Embark on an exploration of Pieter Roelfsema’s groundbreaking work at the Netherlands Institute for Neuroscience. Roelfsema’s revolutionary visual brain prosthesis offers hope to over 40 million blind individuals worldwide. Uncover how electrical stimulation creates artificial perceptions, opening pathways to independence, participation, and inclusivity.

Which wall does your research break?

Approximately forty million people across the world suffer from blindness. The loss of vision is devastating and greatly reduces one’s autonomy and quality of life. Large economic losses to society are accrued due to reduced workforce participation and burden of care. More than half of the people who are blind cannot benefit from treatments of the eye because the connections between eye and brain degenerated. They can only benefit from a visual brain prosthesis, which bypasses the eye and connects a camera to the brains cells involved in the processing of visual information. Such a brain prosthesis would increase the independence of blind users by allowing them to engage in activities for which they now rely on caregivers. We aim to develop a revolutionary method to control brain activity with electrical stimulation and to thereby restore visual function in blind people. The core idea is to develop a large-scale, chronically implanted, wireless device that imparts clinically relevant visual patterns directly to the visual cortex. In 2020 the team published the first proof-of-concept for the utility of the device, demonstrating that monkeys can perceive letters that are directly plugged into their visual cortex with patterned electrical stimulation (Chen et al., Science, 2020). To translate this technology to humans, our team collaborates with engineers in medical devices, microelectronics and wireless communication, and leading industry partners. A brain implant with a high density of electrodes will not only benefit people who are blind, but it can also have other applications, for example, in the restoration of hearing in deaf patients in whom hearing cannot be restored in the inner ear but by targeting deeper structures in the brain. However, the focus of my team is on the visual cortex with the aim to bring this new technology to blind people.

What inspired or motivated you to work on your current research or project?

In my scientific work I have focused on the neuronal processes that allow the visual brain to highlight the objects that are important for behavior and to segregate them from other, less relevant objects and the background. I also investigate how visual information can become part of our conscious awareness. During our work on visual information processing in the brain, we encountered a surprising finding. When we presented weak visual stimuli or electrical stimuli to the visual cortex, we were able to predict whether they were going to be perceived by recording from the frontal cortex (van Vugt et al., Science, 2018). This result indicates that visual stimuli need to propagate strongly enough to the higher areas to be consciously perceived, which is a result that is fundamental for theories of consciousness (Mashour et al., 2020). We quickly realized that our knowledge of how electrical stimulation of the visual cortex elicits artificial, conscious perceptions, combined with the methods that we develop to implant many hundreds of electrodes in the visual brain, could be applied to develop a visual brain prosthesis for blind people. This led to our proof-of-principle study in which we implanted more than 1,000 electrodes in the visual cortex. In the final system, the user will wear a camera, and the images are “plugged in” the visual brain using electrical micro-stimulation. After our demonstration in monkeys, we have started to collaborate with Eduardo Fernandez (Elche, Spain) to test the approach in humans, and we obtained encouraging results in blind volunteers (Fernandez et al., J. Clin. Invest, 2021).

In what ways does society benefit from your research?

We aim to restore a rudimentary form of vision for people who became blind at a later age. Blindness affects >40 million people worldwide and many of these individuals lost the connections between the eye and brain. Their disease can no longer be treated with e.g. gene therapy or implants in the eye. Our previous work demonstrated that it is possible to skip the eyes by directly conveying shape information using patterned electrical stimulation of the visual cortex. We now need to demonstrate the longevity of our new methods for electrical brain stimulation, ensuring that the implants last for many years. The estimated size of the target population of blind people who could benefit from the prosthesis is 8 million worldwide, if we take the following factors into account: (1) the maturity of the health care systems worldwide; (2) the health status of prospective users who will need to undergo brain surgery; (3) exclusion of congenitally blind individuals, because the technology is only suitable for blind individuals who lost their sight at a later age, so that the higher processing stages of the visual system developed normally, allowing them to process phosphene patterns as meaningful shapes. A visual brain prosthesis has the potential to significantly improve the quality of life of many people. When their vision is partially restored, the individuals will be better equipped to engage in social activities, pursue employment opportunities, and participate more actively in society. My team focuses on patients, caregivers and user involvement to ensure that the needs and desires of blind individuals are at the forefront of the technology’s development, making it more likely that the resulting visual prosthesis will be effective and useful for this population. Our projects aim to thereby contribute to an increase in the proportion of blind people who can play an active role in society according to their wishes and capabilities. Furthermore, by enabling blind individuals to see and participate more fully in society, the visual prosthesis has the potential to promote greater inclusivity and equity for individuals with disabilities.

Looking ahead, what are your hopes or aspirations for the future based on your research or project?

Our current goals are to: (1) better understand the functionality of artificially generated percepts, (2) improve the longevity of the device and (3) the degree to which the entire visual field is covered with artificial perception. (1) Regarding functionality, we are currently further investigating the properties of the artificial perceptions that are elicited with electrical stimulation, in collaboration with Prof. Fernandez in Spain who implants electrodes in the visual cortex of blind humans, who can report about the quality of the artificial perceptions. A better understanding of the perceptions that can be elicited in different brain regions is of fundamental importance for the further development of this technology. (2) The intracortical electrodes that we used in our previous work consisted of stiff silicon shanks. Despite their small size, they resulted in damage to the brain that developed over several years caused by a response of glia cells. We are working to replace these stiff electrode shanks with shanks that are ultra-thin and flexible and are made from polymers, which cause minimal tissue damage once implanted. In the coming years, it will be necessary to demonstrate the longevity of these thin, flexible polymer probes, because clinical evidence in humans does not yet exist. (3) In humans, we have targeted the primary visual cortex, which is partially located between the two hemispheres, making it difficult to access. The visual cortex also has a complex three-dimensional shape, and most parts of it cannot be interfaced using existing implants. If these regions stay without electrodes, artificial perceptions cannot be produced at these locations so that the user remains blind in the corresponding regions of the visual field. We are developing new methods to ensure that vision can be restored in the entire visual field so that there are no large regions in which the future user of the prosthesis remains blind. When these goals are achieved, we will be ready to further test the new technology in humans, and we aim to test the new version of the implant in humans in the coming two to three years.

Further information


Pictures illustrating our work:

Podcast from the journal Nature:

Dec 3-4 2020, publicity after our Science paper on the visual cortical prosthesis. The paper gave rise to >300 items in the popular press in more than 51 countries, with a total reach of more than 1,4 billion people. Some of the highlights are:

  • https://edition.cnn.com/2020/12/03/europe/brain-implant-blind-intl-scli-scn/index.html
  • https://www.scientificamerican.com/article/bionic-eye-tech-learns-its-abcs/
  • https://www.newscientist.com/article/2261853-brain-stimulation-device-lets-monkeys-see-shapes-without-using-eyes/
  • https://theophthalmologist.com/subspecialties/visions-of-tomorrow
Further Activities to have a look at