The lesion could work in (at least) two ways:

1. it makes you more likely to use a decision theory that leads you to decide to smoke
2. it only makes irrational people more likely to smoke.
3. it changes people's utility of smoking.

In case 1, you should follow EDT, and use a decision theory that will make you not decide to smoke. In case 2, you know that the lesion doesn't apply to you, so go ahead and smoke. In case 3, conditioned on your utility function (which you know), the probability of the lesion no longer depends on your decision. So, you can smoke.