Extracellular potential recordings are important in neuroscience; however the variability of spike waveforms has not been extensively studied to date. This study examines the variability of spike recordings within and between sessions. Place cell recordings were used in order to identify the cells across successive sessions. Place cells allow neuron spike recordings to be identified across different sessions using place fields, which are independent of the cell's spike waveform. The results show that the distribution of the residues within a session does not follow a normal distribution, a t-distribution is more suitable. The results also show that the amplitude of the spikes can vary largely between successive sessions (up to 47%), this is an important factor to be considered in long term spike recording systems.