The twin will include a network of embedded “neural mass models,” says Ruffini. These, he says, are basically computational models of the average behavior of many neurons connected to each other using the patient’s “connectome”—a map of the neural connections in the brain. In the case of epilepsy, some areas of the connectome could become overexcited; in the case of, say, stroke, the connectome might be altered. Once the twin has been created, the team can use it to optimize stimulation of the real patient’s brain “because we can run endless simulations on the computer until we find what we need,” Ruffini says. “It is, in this sense, like a weather forecasting computational model.”
For example, to improve treatment for an epilepsy patient, the person would wear a headcap every day for 20 minutes as it delivers transcranial electrical stimulations to their brain. Using the digital twin, Ruffini and his team could optimize the position of stimulating electrodes, as well as the level of current being applied.
Digital twinning any organ opens up a whole host of ethical questions. For example, would a patient have the right to know—or to refrain from knowing—if, say, their twin predicts that they’ll have a heart attack in two weeks? What happens to the twin after the patient dies? Will it have its own legal or ethical rights?
On the one hand, virtual body doubles provide us with exciting, revolutionary pathways to develop new treatments, says Matthias Braun, an ethicist at the University of Erlangen-Nürnberg, Germany, who has written about the ethics involved in the use of digital twins in health care. “But, on the other hand, it provides us with challenges,” he continues. For one thing, who should own a digital twin? The company building it? “Or do you have a right to say, well, I refuse the use of specific information or specific predictions with regard to my health insurance or with regard to the use in other contexts? In order to not be an infringement on autonomy or privacy, it is important that this specific person has control of the use [of their digital twin],” he says. Losing that control would result in what Braun dubs “digital slavery.”
Ana Maiques, the CEO of Neuroelectrics, says the company is already grappling with the issue of what happens to the extremely personal data a digital twin is built upon. “When you’re doing these kinds of personalizations, you have to ask difficult questions, right? Who’s going to own that data? What are you going to do with data?” she asks.
The project has enlisted researchers to dissect the ethical and philosophical components of the endeavor, including Manuel Guerrero, a neuroethicist at the University of Uppsala, Sweden. For Neurotwin, a project based out of Europe, the data gathered will be protected by the European Union’s General Data Protection Regulation (GDPR). This means any use of the data requires the consent of its owner, Guerrero says.
Guerrero and his team are also exploring whether the term “digital twin,” which was first coined for manufacturing, is still the most apt term for copying something as intricate and dynamic as a living brain or heart. Could its use lead to misunderstandings or raised expectations within society? “[The brain] is much more complex than other types of twins that are coming from the manufacturing system, so the notion of a twin for the brain is something that, within the neuroscientific community, is being debated,” he says.