Projections from the subfornical region of the lateral hypothalamic area

Abstract

The L-shaped anterior zone of the lateral hypothalamic area's subfornical region (LHAsfa) is delineated by a pontine nucleus incertus input. Functional evidence suggests that the subfornical region and nucleus incertus modulate foraging and defensive behaviors, although subfornical region connections are poorly understood. A high-resolution Phaseolus vulgaris-leucoagglutinin (PHAL) structural analysis is presented here of the LHAsfa neuron population's overall axonal projection pattern. The strongest LHAsfa targets are in the interbrain and cerebral hemisphere. The former include inputs to anterior hypothalamic nucleus, dorsomedial part of the ventromedial nucleus, and ventral region of the dorsal premammillary nucleus (defensive behavior control system components), and to lateral habenula and dorsal region of the dorsal premammillary nucleus (foraging behavior control system components). The latter include massive inputs to lateral and medial septal nuclei (septo-hippocampal system components), and inputs to bed nuclei of the stria terminalis posterior division related to the defensive behavior system, intercalated amygdalar nucleus (projecting to central amygdalar nucleus), and posterior part of the basomedial amygdalar nucleus. LHAsfa vertical and horizontal limb basic projection patterns are similar, although each preferentially innervates certain terminal fields. Lateral hypothalamic area regions immediately medial, lateral, and caudal to the LHAsfa each generate quite distinct projection patterns. Combined with previous evidence that major sources of LHAsfa neural inputs include the parabrachial nucleus (nociceptive information), defensive and foraging behavior system components, and the septo-hippocampal system, the present results suggest that the LHAsfa helps match adaptive behavioral responses (either defensive or foraging) to current internal motivational status and external environmental conditions.

Neural network interactions and ingestive behavior control during anorexia

“…39,40]. If we are to understand how ingestive behaviors are controlled, a major challenge is now to define the detailed connectional and functional architecture of this highly complex brain region and to determine whether any of these neurons receive convergent information from the different inputs that can control feeding (Fig.…”

The periaqueductal gray and primal emotional processing critical to influence complex defensive responses, fear learning and reward seeking

“…2, the dorsal PAG, in particular its dorsolateral part, provides massive ascending projections to the AHN and LHAsf, both of which are known to provide strong inputs into the dorsal premammillary nucleus (PMd; Goto et al, 2005;Risold et al, 1994), where marked activation has been reported in response to electrical stimulation aimed at the dorsal PAG (Vianna et al, 2003). Notably, the PMd appears to be a critical element in the ascending pathway involved in fear learning using dorsal PAG activation as the US, and PMd beta-adrenergic blockade has been shown to impair fear conditioning in a paradigm that associates neutral odor cues as the CS and chemical stimulation of dorsal PAG as the US (Kincheski et al, 2012).…”

Periaqueductal Gray

“…Hypothalamic projections to the dlPAG arise primarily from the dorsal (DHA), posterior (PHA), and anterior (AHA) hypothalamic areas (particularly its lateral aspect; Semenenko and Lumb, 1992), as well as from the dorsomedial subdivision of ventromedial hypothalamic nucleus (VMHdm) (Veening et al, 1982(Veening et al, , 1987(Veening et al, , 1991Floyd et al, 2001). There is also a significant input to the dlPAG, from the dorsal premammillary nucleus of the hypothalamus, particularly its ventromedial portion (Goto et al, (2005).…”