So - given the structure and functions of Hypothalamus, how would a synapse stimulating Implant translate to a self-healing ability?
Well, in the most broad-brush terms, the hypothalamus controls so many of the body's functions, it can focus the needed resources to repair any damaged system.
Let's start with just a few of the hypothalamic functions: control of heart rate via control of the adrenal cortex - control of blood pressure / blood vessel constriction, control of body temperature, indirect control of the immune system via thyroid, adrenals, etc.
Now, suppose that you, the player character in Escaping Titan, has been injured. It's a bad one, your suit is breached, there is a laceration (cut or tear) of the skin, and it nicked a blood vessel. First, the hypothalamus SSI sends a command to slow heart rate to reduce blood loss, then it sends the command to constrict blood vessels in that area, effectively sealing the injured blood vessel. Once the immediate threat of blood loss is handled, the hypothalamus SSI can determine what is needed next - does the region need additional heat for healing or does it need to stay cool and reduce cell damage until additional medical care can be applied? Most of this can again be accomplished by control of local blood flow and hormonal control of metabolism. Time to start healing that cut! The hypothalamus can release growth hormone and direct immune response to the area to form a clot, close the wound with fibrin, and start the growth of new tissue.
These are the processes that occur naturally, although not quickly, nor always efficiently under emergency conditions. The hypothalamus SSI provides direct, voluntary control of body processes such as temperature; metabolism and utilization of body fat via control of thyroid gland; "fight or flight" condition via control of adrenal glands; control of normal body cycles (menstrual for women, day-night circadian cycle, sleepiness-wakefulness); control of "attitude" functions such as thirst, hunger, sweating, irritability, fatigue. There are also some interesting correlations with emotions (at least as far as they are modified by hormones) in which the SSI could potentially damp down emotional response when it is essential to avoid distractions.
So, control of the hypothalamus translates into control of all of the "automatic" functions of the body, turning them from "unconscious" to "conscious" control. The ability to manipulate such functions conveys the ability to not just self-heal, but to "configure" the body to the best condition for the job at hand!
Sorry if this post is briefer than most, but I am currently out of the country, in the middle of a two-week trip which makes it a bit more difficult to write lengthy posts (on a notebook). Next month we'll get back into more anatomy and physiology with the Inferior Frontal Gyrus as we discuss communication and the potential for Mind Control with the appropriate SSI.
Until then, keep exercising, body, brain and mind!