Figure 1.

Morphological and Electrophysiological Features of Defined Excitatory LII Cell Types in Dorsal MEC

(A) Reconstruction of four representative neurons belonging to the indicated cell type (dendrites in black, apical dendrite in blue, axon in red) and their corresponding firing pattern upon somatic current injection (−200 to 600 pA). ISI1/2 plus dAP reveal differences between the four cell types: the stellate cell and intermediate stellate cell exhibit burstiness, the firing pattern of pyramidal cell and intermediate pyramidal cell displays adaptation, and dAP is absent in the pyramidal cell.

(B) Distribution of stellate (gray circles) and intermediate stellate cells (green triangles) when using latency to spike firing, ISI1/2, and dAP as distinction criteria.

(C) Distribution of pyramidal cells (blue squares) and intermediate pyramidal cells (red triangles) when using dAP, sag potential, and latency as distinction criteria.

(D) Principal component analysis based on the same electrophysiological parameters as used in (B) and (C) plus the presence of an apical dendrite. The plot shows the first two principal components, with component 2 representing predominantly latency while component 1 combines information from the four remaining variables. Note the clear separation between stellate (black) and pyramidal cells (blue), whereas both intermediate cells (IM stellate [green] and IM pyramidal [red] cells) display an “intermediate” distribution.

(E) Differences in soma size and numbers of primary dendrites of the four excitatory cell types (^∗p < 0.05).

(F) Sholl analysis reveals difference between the four cell types when plotting dendritic length as a function of circular distance from the soma in 10-μm steps (two-way ANOVA, F_(144,1813) = 4.43, ^∗∗∗p < 0.001). Stellate and intermediate pyramidal cells exhibit locally (10–80 μm) a higher density of dendrites compared to pyramidal and intermediate stellate cells.

Abbreviations are as follows: ISI, interspike interval; dAP, depolarized afterpotential; and IM, intermediate. See also Figure S1 and Table S1.