This interesting article, passed along by a student, suggests that moral behavior is a function of the brain and that if we alter the brain we will disrupt the normal moral decision-making process.
This is no doubt true, but we shouldn't think that this proves determinism to be true. It doesn't follow that because some choices for some people are not free that therefore no choices for anyone are free.
A healthy brain may well work with the mind to produce choices that are not necessitated by prior states of affairs. In other words, in a normally functioning mind/brain system we have the freedom needed to be held morally responsible for our decisions. The future is not predetermined by the past nor by our present brain states. There is right now more than one possible path into the future that we can choose.
The determinist disagrees with this, but he has a difficult time explaining why. After all, he has to admit that ultimately his disagreement is the inevitable product of all the influences that have acted upon him throughout his life, and he has no way of knowing whether the "truth" of determinism is one of those influences or not.
RLC