While we might often take our sense of touch for granted, for researchers developing technologies to restore limb function in people paralyzed due to spinal cord injury or disease, re-establishing the sense of touch is an essential part of the process.
And on April 23 in the journal Cell, a team of researchers at Battelle and the Ohio State University Wexner Medical Center report that they have been able to restore sensation to the hand of a research participant with a severe spinal cord injury using a brain-computer interface (BCI) system.
The technology harnesses neural signals that are so miniscule they can’t be perceived and enhances them via artificial sensory feedback sent back to the participant, resulting in greatly enriched motor function.
“We’re taking subperceptual touch events and boosting them into conscious perception,” says first author Patrick Ganzer, a principal research scientist at Battelle.
“When we did this, we saw several functional improvements. It was a big eureka moment when we first restored the participant’s sense of touch.”
The participant in this study is Ian Burkhart, a 28-year-old man who suffered a spinal cord injury during a diving accident in 2010.
Since 2014, Burkhart has been working with investigators on a project called NeuroLife that aims to restore function to his right arm. The device they have developed works through a system of electrodes on his skin and a small computer chip implanted in his motor cortex.
This setup, which uses wires to route movement signals from the brain to the muscles, bypassing his spinal cord injury, gives Burkhart enough control over his arm and hand to lift a coffee mug, swipe a credit card, and play Guitar Hero.
“Until now, at times Ian has felt like his hand was foreign due to lack of sensory feedback,” Ganzer says.
“He also has trouble with controlling his hand unless he is watching his movements closely. This requires a lot of concentration and makes simple multitasking like drinking a soda while watching TV almost impossible.”
The investigators found that although Burkhart had almost no sensation in his hand, when they stimulated his skin, a neural signal – so small it was his brain was unable to perceive it – was still getting to his brain.
Ganzer explains that even in people like Burkhart who have what is considered a “clinically complete” spinal cord injury, there are almost always a few wisps of nerve fiber that remain intact.
The Cell paper explains how they were able to boost these signals to the level where the brain would respond.
The subperceptual touch signals were artificially sent back to Burkhart using haptic feedback. Common examples of haptic feedback are the vibration from a mobile phone or game controller that lets the user feel that something is working.
The new system allows the subperceptual touch signals coming from Burkhart’s skin to travel back to his brain through artificial haptic feedback that he can perceive.
The advances in the BCI system led to three important improvements. They enable Burkhart to reliably detect something by touch alone: in the future, this may be used to find and pick up an object without being able to see it.
The system also is the first BCI that allows for restoration of movement and touch at once, and this ability to experience enhanced touch during movement gives him a greater sense of control and lets him to do things more quickly.
Finally, these improvements allow the BCI system to sense how much pressure to use when handling an object or picking something up – for example, using a light touch when picking up a fragile object like a Styrofoam cup but a firmer grip when picking up something heavy.
The investigators’ long-term goal is to develop a BCI system that works as well in the home as it does in the laboratory. They are working on creating a next-generation sleeve containing the required electrodes and sensors that could be easily put on and taken off.
They also aim to develop a system that can be controlled with a tablet rather than a computer, making it smaller and more portable.
“It has been amazing to see the possibilities of sensory information coming from a device that was originally created to only allow me to control my hand in a one-way direction,” Burkhart says.
Brain-computer interfaces (BCIs) are increasingly becoming the focus of public and scientific attention. The public interest in BCIs has expanded even more since the well-known entrepreneur Elon Musk co-founded the company Neuralink, whose research focuses on BCIs.
BCIs are neurotechnological devices that detect and measure brain activity and convert these brain signals into computer-generated output, which can consist of various tasks such as moving a cursor, operating computer programs, steering a wheelchair, controlling prostheses or activating muscles [1–5].
The output serves as real-time feedback that the users receive, may it be visual, auditory, tactile, vestibular or proprioceptive . The brain signals can be measured invasively or non-invasively, most commonly an electroencephalography (EEG) is used by placing electrodes on the surface of the skull [2, 3]. Three types of BCIs can be distinguished according to the brain activity production that is being used .
Active BCIs require the user to perform a mental task, which is then used as a command for the BCI application. The mental strategy that is often used in these BCIs is motor imagery, i.e. the user imagines moving a body part.
The recorded brain signal is then translated into a specific BCI output. Imagining closing your hand may lead to a robotic arm grasping a cup .
Reactive BCIs operate via the mental strategy of selective attention. They make use of brain activity that occurs as a result of an individual’s voluntarily focused attention on a specific external stimulus.
A commonly used paradigm for reactive BCIs is the P300 setting, which can detect which stimuli the user is concentrating on. The stimuli may be characters or icons displayed on a screen. This setting is used, for instance, in the Brain Painting application .
Passive BCIs do not require a voluntarily performed task. The user’s brain activity is simply measured when it is confronted with certain tasks. Passive BCIs are used to examine cognitive states like mental workload or attention, or affective states .
BCI applications may fall in the medical arena or the consumer arena. Within the medical arena, BCIs are often intended to restore or increase communication and motor skills for persons with physical impairments, improve rehabilitation for persons who have had a stroke or spinal cord injury, and help to regulate or treat persons with psychiatric conditions or epilepsy [9–13]. The consumer arena consists of BCI applications such as gaming, entertainment and enhancement [14, 15].
These technologies potentially raise interesting questions that ethicists have highlighted and discussed. Burwell et al.  synthesize ethical issues addressed throughout the BCI literature. They comprise safety, risk-benefit deliberations, humanity and personhood, stigma, normality, autonomy, responsibility, informed consent and research ethics, privacy, security and justice. Scoping socio-empirical studies on BCIs, Kögel et al.  show that most studies aim to assess the acceptance of BCIs among users and to improve the performance and quality of the technology.
Empirical studies with BCI users with physical impairments that employed qualitative research methods, such as qualitative interviews or focus groups, assess some points that reach beyond the medico-technological evaluation of BCIs. Users report benefits in terms of increased independence and autonomy , experiencing happiness and enjoyment [10, 19–22], as well as valuing the opportunity for creativity and self-expression [20–22] and self-experience .
The possibility of social participation and communication was positively rated , whereas the additional workload for their caregivers  and their dependence on others  was considered worrisome.
Thus far, little empirical research has been done that explicitly addresses the philosophical or psychosocial aspects of BCI use. By taking the value and importance of the perspective of users with physical impairments into consideration, we aim to explore the subjective perspective of medical BCI users. As BCI actions are achieved by bypassing the peripheral nervous system, acting via a BCI may feel and be different from operating another technology.
The research question of this study is how BCI users with physical impairments perceive using a BCI with regard to the following notions:
(1) Self-experience: How does it feel to operate a BCI?
What effects does BCI use have on bodily sensations and self-image/−understanding?
(2) Interactions: What am I able to do with a BCI?
How do other people react towards me as a BCI user?
(3) Evaluation: Does a BCI benefit me currently or will it benefit me at some point in the future?
Does a BCI enable and empower or does it rather alienate and increase dependence?
Following the methods section, we will give a brief overview of the study participants. Next, we will outline the major themes or categories that emerged from the interviewees’ accounts (being an agent, participation, self-definition). Eventually, the categories will be discussed in relation to each other and the literature.
BCI users with physical impairments regard the potential of BCIs very highly. While they may not be applicable to all at the moment, they see potential for the future and stress the importance of investing in the development of this technology. B
eing an agent is an essential aspect of BCI usage and includes some level of uncertainty regarding the agency in place. BCI use also poses opportunities and challenges regarding the users’ self-definition.
The users appreciated the possibilities for social participation that BCIs made available to them. These aspects stand for negotiation processes that take place in the face of perceptions about what are deemed to be valuable and desirable qualities. In awareness of the benefits of BCIs, users accept risks such as surgeries, unfulfilled hopes or data theft.
We may conclude by stating: if technology is beneficial to users, for example in terms of agency, participation, and defining and working on ourselves, technology is welcome.
Technology does not make us less human even though we increasingly incorporate it. Rather the opposite seems to be the case: this technology can retain or enable valuable qualities such as agency or social participation.
Where technology is at odds with users’ common human experiences, as for example having emotions, the technology at best is engineered in a way that encompasses necessary modifications.
The message that these analyzed interviews can pass along to the development of the technology is to keep and strengthen those aspects of BCI use that promote abilities that are regarded as valuable and at the same time to look for ways to improve aspects that are in conflict with common human experiences.
More information:Cell, Ganzer et al.: “Restoring the Sense of Touch Using a Sensorimotor Demultiplexing Neural Interface” https://www.cell.com/cell/full … 0092-8674(20)30347-0 , DOI: 10.1016/j.cell.2020.03.054