Functional synapses in the central nervous system depend on a chemical signal exchange process that involves neurotransmitter delivery between neurons and receptor cells in the neuro system. Abnormal neurotransmitter levels and distributions can cause intractable diseases involving descending/ascending modulatory pathways or dysfunctional organs. The detection of abnormal neurotransmitter levels is one of the most promising techniques in the diagnosis of brain diseases. Also, numerous effective methods for the detection of neurotransmitters in vivo have been fabricated. Nowadays, electrochemical, optical, magnetic, and microdialysis methods are among the main techniques used to detect neurotransmitters. Herein, we review current techniques for detecting eight types of neurotransmitters with a focus on in vivo neurotransmitter tracking methods intended for the real-time diagnosis of brain disorders.