Neurochemistry and post-mortem neurotransmitters: Toward the study of neurochemical connectivity

Monoaminergic systems, as some other neuromodulators, exert modulatory influences across the entire central nervous system (CNS), participating in basic neurobiological processes, behavioural traits, neuropsychiatric diseases, and responses to psychotropic drugs. Their activity is supposedly balanced across the CNS i.e. a change of input in one region could alter their activities at distal regions. Unfortunately, there are a few attempts to determine the neurochemical relationships between local or distal regions.

In this review article, we present the technical requirements for performing complex analysis of neurochemical, postmortem, quantitative data on neurotransmitter systems. We explore new types of neurochemical analysis beyond quantitative differences to approximate neurochemical connectivity.

Although the lack of temporality and unclear meaning of neurotransmitter tissue content are limitations of this approach, postmortem measurement offers the possibility of quantitatively and qualitatively assessing the content of monoamines and/or metabolites in multiple parts of the CNS. This form of neurochemical connectivity is distinct from anatomical connection and brain functional connectivity.

This expands the study of neurotransmitter systems beyond a specific/limited set of brain regions and allows for the description of possible inter-regional influences within a neurotransmitter system and between neurotransmitter systems across the CNS.

Through this unprecedented discussion, this article advances the use of neurochemical data towards multiple dimensions of analysis, primarily based on monoaminergic systems and their neurochemical connectivity.