Lateral Hypothalamic Nucleus
The lateral hypothalamic nucleus receives olfactory information that contributes to increased hunger when smelling food like pumpkin pie.
Neuroanatomical Pathway
The lateral hypothalamus serves as the primary integration site for olfactory signals that promote feeding behavior through multiple converging pathways:
Direct projections from melanin-concentrating hormone (MCH) and orexin neurons in the lateral hypothalamus to the main olfactory bulb (MOB) create a bidirectional circuit that allows hunger state to modulate olfactory processing while simultaneously receiving processed olfactory information 1.
Indirect polysynaptic projections (two to three synapses) connect the MOB to the arcuate nucleus of the hypothalamus, which then communicates with lateral hypothalamic feeding centers 1.
AgRP (agouti-related peptide) neurons, which are appetite-stimulating neurons located in the arcuate nucleus, receive indirect input from distinct areas of the olfactory cortex and project to the lateral hypothalamus to promote feeding 2.
Functional Mechanism
The lateral hypothalamus acts as the "feeding center" through specific molecular mechanisms:
Neuropeptide Y (NPY) release from AGRP neurons, particularly through projections to the paraventricular thalamus, selectively enhances attraction to food odors over other olfactory cues during hunger states 3.
Cannabinoid type-1 (CB1) receptors in olfactory circuits increase odor detection in fasted mice by decreasing excitatory drive from olfactory cortex to the MOB, with this enhanced olfactory processing ultimately promoting food intake through lateral hypothalamic pathways 4.
The lateral hypothalamus integrates olfactory information with other sensory modalities through connections with the amygdala, where the periamygdaloid cortex (receiving olfactory input) projects to the lateral nucleus of the amygdala 5.
Clinical Context
The ventromedial hypothalamic nucleus, in contrast, functions as a satiety center and would suppress rather than increase hunger. The mammillary, preoptic, and tuberomammillary nuclei serve different functions unrelated to appetite stimulation from olfactory cues 1, 2.
Human studies confirm CB1 receptor expression in the hypothalamus, supporting the translational relevance of these feeding circuits 6.