Hilda's case is a classic example of dissociative identity disorder (multiple personality disorder). Individual with disorder of identity has two or more identities, two or more personality states, which alternately take control of him. This disorder also includes memory gaps, which can not be explained in limits of "normal" oblivion.
Ted has a broken limbic system in which theorist would speculate because the limbic system is the one responsible for the feelings, emotions or even moods that the brain produces in which Ted has difficulty of showing or inferring his emotions to others and self.
