Figure 8. Developmental increase in burst-generating synaptic excitation amongst inspiratory network neurons.
Integrated preBötC network activity (top traces, Int preBötC) with simultaneous intracellular recordings of membrane current fluctuations (lower traces) in rhythmically active preBötC neurons under voltage clamp (holding potential set at −50 mV) obtained at E16.5 (A) and E18.5 (B). Expanded bottom traces in A and B show the excitatory synaptic currents (left side in each case, single burst cycle; right side in red, average of 15 cycles) recorded from individual inspiratory neurons during rhythmic network activity. Dashed lines indicate baseline and maximum amplitude levels of the synaptic currents. Note their larger amplitude at E18.5 for both single cycle and averaged events. (C) Bar histograms representing the mean maximal amplitude (± SEM) of excitatory synaptic current underlying burst discharge measured in 14 neurons at E16.5 (unshaded bar) and 17 neurons at E18.5 (gray bar). The asterisk indicates significant difference (p< 0.001).