Extended Data Fig. 2: Dorsal to ventral axis of hippocampal projections to entorhinal cortex.
From: Hippocampus shapes entorhinal cortical output through a direct feedback circuit
a. (a1) Schematic depicting a horizontal section of a mouse brain showing the various brain regions that are included in the confocal image in panel a2. The position of the horizontal plane of section through the mouse brain is reported as ventral distance from bregma (-2400 µm) in the bottom left corner. (a2) Confocal image of horizontal brain slice of a mouse injected with AAV 2.5 EF1α-double floxed-ChR2-eYFP into dorsal CA1 and immunostained for GFP and DAPI (nuclear marker). Green hippocampal axons were observed in medial entorhinal cortex (MEC) layers 5 and 2/3, and parasubiculum (experiment repeated 10 times with similar results). White dotted lines demarcate the different cortical layers and brain regions. Arrowheads point the layer detailed in panels a3 and a4. (a3) Magnified view of the hippocampal axons in ECL5, an area pointed by the white arrowhead labeled a3 in panel a2. (a4) Magnified view of the hippocampal axons in ECL2/3, an area pointed by the white arrowhead labeled a4 in panel a2. b. Same as a. but for -2800 µm from bregma. c. Same as a. but for -3200 µm from bregma. d. Same as a. but for -3600 µm from bregma. e. Same as a. but for -4000 µm from bregma. Abbreviations used: Au1 – primary auditory cortex, AuV – secondary auditory cortex ventral, DG – dentate gyrus, LEC – lateral entorhinal cortex, LV – lateral ventricle, MEC – medial entorhinal cortex, PaS – parasubiculum, PRh – perirhinal cortex, PrS – presubiculum, S2 – secondary somatosensory cortex, Sub – subiculum, TeA – temporal association cortex.
