Evaluation of methods for assessment of interneuronal interaction

Analysis of motor unit (MU) activity gives an insight to relationships between physiologically activated human motoneurons (MNs). It was assumed that the investigation of recurrent inhibition under these conditions might advance our understanding of the role it plays in motor control. To allow for proper interpretation of experimental results, a series of computer simulations modeling different interactions between MNs was performed. For analysis, several modifications of crosscorrelation technique were applied. These functions complement each other and help to decide about the character of the interaction. The results show that with the same IPSP parameters, inhibition is more pronounced when the firing rate of the target MN is lower. Even IPSP of the amplitude as low as 0.05 mV has characteristic effects on all the functions applied in this study. If the effect is present only on one function, it is certainly an artifact.