This approach allowed us first to determine if darting reflected an alternate conditioned response, and second, whether the expression of conditioned darting predicted distinct behavioral patterns across fear conditioning and extinction.
Microstimulation of PrL increased the expression of conditioned fear and prevented extinction (Vidal-Gonzalez et al., 2006).
Rodent studies implicate the prelimbic (PL) region of the medial prefrontal cortex in the expression of conditioned fear.
In addition, unit activity of the PrL was positively correlated with expression of conditioned fear and extinction failure (Burgos-Robles et al., 2009).
It is thought that IL neurons inhibit expression of conditioned fear by activating the ITC of the amygdala in recall of extinction and PrL neurons induce expression of conditioned fear by activating the BA (Cho et al., 2013; Sotres-Bayon and Quirk, 2010).
Lesions of the LA and BA changed expression of conditioned fear itself and may have compensation effect (Anglada-Figueroa and Quirk, 2005; Nader et al., 2001; Sotres-Bayon et al., 2004).
The selective mGluR5 antagonist 2-methyl-6- phenylethynyl -pyridine (MPEP) was applied systemically (0.0, 0.3, 3.0, 30.0 mg/kg per os) 60 min before the acquisition training and before the expression of conditioned fear, respectively, in the fear-potentiated startle paradigm.
The expression of conditions of existence...is fully embraced by the principle of natural selection... Hence in fact the law of the Conditions of Existence is the higher law; as it includes, through the inheritance of former adaptations, that of Unity of Type.
The expression of conditioned fear includes amygdala dependent activation of the hypothalamic-pituitary-adrenal (HPA) axis.
