In neurons, depolarization refers to a decrease in the magnitude of the membrane potential (the electrical potential difference across the cell membrane). At rest, neurons maintain a negative membrane potential, typically around -70mV, due to the unequal distribution of ions (primarily sodium, potassium, and chloride) across the cell membrane. When a neuron receives excitatory input, such as through the binding of glutamate to AMPA receptors, it causes an influx of positively charged ions (e.g., sodium) into the cell. This influx reduces the magnitude of the negative membrane potential, bringing it closer to zero, which is called depolarization.