Surely this depends on what you mean by 'improve the brain'. You might be able to make it better at things you consider important, by undermining things that the evolutionary environment deems important.
You could also trade off things that were more important in the ancestral environment than they are now. For example, social status (to which the neurotypical brain devotes much of its resources) is no longer the evolutionary advantage that it used to be.
Just thought you guys should know about this. Some work that argues that humans should not enhance their intelligence with technology, and that super intelligence probably never evolves.