Table 1.

Hippocampal disinhibitory connectivity motifs

Mode of disinhibition	Presynaptic interneuron	Molecular marker	CA1 target interneuron	Method	Publication(s)
Interneuron-specific (IS) inhibition	IS-1	CR	CB IN (SCA, PPA); CCK/VIP BC; IS-1	immunocytochemistry; electron microscopy	Acsády et al.92 and Gulyás et al.93
			IS-3	paired recording, in vitro	Luo et al.94
	IS-2	VIP	SCA, PPA, IS-2, CCK/VIP BC	immunocytochemistry; electron microscopy	Gulyás et al.93
			IS-3	paired recording, in vitro	Luo et al.94
	IS-3	VIP; CR	O-LM, BiC, CCK/VIP BC, O-O	paired recording, in vitro	Tyan et al.95
			IS-3	paired recording, in vitro	Luo et al.94
	VIP-LRPa	VIP; M2R; CB	O-LM, BiC, CCK BC	paired recording, in vitro	Francavilla et al.61
Non-IS homotypic inhibition	CCK-BC	CCK; CB1Rb	CCK BC	paired recording, in vitro	Daw et al.96
	PV BC	PV	PV BC	paired recording, in vitro	Daw et al.96 and Cobb et al.97
	SCA	CCK; CB	CCK SCA	paired recording, in vitro	Ali98
	NGFC	NPY; nNOS	NGFC	paired recording, in vitro	Price et al.99
Non-IS heterotypic inhibition	O-LM	SOM; mGluR1α; (PV)	CCK BC, SCA, PPA, NGFC	paired recording, in vitro	Elfant et al.100
	CCK-BC	CCK; CB1Rb	PV BC	paired recording, in vitro	Karson et al.101
	PV BC	PV	CCK BC	optogenetics and Ca2+ imaging, in vitro and in vivo	Dudok et al.13
	TORO	M2R	PV- and CCK-expressing IN	immunocytochemistry	Szabo et al.20
			AAC	paired recording, in vitro	Szabo et al.20
Extrahippocampal GABAergic, long-range input	septo-hippocampal	not specified	PV- and CB-expressing IN	immunocytochemistry, anterograde tracing; electron microscopy	Freund and Antal102
		PV	not specifiedc	antero- and retrograde, and AAV tracing; immunocytochemistry; electron microscopy	Unal et al.103
		PV; SATB1; HCN4	BiC	juxtacellular labeling, electrophysiology immunocytochemistry	Unal et al.104
		GAD67 (not further specified)	PV-, CB-, CR-, SOM-expressing INd	immunocytochemistry; optogenetics, in vivo and in vitro	Sans-Dublanc et al.105
		mGluR8a; in terminals	trilaminar IN (M2R+)	anterograde labeling	Katona et al.59
		not specifiede	TORO	optogenetics and Ca2+ imaging, in vivo and in vitro	Szabo et al.20
	PFC-hippocampal	PV; Som; VIP; CR; NPYf	VIP-expressing IN	optogenetics and Ca2+ imaging, in vivo and in vitro	Malik et al.106

Abbreviations: IN, interneuron; SCA, Schaffer-collateral associated; PPA, perforant path associated; O-O, Oriens-oriens; SATB1, special AT-rich sequence binding protein 1; HCN4, hyperpolarization-activated cyclic nucleotide-gated channel isoform 4; GAD67, glutamate decarboxylase isoform 67.

^aVIP-LRP INs target both PCs and INs in the subiculum⁶¹ and thus, strictly speaking, these cells can only be considered interneuron-specific within CA1.

^bBased on the available literature, it is unclear whether these CCK-expressing BCs belong to the VIP or VGlut3-expressing group.

^cPostsynaptic targets in the subiculum included PV-, CB-, CR-, NECAB1-, CCK- and Reelin-expressing IN, among others.

^dThe majority of postsynaptic somata was found in the pyramidal cell layer. Fractions of postsynaptic somata expressing PV: 44%, CB: 22%, CR: 18%, SOM: 9%, CCK: 4%, VIP: 3%.

^eMedial septum GABAergic neurons were labeled using Dlx5/6-Cre transgenic mice and Cre-dependent viral constructs.

^fPrefrontal cortex GABAergic neurons were labeled using Dlxi12b-Cre transgenic mice and Cre-dependent viral constructs.