From brain implants to neuroprosthetics

The concept of connecting brains to computers has leapt from science fiction into real-world science. In recent years, brain-computer interfaces (BCIs) have been recognized as revolutionary technology that could transform medicine and even redefine human-machine interaction. 

Tech visionaries tout mind-controlled gadgets and “brain chips” that might restore lost abilities or boost our brains. Meanwhile, BCIs are moving from laboratory experiments to human clinical studies, promising new treatments for paralysis, blindness, and other conditions.

However, excitement around BCIs has created a flood of new terms and ways to talk about them. And different researchers, companies, and publications use different terms for similar concepts in neurotechnology. “Brain-computer interface” (BCI) itself is the most common term, but you may also encounter phrases like brain-machine interface, neural implant, neuroprosthetic, brain chip, and many more. 

If all this jargon leaves you scratching your head, don’t worry. In this article, we’ll break down the BCI lingo and explain what each term means, where it comes from, and how these terms overlap or differ. By the end, you’ll have a clearer understanding of this exciting field.

What is a brain-computer interface (BCI)?

At its core, a brain-computer interface (BCI) is a system that enables a direct communication link between the brain’s activity and an external device. In a typical BCI, sensors pick up signals from the brain (for example, electrical impulses produced by neurons firing) and translate those signals into commands to control an external computer or device. This creates a new communication channel that bypasses normal motor output. A person can control a computer or machine simply with their intentions, without moving any muscles.

BCIs were once a niche academic topic, but today the term is widely used in both research and the popular press. The phrase “brain-computer interface” was first coined in 1973 by scientist Jacques Vidal in an academic publication. For decades, BCIs were primarily experimental setups in labs, often involving patients or even monkeys controlling cursors or robotic arms via implanted electrodes. Now, with companies entering the scene, “BCI” has become the umbrella term for any technology linking brains and computers. Whether it’s a paralyzed person moving a robotic limb or a consumer wearing a headset to play a video game, they all fall under the broad definition of brain-computer interfaces.

Academic vs. popular usage: Historically, BCI was an academic term and is still most common in scientific literature. But now it’s also used widely outside academia as media articles, tech blogs, and companies have adopted “BCI” as the go-to label for this technology. In short, “brain-computer interface” is the standard term in both technical and general discussions today.

Before diving into alternate terms, it’s useful to understand a few basic categories and descriptors that further refine what type of BCI we’re talking about:

• Implantable BCI: This term usually highlights that the BCI device is fully implanted inside the body. Many implantable BCIs used in research have external components, for example, a pedestal or plug exiting the skull to connect to electronics. An implantable BCI typically means the entire system (electrodes, electronics, wireless transmitter, battery) is implanted under the skin or skull, with no transcutaneous wires.
  Implantable BCIs aim to be long-term medical devices, like a pacemaker for the brain. By contrast, early BCI implants like BrainGate involved a connector protruding from the head, not exactly practical for daily life.
• Intracortical BCI:This term refers to an implantable BCI with electrodes placed into the cerebral cortex (the outer layer of the brain). These often use tiny electrode arrays (like Blackrock Neurotech’s Utah Array or Paradromics Connexus®  Brain-Computer Interface) that penetrate a few millimeters into the brain to record from neurons in specific regions (e.g. motor cortex). 
  Intracortical BCIs have enabled some of the most dramatic demonstrations of the capabilities of BCI, like people with paralysis controlling robotic arms or computer cursors. In fact, the Utah Array, developed in 1992, became a gold-standard intracortical BCI sensor, used in the early 2000s BrainGate trials where a paralyzed man became the first to have a chip implanted to control a computer cursor by thought. 
  Intracortical devices are a subset of implantable BCIs but not all implantable BCIs are intracortical (e.g. electrocorticography (ECoG) electrodes are placed on the surface of the brain).
• Stentrode BCI: The Stentrode is an endovascular BCI, meaning it is implanted via the blood vessels. Once in place, it can pick up brain activity from inside the vessel wall. In trials, patients with ALS have used a Stentrode BCI to wirelessly control a computer, marking the first time a BCI was implanted via blood vessels instead of directly into brain tissue. The Stentrode requires surgery and carries risks like blood clots and the inability to remove the device.
• Closed-Loop BCI: A closed-loop brain-computer interface is one that not only records brain activity but also provides feedback or stimulation to the user in real-time, forming a loop of interaction. In a closed-loop system, the device might stimulate the brain in response to detected signals, or adjust its output based on the brain’s reactions. For example, a neural device that detects an impending epileptic seizure from brain signals and then delivers a burst of electrical stimulation to stop the seizure is a closed-loop or bidirectional BCI.
  Many current BCI research systems are open-loop, e.g. you think about moving a cursor, the cursor moves, but the BCI isn’t stimulating your brain. Closed-loop designs are important for things like rehabilitation (where feedback can help retrain the brain) and for any BCI that tries to adjust the brain’s state (like mood or sleep BCIs that respond to your brain activity).

With those fundamental definitions in mind, let’s untangle the many alternative terms people use when talking about BCIs.

From brain chips to neural interfaces: Alternate BCI terminology

Over the years, different communities and companies have developed their own preferred terms for brain-computer interfaces. Often these refer to the same basic concept, but each term can carry a different connotation or be used in a different context. Here are some of the most common alternate terms for BCIs, and what you should know about each:

• Brain Chip (Neural Chip): The term “brain chip” is a popular media shorthand for an implanted BCI device. It conjures an image of a microchip in the brain, which is essentially what devices like the Utah Array or Neuralink’s Link are (silicon chips with electrodes). Journalists often use “brain chip” in headlines about BCIs, especially when covering companies like Neuralink.
  The phrase “neural chip” is used similarly. These aren’t technical terms you’ll find in academic papers, but they have caught on in pop culture. If you hear about scientists putting chips in brains or a “mind chip”, it refers to a brain-implantable interface that can read (and sometimes stimulate) neural activity. The flashy term “brain chip” tends to emphasize the high-tech, sci-fi nature of the device.
• Neuralink Chip (Neuralink Implant): This refers specifically to Neuralink’s proprietary BCI device. The Neuralink chip is a coin-sized implant with 1,024 ultra-fine electrode threads, designed to be sewn into the cortical surface.
• Brain Implant (Neural Implant): The term “brain implant” is very general – it can refer to any device implanted in the brain. This could include BCIs, but also things like deep brain stimulators (for Parkinson’s disease) or implantable drug delivery devices. In the context of BCIs, saying “brain implant” emphasizes the physical reality that something is surgically placed in the brain. “Neural implant” is essentially synonymous. These phrases are often used in clinical and popular discussions to make clear we’re talking about implanted tech (as opposed to external headsets).
• Brain-Machine Interface (BMI): “Brain-machine interface” means the same thing as brain-computer interface: a direct pathway between brain and an external machine. In fact, BCI and BMI are interchangeable in many contexts. Some researchers prefer BMI, possibly to emphasize that the other end of the interface could be any machine (not necessarily a traditional computer). That said, some use BMI when referring to animal studies or prosthetic control, and BCI when referring to computer cursor control or human applications, but it is not a hard rule.
  An interesting note is that some authors suggest BMI for implanted devices and BCI for non-implanted devices, pointing out that “brain-computer” highlights the role of computation, whereas “brain-machine” might highlight the physical interface hardware. However, in practice, you’ll see both terms in scientific papers and articles. For a general reader, you can treat brain-machine interface as a synonym for brain-computer interface.
• Brain-Computer Implant: This phrase is essentially a mashup to specify an implanted BCI device. It’s not as commonly used as “brain-computer interface” alone, but it does appear in some articles and reports. Think of it as an explicit way to say “an implanted brain-computer interface.”
• Brain Interface Devices: This is a broader, somewhat more formal phrase that groups BCIs with similar technologies. This term can include implanted BCIs, non-implanted EEG systems, and even things like brain stimulators, because they are all devices interfacing with the brain in some way. It’s an umbrella term, less flashy than “brain-computer interface,” and often used in contexts like grant descriptions or industry reports.‍
• Neural Computer Interface: This term is relatively rare compared to the others. It appears to be a variation on brain-computer interface, essentially flipping “brain” to “neural.” For all intents and purposes, “neural computer interface” means the same concept, i.e. a direct interface between neural tissue and a computer. You might see it in older literature or the occasional article, but it hasn’t caught on widely.‍
• Neuroprosthetic (Neurological Prosthetics): The word “neuroprosthetic” refers to a device that replaces or augments the function of the nervous system. This term often comes up in medical contexts. Classic examples of neuroprosthetics are cochlear implants (which restore hearing by interfacing with the auditory nerve) or retinal implants for vision.
  Some BCIs can be considered neuroprosthetics, especially those aimed at restoring lost abilities. For instance, a BCI that helps a paralyzed person move a limb or a BCI that decodes speech for someone who cannot speak is clearly acting as a neuroprosthetic (replacing the natural motor or speech function).‍
• Brain Interfaces / Neural Interfaces: In casual usage, people sometimes used the shorthand description “brain interface” or “neural interface.” This is essentially a synonym for BCI that is used in more general and futuristic contexts. In some cases, “neural interface” may be expressed as a single word, “neurointerface,” but this is less common.‍
• Brain Prosthesis: This term is usually used to describe an experimental device that aims to replicate or augment an actual part of brain function, effectively acting as an artificial piece of the brain. It’s closely related to neuroprosthetic, but “brain prosthesis” specifically implies a prosthetic for a cognitive function. “Brain prosthesis" is usually used in contexts like “a brain prosthesis to repair memory.” It’s not commonly used to refer to BCIs for motor control or communication.

As you can see, many of these terms overlap heavily. Often, the choice of wording comes down to who is talking and what they want to emphasize:

• Journalists and the public gravitate to simple, catchy terms like brain chip or brain implant.
• Companies might use proprietary or broad terms like neural interface or brain-computer implant to distinguish their tech.
• Academics use precise terms like BCI, BMI, or neuroprosthetic depending on context (e.g., BCI for the system, or neuroprosthetic for the clinical purpose).

The good news is that if you understand “brain-computer interface,” you already grasp the essence. Next, let’s look at one more way the terminology gets sliced: by the specific application or function of a BCI.

BCIs by application: Motor, speech, vision, and more

Another way you’ll see BCI terms broken down is by the capability the interface is providing to the user. Since BCIs can be designed for different goals (moving a limb, communicating, sensing emotion, etc.), specialists often add a descriptor up front to specify the application. Here are a few descriptors you might encounter:

• Motor BCI: This refers to a brain-computer interface designed to restore or bypass motor function, in other words, controlling movement. A motor BCI usually reads signals from brain areas responsible for movement (like the motor cortex) and translates them into commands to control an external device or even the person’s own muscles. The classic example is a BCI that lets a paralyzed individual move a computer cursor or a robotic prosthetic arm using their mind.
• Speech BCI: A speech BCI (or speech neuroprosthesis) is a BCI that enables communication by decoding neural signals related to speech. This is often aimed at people who cannot speak due to paralysis or disease (like ALS, brainstem stroke, etc.). A speech BCI typically works by implanting electrodes over speech-related brain areas (such as the motor cortex areas for the vocalization) and interpreting the neural activity when the person tries to speak or formulates words. Recent breakthroughs have shown it’s possible to translate a person’s attempted speech into text or even synthesized voice in real time.
• Vision BCI: BCIs for vision aim to restore or augment sight by connecting directly to the visual system. A vision BCI could take the form of a visual neuroprosthetic, for instance, an implant that stimulates the visual cortex or retina to produce visual perceptions (phosphenes) for blind individuals. One approach uses a camera to capture images and then feeds that information into the brain. For example, there have been devices where a camera sends signals to an array of electrodes on the visual cortex, allowing a blind person to perceive a rudimentary dot-matrix version of the visual scene (often termed a “bionic eye” if it involves an implant).
  The term “vision BCI” can also encompass non-implanted sensory substitution devices like The vOICe, which converts camera input to sound for the blind (training the brain to hear images). However, the cutting-edge research is on implants: BCIs that transmit visual information from a camera directly to the brain’s visual areas, effectively creating artificial vision.
• Affective BCI: Affective BCIs are systems that monitor your brain’s emotional state and potentially help modulate it. For example, a BCI could detect when a user is experiencing stress or depression from their brain signals and then trigger an intervention to help. These BCIs extract features related to emotional states from neural signals and can even respond in real time to those states.
  More advanced concepts involve treating mental health disorders: for instance, a closed-loop BCI that detects depressive brain patterns and stimulates reward centers, or one that monitors focus/attention (an aspect of cognitive state) and helps ADHD patients. Affective BCIs are still largely confined to research, piggybacking off of clinical treatments like epilepsy, but they represent an exciting frontier where BCIs interpret and influence our emotions. You might also hear terms like “emotive BCI” or “emotional BCI,” all pointing to this idea of brain-computer interfaces centered on emotion-driven signals.

These application-based terms can overlap with each other. For example, a speech BCI and a motor BCI might use very similar technology (since speaking is a motor act, some speech-BCIs decode motor cortex activity of the tongue/jaw). A vision BCI could be considered a sensory neuroprosthetic. An affective BCI might overlap with neurofeedback devices used for meditation or with psychiatric deep brain stimulators (if they become adaptive).

The key takeaway is that sometimes people will refer to a BCI by what it’s used for rather than the technology itself. If you keep the definitions in mind, it’s easy to decode these phrases.

Conclusion

From brain-computer interfaces in research labs to sensational “brain chips” in news headlines, the terminology around this field can certainly be bewildering. We’ve seen that many terms are closely related, often describing the same core idea with different nuances. Some terms come from academic tradition, others from popular culture or company branding. Yet, despite the linguistic confusion, what’s important is the reality behind the terms: a rapidly advancing technology that directly links minds and machines.

No matter what we call it, BCI, BMI, brain chip, neuroprosthesis, or neural interface, this field is poised to grow and capture our imagination. The coming years will bring BCIs out of experimental trials into real-world clinical use, under one name or another. And despite the jumble of jargon, one thing is certain: the idea of connecting brains to computers will continue to fascinate us and drive technological and medical innovation for years to come.

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