I don't know where I stand neurologically, but I've had loads of trouble with this all my life. I'm great at writing, drawing, and lots of crafty things (so I get the "creative" label all the time, although it doesn't seem deserved)... only someone else needs to give me an idea first, and then I'm able to carry on from there. I remember dreading the written portion of standardized tests for this reason. Occasionally, we'd get a prompt that told us to write about whatever we wanted. Other kids would be thrilled, but I'd waste half of the allotted time just sitting there panicked, trying to come up with something, anything. I needed a starting point. Technical writing, on the other hand, is my friend.