TedEd: How fast is the speed of thought?

By Seena Mathew

Imagine a scenario where an enemy has captured you and agrees to let you go if you win a contest. Your brain has been connected via one long neuron to a target. At some point, he will fire an arrow to the target, at which point you need to send a thought to the target before the arrow hits it. To determine if you can win, you need to know how fast your thought can move. 86 billion neurons make up your brain, and these cells have axons that move electrical signals along them. At the end, points called synapses transfer the signal to the dendrites of the next axon in the chain. The first part of figuring out your dilemma is finding out how long it takes to start an action potential (thought), then how fast it can travel down an axon. Based on how fast your knee jerk reaction takes, the average thought takes moves at around 240 km/h. But if an axon is wider or coated with a myelin sheath, it can travel faster, at around 432 km/h. These structures can also degrade with the onset of age. Since the arrow travels at 240 km/h, your thoughts could probably win the race. But you also need to know how long it takes for you to actually perceive the arrow, since you have to wait for the arrow to fire before sending your thought. Your eyes can see the arrow in about 13 milliseconds, but it will take another 200 milliseconds for your brain to process it, giving the arrow a head start of 13 meters. But because your thoughts are faster, they might just be fast enough to win the race.