Generating Quantitatively Accurate, but Computationally Concise, Models of Single Neurons - Computational Neuroscience: A Comprehensive Approach - page 197

0.04

A

0.03

0.02

0.01

0

0.06

B

0.04

0.02

0

0 100 200 300

400 500

Interspike interval (ms)

Figure 7.2
Representative inter-spike interval distributions from an oxytocin cell (A) and a va-
sopressin cell (B) showing exponential curves fitted to the tails of the distributions
and extrapolated to lower interval values. Both oxytocin cells and vasopressin cells
show a deficit of intervals below the fitted curve in the region 0-30 ms, reflecting the
presence in both cells of a strong post-spike hyperpolarisation (the HAP). For vaso-
pressin cells, but not for oxytocin cells, such extrapolations revealed a large excess
of intervals above the fitted curve in the range 30 to 150ms, reflecting the presence
in vasopressin cells only of a depolarising afterpotential (DAP) following the HAP.

activation (at ≈ 12Hz) is attained after osmotic stimulation has raised extracellular

[Na + ]by 3 to 5mV. The equilibrium

value for T , T 0 , was thus set at 12mV for the simulations shown, and simulations
were conducted over 1mV below to 5mV above this level. We conducted simula-
tions with parameter values systematically spanning the ranges above, restricted to
output ranges (0 to 16Hz) consistent with the behavior of oxytocin cells.

∼ 10mM, producing a direct depolarisation of ≈

7.3.4 Simulating oxytocin cell activity

We found that the inter-spike interval distribution from each oxytocin cell could be
closely matched by a model cell with a resting potential ( T 0 ) of 12mV below spike
threshold subject to random EPSPs of 4mV amplitude and 7.5ms half-life (Figure