Direction
Neuro → EE
Nervous systems solve engineering problems under constraints no chip designer would accept, and they solve them on a few watts. These are the designs worth stealing, and the circuits built from them.
Devices
- Event cameras 2008 Image sensors whose pixels each report a change in log intensity the moment it happens, with a microsecond timestamp — the retina's transient pathway in silicon, in place of frames.
- 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.
- The silicon retina 1988 Analog VLSI built to copy the retina's habit of reporting change rather than absolute brightness, which is the ancestor of today's event cameras.
Models
- Spike-timing-dependent plasticity 1997 A synapse strengthens when its input arrives up to a few tens of milliseconds before the cell fires and weakens when the order reverses — Hebb's rule, with spike order setting the sign.
- Neuromorphic computing 1990 Building computation from analog devices in their physics-limited regimes and from spikes rather than clocked arithmetic, on the argument that the brain's efficiency comes from its style of computing.
- 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.
- Lateral inhibition 1957 Neighbouring receptors inhibit one another, so a sheet of them exaggerates edges and suppresses uniform regions — measured in the horseshoe crab's eye, later rebuilt in silicon.
- The Reichardt motion detector 1956 Delay one receptor's signal, multiply it by its neighbour's and subtract the mirror image: a motion detector inferred from a beetle's turning in 1956, since built in silicon and found in the fly.
- 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.
- Hebbian learning 1949 Neurons that fire together, wire together — a synapse strengthens when the cells it joins are repeatedly active together, using nothing but signals already present at the synapse.
- The artificial neuron 1943 Stripping the neuron to a weighted sum and a threshold, which gave engineering a computing element built from biology and is still the unit inside every network built since.
- Central pattern generators 1911 Neural circuits that produce the rhythms of walking, swimming, flying and breathing from an input with no rhythm in it, leaving sensory feedback to adjust the pattern rather than create it.
- 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.
Materials