referring to neuralink
Theoretically a lot. Realistically is yet to be seen.
I guess in short anything that there's a broken connection between body and brain. For example blindness you'd be able to directly input an image to the brain so a blind person will be able to see.
Paralyzed people. Memory loss. Basically a lot of things
Those are all input applications but I think it was mentioned that somehow this will also be able to upload all your memories to the cloud so you can make a copy of your brain. Something like that.
From their site
VISUAL CORTEX
Processes visual information from our eyes.
AUDITORY CORTEX
Assists with the perception and interpretation of sound.
SOMATOSENSORY CORTEX
Helps process sense of touch.
MOTOR CORTEX
Responsible for planning and executing motor movements