The Action Potential: The Eletrical Signals That Power Our Brain

The Action Potential: The Eletrical Signals That Power Our Brain

In 1952, Alan Hodgkin and Andrew Huxley made history with their research into the neuron. Their work on the action potential theory laid the foundations for modern computational neuroscience, artificial intelligence, and earned them both a Nobel Prize and a spot in the science Hall of Fame. But what exactly are action potentials, and why are they so crucial to our understanding of neuroscience?

In the field of neuroscience, the creation of a signal in a neuron is known as a spike or an impulse. These impulses are binary in nature, with the cell either being off when it isn't spiking or on when a spike occurs. The action potential is simply the technical name for these impulses, which are carried along the whole body of the neuron to transmit information through an ingenious biological Morse Code system.

To better visualize how they work, imagine walking around your hometown and coming across your childhood home. When you see it, neurons in your brain start firing for multiple reasons, but the important bit here is that these firing neurons generate action potentials, passing them onto other neurons in their vicinity. This process generates a widespread response to seeing that house, creating memories, thoughts, emotions, and ultimately shaping who you are as a person in that exact moment. It's a process so simple yet so complex that neuroscientists still don't fully understand how it works at a brainwise scale.

At its core, an action potential originates from the difference in quantities of two specific ions, potassium and sodium, existing on the outside versus the inside of the neuron. This difference occurs at specific parts of the membrane of the cell, meaning that one very specific part of the neuron will be having an action potential occurring whilst its surrounding parts do not. We call this difference polarization, and the channels that allow for the transfer of the ions between the inside and the outside of the membrane are responsible for this.

Usually, this difference is at a resting state in which the cell has a certain amount of difference between the two ions. However, when a certain stimulus activates the neuron, this difference starts to change. Once it reaches a certain level known as the threshold potential, the membrane of the neuron is activated and starts taking in sodium. Once past this point, the action potential is irreversible, and the neuron will spike. The membrane is now in the depolarization stage as the polarization levels continue to shift.

This process cannot continue indefinitely, as it would essentially break the neuron. Because of this, the membrane stops taking in sodium and works towards going back to its resting state by allowing potassium to enter in a process called repolarization. Once this process is complete, there is a refractory period, a time span during which the neuron cannot fire again. This period functions to prevent the signal from propagating backwards towards parts of the neuron that have already fired.

When the part of the membrane generates this signal, it makes it so that its surrounding parts, which until then were simply resting, also start taking sodium. This process propagates the signal along the neuron's membrane, carrying it towards other neurons. The refractory period works to not allow the signal to be passed back to where it came from, ensuring it will continuously move forwards.

It is from this process that every idea, emotion, and memory you ever had started. If you really think about it, we are nothing else but these action potentials, occurring simultaneously and in ways that allow us to think and have personalities.

In conclusion, the action potential is a critical concept in the field of neuroscience, and it has far-reaching implications beyond our understanding of the brain. This simple but complex process of electrical signaling is the foundation of who we are as individuals, and it is a testament to the beauty and complexity of the human brain.

Pritam Chakraborty

As I was moving through life, I occasionally saw brief glimpses of beauty.

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