Is it true? There were different responses in the survey. Thought treatments that involve multiple trips to the doctor's office are not a good idea. Treatments that rely on devices are less intrusive than traditional talking-based therapies because they don't need to regale a stranger with one's life story. Others said that it was the impact on the brain that made it so intrusive.

The effects can go all the way to the brain. Brain stimulation can be used to target specific areas of the brain. Nick Davis at Manchester Metropolitan University points out that it is difficult to find small areas when you are stimulating the brain.

If it can help treat the symptoms of chronic pain, depression, or Parkinson's disease, then it must be changing the brain. It could be in the way signaling molecule are produced, the way brain circuits connect or fire, or something else.

It is difficult to know how these changes will affect the brain in the long run.

If the way a person's brain works is changed by a treatment, is it a bad thing? Maybe it depends on the change. It's known that brain stimulation can cause headaches, twitches, and possibly seizures. The therapy can cause a seizure and cause memory loss.

This can cause a lot of distress to some people. We are who we are because of our memories. One of the concerns about brain-modifying technologies is the possibility of changing our personality. Some people with Parkinson's disease experience temporary changes in their behavior when they have deep brain stimulation. They could become more irritated.

The effects of stimulation will not be as dramatic as that. What does it mean to be "invade"?

It's a big question. Some treatments are reserved for people who have no other options. They are viewed as riskier. According to a University of Toronto neurosurgeon and his colleagues, treatments that are considered too intrusive may never be used.