  The neuromuscular junction represents a relevant substrate for revealing
important biophysical mechanisms of synaptic transmission. In this context,
calcium ions are important in the synapse machinery, providing the nervous
impulse transmission to the muscle fiber. In this work, we carefully
investigated whether intervals of spontaneous electrical activity, recorded in
seven different calcium concentrations, conform Newcomb-Benford law. Our
analysis revealed that electrical discharge of neuromuscular junction obeys the
expected values for Newcomb-Benford law for first and second digits, while
first-two digits do not perfectly follows the law. We next examined previous
theoretical studies, establishing a relation between the law and lognormal and
Weibull distributions. We showed that Weibull distribution is more appropriate
to fit the intervals as compared to lognormal distribution. Altogether, the
present findings strongly suggest that spontaneous activity is a base-scale
invariant phenomenon.
