Hypothalamic sites responding to predator threats - the role of the dorsal premammillary nucleus in unconditioned and conditioned antipredatory defensive behavior

Autor(es)

Cezario, A. F. ^[1] ; Ribeiro-Barbosa, E. R. ^[1] ; Baldo, M. V. C. ^[2] ; Canteras, N. S. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Biomed Sci, Dept Anat, BR-05508900 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Biomed Sci, Dept Physiol & Biophys, BR-05508900 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: European Journal of Neuroscience; v. 28, n. 5, p. 1003-1015, Sept. 2008.
• Área do conhecimento: Ciências Biológicas - Fisiologia
• Citações Web of Science: 64
• Assunto(s): Tonsila do cerebelo Hipotálamo Substância cinzenta periaquedutal Estados emocionais Medo

Resumo

In this study we provide a comprehensive analysis of the hypothalamic activation pattern during exposure to a live predator or an environment previously associated with a predator. Our results support the view that hypothalamic processing of the actual and the contextual predatory threats share the same circuit, in which the dorsal premammillary nucleus (PMd) plays a pivotal role in amplifying this processing. To further understand the role of the PMd in the circuit organizing antipredatory defensive behaviors, we studied rats with cytotoxic PMd lesions during cat exposure and examined the pattern of behavioral responses as well as how PMd lesions affect the neuronal activation of the systems engaged in predator detection, in contextual memory formation and in defensive behavioral responses. Next, we investigated how pharmacological blockade of the PMd interferes with the conditioned behavioral responses to a context previously associated with a predator, and how this blockade affects the activation pattern of periaqueductal gray (PAG) sites likely to organize the conditioned behavioral responses to the predatory context. Behavioral observations indicate that the PMd interferes with both unconditioned and conditioned antipredatory defensive behavior. Moreover, we have shown that the PMd influences the activation of its major projecting targets, i.e. the ventral part of the anteromedial thalamic nucleus which is likely to influence mnemonic processing, and PAG sites involved in the expression of antipredatory unconditioned and conditioned behavioral responses. Of particular relevance, this work provides evidence to elucidate the basic organization of the neural circuits integrating unconditioned and contextual conditioned responses to predatory threats. (AU)

• Processo FAPESP: 05/59286-4 - Bases neurais dos comportamentos motivados
• Beneficiário: Newton Sabino Canteras
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 01/14039-9 - Estudo anátomo funcional do comportamento de avaliação de risco e da participação do núcleo pré-mamilar dorsal na mobilização dos sistemas neurais envolvidos na resposta de defesa inata durante confronto com predador
• Beneficiário: Newton Sabino Canteras
• Modalidade de apoio: Auxílio à Pesquisa - Regular