Fig. 5.

Slow PSC kinetics of dendritic GABAergic inputs. a Representative mean IPSCs generated by optogenetically activated inputs from SOM (top) and PV interneurons (bottom). The internal Cs-gluconate-based solution had a realistically low chloride concentration of 8 mM. Outward currents were measured at –10 mV, inward currents at –82 mV. Biexponential fits to rising and falling phases of IPSCs are indicated. b Group means of rise and decay τ. Outward currents are indicated by solid colors, inward currents by striped bars. Note the slower rise and decay τ for all dendritric inputs compared to PV-ChR2-evoked perisynaptic IPSCs. The significant differences in outward decay τ are indicated (all: P < 0.001; two- sample t test, NOS: n = 9; SOM: n = 9; PV: n = 8; SR stim: n = 11). c Representative mean IPSCs optogentically activated from NOS interneurons before and after application of the α5-IA L-655,708 (L-655, 50 nM). Outward currents were measured at –10 mV, inward currents at –90 mV. Monoexponential fits to the decay phase of IPSCs are indicated. Note the faster decays after application of L-655,708. d Group means of decay τ for NOS-ChR2- evoked IPSC before and after L-655,708 and the α5-GABAR-mediated difference current. Decay τ significantly sped up after application of L-655,708 for both inward (P < 0.001; paired t test, n = 10) and outward currents (P < 0.001). Control decay τ was also significantly faster than for the α5-GABAR-mediated difference current (both: P < 0.05, n = 7). Recording temperature T ≈ 33 °C for a, b and T ≈ 22 °C for c, d