Figure 6.
Action potential phase-coupling strength and synaptic input. A, Phasic excitatory/inhibitory charge ratio (Qe/Qi) in different cell classes. Coupling strength in perisomatic-targeting interneurons differed between strongly and weakly coupled cells, with strongly phase-coupled cells showing, on average, Qe/Qi > 1, whereas weakly phase-coupled cells received a dominant phasic inhibition (Qe/Qi < 1). This relationship did not hold for other cell types. The dashed line shows Qe/Qi = 1. Filled symbols, Strongly phase-coupled cells; open symbols, weakly/non-phase-coupled cells. PTI, Perisomatic-targeting interneuron; DTI, dendritic-targeting interneuron; ISI, interneuron-selective interneuron. The same symbol key applies to all panels. B, Action potential phase-coupling strength (rAP) and phasic excitatory charge (Qe) and phasic inhibitory charge (Qi) in interneurons. Significant correlations were found between phasic charge transfer and rAP (Pearson's correlation). C, rAP and peak EPSC coupling strength (re; i), peak IPSC coupling strength (ri; ii), and half-width of Esynrev (iii) in interneurons. A significant positive correlation was found between rAP and the coupling strength of both EPSC and IPSC peaks. No significant correlation was found between rAP and the half-width of Esynrev (Pearson's correlation). D, As in C, but in PCs. A correlation was seen between rAP and re in PCs, whereas no such correlation was seen for either ri or the half-width (Pearson's correlation). The dashed line in B–D shows rAP = 0.2, the cutoff value used to distinguish between strongly and weakly phase-coupled cells. A least-squares fit line is shown for significant correlations.