THE LIAR BRAIN: EVIDENCE FOR MULTIPLE BRAIN NETWORKS FOR DECEPTION 1Mameli
1Centro
F., 1Mrakic-Sposta S., 1Vergari M., 2Fumagalli M., 1Macis M., 1Ferrucci R., 3Barbieri S., 1, 2, 3Priori A. Clinico per le Neuronanotecnologie e la Neurostimolazione, Fondazione IRCCS Cà Granda-Ospedale Maggiore Policlinico, Milano, Italy 2Dipartimento di Scienze Neurologiche, Università degli Studi di Milano, Milano, Italy 3U.O. Neurofisiologia, Fondazione IRCCS Cà Granda-Ospedale Maggiore Policlinico, Milano, Italy
INTRODUCTION Reliable ways of detecting deception have attracted growing interest for legal, moral and clinical purposes (Pavlidis et al., 2002; Vrij 2006). Research on deception conducted over the past ten years has focused primarily on lie detection techniques intended to study deceptive processes in the brain. Functional magnetic resonance imaging (fMRI) studies show that the dorsolateral prefrontal cortex (DLPFC) are activated during lying (Langleben et al., 2005). Other studies used brain stimulation to investigate changes in cortical excitability during deception (Priori et al., 2008; Karim et al., 2009). Despite several studies have indicated a predominant role of the prefrontal cortex in deception, yet few experimental data are available on the neural substrate of different types of lies.
WE INVESTIGATED WHETHER DLPFC-tDCS CAN SPECIFICALLY INFLUENCE COGNITIVE PROCESSING OF GENERAL KNOWLEDGE DECEPTION OR ALSO INFLUENCE PROCESSING OF PERSONAL INFORMATION DECEPTION
METHODS 20 healthy volunteers were tested before and after tDCS (anodal and sham). All participants received anodal and sham (placebo) tDCS, tested during two separate experimental sessions held at least 1 week apart. The two types of stimulation were presented in counterbalanced order across subjects, half of the participants received first anodal tDCS.
I Experimental Design
II Tasks In each session the Guilty Knowledge Task (GKT) and Visual Attention Task (VAT) were administered at baseline and immediately after tDCS ended. Guilty Knowledge Task A computer-controlled task was used to evaluate truthful responses and lie responses to questions referring to personal information and general knowledge. Dependent variables collected were reaction times (RTs) and accuracy.
III Statistical Analysis A repeated-measures analysis of variance (ANOVA) was run using Greenhouse-Geisser corrections for both tasks. Post hoc analysis with Tukey’s Honest Significant Difference (HSD) test was used to assess differences between the dependent variables measured at baseline and after tDCS for each task.
RESULTS Neither sham nor anodal tDCS induced significant changes in VAT RTs (F1,57 = 0.8, p = 0.37). After anodal DLPFC-tDCS repeated-measures ANOVA identified significant 2-way and 3-way interactions for RTs in the GKTRESULTS (time×tDCS: F1,64 = 4.3, p = 0.04; time×tDCS×response type: F3,64 = 2.6, p = 0.05). Post hoc analysis confirmed that tDCS speeded up lies to general knowledge (1244.5 ± 110.3 ms vs 1083.5 ± 97.2 ms; F2,64 = 2.8; p = 0.02). Conversely, tDCS failed to change the RTs for personal lies (1033.6 ± 64.3 vs 1114.5 ± 91.7; p = 0.92).
GENERAL KNOWLEDGE
PERSONAL INFORMATION
CONCLUSIONS These findings show that modulating DLPFC excitability with tDCS specifically modulate deceptive responses for general information leaving those on personal information unaffected. These findings show that focal manipulation of brain function with tDCS specifically influences lie production and that distinctive neural mechanisms underlie different types of lies. REFERENCES -Pavlidis I, Eberhardt NL, Levine JA. Seeing through the face of deception. Nature, 2002;415:35. -Vrij A, Mann S, Fisher RP. An empirical test of the behaviour analysis interview. Law Hum Behav, 2006;30:329-345. -Langleben DD, Loughead JW, Bilker WB, Ruparel K, Childress AR, Busch SI, Gur RC. Telling truth from lie in individual subjects with fast event-related fMRI. Hum Brain Mapp, 2005;26:262-272. -Priori A, Mameli F, Cogiamanian F, Marceglia S, Tiriticco M, Mrakic-Sposta S, Ferrucci R, Zago S, Polezzi D, Sartori G. Lie-specific involvement of dorsolateral prefrontal cortex in deception. Cereb Cortex, 2008;18:451-455. -Karim AA, Schneider M, Lotze M, Veit R, Sauseng P, Braun C, Birbaumer N. The Truth about Lying: Inhibition of the Anterior Prefrontal Cortex Improves Deceptive Behavior. Cereb Cortex, 2009; 20(1):205-13.
francesca.mameli@unimi.it