Electrocortical markers of lying

Lying, as a deplorable behavior, induces changes in the vegetative system because of the sense of guilt and the anxiety of being uncovered, and the current lie-detectors, as the polygraph, register these changes as cues of a deceptive behavior. Such modulations, however, aren't direct measures of deception per se, but products of emotions in general, that could also affect an innocent suspect, wrongly accused. But what happens in the brain? Is it possible to define the relationship between lies and emotions? The purpose of this study was thus to investigate the neural correlates of deceptive behavior in response to neutral and affective questions, created ad-hoc, through the analysis of the electrocortical indexes registered in healthy volunteers. ERPs were recorded from 128 sites. From ERP responses it was possible to notice, at anterior brain areas, a late modulation of the electrocortical activity during the lying versus the telling the truth condition, according to the affective valence of the stimuli. This finding is particularly relevant in that it confirms the ambiguity of data coming from studies related to peripheral indexes measures. An earlier peak was found over the prefrontal regions that distinguished between truthful and mendacious responses, irrespective of the affective context. This component would thus represent the neural marker of deception. A swLORETA linear inverse solution was computed on its amplitude. The results showed that a deceptive behavior is related to the activation of anterior brain areas reflecting an increasing need in higher-level cognitive functions, namely working memory, conflict monitoring, controlled- and task switching-processes, also suggested by behavioral responses.