Some fundamental theoretical and practical problems associated with neurochemical techniques in mammalian studies.

The assumptions inherent in (i) a pharmacokinetic experiment in vivo, (ii) a subcellular fractionation, (iii) a chemical assay in an isolated neuron, are listed as three examples of well known neurochemical techniques. From these lists of assumptions a number of general hiatuses in knowledge of the effect of preparation of tissue on the results of experiment have been identified. The importance and different kinds of control experiments are discussed. Comment is made on how the different parameters to which measurements are referred may affect the result of the experiments. Optimal techniques are preferably non-disruptive and non-invasive. A few new techniques are proposed.