Fig. 5.
Burst threshold is jointly determined by K+ conductance and somatic ISI. A–C, Burst discharge is sequentially blocked by 1 mm TEA ejections in the cell body layer but reinstated each time by higher levels of current injection (B, C).Asterisks denote the occurrence of spike doublets;linked arrows indicate burst AHPs. D, A plot of the average ISI for each of the experiments inA–C (spike doublets and burst AHP intervals omitted). Adashed line at 8 msec ISI approximates an interface between tonic and burst discharge. E, A plot of burst threshold-somatic gDr,s from the multicompartmental model (compare Fig. 4C).Dashed lines illustrate how TEA ejections and current adjustments sequentially shift spike output across the threshold for burst discharge. The corresponding time frames are designated by theletters A, B, and Caccording to the records shown in A–C.