Fig. 6

Synaptic responses induced by the ten-pulse stimulation train at the dorsal, medial and ventral hippocampal synapses plotted against stimulus number. Different diagrams illustrate the responses induced by the eleven different stimulation frequencies. The graph at the bottom right corner of the figure illustrate the steady-state responses (8–10) of the three hippocampal segments plotted as a function of stimulus frequency. Note that facilitation dominates dorsal hippocampal synapses at stimulus frequencies 1–50 Hz whereas ventral hippocampal synapses are dominated by depression at all stimulus frequencies showing only a transient facilitation at the start of 10–50 Hz stimulation. The synapses of the medial hippocampus show intermediate properties. Data for the dorsal, medial and ventral hippocampus were obtained from positions 2–7, 8–14 and 15–19 respectively