Modulation of lateral hypothalamic activity by olfactory bulb and sciatic stimulation.

Lateral hypothalamic area (LHA) single unit activity (extracellular) was studied in response to electrical stimulation of the olfactory bulb (OB) or sciatic nerve in adult albino rats (n = 39) anesthetized with dialurethane. Olfactory stimulation resulted in a greater proportion of LHA units showing inhibitory rather than excitatory responses, while sciatic nerve stimulation resulted in similar proportions of units showing inhibitory and excitatory responses. Of the 76 LHA units tested with both OB and sciatic nerve stimulation, 36% responded to both stimulation sites, 18% responded only to OB stimulation, 26% responded only to sciatic nerve stimulation, and 20% were unresponsive to either stimulation. The locations of responsive units were diffuse throughout the LHA sampled. The response characteristics of LHA neurons to external sensory stimulation are consistent with the anatomy and putative integrative functions of this brain region.