Subcortical low-rhythmic firing GABAergic medial septal neurons (LRNs) preferentially innervate interneurons in the dentate gyrus and the CA3 region of the mouse hippocampus. Here, one such LRN (black, 2D reconstruction) is superimposed with its firing patterns during locomotion (upper trace, hippocampal CA1 theta and gamma oscillations; lower trace, action potentials of the LRN). In the background, a parvalbumin-expressing interneuron (cyan) in the molecular layer of the dentate gyrus is innervated along its somato-dendritc membrane by dozens of axon terminals of the displayed LRN, providing a powerful subcortical GABAergic control. For more information, see the article by Salib et al. (pages 4527–4549).