Voltage-dependent amplification of synaptically generated and simulated EPSPs in vSUB pyramidal neurons is dependent on TTX-sensitive Na + channels. A, Scatter plot shows the similarity in voltage-dependent amplification between synaptically generated EPSPs and simulated EPSPs from negative holding potentials (–75 mV) to near-threshold potentials (–59 mV). EPSPs (filled squares) and sEPSPs (open circles) were collected in the same sweep 500 msec apart. The averages for EPSPs (large filled squares) and the sEPSPs (large open circles) were taken from six consecutive sweeps in both RS and BS neurons (n = 4). The inset shows superimposed representative sweeps of EPSPs (open triangle) and sEPSPs (open diamond) at both negative and near-threshold holding potentials. B and C show near-threshold EPSP and sEPSP amplification before and after bath application of a submaximal concentration of TTX (50 nm, gray traces). D and E show the average (n = 2) voltage-dependent TTX-sensitive amplification of the peak (D) and integral (E) from EPSPs (squares) and sEPSPs (TTX, 50 nm, circles). NMDA, GABAA, and GABAB receptors were blocked by using MK-801 (20μm), SR 95531 (2μm), and CGP 55845 (1 μm) in the bath solution.