Ann Johnson's life recently took an impossible turn. Some 18 years ago the then teacher suffered a strokeA medical emergency that occurs when the blood supply to a part of the brain is cut off. They can cause lasting brain damage if not treated quickly.. She was left unable to move or speak.

Now that has changed. She has become the first person to trial a new brain implant. It can turn her thoughts into speech. After being unable to communicate at all, Johnson can move her head to type slowly.

Researchers believe it will help people with aphasiaA communication disorder that makes it difficult to speak. to regain lost parts of their identity. Johnson said: "Hearing a voice similar to your own is emotional."

This technology is not the only one reaching into our minds. London-based Cogitat is making mind-controlled computer games. 

Elon Musk's company Neuralink is making chips that translate brain data into computer commands.

Brain data is not the same as thought, but these new developments open up the possibility that mind-reading is on its way. Soon we might be able to use a phone app to browse the thoughts of others.

Imagine if you could look into thoughts. You could probe a doctor's mind before she tells you your diagnosisThe process of identifying a condition, injury or disease by looking for the signs and symptoms of that condition. . You could find out how your teacher regards you. You could see what your friends really think about you - or if they think about you at all.

It could usher in a new age of frankness and honesty. If your lies can be detected, you might be less likely to lie. Everyone would have to be completely open with each other. Even politicians would have to tell the truth. 

Yet it could also be a burden. Imagine being on a train surrounded by the thoughts of others. The relentless flow of thoughts could drive you to madness. You might lose your sense of self.

It also raises a host of other issues. One is privacy. As neuroscientist Anil Seth says: "Once you've got access to stuff inside your head, there really is no other barrier to personal privacy left." We would lose our freedom of thought.

What if a device fed your thoughts back to the highest bidder? What if a hacker gained control of it? Or if it stored your thoughts up for future use against you? Politicians and advertisers could analyse people's minds to try to control them.

Would it be great to read people's thoughts?

Yes: It would open up a whole new world. We would be able to see people for who they really are, rather than the wall they put up to the world. We could become closer to others than ever before.

No: Thoughts define who we are. If we start listening to other people's thoughts about us it might disrupt our sense of self. It might also be profoundly depressing to learn what others think of us.

Or... Thoughts fly through our heads at rapid speed, shifting and combining as they go along. We would not learn clear things but a babbling mess of impressions, more confusing than anything else.

Stroke - A medical emergency that occurs when the blood supply to a part of the brain is cut off. They can cause lasting brain damage if not treated quickly.

Aphasia - A communication disorder that makes it difficult to speak.

Diagnosis - The process of identifying a condition, injury or disease by looking for the signs and symptoms of that condition.