The activity of multiple neurons can be recorded by micro-electrodes implanted  in brain tissue. Spike Sorting is the procedure to extract single cell activity from this recordings. In this study we propose a general framework that allow multiple classic spike sorting algorithms to analyze recordings with neuron's waveforms that changes in time.
There have been recent work to develop methods for long-term tracking of neurons
DIFFERENT ELECTRODES, DIFFERENT STABILITY. 
Fiscella et al, J Neurosc Methods, 2012.  Mouse retina patch placed ganglion-cell-side-down on the electrode array.