Your mortal enemy has kidnapped you and forced you to participate in a strange experiment. He’s used one very long neuron to stretch the nervous system to a target about 70 metres away.
He’s going to shoot an arrow at some point. He’ll let you go if you can think a thought to the target before the arrow reaches it. So, who came out on top in that race? To find an answer, we must look at the brain’s hardware: neurons.
There are approximately 86 billion of these cells in the human brain. Electrical impulses, or action potentials, are used to send signals down their axons. Chemical neurotransmitters enable one neuron to transfer a signal to the next at a synapse.
The signal is received by the dendrites of the next neuron, propagated down its axon, and passed on.
The time it takes to produce an initial action potential, spread it down the length of the axon, and transport it through the synapse are all important factors in determining how quickly you think.
We must also consider the number of neurons involved and the signal’s travel distance. Let’s take a look at a basic example: your knee-jerk reaction.
An electrical impulse is triggered when your patellar tendon is struck, and it passes up a sensory nerve to your spine. There are many branches to the signal, and for the sake of convenience, we’ll focus on the part that enters a motor neuron and travels back down your leg.
In a 5 foot 5 inch individual, the total length of the neurons in that pathway is about 1 metre, and it takes 15 to 30 milliseconds from strike to kick.
Since distance divided by time equals speed, this signal travels at a speed of 120 to 240 kilometres per hour. Synaptic transmissions take only a few milliseconds after the initial action potential. The majority of the time is spent inside the axons, which takes 1 to.5 milliseconds.
This is in line with research results that show the average neuron transmits signals at a speed of about 180 kilometres per hour. Myelination and increased axon diameter, on the other hand, can improve speeds.
Myelin is a fatty sheath that surrounds an axon and protects it from electrical current leakage. Axons with greater diameters, on the other hand, have fewer internal resistance. These combined factors will propel an action potential to speeds of up to 432 kilometres per hour.
There’s a lot of variation: some people think faster than others, and your own thinking pace shifts over time. The myelin sheath that covers your axons breaks down as you get older, and other neuronal structures decay.
Returning to the heinous experiment. Recurve bow arrows travel at a speed of about 240 kilometres per hour on average.
That is to say, if you have a long enough myelinated or large-diameter neuron, your thoughts might possibly win the race. But… there’s a snag.
The arrow and thought do not leave the gate at the same time; the arrow fires first, and then the signal will begin its journey until you perceive it.
Processing images or music, engaging in inner expression, and remembering memories all necessitate complex neural processes that are not at all like the knee-jerk reflex’s linearity.
The rate at which these thoughts occur is mostly constant, with minor differences due to myelination and axon diameter. However, the length of a thought varies greatly depending on its paths, pitstops, and final destination.
In this situation, a fear startle response will be elicited when you encounter a threatening stimulus. A startle, like a knee-jerk reaction, can be spontaneous and very sharp.
You could respond in less than 65 milliseconds if the string twangs loudly enough. Your startle reaction will most likely be triggered by sight.
Our eyes can process a picture in as little as 13 milliseconds, but it can take up to 180 milliseconds to compute what you’re seeing and determine the danger it presents.
In that time, the arrow would have acquired a 13-meter head start. The goal is far enough away that you have just enough time to catch up if you can figure your way out quickly and literally.