Fig. 1.
5-Hydroxytryptamine (5-HT) does not alter evoked excitation onto granule cells or granule cell membrane potential directly. A: schematic of the voltage-clamp recording configuration. B: whole cell voltage-clamp recordings from an example granule cell. Averaged excitatory postsynaptic currents = recorded in control, 5-HT (10 μM), and NBQX (5 μM) at −70 mV. C: summary of paired-pulse ratio (PPR), failure rate, mean amplitude, and potency for recorded granule cells. Overall mean and SE (solid bars) are overlaid (n = 10 granule cells). D: schematic of current-clamp recording configuration. E: average membrane potential (Vm) of granule cells before and after 5-HT application (n = 11) in the presence of NBQX (5 μM), R-CPP (5 μM), and SR95531 (5 μM). F: whole cell current clamp recordings from two example granule cells given a series of 2 pA steps in the presence of NBQX (5 μM), CPP (5 μM), and SR95531 (5 μM). G: average relationship between firing rate and current steps (2 pA steps, input/output relationship) for granule cells with synaptic blockers only (control, n = 13) or synaptic blockers and 5-HT (n = 10). n.s., statistically nonsignificant.