(a) Reconstruction of part of the axon of neuron TV58g axon (cortical regions color-coded). Black dashed line, rostral (left) and caudal (right) innervation zones. Pie chart, number (parentheses) and proportion (%) of axonal varicosities. Projection axon enters the cortex via the dorsal fornix (green dashed line). (b) Presubicular terminals of TV58g (cyan) were VGAT+ (yellow, arrows). (c) Micrograph (left, asterisk) and reconstruction (right) of the soma and dendrites (blue) and axon (cyan, ax) of TV58g in the tip of dorsal MS. Black dashed line, midline. A local axon collateral is marked by an arrowhead. A cut dendrite is marked by a small bar. (d) The soma of TV58g (cyan, neurobiotin, arrow) was SATB1+ (green, nuclei) and PV+ (yellow). Note similar profiles of adjacent neurons. (e) Dendrites of TV58g (cyan) were mGluR1a+ (magenta, arrows). (f) Rhythmic burst firing during locomotion. CA1 LFP, local field potential in SP. Red, examples of detected peaks of CA1 theta oscillations and associated MS neuron spikes. Note preferential coupling of bursts to theta peak. (g) Rhythmic burst firing during immobility with some spikes during some SWRs (magenta; ripples, 130–230 Hz filtered CA1 LFP). Examples of accommodating bursts are shown below asterisks in (f) and (g). Nb, neurobiotin. FC, fasciola cinereum, AB, angular bundle, LS, lateral septum, vDB, vertical diagonal band. Images (z-thickness in µm and z-projection type): (d) 2.3, maximum, (b) 2.61, maximum, (e) 0.37, single optical section. Scale bars (µm): a, 500, b,e, 5, c, 50, inset, 500, d, 10.