Brain-machine interface technology is a rapidly growing area of neuroscience research and development. The technology enables a person to control an external device using brain signals, and while it is still largely experimental, the possibilities are vast and exciting.
This article looks into the current use and future potential of brain-machine interface technology, from enabling sound processing through cochlear implants to helping people with paralysis regain control of their limbs.
What are brain-machine interfaces?
Brain-machine interfaces (BMIs), also known as brain-computer interfaces (BCIs), operate via a direct communication pathway between the brain and a computer.
They work via the same principle as neuroplasticity, the adaptive structural and functional changes to the brain that can be learned after a stroke or traumatic brain injury. The human nervous system has the ability to change its activity in response to intrinsic or extrinsic stimuli by reorganizing its structure, functions, or connections. Similarly, BMIs introduce artificial pathways and this creates new relationships between sensory input and motor output that the brain must then learn.
These processes may include changes in existing synaptic strengths, formation of new synapses, or even formation of new neurons. Neural circuits must undergo some change for motor memory to be formed, consolidated, and easily recalled, and studies have consistently shown that changes in neural activity correlate with BMI performance improvement.
BMIs do not read minds in the sense of extracting information from unsuspecting or unwilling users but instead enable users to impact their environment through brain signals rather than muscles. After a period of training, the user and the interface work together – the user generates brain signals that encode intention, and the BMI then decodes the signals and translates them into commands to an output device, accomplishing the original intention.
Use and impact of BMIs
BMIs generally connect to the brain either through an implanted or a wearable device:
Implanted BMIs are usually surgically attached directly to brain tissue and measure signals directly from the brain, reducing interference from other tissue. An example is cochlear implants.
Wearable BMIs on the other hand often require a cap to be worn containing conductors that use electroencephalography (EEG) to measure the brain’s electrical activity. Wireless EEG will enhance the portability and mobility of collecting this data. In April 2021, a device that uses a wireless EEG headset to help stroke patients regain arm and hand control became the first wearable BMI for rehabilitation to receive market authorization from the U.S. Food and Drug Administration. A number of other wearable and implanted BMIs for medical uses are currently in clinical trials.
BMI technology promises to have a major impact on the lives of people disabled by neuromuscular disorders such as amyotrophic lateral sclerosis, cerebral palsy, stroke, or spinal cord injury, or sensorimotor neurological disorders where nerve damage is causing a decreased ability to move or feel sensations.
BMIs have been developed that allow people with paralysis to spell words on a computer screen or regain control of their limbs. In addition, researchers are developing BMI-controlled robotic limbs that can provide users with a sense of touch, as well as increasingly complex control of cursors, prostheses, wheelchairs, and other devices.
Challenges
As with any new technology, potential issues have arisen that need to be worked through, including:
- Learning to use a BMI can require substantial user training
- Creating a direct connection between the brain and a machine may have security and privacy concerns, e.g. BMIs could be vulnerable to cyberattacks that expose brain data or interfere with a device’s function
- Each user generates unique brain signals that are difficult to measure clearly
- Inaccurate translation of brain signals might indicate legal or medical consent that the user did not intend to give
- There are also societal implications around the current high costs of wearable BMIs and whether they may result in unequal access
Future potential of BMIs
Scientists could use BMIs to facilitate brain research and improve our understanding of how the brain works. Some researchers have already started using BMIs to detect the emotions of patients in a vegetative or minimally conscious state.
BMIs also have great potential to accelerate and simplify interactions between humans and machines in other fields, such as defense and space. Some researchers have also suggested that BMI-controlled robots could assist people in hazardous environments, such as coal mines.
