The foundations of neurotechnology
Neurotechnology is any device that records from the nervous system, stimulates it, or does both. A cochlear implant is neurotechnology. So is an EEG cap, a deep brain stimulator, and an implant that lets a paralysed person move a cursor. This site sets out the principles they share.
Signals from the brain are personal in a way few other data are. The OECD adopted a recommendation on responsible innovation in neurotechnology in 2019; Chile amended its constitution in 2021 to protect mental integrity; Colorado and California extended privacy law to neural data in 2024.
An open-loop stimulator runs to a fixed programme. A closed-loop one watches the signal and acts only when needed: the RNS system for epilepsy, approved in the United States in 2013, detects the onset of a seizure and stimulates to stop it.
Recorded activity becomes useful once it is mapped to intention. Jacques Vidal coined “brain–computer interface” in 1973. People with paralysis have since controlled cursors (BrainGate, from 2004), robotic arms (2012) and, in studies published from 2021, had attempted speech decoded — first as text, then in 2023 as a synthesised voice.
Current delivered through an electrode, or induced by a changing magnetic field, makes neurons fire or stops them firing. Cochlear implants, deep brain stimulation, spinal cord stimulation and transcranial magnetic stimulation are all variations on this.
Every method trades detail against invasiveness. Scalp EEG is safe and coarse; electrodes inside the cortex resolve single neurons but need surgery. Hans Berger recorded the first human EEG in 1924; functional MRI, shown in rats in 1990 and in people in 1992, measures blood oxygenation as a proxy for activity.
A neuron carries information as brief voltage pulses — action potentials — produced by ions crossing its membrane. Hodgkin and Huxley described the mechanism quantitatively in 1952. Everything else in neurotechnology rests on it.
Read from the bottom up. Every device on this site depends on the first fact: neurons signal with electricity, and electricity can be measured and delivered.