In our third drug, it actually impacts the presynaptic neuron.
In most neurons, when they release the neurotransmitter, they bind to the postsynaptic neuron, and then release from the receptor.
In many kinds of neurons, the neurotransmitter is then taken back up by the presynaptic neuron.
But when this drug is present, the neurons are not taken back up by the presynaptic neuron, they stay in the gap and may even bind again.
The synapse becomes more active.