@QuantMech, with a dead brain, the hypothalamus would not factor in. Also, a body with a dead brain cannot properly regulate body temperature, which means that Jahi’s caregivers were having to manipulate that with blankets and other measures. I remember that being an issue they talked about in their blogs and facebook page. Often, photos of her showed piles of blankets on her.
Vent settings are often changed, depending.
Sorry, I don’t believe that Jahi was aware of her mother’s presence, so any change in heart rate had nothing to do with that. Dead brains cannot hear, see, or have knowledge of the comings and goings of others.