Table 2.

Comparison of LPO and LHAa connections with other gray matter regions and circuits identified in three models of innate (unconditioned) defensive behavioral responses relating to three different categories of threat stimuli: predator, social, and interoceptive (Canteras & Graeff, 2014). For each stimulus category, three separate columns associated with the model list (from left to right): 1) stimuli and responses, 2) major brain divisions involved, 3) gray matter regions involved. Arrows in the first two columns indicate direction of information flow. Two columns on either side of the Regions column list LPO and LHAa output and input connections with the associated regions. LPO and LHAa connection weights are highest binned values following a 1–7 / weakest-strongest color scale (see Supporting Information 1 and 2, and text for further details). Note that for the dorsal premammillary nucleus (PMd), a distinction is made in the behavioral model between ventrolateral and dorsomedial subdivisions; however, no clear distinction in this regard was apparent in LPO and LHAa PMd connections, therefore the same PMd connection value was applied to both. Additionally, for divisions identified in the behavioral model that contain more than one gray matter region (that are listed in the Regions column), the highest LPO and LHAa connection weights across all constituent regions was selected, which applies to the following divisions: Septohippocampal system (SHS) that includes the septal nuclei and the hippocampal formation; anterior hypothalamic nucleus (AHN), dorsomedial hypothalamic nucleus (DMH), and central amygdalar nucleus (CEA). Additional abbreviations: BLA, basolateral amygdalar nucleus; BMAp, basomedial amygdalar nucleus posterior part; LA, lateral amygdalar nucleus; LHAjd, lateral hypothalamic area juxtadorsomedial region; LHAs, lateral hypothalamic area suprafornical region; MEAad, medial amygdalar nucleus anterodorsal part; MEApd, medial amygdalar nucleus posterodorsal part; MEApv, medial amygdalar nucleus posteroventral part; MPO, medial preoptic area; PAGdl, periaqueductal gray dorsolateral column; PAGdm, periaqueductal gray dorsomedial column; PAGl, periaqueductal gray lateral column; PAGvl, periaqueductal gray ventrolateral column; PMv, ventral premammillary nucleus; VMHdm, ventromedial hypothalamic nucleus dorsomedial part; VMHvl, ventromedial hypothalamic nucleus ventrolateral part.

Neural circuits underlying innate (unconditioned) responses to threat stimuli
Predator threat		LPO & LHA Outputs		Regions	LPO & LHA Inputs
		LPO	LHAa		LPO	LHAa
Polymodal sensory predator cues →	Amygdala ↓	0	0	LA	1	1
		3	2	BMAp	2	2
Predator odor →		0	0	MEApv	0	0
	Predator-responsive hypothalamic circuit ↓	4	3	AHN	2	2
		1	0	VMHdm	3	4
		2	4	PMd (vl)	0	1
Unconditioned behavioral responses to predator threat	← Brainstem	2	2	PAGdl	1	1
Social threat		LPO & LHA Outputs		Regions	LPO & LHA Inputs
		LPO	LHAa		LPO	LHAa
Constraint stress →	Septo-hippocampal system (SHS)	7	7	SHS	7	7
Conspecific cues →	Amygdala ↓	3	3	MEAad	4	3
		0	0	MEApv	0	0
	Conspecific-responsive hypothalamic circuit ↓	6	4	LHAjd	2	3
		6	6	LHAs	1	3
		2	4	PMd (dm)	0	1
		4	3	MPO	4	4
		1	3	VMHvl	3	3
		2	2	PMv	2	4
Unconditioned behavioral responses to social threat	← Brainstem	5	6	PAGl	3	3
		1	2	PAGdm	2	1
Interoceptive threat		LPO & LHA Outputs		Regions	LPO & LHA Inputs
		LPO	LHAa		LPO	LHAa
	Hypothalamus (interoceptive inputs to periventricular zone, PVZ) ↓	4	5	DMH	3	1
		6	4	LHAjd	2	3
		6	6	LHAs	1	3
		2	4	PMd (dm)	0	1
Unconditioned behavioral responses to interoceptive threat	← Brainstem	5	6	PAGl	3	3
		1	2	PAGdm	2	1