Figure 6.

Near-threshold spike timing variability in RS and BS vSUB neurons. A shows a scatter plot and median line of the action potential timing response to near-threshold sEPSC injection in RS (open circles, n = 19) and BS (filled triangles, n = 16) neurons. The near-threshold spike timing median latencies were significantly different between RS and BS neurons (*p < 0.05; Mann–Whitney U test). RS and BS neurons were held at similar holding potentials (RS =–60.07 ± 0.73 mV; BS =–60.08 ± 0.70), and there were no differences in the amplitude of the sEPSC current injection between groups (see supplemental material, Fig. S1). The insets show representative RS (top) and BS (bottom) traces, symbolized in the scatter plot by a filled square (RS) and an open diamond (BS). B shows the action potential threshold (top panels) and holding potential (bottom panels) relationship to the spike latency triggered by a near-threshold input. To optimize the R² values, the action potential threshold/latency data were fit by a logarithmic equation (see Appendix) to the pooled SAL/EW and SAL/LW control groups (RS, R² = 0.30, p < 0.01; BS, R² = 0.20, p < 0.05), and the holding potential/latency data were fit with a linear equation (RS, R² = 0.0046; BS, R² = 0.037). The AMPH/EW group (filled diamonds) exhibited the same relationship between threshold and spike latency as the SAL control group (AMPH RS, n = 16; AMPH BS, n = 10).