Figure 7.
Distal dendritic inputs drive powerful and reliable postsynaptic excitation. A, Averaged uEPSPs evoked by a train of presynaptic action potentials. The firing patterns were replicated from a somatodendritic recording, where action potential firing was generated by somatic excitation alone or soma plus dendritic (640 μm) excitation. Vpost, Postsynaptic voltage; Vpre, presynaptic voltage. B, Response of an ideal synapse (gEPSP) generated with identical timings. C, Ratio of the cumulative amplitude of EPSPs recorded in response to soma and soma plus dendritic excitation. Note that in the majority of recordings the ratio of uEPSPs is greater than those of gEPSPs (1 and 3 nS). The dashed lines represent ±3 SD. The inset shows the paired-pulse ratio (PP; 40 Hz) of uEPSPs that performed suboptimally (sub.; filled bar) or greater than suboptimally (open bar). D, Failure analysis of uEPSPs evoked during soma only and soma plus dendrite action potential trains. The gray boxes delineate action potential burst discharges. Error bars represent SEM.