Spatial firing fields (place fields) of rat hippocampal cells undergo changes when the rat runs stereotyped routes. Previously, Mehta et al. [Experience-dependent asymmetric shape of hippocampal receptive fields, Neuron 25 (2000) 700–715] indicated that spike timingdependent plasticity (STDP) might explain the observed shift of the place field center of mass and the development of skewness. In this study, by using simulations of spiking neurons with STDP, we demonstrate that STDP may cause a shift and negative skewness in the synaptic weights vector; however, we explain why these changes do not necessarily result in negative skewness of place fields. We further explore the parameters and additional mechanisms that favor the development of skewness.