Fig. 5

Neuronal responses to stimulation paradigms with various pulse frequencies. a Schematic diagram of a recording electrode (RE) in the CA1 pyramidal cell layer and an antidromic stimulation electrode (ASE) in the alveus of rat hippocampus. b Example of CAl neurons’ responses to 1-min A-HFS with constant parameters of an intensity 0.3 mA and a frequency 100, 200 and 400 Hz, respectively. Large APS events were always evoked by pulses at the initial phase of A-HFS with constant parameters. Red bars indicate the periods of A-HFS. c Scatter diagrams of the amplitudes of APS evoked by each pulse (normalized by the baseline APS evoked by a single pulse) during the whole 1-min A-HFS (left) and during the initial 2 s period (right)