This discussion of the spike train data applies the approach of Hadjipantelis et al. developed for Linguistic data to jointly model both the phase and amplitude functions via a mixed effects model. The approach shows that care needs to be taken when assessing amplitude and phase functions, particularly if separate analysis is undertaken, as there can be high levels of correlation between the warping and amplitude component functions.
"Analysis of spike train data: A multivariate mixed effects model for phase and amplitude." Electron. J. Statist. 8 (2) 1797 - 1807, 2014. https://doi.org/10.1214/14-EJS865E