Direction
EE → Neuro
Almost every fact we know about the nervous system arrived through a piece of electrical engineering. These are the amplifiers, electrodes, converters, and coils that turned questions into measurements.
- Devices 11
- Methods 6
- Models 7
- Algorithms 1
Devices
- Neuropixels probes 2017 A CMOS shank carrying nearly a thousand recording sites with the amplifiers and multiplexers on the probe itself, which made recording hundreds of neurons at once routine.
- Responsive neurostimulation 2013 A skull-mounted implant that reads the cortex at a seizure focus and stimulates it when a detector fires — closed-loop brain stimulation, approved in the US in 2013.
- Retinal prostheses 2013 Electrode arrays that stand in for dead photoreceptors by stimulating the retinal cells that survive, and that show why the optic nerve is far harder to write to than the auditory nerve.
- Intracortical brain–computer interfaces 2006 An electrode array in motor cortex and a filter that estimates intended movement from many broadly tuned neurons let people with paralysis point, reach and, lately, speak.
- Vagus nerve stimulation 1997 A pacemaker-like generator in the chest drives a helical electrode on the left vagus nerve in the neck, reaching the brainstem through the nerve's sensory fibres to reduce seizures.
- Cochlear implants 1991 An electrode array in the cochlea driven by a filter bank, which restores speech understanding using a couple of dozen channels where the ear has thousands.
- Two-photon microscopy 1990 Using the near-simultaneous arrival of two photons to confine fluorescence to a single focal point, which made optical recording deep in living tissue possible.
- The patch clamp 1976 A glass pipette sealed against a membrane made the current through single ion channels measurable, turning channels from inference into instrument readings.
- Magnetoencephalography 1972 Sensing the brain's femtotesla magnetic field from outside the head, to time cortical currents to the millisecond through a skull that barely distorts them.
- Microelectrode arrays 1972 Photolithographed electrode grids traded single-channel resolution for many cells at once, which helped turn single-unit recording into population dynamics.
- Electroencephalography 1929 Microvolt potentials measured at the scalp, which established that the brain has continuous electrical rhythms and states rather than only responses to stimuli.
Methods
- Optogenetics 2005 Putting a light-gated algal ion channel in genetically chosen neurons, so that light drives one cell type on a millisecond timescale — which an electrode cannot do.
- Functional MRI 1990 Imaging brain activity indirectly through the magnetic signature of blood oxygenation, which gave whole-brain maps of task-related activity without surgery or tracers.
- Deep brain stimulation 1987 Chronically implanted electrodes delivering continuous high-frequency pulses, which treat Parkinsonian symptoms effectively while nobody fully agrees on why.
- Transcranial magnetic stimulation 1985 Discharging a capacitor bank through a coil induces enough electric field inside the skull to fire cortical neurons, making non-invasive stimulation of a chosen region possible.
- The voltage clamp 1949 A feedback amplifier that holds membrane potential at a commanded value and reports the current needed to do it, which is what turned excitability into a measurable quantity.
- Programmable stimulation waveforms — Synthesising the stimulus pulse with a modular converter instead of inheriting whatever the output stage rings at, which turns shape and timing into experimental variables.
Models
- Reward prediction error 1997 Dopamine neurons signal not reward but the difference between reward received and reward expected — an error signal, of exactly the kind a feedback controller runs on.
- Receptive fields in visual cortex 1962 Cortical cells respond not to spots of light but to oriented edges at particular positions, and to progressively more abstract features further along the pathway.
- Efficient coding 1961 The proposal that sensory systems are built to remove redundancy from their input, which turns "why is the retina wired this way" into an information-theory question.
- Cable theory 1959 Treating a dendrite as a leaky transmission line, borrowed from nineteenth-century telegraph engineering, which showed that dendrites compute rather than merely collect.
- The Hodgkin–Huxley model 1952 Circuit theory borrowed to explain the axon as a capacitor with voltage-dependent conductances — then handed back decades later as the template for analog silicon neurons.
- Rate coding 1926 A sensory nerve fibre signals how strong a stimulus is by how often it fires identical impulses, not by their size — seen in 1926, once valve amplifiers could record one fibre.
- The integrate-and-fire neuron 1907 A neuron reduced to a leaky capacitor that fires and resets at a threshold — Lapicque's 1907 circuit for nerve excitation, made a spiking model in the 1960s and now built into neuromorphic chips.
Algorithms