Cortical paired-pulse suppression is dependent on inhibitory GABA
activity. (A) Schematic of a sagittal brain slice illustrating the recording and stimulating electrode placements for the model used in these studies. (B) Representative samples of paired-pulse fPSP recordings in layer II/III before and after bicuculline addition to the slice perfusate. (C) A time series (recordings every 20 s) representation of the average ratios of pulse 2 amplitude over pulse 1 amplitude before and during bicuculline addition to the bath perfusate. (D) P2/P1 ratio comparison before and after bicuculline addition for assessment of evoked inhibition. (E) P1 amplitude comparison before and after bicuculline for assessment of spontaneous inhibition. For D and E, the average of five responses were obtained from each recording at time points demarcated by grey shading in C. N = 17 slices from five mice. *P < 0.001, paired t-test. Con, control; bic, bicuculline; P1, pulse 1; P2, pulse 2; aCSF, artificial cerebral spinal fluid; min, minutes.