How neurons work in a synapse transmission?

At a synapse in the brain, there is always a receptor site at one end, and the the neurotransmitters are sent from the other end. At one end, the neurotransmitter, such as dopamine or serotonin is released, and it attaches itself to the receptor neuron. After the connection is made, the effect takes place. For instance, if too much serotonin is in the brain, people can cause depression.