How far are we, scientifically, from reading thoughts


On January 29, Elon Musk published in X the success of the first surgical intervention implanting a device developed by his start-up Neuralink in a human . The name of the device: Telepathy (Telepathy).

In the scientific community we were attentive to what Elon Musk’s team had achieved since in September 2023 the competent body, the United States Food and Drug Administration (FDA), certified that the device could be implanted in humans .

After approval from the FDA, Neuralink implanted Telephaty in a person chosen from a group of volunteers, affected by tetraplegia and amyotrophic lateral sclerosis. For now we can say that the implant has been a success, but to know the results we will have to follow the steps of a study that promises to be long.

The undisputed technological advance of Telepathy

What Elon Musk’s team has achieved is very revolutionary from a technological point of view . Telepathy carries a battery that is recharged externally and has 1,024 electrodes, distributed in 64 wires, that transmit measurements of brain activity wirelessly. The fact that the device has been approved by the FDA guarantees that it is made with rigor.

It is expected that Telepathy will be able to measure brain signals related to movement in people with reduced mobility, and that they will be used to govern the movement of a prosthesis or interact with a computer. But a muscle signal is in no way equivalent to a thought.

This is what is known as the brain-machine interface . But this is not telepathy. The truly revolutionary thing would be if the Neuralink device worked by recognizing the neural activity that generates thought. And this may never be achieved.

The blind zone

What is the challenge we face when trying to measure signals from the brain?

The challenge is the darkness in which the observer finds himself after a neuron is activated. This does not happen with other types of cells, such as a heart muscle cell (myocyte). The same technology is used to measure the electrical activity of a neuron and to measure the electrical activity in a myocyte . But when a myocyte “fires”, the observer verifies that it contracts, that is, he can directly relate the electrical signal to the contraction of the muscle cell. And so he understands the effect of contraction, since he observes that the contraction of all the myocytes of the heart causes blood to circulate throughout the body.

This does not happen when we observe the firing of a neuron. In this case the observer does not see that there is any significant change, because the thought generated is not visible: the firing of the neuron is lost in the darkness.

Deep brain stimulators

There are already devices that are implanted inside the brain or very close to the brain and interact with it. An example is cochlear implants , devices with stimulators located in the cochlea (structure of the inner ear). They are used by people who lack the cells that are responsible for transforming the acoustic signals that come from the outside into the electrical signals that we recognize as sounds. The implant uses small microphones located in the ear, and sends the sounds collected to electrodes that are spread throughout the cochlea. And there we are acting very close to the brain: we are reaching the auditory nerve.

Another device that acts, this time, inside the brain – and that is also duly approved – is the deep brain stimulator. It began to be used to treat Parkinson’s and, later, was extended to other pathologies, such as morbid obesity or depression.

Disable neurons without really knowing how they work

These devices act on deep nuclei of the brain, although it is not well understood how the brain works.

For example, the device used to control motor disorders in Parkinson’s disease (be careful! Not to cure the disease), was developed knowing that it was better to disable a group of neurons than to leave them as they are. This device allowed, instead of practicing ablation (that is, burning the cells), to render the neurons useless through the constant application of electrical pulses that blocked them. And it is possible to reverse the effect by stopping the device.

However, work is still being done to deeply understand the connections between the different nuclei related to movement and to find out why a deep brain stimulator works .

And what about measuring thought

At this moment we are far from measuring thoughts, intentions, memories or desires. With these types of devices we cannot know what people are thinking about. Even with well-known devices, such as deep stimulators, there is a lot of darkness about why they work (not how they work) and what effect they have.

The controversies raised by the implementation of Elon Musk’s chip are understandable. We are intrigued by how the brain works. It seems that it is in this organ where our deepest intimacy is found and we want to respect it. We do not want other people to control us. But, for the moment, having our minds read or influencing our thinking is not something to worry about.

Will it be possible to relate neural activity to our thoughts? Everything indicates that progress will be made in interaction with machines, but it will not be based on the relationship between neural activity and thinking. Among other things, because we are not even very clear about what thinking is. Could it be that thought escapes physics and cannot be measured?

Author Bio: Javier Díaz Dorronsoro is Professor of Biomedical Instrumentation at the University of Navarra