Academic journal article Cognitive, Affective and Behavioral Neuroscience

Trait Anxiety Modulates Supraliminal and Subliminal Threat: Brain Potential Evidence for Early and Late Processing Influences

Academic journal article Cognitive, Affective and Behavioral Neuroscience

Trait Anxiety Modulates Supraliminal and Subliminal Threat: Brain Potential Evidence for Early and Late Processing Influences

Article excerpt

Analysis of threat is drought to involve a "quick and dirty" stage in conjunction widi slower processing that is more complete. We investigated both types of threat analysis by recording brain potentials in response to threat and neutral words. Personality testing was used to identify participants who were eidier high or low in trait anxiety (TA). An observed enhancement of occipital PI potentials to threat words during an emotional Stroop task was interpreted as a signal of unconscious processing, since it was early, independent of whetiier word exposure was subliminal or supraliminal, and more prominent die higher die level of TA. Later positive potentials were also enhanced for threat versus neutral words, but die amplitude enhancement increased widi higher TA only in die subliminal condition. These results suggest diat unconscious analysis of threat is intensified in those prone to anxiety, as is a later stage of tiireat processing subject to dynamic interactions between automatic and strategic influences.

Neural mechanisms for efficiently extracting and processing signals of impending danger have critical survival value. Indeed, research has demonstrated privileged threat processing from behavioral, physiological, and neuroimaging perspectives. Such processing is more salient among anxious than among nonanxious individuals and has been posited to be fast, automatic, and even unconscious (for reviews, see Damasio, 1994; Davidson, 1998; Dolan, 2002; Lang, Bradley, & Cuthbert, 1997; Ohman & Mineka, 2001; J. M. G. Williams, Watts, MacLeod, & Mathews, 1997). In addition, it has been conjectured that analysis of threat information includes a "quick and dirty" phase that can promote autonomic arousal and prepare the body for action, followed by a more deliberate and accurate phase diat can promote strategic responses to threat (for reviews, see LeDoux, 1995, 1996; Öhman, 1979, 1993). In this study, we investigated threat processing with regard to (1) its automatic or unconscious nature, (2) its temporal dynamics, and (3) the influence of anxiety, thus combining multiple perspectives that together can shed new light on threat processing.

Automatic Processing of Threat at Early Stages

It is well documented that threat information leads to augmented amygdala activation and that such activation can be automatic (for reviews, see Davis & Whalen, 2001; Dolan & Vuilleumier, 2003). Neuroimaging research has also suggested that threat information leads to greater activation than neutral information in visual association cortex (see, e.g., Pessoa, McKenna, Gutierrez, & Ungerleider, 2002; Vuilleumier, Armony, Driver, & Dolan, 2003; also see Phelps, 2006, for a review), which may reflect a boost in visual analysis caused by input from die amygdala (Vuilleumier, Richardson, Armony, Driver, & Dolan, 2004). These data thus support the notion of automatic preferential perception of threat.

Nevertheless, these data are silent about the temporal aspects of threat processing. Electrophysiological measures with high temporal resolution, on the other hand, have provided insights into the temporal nature of enhanced analysis of threat. The occipital or occipitoparietal P1-a visual event-related potential (ERP) peaking around 100 msec poststimulus and reflecting visual perceptual processing (Gomez, Clark, Fan, Luck, & Hillyard, 1994; Mangun, Hillyard, & Luck, 1993)-has attracted special attention from researchers. Several studies revealed that P1 differentiated threat and nonthreat faces or pictures as early as 80 msec after stimulus onset (Pizzagalli et al., 2002; Pizzagalli, Regard, & Lehmann, 1999; Pourtois, Grandjean, Sander, & Vuilleumier, 2004; Smith, Caccioppo, Larsen, & Chartrand, 2003). Pourtois et al. localized the source of this P1 component in extrastriate cortex. In line with these findings, magnetoencephalographic results showed differential processing of emotional versus neutral faces in occipital cortex 120 msec after stimulus onset (Halgren, Raij, Marinkovic, Jousmaki, & Hari, 2000). …

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