Representative example of excitatory postsynaptic currents (EPSCs) before and after a 20-Hz stimulation train: chronic intermittent hypoxia (CIH) alters glutamate signaling. A: baseline spontaneous EPSCs (sEPSCs) occur before the tractus solitarii (TS) stimulation. Events occurring during the 1 s following the stimulus train were classified as peak asynchronous EPSCs (aEPSCs), whereas the average aEPSCs include all events after the stimulus train. Example is from a single trace. Inset demonstrates low variability (i.e., jitter) in the first TS-EPSC (overlay of 10 traces). Stimulus artifacts are reduced for clarity. B–D: aggregate data of cells used in the current study. Compared with normoxia (NORM), CIH decreased TS-EPSC amplitude (B; NORM, n = 21; CIH, n = 19; t-test) and enhanced miniature EPSC (mEPSC) frequency (C; NORM, n = 17; CIH, n = 21; t-test) and asynchronous events (D; NORM, n = 16; CIH, n = 18) (2-way RM ANOVA with Fisher’s least significant difference post hoc: EPSC, P = 0.001; hypoxia, P = 0.08, EPSC × hypoxia, P = 0.94). Ave, average; Bsl, baseline.