I came upon this old post by Christopher Roach, Where Does the Mind End and the Soul Begin?, in which he questions the adequacy of Thomistic natural philosophy regarding the mind:

The more I study Thomistic philosophy considered in the light of modern psychology and neuroscience, the more troubled I am by the encroachment of science on the traditional idea of the soul. But these insights are real, and the more I understand about them, the more I find the traditional Thomistic and Aristotelian formulae inadequate. Under Aristotelian and Thomistic accounts of the soul dominant in the Catholic Church, the soul is the seat of reason and the intellect, as well as the animating principle of the entire unified person (including the body). The soul is evident and coextensive with the body in this account–it is its “formal cause,” from which any person or thing is by definition inseparable–but the soul is also deemed immaterial, permanent, and the reason we have the potential of eternal life.

Neuroscience has begun to demonstrate that a variety of matters traditionally thought to lay outside the realm of purely material explanation–will, decision-making, personality, moral reasoning, imagination–in fact have strong components in the brain itself, where specific areas “light up” when certain kinds of decisions are made or feelings are felt. Injuries to certain areas of the brain–like the frontal lobes–can yield irrational behavior traditionally thought of as immoral. Finally, the dramatic effects of psychopharmaceuticals in manipulating behavior suggest that we may really be much more determined materially than traditional Christian theology would suggest.

How would you respond to him? I would recommend Dr. Baars treatment of compulsive behavior as start, and perhaps the recent mult-ivolume work by Fr. Ripperger, F.S.S.P. on psychology (I will have to check and see if he deals with these sorts of phenomena, and the semblance of determinism.)