First, the output neuron on the left receives excitatory signals from two
neurons on the right, generating an action potential. Then the third
neuron on the right fires. This time, the output neuron on the left does
not generate an action potential, and so no feelings of anxiety leave the
amygdala. That's because the third neuron produced an inhibitory
postsynaptic potential. Let's follow the action potential down the axon
and find out how the GABA receptor works to produce this inhibition.