Brain-computer interfaces, also known as neural interfaces, are essentially bridges between the brain and external devices.
These neuroprostheses record and transmit neuronal activity to external devices, such as a computer, prosthetic, or (maybe one day) passive exoskeleton. The external devices then translate the activity into digital output, improving over time as machine learning allows it to create a dictionary of neural activity and the patient's intended outcome.
Types of Brain Implants
Some BCIs are implanted directly in the brain, meaning they're inherently closer to the neuronal activity they'll be recording. These sorts of implants have so far proven the best at "reading" neuron activity.
Medical professionals know where to implant these devices based on mapping data obtained through brain mapping paired with scans from devices, including MRIs, EEGs, and electrocorticography recordings.
Other BCIs are tucked onto the surface of the brain or inside nearby blood vessels, specifically the superior sagittal sinus, which runs along the top of the brain.
Stentrodes, electrode-ridden stent-like BCIs, implanted in the SSS near the primary motor cortex have been shown to enable "instrumental activities of daily living," including communicating with others and managing finances, by ALS patients.
Noninvasive BCIs aren't implants at all. This category of BCIs, which includes EEGs or electroencephalograms, has been around for decades and records the brain's electrical activity from outside the skull.
Deep Brain Stimulation
BCIs can also send information into or stimulate the brain via a process known as deep brain stimulation. This is when electrodes implanted in the brain electrically stimulate neurons to regulate abnormal signaling, such as in Parkinson's, or mitigate mental health conditions, including OCD and treatment-resistant depression.
Similar to how BCIs can send brain signals to external devices, the technology can also be used to send brain signals past damaged neurons and into other regions, such as the spinal cord, that can act on those signals.
Ethics
In April 2024, the US took its first step toward protecting data found in brainwaves when the governor of Colorado, Jared Polis, signed into law a measure that amends the state's privacy law to include neural data.
In addition to the newer concern over neural privacy, some scientists have voiced concerns about manipulating neuronal activity to influence behavior or implant false memories.
Dangers
Outside of the immediate medical risks of surgery and infection, implanting a foreign body into the brain triggers natural reactions, such as the development of scar tissue.
There may also be long-term and yet-to-be-determined side effects of squidging tech into the brain or stimulating the brain with electricity, the latter of which could trigger the brain to normalize the new input, an adaptation whose implications are currently unknown.
In addition to the medical dangers, the early nature of BCIs means there's also the risk of implants being discontinued, technology losing support, and implant manufacturers and developers going out of business, potentially taking their implants with them.
Neural interfaces, also known as brain-computer interfaces, record the brain's electrical activity, which it then sends to an external device, such as a computer or prosthetic, that responds in kind. The first neural devices were cochlear implants, designed to treat hearing loss. These neuroprostheses have enabled the restoration of mobility, communication, and activities of daily living that might otherwise require a caregiver.
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A growing number of companies developing brain implant technology have reached the human testing stage. These intracranial brain-computer interfaces have so far been able to successfully reanimate paralyzed limbs and restore communication and mobility via BCI-controlled external interfaces, such as prosthetic devices or computers. The field's nascent nature begets ethical concerns over the privacy and assumed inalienability of one's brain activity, including their memories.
As brain implants pass human trial stages and more people go or have gone about their everyday lives with BCIs, many patients report becoming a different person after surgery and subsequent symptom relief. Some see a surge in potentially hazardous conditions and behaviors, such as depression, depersonalization, or uncharacteristic impulsivity. The extent to which these implants influence these changes is unclear.
An Australian woman was given a brain implant in a clinical trial to help people with epilepsy. After years of struggling with life-disrupting seizures, she felt like "I could do anything"—at least until her implant was removed against her will two years later when the company that made it folded. Ethicists question whether this removal violates "neuro rights," a subset of human rights focused on the mind.
Brain-computer interfaces have elevated wearable technology to a new level of integration. Electrodes inside earbuds, headphones, watches, and headbands allow users to monitor their brain activity, potentially using these insights to manage conditions such as flow state, ADHD, migraine, and cognitive decline. These devices record and transmit brain activity, begging the question of who or what—like governments, insurance companies, and employers—will have access to this data.
These prosthetics are plugged directly into the skeletal system using titanium implants like those used in dentistry. Electrodes are implanted in the muscles and nerves around the residual limb, which may require reconfiguration of muscle movement and contraction to restore full range of motion. Neural signals related to commands like "close your hand" are then translated into code and trained into a tiny computer in the limb.
Roughly half of people who've experienced addiction relapse after treatments such as medication, therapy, and residential programs, pushing their substance use disorder into the subcategory of treatment-resistant. Those with such a manifestation of SUD may benefit from neural stimulation by implants threaded beneath the cerebral cortex in the "deep brain." Researchers are hopeful, though further study is needed and currently hindered by high costs and tiny trial sizes.
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