Not only can they be coupled to novel stimuli through experience and learning, they can be regulated in terms of their time course and intensity, and perhaps in other ways. Innate and experience-based evaluative mechanisms are, as noted, circuit-specific. Thus, defense, nutritional, reproductive, thermoregulatory and other survival systems are wired to

detect unique innate triggers. By entering into associations with biologically significant stimuli, novel sensory events become learned triggers that activate survival circuits. We will consider innate and learned survival circuit triggers in the context of defense next. In the field of emotion, these are described as unconditioned and conditioned http://www.selleckchem.com/products/Trichostatin-A.html fear stimuli. The evidence for conservation across MS-275 research buy mammals of mechanisms underlying survival

functions such as defense (e.g., LeDoux, 1996, LeDoux, 2012, Phelps and LeDoux, 2005, Motta et al., 2009, Choi et al., 2005, Kalin et al., 2004, Amaral, 2003 and Antoniadis et al., 2007), reproduction (e.g., Pfaff, 1999, Oomura et al., 1988 and Blaustein, 2008), thermoregulation (Nakamura and Morrison, 2007), fluid balance (Johnson, 2007 and Fitzsimons, 1979), and energy/nutritional regulation (Elmquist et al., 2005, Morton et al., 2006 and Saper et al., 2002) is strong. Space does not permit a detailed discussion of these circuits and their functions. Defense circuits in mammals will be used as an initial illustration. Defense against harm is a fundamental requirement of life. As noted above, even single-cell organisms can detect and respond to harmful

environmental stimuli. In complex organisms (invertebrates and vertebrates), threat detection involves processing of innate and learned threats by the nervous system via transmission of information about the threat through sensory systems to specialized defense circuits. Unconditioned threat stimuli are species-specific. The most common threat triggers are stimuli that signal other animals (predators and potentially harmful conspecifics), and these will obviously be different for different species. Examples of innately wired Rolziracetam stimuli for rodents include predator odors (e.g., Motta et al., 2009, Pagani and Rosen, 2009 and Blanchard et al., 1990), as well as high-frequency predator warning sounds emitted by conspecifics (e.g., Litvin et al., 2007 and Choi and Brown, 2003), high-intensity auditory stimuli (e.g., Bordi and LeDoux, 1992), and bright open spaces (Thompson and LeDoux, 1974, Gray, 1987 and Walker and Davis, 2002). In primates, the sight of snakes and spiders has an innate propensity to trigger defense (Amaral, 2003, Öhman, 1986 and Mineka and Öhman, 2002). In spite of being genetically specified, innate stimulus processing is nevertheless subject to epigenetic modulation by various factors inside and outside the organism during development, and throughout life (Bendesky and Bargmann, 2011, Monsey et al., 2011, McEwen et al.