Figure 9.

TEA but not cesium mitigates the voltage-dependence of the relationship between PSP and clusters. A) Cesium (Cs⁺) was included in the recording pipette to block a subset of ion channels that are active near V_rest. With Cs⁺ present the relationship between clusters and individual PSPs (measured as the ratio of their areas), was significantly dependent upon membrane potential (left), even when analyzed from predefined membrane potential values (−85 mV, −70 mV, −55 mV; right), indicating that Cs⁺ does not block the voltage-dependence of integration of PSPs. B) TEA was included in the recording pipette to block a range of voltage-sensitive K⁺ channels. When TEA was included in the pipette there was no significant voltage-dependence of the relationship between PSP clusters and individual PSPs, measured as the slope of the area ratio as a function of membrane potential (left), or as the ratio at predefined membrane potentials (−85 mV, −70 mV, −55 mV; right). F) The ratio of cluster and individual PSP area indicates that PSPs summate more effectively in the presence of Cs⁺ and TEA, and that ability is not dampened at depolarized membrane potentials when TEA is present, compared to the other groups. This is consistent with a blockade of voltage-sensitive K⁺ channels that suppress summation of inputs. * indicates p<0.05, post-hoc Tukeys test after one way repeated-measures ANOVA.