What is the likelihood of you remembering how to fight after your brain was pierced by a skull shattering projectile spear if it was regenerated?

Question

The enemy boss just threw a spear at you, you tried animation cancelling to iframe and dodge the projectile spear but your finger slipped off the controller and now you've got a spear piercing your skull through the mouth and stuck on a wall, you are basically hanging off the spear like a sack of dead meat.

Your party members are dividing tasks to handle the situation, some of them are hooking the enemy boss with leashes and chains while others are shooting arrows and bolts at his knees, the party tank has climbed over the boss head and is stabbing his eyes repeatedly.

But this will only slow down the boss as he can regenerate really fast, and your party needs you in order to survive and kill the boss.

Meanwhile the party healer is resurrecting you, but they can't recreate neural pathways, they can only force your body to regenerate at incredible speeds.

The dead parts of your brain will be replaced with new neurons, and the blood loss will stop. Now that you gained back conscience you feel a lot lighter, overheating whilst also suffering immense thirst and hunger. The healing spell consumed a lot calories.

But you can't stop, the lives of your comrades depend on you, you have to fight as soon as you cross the line between death and the living.

So wake up party leader! We've got a giant troll to kill.

Question below

What is the likelihood of you remembering how to fight after your brain was pierced by a skull shattering projectile spear if it was regenerated?

For real, I need to know the mathematical odds, this is part of the game. If such data is impossible to guess/gather, please suggest some specific works about brain injury that could enlighten me.

Answer 1

Through the mouth will miss the cerebral cortex.

I have from the OP: the spear entered through the mouth and the end result is that you are hanging from the spear.

I have added blue lines to represent possible spears. The steepest line (and one which would, I think, result in you sliding off of the end of of the spear instead of hanging) disrupts the brainstem and cerebellum, neither of which contain higher functions and learned behaviors. Realistic trajectories for a spear from which you could hang have the spear missing the brain entirely and disrupting the cervical spinal cord - or not even that.

Assuming you are healed, the functions of the spinal cord and brainstem are hardwired. You do train your cerebellum to some degree using muscles and balance as an infant and toddler. If you want to have some sort of aftereffect of cerebellar damage, it could be the functional motor equivalent of being very drunk - staggering, missing, slurring words.

Higher functions that you learned - words, concepts, how to load up your magical megaweapon, how your kungfu kata goes move by move (the moves themselves might be in the cerebellum) are up in the cerebral cortex which was spared. You would remember what to do. Whether you could do it depends on the cerebellum. It might take you a couple of tries.

Answer 2

Ever heard of Phineas Gage?

Had an unfortunate accident involving a metal bar and an explosive charge.

the tamping iron‍—‌1+1⁄4 inches (3.2 cm) in diameter, three feet seven inches (1.1 m) long, and weighing 13+1⁄4 pounds (6.0 kg)‍—‌entered the left side of Gage's face in an upward direction, just forward of the angle of the lower jaw. Continuing upward outside the upper jaw and possibly fracturing the cheekbone, it passed behind the left eye, through the left side of the brain, then completely out the top of the skull through the frontal bone.

Illustration of the damage:

From an account by the physician who was first on the scene:

Mr. G. got up and vomited; the effort of vomiting pressed out about half a teacupful of the brain [through the exit hole at the top of the skull], which fell upon the floor.

Astonishingly, Gage survived... it took him a few months to recover physically (at least in part due to infections received from the wound) though his personality was significantly and permanently altered.

There is precedent, therefore, for humans to survive quite unpleasant brain trauma. Good news for your player!

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What are the likehoods of you rembering how to fight after your brain was pierced by a skull shattering projectile spear if it was regenerated?

You would need to model which bits of the brain were damaged. There's plenty of scope for simplification and abstraction here. Mr. Gage was "fortunate" in that the bits of his brain that were damaged didn't drive anything absolutely critical. He could still walk, speak, hear, see, remember. Piercing the brain side-to-side or front-to-back has a worse prognosis. Bits of brain don't always have a clearly defined role... this stuff is diffused across the brain to some extent, though some things are certainly localized. You can research this sort of thing yourself, in as much detail as you felt you needed.

I'm not going to elaborate on this stuff here, but you could conceivably model this as a kind of amnesia where both physical skills and memories may be lost. Maybe you act and feel fine, but forgot how to operate a sword. Maybe you're as deadly as you ever were, but no longer know who your friends are. You might recognise the threat of the Big Bad, but might not know how to finish them.

Exactly how this is modelled (as a complex 3d voxel-based model of the brain with a trajectory calculator and a dice roll per voxel damaged, to a simple coin toss) depends very much on the style of rules you're working with (slow, complex, simulationist? fast and simple?), and the flavour of combat you want to impart (terrifying and deadly? cartoony?) and as such is a bit out of the scope of this question.

Answer 3

Either impossible or as accurate as the healing spell is.

It is impossible since your reactions and capabilities are a combination of specific neural pathways, how much myelin the pathways have received and the trillion feedbackloops that never stop in your body as part of the remembering and steering processes in your brain. Unless the spell repairs your neural pathways exactly down to the last neuron with its processes intact and the way they were you will not just forget things, you will have a different personality and capability. Side-note: if you had your memories transferred to someone else's body then you would inherit their personality as their brain composition defines that rather than your memories.

That leaves the other option: the accuracy of the spell. Spells usually are impossibly accurate. They can discern between friend and foe and they can identify what constitutes a wound that needs healing, how it needs to be healed and what is undamaged tissue. Since the spell is able to regenerate the face muscle tissue and its relevant neurons and connect those neurons to the nerves they were severed from the accuracy is likely incredibly high, and the brain tissue would have no problem healing completely, memories, skills and all.