What is the process called when a neuron firing causes the inside to briefly become positive?

What is the process called when a neuron firing causes the inside to briefly become positive?

• A. Hyperpolarization
• B. Depolarization
• C. All-or-None Response
• D. Lesion

Answer: (B)

Depolarization is the rapid shift of the neuron's membrane potential from negative toward positive during a spike. When a neuron is stimulated, voltage-gated sodium channels open and Na+ rushes into the cell. That inflow of positive charge makes the inside briefly positive, which is the rising phase of the action potential. After the peak, potassium channels open and the membrane returns to a negative resting state, a process called repolarization. Hyperpolarization would be the inside becoming more negative than resting after the spike, not the initial positive flip. The all-or-none principle describes whether an action potential happens at all (and with the same size once threshold is reached), not the direction of the voltage change. A lesion refers to tissue damage, not this electrical event.

Depolarization is the rapid shift of the neuron's membrane potential from negative toward positive during a spike. When a neuron is stimulated, voltage-gated sodium channels open and Na+ rushes into the cell. That inflow of positive charge makes the inside briefly positive, which is the rising phase of the action potential. After the peak, potassium channels open and the membrane returns to a negative resting state, a process called repolarization. Hyperpolarization would be the inside becoming more negative than resting after the spike, not the initial positive flip. The all-or-none principle describes whether an action potential happens at all (and with the same size once threshold is reached), not the direction of the voltage change. A lesion refers to tissue damage, not this electrical event.