A crucial function of sensory systems is to facilitate adaptive behavior in constantly changing environments. Hence, recurring cues that reliably predict impending danger or reward elicit enhanced sensory processing (Sokolov, 1963). In the mammalian Selleckchem BI-6727 brain, aversive and appetitive learning leads to cue-related retuning of neuronal response profiles within primary sensory cortex (Weinberger, 2004; Shuler & Bear, 2006), driven perhaps by lowering response thresholds or altering synaptic connectivity in primary representation areas (Keil

et al., 2007), potentially via re-entrant feedback originating in deep structures such as the amygdala (Amaral, 2003). Thus, sensory processing becomes biased towards affectively conditioned cues, which are more easily identified than non-relevant

stimuli (Quirk et al., 1995). In the human visual system, such prioritization has been selleck chemicals demonstrated with phobic content (Öhman et al., 2001) and during classical conditioning (Moratti et al., 2006), where neutral stimuli [i.e., the conditioned stimulus (CS+)] paired with noxious events (e.g., electric shock) elicit facilitated sensory responses, compared to the non-paired stimuli (i.e., the CS–; Stolarova et al., 2006). It remains unclear, however, what sensory pathways mediate the acquisition of threat-cue-specific response amplification. Work examining the perception of emotional faces or complex scenes has attempted to uncover the precise compositional features that drive sensory facilitation by manipulating the physical

properties of images, thus challenging specific subsystems within the visual system (Bocanegra & Zeelenberg, 2009). This research suggests that perceptual biases for threat-related stimuli may depend on the brain’s ability to extract information from low-spatial-frequency and luminance channels, sometimes equated with the magnocellular Unoprostone pathway of the human visual system (Pourtois et al., 2005). For instance, effects of spatial frequency on electrophysiological indices of emotion perception are observed for visual event-related potentials such as the N1 (Carretie et al., 2007) but not for late positivities (> 300 ms latency) to complex affective scenes (De Cesarei & Codispoti, 2011) or conditioned cues (Baas et al., 2002). One may hypothesize that different visual pathways vary in their ability to mediate experience-dependent sensory amplification of learned danger signals. In this study, we tested this hypothesis by preferentially stimulating distinct pathways: (i) luminance and (ii) chromatic pathways.