Those of you who believe in an immortal soul, how do you explain the physical connections to mental behavior?

We have known for quite some time that people’s behavior can be influenced by alcohol and other mood altering substances. If our behavior is ruled by our souls, how can this be? How can chemicals suddenly make a person violent and abusive?

In recent times we have found chemicals that can alleviate symptoms of psychological disorders. There are drugs that help with ADHD, schizophrenia and depression. How is such a thing possible if the brain and mind are separate?

We know that memories are physical. It is common knowledge that memories deteriorate with age. Recently, it has been shown that stimulating a specific portion of the brain causes recall of an associated memory. Does the soul keep a separate copy of memories? Who would we be without our memories?

We have also learned that the brain is highly compartmentalized. Damage to a small portion of the brain can cause highly specific abnormalities, including possible personality changes. How does the soul figure into this?