Making quantal analysis easier and more accurate

Problems inherent in applying quantal analysis to synapses are discussed. These include the dispersion in time of the evoked quantal releases and the skew to the right in the distribution of the sizes of the spontaneous miniature potentials. To circumvent some of the problems, quantal analysis was performed at the neuromuscular junction by dividing each individual endplate current (EPC) by the mean miniature endplate current (MEPC) or each individual time integral of the endplate current (∫ EPC) by the mean ∫ MEPC. The results were evaluated by comparing the resulting distributions to the predictions of Poisson's law, based on the number of stimuli not followed by a response. The quantal distributions obtained from the ∫ MEPCs by this `point-by-point' were in excellent agreement with these predictions. This method may make quantal analysis easier and more reliable.