What does resting membrane potential indicate in a neuron?

Resting membrane potential refers to the electrical charge difference across the neuron's membrane when the neuron is not actively transmitting a signal. It is typically around -70 mV, which indicates that the inside of the neuron is more negatively charged than the outside.

The correct option highlights that there is low permeability and a negative charge inside the cell. This reflects the fact that the resting membrane potential is primarily established by the distribution of ions, specifically the high concentration of potassium ions inside the neuron compared to outside, as well as the relative impermeability of the membrane to sodium ions at rest.

At rest, the neuron maintains a negative intracellular environment mainly due to the activity of the sodium-potassium pump that moves sodium ions out of the cell and potassium ions into the cell, resulting in a net loss of positive charge inside. This establishes the low permeability to other ions, such as sodium, under resting conditions, further contributing to the negative charge within the neuron.

The other options do not accurately reflect the characteristics of resting membrane potential. High permeability to sodium would indicate an active state (depolarization), while a positive charge inside would imply depolarization as well. Equal charge distribution would negate the very existence of a resting membrane potential, as that condition would imply there