I don’t think so – not in the way you are referring. We can use a lot of different types of technology to replace bits of us, but I don’t think we’re advanced enough to do the brain yet. We’d need a lot of storage in a very small place – and what would happen if the computer crashed? open brain surgery with an IT technician in your head? yikes!
You could argue that our phones function as a type of brain, though – you don’t have to remember your appointments or phone numbers anymore, because your phone remembers for you. But 10 or 15 years ago everyone used to remember phone numbers as a matter of course. These are brain functions we’ve offloaded to computers (our phones).
Not currently! Our brains are fascinating in how changeable and resilient they are! If you smashed a computer in half, it’s just not going to work anymore. However, humans have survived with surprising amounts of damage to the brain, and still been able to function. Their behavior has changed, but they can still live. Changing from a human brain to a computer only would definitely be a downgrade right now.
We can’t really even create a perfect computer version of a single brain cell, and there are 86 billion brain cells!
It would be a great thing to do though, because we could maybe upload our minds into computers and live on after our bodies get too crumbly to live in.