The vesicle release of two particular pre-synaptic neurons results in an action potential firing in a postsynaptic neuron. When the vesicle release of an additional third pre-synaptic neuron is added to this circuit, no action potential is triggered in the postsynaptic neuron. Why might this be the case?
A) Activity of the third pre-synaptic neuron results in the opening of chloride channels on the postsynaptic neuron, thus leading to hyperpolarization.
B) The negatively charged neurotransmitters released from the third pre-synaptic neuron enter and hyperpolarize the post-synaptic neuron.
C) Neurotransmitters released from the third pre-synaptic neuron, bind to receptors on the postsynaptic cell, opening sodium channels.
D) Vesicle release from the third pre-synaptic neuron depolarizes the postsynaptic neuron, moving it away from the action potential threshold.
Anaswer: A