Figure 4. In cell-attached configuration, activation of PSAM⁴-GlyR triggers firing of D1-MSNs when the membrane is depolarized to subthreshold potentials.

(A) Representative traces of cell-attached recordings from a control (gray) or PSAM⁴-GlyR⁺ neuron in standard aCSF (4.5 mM [K⁺]). Action currents were evoked following uPSEM⁷⁹² by applying a high external concentration of potassium (high K⁺, ~40 mM). The insets below the high K⁺ traces represent an expanded timescale at the beginning of firing; Inset scale bar = 200 ms. (B) In PSAM⁴-GlyR⁺ neurons, activation of PSAM⁴-GlyR with uPSEM⁷⁹² had no effect on the frequency of action currents in response to high K⁺. (C) Representative traces of cell-attached recordings from a control (gray) or PSAM⁴-GlyR⁺ neuron in aCSF containing 10–13 mM [K⁺]. In PSAM⁴-GlyR⁺ neurons, activation of PSAM⁴-GlyR with uPSEM⁷⁹² produced firing. There was no further firing with application of high K⁺. uPSEM⁷⁹² had no effect on firing in control neurons. (D) Plot of the frequency of action currents in control and PSAM⁴-GlyR⁺ neurons in aCSF, uPSEM⁷⁹² and high K⁺ (mixed effect two-way ANOVA with Sidak’s multiple comparisons test). Line and error bars represent means ± SEM. * indicates statistical significance, ns denotes not significant.