Table 1.

Key studies of interlamellar connections in the hippocampus

Interlamellar connection		Finding	Method	Species	References
From	To
DG	DG	Electrical activation of the perforant path causes signals to spread longitudinally over DG neurons	Multiple field potential recordings with ex vivo whole‐brains	Guinea pigs	Pare and Llinas (1994)
			Extracellular field recording	Rabbits	Lomo (2009)
DG	DG	Stimulation of the septal DG activates the intermediate and septal DG	Optogenetics and IHC staining	Transgenic mice	Kheirbek et al. (2013)
DG	DG	DG granule cells project to neighboring granule cells longitudinally	Whole‐cell recording	Mice	Choi et al. (2021)
DG	DG	DG‐DG granule longitudinal connections possess LTP	Whole‐cell recording with glutamate uncaging	Mice	Pak et al. (2022)
DG	CA2	DG granule cells project functional synapses to CA2 pyramidal cells longitudinally	Optogenetics and whole‐cell recording	Cell type–specific transgenic mouse lines	Kohara et al. (2014)
CA3	CA3	Synchronous neuronal firing spread throughout the disinhibited longitudinal CA3 region	Field potential, extra‐ and intracellular recordings	Guinea pigs	Miles et al. (1988)
CA3	CA3	CA3‐CA3 axonal projection at the septo‐temporal level	HRP staining	Sprague–Dawley rats	Ishizuka et al. (1990)
CA1	CA1	Electrical stimulation at septal hippocampus results in excitatory response in more temporal CA3 and CA1 regions.	Local field potential recording in vitro	Guinea pigs	Bartesaghi et al. (1983)
CA1	CA1	Being evoked at medial EC, electrical responses of CA1 cells propagate along longitudinal axis	Multiple field potential recordings with ex vivo whole‐brains	Guinea pigs	Pare and Llinas (1994)
CA1	CA1	Longitudinal connection between CA1s	PHA‐L staining	Sprague–Dawley rats	Cenquizca and Swanson (2007)
CA1	CA1	CA1 pyramidal cells project functional synapses to CA1 pyramidal cells longitudinally	Extracellular field recording, whole‐cell recording with glutamate uncaging	Sprague–Dawley rats	Sun et al. (2018); Yang et al. (2014)

Abbreviations: CA1, cornu ammonis 1; CA2, cornu ammonis 2; CA3, cornu ammonis 3; DG, dentate gyrus; EC, entorhinal cortex; HHC, immunohistochemistry; HRP, horseradish peroxidase; PHA‐L, Phaseolus vulgaris leucoagglutinin.