Index
Concepts
The ideas both fields lay claim to. Each one is shown from both sides — the bar underneath says how the topics split.
- Energy efficiency 15 topics Work done per joule spent. The brain runs on roughly 20 watts, which is the benchmark that makes most computing hardware look profligate — and anything implanted faces a far lower ceiling, set by the heat tissue will tolerate.
- Population coding 14 topics Information carried across many noisy units rather than any single reliable one — which turns a wiring problem into a measurement problem, and sets the specification for most neural instruments.
- Noise 13 topics The floor set by physics beneath every measurement and every signal — the thing instrument designers fight, and that nervous systems seem in places to exploit.
- Feedback 12 topics Routing a system's output back to its input so it corrects itself — long used in steam-engine governors, brought to amplifiers as negative feedback in 1927, and since found running almost everywhere in the nervous system.
- Impedance 12 topics What a circuit presents to a signal at a given frequency — the quantity that decides whether an electrode can hear a neuron, or a coil can reach one.
- Adaptive control 10 topics Adjusting a controller's own parameters as the plant changes underneath it — necessary when the thing being controlled is alive, and therefore never twice the same.
- Sparse coding 6 topics Representing information with few active elements at a time, rather than many slightly-active ones — cheap in energy and bandwidth, and apparently the strategy sensory systems settled on.
- Learning rules 5 topics How a system changes its own parameters from experience — the question neuroscience asks about synapses and control engineering asks about adaptive controllers.
- Temporal coding 5 topics Carrying information in when spikes happen, not only in how many — the question a rate code leaves open, and the reason an event-driven circuit timestamps what a clocked one samples.
- Hierarchy 3 topics Building complicated selectivity out of layers of simple selectivity — how the visual system turns spots of light into objects, and why where a signal enters a structure matters. Engineers build levels too, by scale in filter banks and by speed in control loops.
- Oscillation 3 topics A signal that repeats because a system feeds back on itself with gain and delay — the oscillator an engineer designs on purpose, and the rhythms a nervous system produces whether anyone asked or not.