All the phys books have the 'old' model
CTZ - -> . Vo Ce - > X
two bits of the brain, chemosensitive trigger zone and vomiting centre
and different drugs affect the two bits. X is the tenth cranial n - the vagus
what anax is talking about are 'cortical influences' - we know that because sight and sound are represented in the cortex and not below
and over the last twenty y there has been virtually nothing written on cortical influences on the vomiting centre ( or CTZ )
Sqad will have learnt all this at med sch - and I am surprised how little it has changed over 50 or so years.