Early frontal responses elicited by physical threat words in an emotional Stroop task: Modulation by anxiety sensitivity.

High-density brain electrical activity elicited by physical threat, positive and neutral words were recorded in 33 healthy individuals screened for high or low anxiety sensitivity (AS) during a modified emotional Stroop task. The paradigm allowed the separate assessment of block and mixed-trial effects. In the block analysis, a significant emotional RT slowing was observed along with the modulation of a frontocentral negativity (350-400ms) in the high AS group only. In contrast, the mixed-trial analysis revealed a positive enhancement of the ERP to threat words peaking earlier (200-300ms) over anterior frontal scalp in the absence of RT slowing. This component was preceded by a very early positive modulation (peaking 50ms) in the high AS group only. It is concluded that frontal ERPs to physical threat words can distinguish the contribution of emotional conflict and emotional salience, particularly in individuals with high trait-anxiety.