What Is the Lower Nature of the Mind?

According to sankia and vidanthe mind and brain are both material. The problem starts with the decartian mind brain duality, where he sees the mind as something entirely different,. Thus raising the problem of interaction. Mind and brain are interacting, or somehow mind is using the brain. An activity in the mind can be reflected in the brain, and should be reflecting in the brain. Actually, they are not entirely different. They both objects.