How are custom organs controlled by the brain?

Question

In various sci fi settings you'll often see soldiers that have been modified beyond their baseline human level. Sometimes they are genetically grown this way, but other times they're modified as adults. The latter is the focus of this question.

If one were to place a custom organ into a person, how does the brain control it in the first place?

Such organs aren't mere replacements to existing body function, but entirely new body parts in this situation. I.e extra glands that secrete a hormone, or help the immune system, or filter air before it gets to the lungs etc.

Answer 1

Your brain doesn't really have any spare capacity... the jobs of various bits can be shifted around thanks to neuroplasticity, but there aren't idle bits just hang around waiting for something to do.

Peter Watts had augmented humans in Blindsight (full book available for free on the author's webpage, worth a read) make functional tradeoffs. One guy has effectively lost his ability to form facial expressions, but because facial muscles are complex and there's a lot of wetware controlling them, that freed up a lot of brainpower for driving new bits of equipment.

Many things don't actually need to be directed by the brain, though. They can detect and maintain homeostasis itself, like modern-day combinations of blood glucose meters and insulin pumps.

Other things could be driven via manual intervention, eg. by operating an external control system. That's technically brain control, in the same way that when driving something like a backhoe or other complex multijointed arm a human is technically controlling it via their brain and is limited in the other things they can do at the same time, but is then free to use their various limbs for their regular purposes once they've finished operating their tools.

Another alternative might be to augment the brain, but that's something for another question, I think, and has substantial implications for any scifi setting it appears in.

Answer 2

Neuroplasticity!

Humans are exceptionally adept at learning and operating new machinery. Let's get an example that everyone knows, if not has experience with. Computers! They have a multitude of ways to operate them, and we can learn to operate an absolutely incredible amount of different things.

Seeing it in action is easy. Watch someone type in a text program for the first time, then at someone adept at it. Pne is taking an incredible amount of effort, the other isn't even thinking about typing, but is just making the sentences as the words materialise on the screen. In games we have a ton of different movements. 2D, 3D, walking, flying, driving, operating weird machinery. The list is endless.

An interesting study about brain augmentation showed people can learn how to move a mouse on a screen. I cannot remember if it was the hand or arm they moved, but this was translated to the mouse. After some time they had learned to move the mouse without moving the arm or hand. They could thus use the same part of the brain controlling different things.

This means that as long as someone can have feedback on the workings of an organ, it can be learned at used.

Do keep in mind that it isn't 'free'. Brain areas are being used, making the traffic in the brain higher and possibly shutting out other things at moments. But learning and using an extra organ should be less difficult in most cases than learning how to control a character in a game. The functions and translations required fir a gane are generally much higher (movements, interactions, etc through fingers and different kinds of controllers).

Worst case scenario you "just add some extra brain matter".

Answer 3

Already been done

Dr. Miguel Nicholelis had made a Rhesus monkey control a robotic arm in 2003. In 2014 he had a paralyzed person controlling an exoskeleton:

He is currently working on a project that allowed paraplegic Juliano Pinto, a 29-year-old with complete paralysis of the lower trunk to deliver the kickoff at the opening game of the 2014 FIFA World Cup, in Brazi.

Also from the wiki on him:

He and his colleagues at Duke University implanted electrode arrays into a monkey's brain that were able to detect the monkey's motor intent and thus able to control reaching and grasping movements performed by a robotic arm. This was possible by decoding signals of hundreds of neurons recorded in volitional areas of the cerebral cortex while the monkey played with a hand-held joystick to move a shape in a video game. These signals were sent to the robot arm, which then mimicked the monkey's movements and thus controlled the game. After a while the monkey realised that thinking about moving the shape was enough and it no longer needed to move the joystick.

By the way:

A system in which brain signals directly control an artificial actuator is commonly referred to as brain-computer interface ("BCI").

Going further:

On January 15, 2008, Dr. Nicolelis lab saw a monkey implanted with a new BCI successfully control a robot walking on a treadmill in Kyoto, Japan. The monkey could see the robot, named CB, on a screen in front of him, and was rewarded for walking in sync with the robot (which was under the control of the monkey). After an hour the monkey's treadmill was turned off, but he was able to continue to direct the robot to walk normally for another few minutes, indicating that a part of the brain not sufficient to induce a motor response in the monkey had become dedicated to controlling the robot, as if it were an extension of itself.

Just so you don't think this guy is a lone mad scientist doing these things, making monkeys control robotic arms has been fairly commonplace for over a decade now:

Monkey controls robotic arm using brain signals sent over Internet - the work of professors James Biggs and Mandayam Srinivasan

Advanced Robotic Arm Controlled by Monkey’s Thoughts - the work of Dr Andrew Schwartz

In all cases, monkeys (abd one people) learn to map their robotic extensions to their body schema (see Shern Ren Tee's answer)

Answer 4

An augmented appendage (like a power suit or extendable arms or even shooting webs) will be incorporated into the brain's internal body schema. Most people's body schemas already incorporate mobile phones. (Is that making us less smart? You decide.)

A synthetic internal organ will have to be wired up to the nervous system. People don't have existing nervous structures for consciously effecting glandular actions (you can't pause your kidneys), only muscles, so it would be unnecessarily risky to try to create direct nerve-gland controls. Instead, such organs would likely be wired into the autonomic nervous system which handles our unconscious functions.

New "reflexes" could be created to fire off these organs (for example, an artificial detoxifier could be hooked up to the vagus nerve sensation of abdominal discomfort). Organs could also be wired to either the sympathetic or parasympathetic nervous system, depending on whether they should be activated by stress or by rest. This would also allow users some conscious control -- clenching muscles activates the sympathetic nervous system (different muscles trigger different levels of response), and deep breathing activates the parasympathetic nervous system.

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EDIT: Every answer here (including mine!) has missed an obvious interface, which is conscious input. Nothing stops an artificial organ from coming with a dial or switch or Bluetooth app. After all, that's already how real-world humans manage prosthetic pancreas replacements -- also known as insulin pumps.

Answer 5

The brain doesn't actually control glands, in the sense that the central nervous system is not the prime mover. Glands react to chemicals in the body, which can include those produced by the brain, but usually are chemicals that are produced by other glands, by-products of chemicals it produced itself, or foreign chemicals/stimuli. A well-designed artificial gland will tap into existing biology accordingly. It just needs access to blood and lymph. This fact didn't stop Iain Banks claiming his Culture people could activate glandular reactions simply by thinking about it, and his books are very popular.

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There are reactions the peripheral nervous system triggers, like fight or fight, which as an example is a whole body reaction that cascades into a hundred different things. Overall though, the brain itself is not really responsible to the parts of your body you don't control. This is why a brain dead body can be kept alive and "healthy" on a respirator, but remains totally unresponsive to rousing stimuli (like loud noise, or pain).

Answer 6

Humans have small nerve bundles spread throughout the body which help control "autonomous" functions. Some of these can still function after connection to the brain has been lost. https://www.innerbody.com/anatomy/nervous/lower-torso In order to control a new organ, first add the local nerves but connect them to a nerve bundle that provides the moment to moment control over that organ. Then, add controlling nerves that connect to the brain. In that way, you don't need to use a lot of brain power to control that new organ.