Matching ISI distributions from oxytocin neurons <i>in vitro</i>.

<p>Neurons recorded <i>in vitro</i> (redrawn from [<a href="" target="_blank">6</a>]), stimulated by a constant depolarising current, show a much narrower ISI distribution, indicating a more regular spiking rate, much closer to a normal distribution than observed <i>in vivo</i> (<a href="" target="_blank">Fig 1</a>). The remaining variability can be attributed to membrane noise, or some low level of residual synaptic input. Using the same HH and IF models, with parameters fitted to the <i>in vivo</i> reference data, we were able to match the <i>in vitro</i> ISI distribution using a constant applied input combined with a low rate of low magnitude excitatory synaptic input. In the HH model (red) we used a 4.5 nA constant input with EPSC parameters Δ<sub>epsc</sub> = 0.008 and <i>R</i><sub>epsc</sub> = 120 Hz, producing 5.3 spikes/s. In the IF model we used <i>V</i><sub>ext</sub> = 20.3 mV with EPSP parameters <i>I</i><sub>re</sub> = 120 Hz and <i>e</i><sub>h</sub> = 0.08 mV, and <i>I</i><sub>ratio</sub> = 0. The cluster plots indicate that ISIs are independent of the preceding ISI.</p>