Emergent Synchronous Bursting of Oxytocin Neuronal Network
Figure 8
Paradoxical Behaviour, Observed Experimentally, Reproduced in the Model.
(A) Left trace: A large increase in excitatory input rate will stop ongoing bursting activity in the model network. The bar marked ‘Glutamate’ corresponds to a 150% step increase in the excitatory input rate (from basal levels Hz; Hz). Right: Similarly, excitatory stimuli, such as systemic injection of hypertonic saline block ongoing bursting in oxytocin cells in vivo; from [36]. (B) Left: increasing the inhibitory synaptic input can paradoxically start bursting activity in the model when the suckling input is sub-threshold (kp = 1.4/s). The bar marked ‘GABA’ corresponds to a 150% step increase in the inhibitory input rate (from a basal level of 80 Hz). Right: The effect of local application of a GABA agonist to an oxytocin cell recorded from the supraoptic nucleus in vivo, from [36]. In the experiments, GABA was applied by local pressure injection; the timing of applications is marked, but the resulting exposure to GABA exceeds this, as evident here by the sustained reduction in background firing rate. Thus the burst occurs during elevated GABA exposure. (C) Firing rate of a model cell showing bursting in response to suckling input (bar). Note that, in this rare example, a single burst occurs after removing the suckling stimulus.