The electrode may drift in the tissue during the course of the experiment, changing the current waveform as recorded at the probe tip. More than one of the foreground cells may fire simultaneously, leading to a complex combination of foreground currents. A number of approaches have appeared in the literature over the years. Some of these authors have made software available for general use. Finally, a few companies are selling tools that might be of use.
Various companies have commercial spike sorting products available.
Some academics have also made their software available for free over ftp. A manual cluster-based sorter for tetrode data written by Sergei Rebrik called spiker . Datawave have both an interface to manual cluster cutting and autocut for automatic clustering.