Article Figures & Data
Figures
- Figure 1.
Anatomic segregation of presubicular neurons that project to MEC, LMN, or ATN. A, Injection of retrobeads into layer III of MEC. Low-magnification image of a horizontal section of the temporal lobe. B, Injection of retrobeads into LMN (coronal section). C, Injection of retrobeads into ATN (coronal section). D, Higher-magnification image of the PrS (rectangle in A). Retrogradely labeled MEC-projecting neurons are mostly found in superficial layers of PrS. E, LMN-projecting neurons are confined to layer IV of PrS (horizontal section, same animal as in B). F, ATN-projecting neurons are present in layers V-VI of PrS (horizontal section, same animal as in C). Retrobeads in red, DAPI staining in blue. PaS, parasubiculum; DG, dentate gyrus; 3Vd, dorsal third ventricle. Scale bars, 200 µm (A–C) and 100 µm (D–F).
- Figure 2.
Morphology and firing patterns of retrogradely labeled presubicular projecting neurons. A, E, MEC-projecting pyramidal neuron. B, F, MEC-projecting Martinotti interneuron. C, G, LMN-projecting neuron. D, H, ATN-projecting neuron. A–D, Reconstruction of cell morphology with dendrites in blue and axons in red. Scale bars, 50 µm. Additional examples of reconstructions of presubicular projection neurons can be found in Extended Data Fig. 2-1. E–H, Firing patterns at rheobase (upper traces) and at double rheobase (lower traces). Membrane voltage responses to hyperpolarizing current steps of -150 pA are shown in light blue. Insets show larger scale traces of the first AP.
- Figure 3.
Comparison of intrinsic properties of presubicular neurons that project to MEC (blue), LMN (red), or ATN (green). A, Resting membrane potential (RMP). B, Input resistance. C, Time constant. D, Sag ratio. E, AP threshold. F, AP amplitude. G, AP width. H, AHP. I, AP maximum depolarization rate. J, AP maximum repolarization rate. K, Latency to first spike at rheobase. L, Firing rate at double rheobase. M, Fast doublet index. N, f-I slope. Kruskal Wallis and Dunn's multiple comparison post hoc test were performed for significance among projecting neurons, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. Data for one MEC projecting Martinotti-type interneuron are represented as filled blue circles in the graphs, but they are not included for the statistical comparison among the groups of MEC-, LMN-, or ATN-projecting neurons.
- Figure 4.
Segregation of MEC projectors (blue), LMN projectors (red) and ATN projectors (green) in PrS. A, Schematic of layering and cell types of the PrS with their preferential projection profiles. Layer II contains neurons targeting the MEC, contralateral PrS, and retrosplenial cortex (Preston-Ferrer et al., 2016). Layer III contains mostly pyramidal MEC projectors. Large pyramidal neurons targeting LMN lie in layer IV. Neurons targeting ATN lie in layer V/VI; their dendrites may or may not reach to layer I (Fig. 2-1) B, Segregation of projection-specific presubicular neurons based on electrophysiological parameters. Score plot of projecting neurons on PC1, PC2, and PC3 planes. C, Cluster analysis of presubicular projecting neurons.
Tables
MEC projectors LMN projectors ATN projectors MEC proj. Mean SEM N Mean SEM N Mean SEM N Martinotti N Resting membrane potential (mV) −70 2 18 −62 2 18 −68 2 20 −33 1 Input resistance (MΩ) 367 49 18 166 17 18 444 30 20 262 1 Time constant tau (ms) 18 1 18 13 1 18 21 1 20 11 1 Sag ratio 1.06 0.01 18 1.22 0.04 18 1.18 0.04 20 1.16 1 AP threshold (mV) −33 1 18 −37 1 18 −33 1 20 −32 1 AP amplitude (mV) 80 1 18 81 3 18 76 1 20 84 1 AP width (ms) 0.63 0.02 18 0.53 0.02 18 0.61 0.03 20 0.34 1 AP AHP (mV) −17.0 0.7 18 −8.1 1.1 18 −17.4 0.5 20 −26.8 1 AP max. depol. (V/s) 457 25 18 524 38 18 417 21 20 537 1 AP max. repol. (V/s) −119 4 18 −144 6 18 −126 8 20 −259 1 Latency to spike 146 25 18 48 5 18 281 62 20 74 1 Firing rate at double rheobase (Hz) 25 1 18 13 3 18 28 4 20 26 1 Fast doublet index 1.7 0.1 18 10.1 2.4 11 1.7 0.2 20 2.4 1 f-I slope (Hz/nA) 334 34.8 18 190 37 18 499 54 20 654 1 The parameters in bold are used for PCA and cluster analysis in Figure 4.
MEC projectors LMN projectors ATN projectors Mean SEM N Mean SEM N Mean SEM N Layer I (µm) 447 163 8 319 122 8 24 17 7 Layer II (µm) 126 38 8 75 16 8 54 27 7 Layer III (µm) 1144 246 8 407 77 8 174 66 7 Layer IV (µm) 144 98 8 802 134 8 433 206 7 Layer V/VI (µm) 2 2 8 616 134 8 617 131 7 Extra PrS (µm) 50 42 8 196 106 8 340 245 7 Total (µm) 1911 335 8 2415 266 8 1643 354 7 Figure 2-1 shows corresponding biocytin reconstructions of projection neurons.
MEC projectors LMN projectors ATN projectors Mean SEM N Mean SEM N Mean SEM N Layer I (µm) 0 0 8 0 0 8 0 0 7 Layer II (µm) 10 10 8 0 0 8 0 0 7 Layer III (µm) 213 67 8 77 71 8 0 0 7 Layer IV (µm) 157 78 8 333 136 8 0 0 7 Layer V/VI (µm) 223 113 8 506 166 8 248 60 7 Extra PrS (µm) 296 294 8 215 180 8 477 109 7 Total (µm) 899 400 8 1131 295 8 725 125 7 Figure 2-1 shows corresponding biocytin reconstructions of projection neurons.
Figure 2-1
Reconstructions of 23 biocytin filled, retrogradely labeled presubicular principal neurons. A, MEC-projecting neurons. B, LMN-projecting neurons. C, ATN-projecting neurons. Dendrites in blue and axons in red. Presubicular layers II and IV indicated by parallel black lines. Scale bars, 100µm. PaS, Parasubiculum; Sub, Subiculum. Download Figure 2-1, EPS file.
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