Academic journal article Cognitive, Affective and Behavioral Neuroscience

Neurocognitive Effects of Phobia-Related Stimuli in Animal-Fearful Individuals

Academic journal article Cognitive, Affective and Behavioral Neuroscience

Neurocognitive Effects of Phobia-Related Stimuli in Animal-Fearful Individuals

Article excerpt

Two experiments were conducted to explore neurocognitive effects of phobia-related stimuli. Contingency assessments and event-related potentials (ERPs) were collected from animal-fearful individuals during probabilistic classification learning in diverse motivational-affective contexts. As revealed by ERPs, attentional amplification of cortical sensory processing occurred in response to phobiarelated stimuli. In particular, the posterior selection negativity in the ERPs to phobia-related stimuli had its origin in a bottom-up route, probably the amygdaloid-extrastriate cortex path. No evidence for top-down modulation of phobia-related attentional amplification was obtained. The covariation bias occurred only when aversive motivational-affective expectancies prevailed, suggesting a role of retrieval from associative emotional memory. Finally, phobia-related cue competition was probably related to the disruption of elaboration in memory of neutral and aversive stimulus pairings that was induced by belonging pairings of phobia-related and aversive stimuli. The findings have far-reaching implications for the interface between cognition and emotion.

Emotions such as phobie fear have important signal functions that prompt the organism to selectively focus attention on particular attributes, stimuli, or events. Fear is a central motive state that activates defense behavior and associated emotional feelings (Lang, Davis, & Öhman, 2000). Phobic fear may be defined as exaggerated fear that occurs in response to certain attributes, stimuli, or events in certain individuals (Fyer, 1998). The details of the neural and psychological mechanisms that link emotions like phobic fear and selective attention remain largely undisclosed. How does phobic fear guide selective attention? In two experiments, we examined the notion that phobic fear leads to amplified neural representations at the cortical level, a primary mechanism thought to implement selective attention (see below). Is there evidence that phobic fear is actually related to an amplification of sensory processing, or in other words, to attentional amplification in the sense of increased activity in cortical regions coding for phobia-related stimuli? For visually presented stimuli, the hypothesis of phobia-related attentional amplification would imply amplified activity in the portion of extrastriate cortex that represents phobia-related stimuli.

Encoding of emotional significance occurs very rapidly within the processing stream, in a "preattentive" stage of processing that occurs prior to attentional selection, is relatively fast, and often occurs outside of or prior to conscious awareness (Compton, 2003; Öhman, 2000; Öhman & Mineka, 2001). For example, a growing number of behavioral (see, e.g., Ohman, Flykt, & Esteves, 2001) and psychophysiological (e.g., Globisch, Hamm, Esteves, & ¨hman, 1999) studies indicate that animal-fearful individuals respond very rapidly to phobia-related stimuli. Moreover, numerous studies using a variety of paradigms have confirmed that emotionally relevant stimuli are likely to capture attention. The study of attentional bias toward emotional information has consistently emphasized the role of individual differences, and a large body of research has indicated that anxious individuals are more likely than controls to display attentional biases toward threatening information (Compton, 2003).

Neuroimaging studies have indicated that several areas of the visual association cortex are more strongly activated in response to emotionally arousing images, irrespective of their emotional valence (see, e.g., Lang, Bradley, & Cuthbert, 1998). Other studies (Fredrikson, Wik, Annas, Ericson, & Stone-Elander, 1995; Fredrikson et al., 1993) have revealed activation in the extrastriate cortex in response to phobia-related, in contrast with neutral, stimuli. These findings have been interpreted as indicating an attentional response toward emotionally arousing and phobia-related stimuli, respectively. …

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