Brain-computer interfaces are already a reality, even though still a primitive ones. They mostly rely on weak signals to interact or enhance different things. But we are still far from being able to transmit any complex information directly to our brains.
While we might understand the basic concepts of how the brain works there is still a long way to understand enough of it be able to for example "write" into it directly. And even then it would most probably be analogous to writing to a traditional hard disk drive with a magnetic needle by hand.