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Functional ethological investigations into the role of discrete regions of the lateral hypothalamic area implicated by their neuronal connections in the control of defensive behaviors


The hypothalamus has a central role in the control of fundamental goal-oriented behaviors, but a clear understanding of its structure-function relations remains incomplete. The gaps in our knowledge are particularly evident for the poorly studied lateral hypothalamic area (LHA). However, a series of recent tract-tracing studies have made substantial inroads in to this relatively unstudied part of the brain REFS. In parallel with new structural knowledge, a series of functional studies have sought to characterize hypothalamic circuitry related to defensive behaviors (REFS); the latter have shown that discrete, highly interconnected hypothalamic, regions are involved in stereotyped defensive responses. Moreover, the connections of discrete LHA regions indicate they too may participate in defensive responses. Experiments will be carried out to investigate the possible contribution of recently characterized LHA regions to defensive responses involving other hypothalamic (and extra hypothalamic) regions shown to be involved in defensive responses, and with which they are connected. Discrete chemical lesions will be made in LHA regions of interest, to be followed by behavioral testing using an ethological approach with two models of defensive behavior: 1) resident-intruder, and 2) predator defense. In sum, the project will build on recent and ongoing work by both principle investigators and their colleagues into hypothalamic structure and function. (AU)