The LFS protocol, applied to the VHC while recording from bilateral CA1 as shown in Fig. 1B, did not induce significant changes in evoked responses (n= 19). Evoked field potentials (A) or action potentials (B) were recorded from CA1 before, during and after 1 Hz LFS in slices with 4-AP. A, the average normalized evoked potential amplitude did not change across the stimulation protocol (P > 0.99, ANOVA). Evoked potential amplitudes were determined as the average potential of (a, b) minus the potential of (c), as shown in the inset. B, similarly, the mean number of action potentials elicited by each electrical stimulus remained relatively consistent throughout the LFS protocol (P= 0.99, ANOVA). Responses to LFS with potential amplitudes above –20 mV following each stimulus were counted as action potentials as shown in the inset. Box plots represent data means ± SD.