The brainstem is responsible for autonomic functions, the midbrain is associated with emotion and autonomic responses like pupil dilation, and the neocortex handles higher-level visual processing.

“there's sort of the brain stem the most you know primitive piece of our brain that is basically responsible for autonomic function you then have sort of this midbrain that sits on top of it that we call the sort of reptilian brain a lot of emotion there but of course what in theory distinguishes us from all the other animals is this remarkable cortical piece that sits on top of it”