Neurochemical Assessment of Tissue Levels of Neurotransmitters for Approximating Neurotransmitter System Connectivity

The post-mortem measurement of tissue neurotransmitters is an interesting technique to address the gross biochemical activity. Its primary limitation is a lack of temporal resolution, although this is mitigated by enhanced spatial resolution, compared to in vivo methods. This neurochemical data is quantitative and requires no complex transformation, making it ideal to analyze neurochemical connectivity via the correlation of the biochemical signals between brain regions. These correlative approaches to quantitative measurements are fundamentally based on the variability of the data, an underdeveloped area of analysis in neurochemistry. One of the main reasons, as discussed in this Viewpoint, is that neurochemists recognize that variability in quantitative data stems not only from the biological variability, such as interindividual differences, but also from factors such as analytical devices. There are several ways to reduce variability caused by analytical and experimental biases through well-designed, precise protocols, allowing for the study of meaningful biological variability, such as interindividual differences between subjects.