The relationship between EPSP, action potential and EPSP interval in the ventral cochlear nucleus.

Note that EPSP amplitudes were normalised by dividing by the mean amplitude of the three longest binned intervals. Three single units have been selected to illustrate the range of responses (A-C) and a population of units averaged in (D). Red dots indicate the EPSPs that were accompanied by an AP i.e. were suprathreshold; Blue dots represent EPSPs that failed to elicit an AP i.e. subthreshold. In A there is a slight decline in the percentage of failures with increasing EPSP interval. In B there are relative few failures although they are fairly evenly spaced as a function of EPSP interval. In C the failures outnumber the successes and increase with increasing EPSP interval. A summary for 26 units is shown in panel D. The number of failures is greatest at the smallest EPSP intervals and then plateaus around an EPSP interval around 3 ms.