  Recently, we demonstrated the existence of nonextensivity in neuromuscular
transmission [Phys. Rev. E 84, 041925 (2011)]. In the present letter, we
propose a general criterion based on the q-calculus foundations and
nonextensive statistics to estimate the values for both scale factor and
q-index using the maximum likelihood q-estimation method (MLqE). We next
applied our theoretical findings to electrophysiological recordings from
neuromuscular junction (NMJ) where spontaneous miniature end plate potentials
(MEPP) were analyzed. These calculations were performed in both normal and high
extracellular potassium concentration, [K+]o. This protocol was assumed to test
the validity of the q-index in electrophysiological conditions closely
resembling physiological stimuli. Surprisingly, the analysis showed a
significant difference between the q-index in high and normal [K+]o, where the
magnitude of nonextensivity was increased. Our letter provides a general way to
obtain the best q-index from the q-Gaussian distribution function. It also
expands the validity of Tsallis statistics in a more realistic stimulus
condition. Physical and physiological implications of these findings are
discussed in detail.
