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NeuroTechGuide

Glossary

Neurotech, decoded

48 terms and in-depth guides covering how BCIs work, how the brain is recorded and stimulated, and the ethics of neural data. Start with the guides, or search for any term.

Start here: in-depth guides

All terms A–Z

A

Action potential
A brief electrical pulse (a "spike") that a neuron fires to send a signal down its axon.
Foundations
ALS (amyotrophic lateral sclerosis)
A progressive disease that destroys the nerve cells controlling muscles, eventually affecting speech, movement and breathing.
Clinical & medical
Artifact
Any recorded signal that doesn't come from the brain activity of interest, such as eye blinks, jaw clenches or power-line hum.
Signals & decoding

B

Biocompatibility
How well an implanted material coexists with body tissue over time without causing harm or being walled off by scar tissue.
Clinical & medical
Brain waves (frequency bands)
Rhythmic patterns in brain activity, grouped by frequency: delta, theta, alpha, beta and gamma.
Signals & decoding
Brain-computer interface (BCI)Guide
A system that measures brain activity and translates it into commands for a computer or device, without using muscles or speech.
Foundations
Breakthrough Device designation
An FDA program giving promising devices for serious conditions faster, more interactive review. It isn't an approval.
Clinical & medical

C

Calibration
The training session in which a BCI learns how a specific user's brain activity maps to their intentions.
Signals & decoding
Channel count
The number of separate recording sites a device has. More channels generally means more information about the brain.
Recording the brain
Clinical trial pathway for BCIsGuide
The regulatory steps a medical neural device takes, from first-in-human tests to market approval. In the US this means an IDE, feasibility studies, a pivotal trial and an FDA decision.
Clinical & medical
Closed-loop system
A neurotech device that senses brain activity and responds to it automatically, for example by stimulating only when a seizure starts.
Foundations
Cochlear implant
An implanted device that restores hearing by stimulating the auditory nerve directly. The most successful neural interface to date.
Stimulating the brain

D

Deep brain stimulation (DBS)
An implanted "brain pacemaker" that sends electrical pulses to deep brain structures, mainly to treat Parkinson's disease and tremor.
Stimulating the brain
Dry vs. wet electrodes
Wet EEG electrodes use conductive gel for a clean signal; dry electrodes skip the gel for convenience at some cost in quality.
Recording the brain
Dual use
When a technology built for medicine or research can also serve military, surveillance or enhancement purposes.
Ethics, policy & safety

E

ECoG (electrocorticography)
Recording from electrodes placed directly on the brain's surface, under the skull. Much clearer than EEG, without penetrating tissue.
Recording the brain
EEG (electroencephalography)
Recording the brain's electrical activity with electrodes on the scalp. Safe, cheap and fast, but low in spatial detail.
Recording the brain
EMG (electromyography)
Recording the electrical signals of muscles. Neural interfaces use it to detect intended movements at the wrist or in a residual limb.
Recording the brain
Endovascular BCI
A BCI delivered through blood vessels: a stent-like electrode is threaded up a vein and lodged next to the motor cortex, with no open brain surgery.
Recording the brain

F

fMRI (functional MRI)
A brain scan that maps activity by detecting changes in blood oxygen. Very detailed in space, slow in time, and needs a large scanner.
Recording the brain
fNIRS (functional near-infrared spectroscopy)
A wearable method that shines near-infrared light through the scalp to measure blood-oxygen changes linked to brain activity.
Recording the brain
Focused ultrasound
Sound waves focused through the skull to a precise point, used to treat tremor, deliver drugs and, increasingly, to image or modulate brain activity.
Stimulating the brain

H

How the brain produces signalsGuide
Neurons communicate with electrical spikes and chemical messages. BCIs read these at different scales, from single spikes to whole-brain rhythms.
Foundations

I

Information transfer rate (ITR)
How much information a BCI can communicate per unit of time, often given in bits per second or words per minute.
Signals & decoding
Informed consent (in neurotech)
Making sure people understand the risks, benefits and long-term implications before agreeing to a neural device or sharing brain data.
Ethics, policy & safety
Invasive vs. non-invasive BCIsGuide
The central trade-off in neurotech: the closer a sensor gets to neurons, the better the signal, and the greater the medical risk.
Foundations

L

Local field potential (LFP)
The combined, slower electrical activity of many neurons near an electrode, recorded inside the brain.
Recording the brain
Locked-in syndrome
A condition in which a person is conscious and aware but almost completely paralyzed, often able to communicate only with eye movements, or not at all.
Clinical & medical

M

MEG (magnetoencephalography)
Measures the tiny magnetic fields produced by brain activity. Fast like EEG, with better spatial detail.
Recording the brain
Microelectrode array
A set of tiny electrodes inserted into brain tissue to record individual neurons. The highest-resolution BCI sensor.
Recording the brain
Motor cortex
A strip of the brain's outer layer that plans and controls voluntary movement, and the most common target for BCI implants.
Foundations
Motor imagery
Imagining or attempting a movement without actually making it. This produces brain activity a BCI can detect and use as a control signal.
Signals & decoding

N

Neural data
Information generated by measuring the nervous system. Increasingly treated by law as highly sensitive personal data.
Ethics, policy & safety
Neural decodingGuide
Using algorithms, usually machine learning, to infer what a person intends from patterns in their brain activity.
Signals & decoding
Neuron
A nerve cell, the basic unit of the nervous system, which sends information using electrical and chemical signals.
Foundations
Neuroplasticity
The brain's ability to rewire itself by forming and strengthening connections in response to learning, experience or injury.
Foundations
Neuroprosthetics
Devices that replace or restore a lost nervous-system function, such as hearing, sight, movement or speech.
Foundations
NeurorightsGuide
Proposed human rights that protect the mind from misuse of neurotechnology: mental privacy, personal identity, free will, fair access and protection from bias.
Ethics, policy & safety
Neurotechnology
Any technology that records, stimulates or interacts with the nervous system, including BCIs, brain stimulators, neural implants and brain imaging.
Foundations

O

Optogenetics
A research technique that genetically makes neurons light-sensitive so they can be switched on or off with light.
Stimulating the brain

P

P300
A brain response that appears about 300 ms after you notice something you were looking for. It powers classic EEG "speller" BCIs.
Signals & decoding

S

Signal-to-noise ratio (SNR)
How strong the useful brain signal is compared with unwanted noise. Higher SNR means more reliable decoding.
Signals & decoding
Speech neuroprosthesis
A BCI that decodes attempted speech from the brain and outputs text or a synthesized voice for people who can't speak.
Clinical & medical
Spinal cord stimulation
Electrical stimulation of the spinal cord, used for chronic pain and, more recently, to restore movement after spinal cord injury.
Stimulating the brain
SSVEP
When you look at a light flickering at a fixed rate, your visual cortex echoes that rate. BCIs detect which flicker you're looking at.
Signals & decoding

T

tDCS / tES (transcranial electrical stimulation)
Gentle electrical current applied through scalp electrodes to nudge brain activity up or down. Used in depression treatment and research.
Stimulating the brain
TMS (transcranial magnetic stimulation)
A non-invasive treatment that uses magnetic pulses from a coil held over the head to activate brain areas. FDA-cleared for depression.
Stimulating the brain

V

Visual prosthesis
A device that restores partial sight by stimulating the retina or visual cortex, producing spots of light called phosphenes.
Stimulating the brain