Drugs that block the reuptake of serotonin will thereby increase the concentration of serotonin molecules in the?

The answer is "Synaptic gaps". 

Synaptic gapes otherwise called synaptic cleft is the little space in the middle of the cell membrane of an axon terminal and furthermore of the target cell with which this synapses. Synapses are intersections between neurons in which data is passed by neurotransmitters.

Well, l think that some effective communication is, emotional barriers and lack of attention, interest distraction or irrelevance. also some physical disabilities such as hearing problems or speech difficulties.      l hope i am correct  and you good luck.