Can brain implants read and control our minds?

Longer answer

Thoughts and ideas are the result of communication between many brain cells that can be distributed over many regions in the human brain. So far, nobody has been able to find out how thoughts are exactly coded into the brain, even when measuring activity from multiple brain areas at the same time. When we measure brain activity, we measure how brain cells “talk to each other”, through electrical currents. To do this we connect wires with electrodes to the brain. Electrodes can measure the electrical activity in the neuron. This brings us to the connectivity issue: we have close to 90 billion brain cells that talk to each other, each being connected to thousands of other brain cells. Currently, it is very difficult to record information from a single cell, since they are so small and inaccessible. It is therefore impossible to record from multiple single cells simultaneously. Apart from that, we barely know how to interpret signals we do manage to measure, let alone how to interpret what is happening when thousands of brain cells talk to thousands of other brain cells. It is only in very controlled situations that we can try to interpret brain activity, as we will explain in the last section of this answer.

Reading the mind?
Currently, brain implants are mostly used for research and innovative medical purposes. A brain region that is often “read” with these brain implants is the motor cortex. This brain region determines what movements somebody is planning and executing and we know very accurately in which area which body movement is displayed along this cortex. The brain implants that are currently used in different patients often “read” a relatively simple circuit in this motor cortex: the part that symbolizes movement of the right hand as if you were to click a mouse. The electrical activity in this part of the brain is recorded by an electrode that was implanted on top of the brain tissue: a pretty invasive procedure! This mouse-click movement is not very informative at first, but it is relatively easy to measure in the brain, and can be used in many ways to convey information. For example, these brain implants are used to help paralyzed people move robotic arms and operate communication software. 

In a similar study, researchers in Berkeley have recently managed to reproduce the song Another Brick in the Wall, Part 1 by Pink Floyd directly from the brain. They did so by using such implanted electrodes on the brain area that is associated with music perception: the electrodes read the music from brain activation while people listened.  

Controlling the mind?

Electrodes can not only record electrical activity of brain cells, but they can also stimulate cells by producing electrical activity themselves. That is why it is thought that brain implants can potentially control minds. However, at this point it is impossible to manipulate thoughts with brain implants, because of the same reason as described above: too many cells that are too small. Not only do we not know exactly where to stimulate, we also don’t know how to manipulate brain cells without disrupting their usual function. Trying to control the mind may therefore interfere with other essential processes in the brain which we need for normal functioning. 

Current applications of computers “controlling” the brain, by feeding the brain electrical signals, only influence small areas of the brain. For instance, directed brain stimulation can relieve symptoms in some neurological diseases, allow deaf people to hear basic sounds and blind people to see faint images. Scientists are only beginning to learn how to influence the brain tissue and will hopefully discover new ways to treat people with brain disorders. 

So even though we are now able to use brain implants to read or alter brain activity, these implants are only operating under very controlled circumstances and only interacting with a very small facet of the brain’s activity. It is very unlikely that fully reading or controlling minds will occur in the near future. 

Further reading & citations: 

• Music can be reconstructed from human auditory cortex activity using nonlinear decoding models Bellier L, Llorens A, Marciano D, Gunduz A, Schalk G, et al. (2023) Music can be reconstructed from human auditory cortex activity using nonlinear decoding models. PLOS Biology 21(8): e3002176. https://doi.org/10.1371/journal.pbio.3002176
• Vansteensel, M. J., et al. (2016). “Fully Implanted Brain-Computer Interface in a Locked-In Patient with ALS.” N Engl J Med 375(21): 2060-2066.
• Ptito M, Bleau M, Djerourou I, Paré S, Schneider FC, Chebat DR. Brain-Machine Interfaces to Assist the Blind. Front Hum Neurosci. 2021 Feb 9;15:638887. doi: 10.3389/fnhum.2021.638887. PMID: 33633557; PMCID: PMC7901898.