Minerva really is experiencing effects that are stroke-like and neurology is weird.

For some really interesting reads on weird neurological things you should read Oliver Sacks. His book "The Man Who Mistook His Wife for a Hat" talks about different types of aphasia.

Some of the effects Minerva is experiencing come from those accounts.

The use of unusual-for-the-patient slang only when she gets angry is well documented. It happens (to put it simply) because the emotional/less verbal part of her brain is the part least damaged. When she gets hijacked by her emotions, the words available to her are the words most emotionally charged. So, she might even be using student slang that annoys her, f'r instance. Not because she'd ever *normally* use them, but because the words are emotionally charged and thus available.

My aunt actually had just this sort of aphasia after a stroke. She would get angry and use Welsh words and curse (which she never did before). We could never actually tell if she was having us on or not--sometimes we'd swear she was using it a license to say things that would normally be politely kept in one's head.

Curiously, she picked up words she never used when she was younger, or she used nonsense words that sounded like they had meaning in context. Her doctor actually told my cousin that perhaps the old woman should go to a home where there were more native Welsh speakers. Her accent was Pure North Wales (he said) and given her use of Welsh words when English words failed her, obviously she needed to be among people who had less trouble understanding her.

Except that she was from Newport (South Wales) and was a native English speaker. Her accent only sounded "North Wales" because the damage from the stroke actually changed the way she heard and pronounced things. It is also not uncommon for people with word finding problems to use unusual (for them) wordage to substitute the meaning.

The accent might be colloqial OR it might actually be a symptom of her health problems.