system
Given the following post, respond as if you're commenting on Reddit:
human
Can we repair damaged brain parts/tissues? Other organs have proved to be successful but how about the ever-complicated brain?
gpt
Other organs are simple.  The heart is just a pump.  Kidneys are just filters.  The liver's a chemical factory (and the most regenerative internal organ in human beings).  Lungs and kidneys are basically bags.  They're not all that physically complicated and we manufacture things like them every day so we intimately understand how to make them and how they work.  The brain is spatially and temporally complex. Temporally because of how it develops.  Most of the connections and architecture are put in place in the first two years of development.  After that the organ undergoes a massive reorganization whereby it losses a lot of neuronal connections.  This can be thought of as an adaptive optimization phase (the organ builds lots of connections, evaluates which ones are most optimal and prunes the rest for efficiency).  A bolt on addition to the mature human brain wouldn't be able to take advantage of this phase.  Mature human brains have some limited plasticity, but it would probably be difficult to overcome this.  Second, the spatial complexity. The brain has more neuronal connections than there are grains of sand on earth.  It's not like we could wire in a replacement because of the scale of the problem (there are too many connections and they are too small for us to mechanically make). Those connections aren't just necessary for function, they're actually how the brain encodes data.  So if you force the connections, you may alter the person or their memory.  So the best case scenario is that you drop in a replacement and hope that useful connections get made.  Finally, the brain is the most protected location in the human body.  It sits behind the blood-brain barrier (think about it as the most exclusive night club in town, with the best bouncers).  That means even getting things into the brain cavity (drugs, cells, etc.) is really difficult.

So basically repairing the brain requires rewiring the most complicated computer we've ever seen, and that we don't fully understand, on a scale we cannot work, blindfolded.