Comparison of electroreceptor organ functioning in vivo and in vitro

We compared the functioning of catfish electroreceptors in vivo and in vitro by recording the resting discharge and the sensitivity of organs before and immediately after skin patch excision. The in vitro preparation functions for several hours and can be used to assess synaptic functioning and other aspects of sensory transduction. However, both the sensitivity and the resting discharge rate are lower in vitro than in vivo. The sensitivity reduction can be caused by shunting of the stimulus current in the recording chamber, but the reduction of the spontaneous activity cannot. This is most likely due to hypoxia in the excised skin patch. In addition, interspike interval histograms showed mild anomalies in the firing pattern in vitro, as indicated by the parameters λ and r of fitted Γ distributions. We conclude that (i) in vitro recording is best suited for neuropharmacological research, and (ii) in vivo recording is better suited for long-term studies and analyses of stochastical spike processes.