A model of how rapid changes in local input resistance of shark electrosensory neurons may enable detection of small signals

Sharks and other elasmobranchs hunt by detecting weak electric fields produced by their prey (Kalmijn, 1982). The behavioural threshold for initiating an electrically-guided attack is a few nanovolts (Kalmijn, 1982), but the sensitivity of primary afferent neurons is in the order of a few spikes per second per microvolt (Montgomery, 1984a; Conley and Bodznick, 1994). Thus the change in afferent firing rate caused by prey at the threshold is in the order of 1 spike per minute, or about 0.1% of the spontaneous rate (~15/sec, Montgomery, 1984a).