Action Potential

Alan Hodgkin and Andrew Huxley chose the giant squid's massive nerve fiber—nearly 1mm wide compared to our hair-thin neurons—to crack the mystery of nerve signals in the 1950s. Their electrode experiments on this humble sea creature revealed the precise choreography of sodium and potassium ions that creates action potentials, earning them a Nobel Prize and giving us the mathematical foundation for understanding all neural activity.

Your neurons fire at wildly different speeds depending on their job: pain signals crawl at just 2 mph while your fastest motor neurons zip along at 270 mph—faster than a Formula 1 car. The secret is myelin, a fatty insulation that lets signals jump between gaps like electricity arcing between power lines, speeding up transmission by up to 100 times.

Unlike a dimmer switch, action potentials are pure binary—they either fire at full strength or not at all, like a gun that only shoots blanks or bullets. Yet somehow this digital system creates the infinite analog richness of human experience, thoughts, and emotions. The magic lies not in the individual spikes but in their patterns, timing, and the vast networks they create.

Every second, your brain generates roughly 20 watts of power through billions of simultaneous action potentials—enough to dimly light a small bulb. This electrical activity is so robust that scientists can detect and decode your thoughts, movements, and even dreams from outside your skull using increasingly sophisticated brain-computer interfaces.

Each action potential burns about 10 million ATP molecules to reset the sodium-potassium pumps afterward—making neural activity one of your body's most energy-expensive processes. Your brain, despite being only 2% of your body weight, consumes 20% of your daily calories largely because of this constant electrical firing and recovery cycle.

Epileptic seizures occur when action potentials lose their normal coordination and fire in massive synchronized waves, like a crowd that suddenly starts clapping in unison. Ironically, this hypersynchrony—which might seem more organized—actually disrupts normal brain function because healthy neural networks depend on the seemingly chaotic but precisely timed independence of individual nerve firing patterns.