The hippocampo-septal projection in mice: long-term potentiation in the lateral septum.

In anaesthetized young mice, the fimbria was stimulated and field potentials were recorded ipsilaterally in the lateral septum (LS). Evoked responses were typically characterized by a two-component negative wave (N2 and N3) followed by a low amplitude positive wave. The amplitudes and latencies were highest and shortest respectively in the dorsal LS for the N3 component and in the ventral LS for the N2 component. Tetanic stimulation of the fimbria induced long-term potentiation (LTP) only in the case of the N3 component. The differential changes in N2 and N3 following tetanic fimbrial stimulation are discussed in the context that the dorsal LS appears to exhibit a higher density of LTP-mediating receptors.