Tetrodotoxin (TTX or blowfish toxin) is a neurotoxin that blocks voltage-gated sodium channels on axons. What effect does this neurotoxin have on a neuron? 1) Increases the firing rate of the neuron 2) Decreases the firing rate of the neuron 3) Causes the neuron to become hyperpolarized 4) Causes the neuron to become depolarized