This is a lengthy site on learning and the brain. I find it important to know how the brain works and how we actually learn in order for Instructional Designers to be able to design and deliver learning that is actually helpful and will stick with the learners. I think it helps us all to keep these factors in mind. It is important to build in reinforcements for the learning to stay with the the learners. It is noted that in order for learning to stick it has to be relevant, something they are interested in, it helps to make it fun, and allow time for the user to think on it.

http://www.sedl.org/scimath/compass/v03n02/1.html