Brain reactivity to emotional, neutral and cigarette-related stimuli in smokers
Addiction has been described as the pathological usurpation of the neural mechanisms normally involved in emotional processing. Event-related potentials (ERPs) can provide a non-invasive index of neural responses associated with the processing of emotionally relevant stimuli and serve as a tool for examining temporal and spatial commonalities between the processing of intrinsically motivating stimuli and drug cues. Before beginning a smoking cessation program, 116 smokers participated in a laboratory session in which dense-array ERPs (129 sensors) were recorded during the presentation of pictures with emotional (pleasant and unpleasant), neutral and cigarette-related content. ERP differences among categories were analyzed with use of randomization tests on time regions of interest identified by temporal principal component analysis. Both emotional and cigarette-related pictures prompted significantly more positivity than did neutral pictures over central, parietal, and frontal sites in the 452–508 ms time window. During the 212–316 ms time window, both pleasant and cigarette-related pictures prompted less positivity than neutral images did. Cigarette-related pictures enhanced the amplitude of the P1 component (136–144 ms) above the levels measured in the emotional and neutral conditions. These results support the hypothesis that for smokers, cigarette-related cues are motivationally relevant stimuli that capture attentional resources early during visual processing and engage brain circuits normally involved in the processing of intrinsically emotional stimuli.