I'm in the editing process on a book at the moment, and had mentioned the idea of the left brain/right brain split in terms of creativity. There are two concepts involved here. One is that you effectively have two brains. The left and right halves are pretty well separate, joined only at the corpus collosum, the big bundle of nerves at the back. The second is that the we have two distinct modes of operation, one is 'left brain' thinking that deals with the logical, sequential, verbal, rational, analytic, linear style of thinking. The other, 'right brain' thinking deals with the overview, spatial thinking, colour, art, imagery and the like. The assertion is that for creativity it is good to have both sides of the brain active, but when we settle down in a meeting (say) we tend to plug solidly into left brain mode.
Now my editor pointed out that there as been some doubt cast on the left brain/right brain split in this regard. (And, to be fair, I had actually said this, just not clearly enough). With evidence from fMRI and the like it becomes clear that both sides of the brain are involved in both types of thinking. However, what I was saying in the book is that the 'left brain' and 'right brain' labels are still quite useful, because there certainly are two clear modes of operation corresponding to these types of attribute.
If you'd like to feel your brain switch modes, there is a simple exercise you can do to experience it. Run the video below. It will put up a series of words. Your task is to say out loud the colour each word is printed in. Ignore what the word says, just say the colour. It's important that you do it out loud. Try it now:
What you should feel is a grunge as your brain desperately tries to switch mode. It doesn't matter what I told you, it pretty soon accepts it's dealing with words and selects left brain mode. Then, panic, it has to engage right brain. After a few words it should settle down and be fine again.
So, yes, technically the labels are out of date. But then so is the direction of flow of current in electricity, which goes the opposite way to the electrons. But it's still quite handy to use the left/right brain tags.