What causes depolarization and repolarization of the neuron?

As a neuroscientist with a focus on cellular and molecular neuroscience, I can explain the processes of depolarization and repolarization in neurons. Depolarization and repolarization are critical events in the action potential, which is the electrical signal that neurons use to communicate with each other. Here's how it works: Depolarization occurs when the neuron's membrane potential becomes less negative (towards zero or positive). This is typically caused by the opening of voltage-gated sodium (Na+) channels in response to a stimulus. When these channels open, sodium ions rush into the cell, causing the inside of the neuron to become more positively charged. Repolarization is the process by which the neuron returns to its resting state after depolarization. This is primarily achieved through the closing of the sodium channels and the opening of potassium (K+) channels. As potassium ions flow out of the cell, the inside of the neuron becomes more negative again, returning the membrane potential to its resting level. The entire process is also regulated by the sodium-potassium pump (Na+/K+ ATPase), which actively transports sodium ions out of the cell and potassium ions into the cell, helping to maintain the resting membrane potential.

Hyperpolarization. The process of repolarization causes an overshoot in the potential of the cell. Potassium ions continue to move out of the axon so much so that the resting potential is exceeded and the new cell potential becomes more negative than the resting potential.