the brain really a reptilian core wrapped in a limbic layer and a rational neocortex?

That picture is the triune brain model, proposed by Paul MacLean from the 1960s and popularised by his 1990 book, and it remains a common teaching map. As an account of evolution it is wrong: reptiles, birds and mammals all have homologues of the cortex, the basal ganglia and the limbic structures, which evolved together and were modified rather than stacked as new layers. As a functional map it misleads as well, since emotion and reason are carried by interacting circuits across all levels (the prefrontal cortex is central to emotion, the amygdala to decisions). It can still serve as a mnemonic for where the vital, the emotional and the deliberative tend to be concentrated, provided it is not taken as the brain's history.