, 2006). We have confirmed that the N450 is most Tanespimycin cost representative of general conflict detection (Szucs and Soltész, 2010a, Szucs and Soltész, 2010b, West et al., 2004 and West and Schwarb, 2006). Previously the N450 had been ambiguously related to both response conflict (Liotti, Woldorff, Perez, & Mayberg, 2000) and semantic conflict (Rebai et al., 1997). As we found no significant differences in the mean amplitude of the N450 in the SC and RC conditions we conclude that the N450 is

most sensitive to general conflict (Szucs and Soltesz, 2012, Szucs et al., 2009b and West et al., 2004). Our second objective was to map maturational changes in the N450. There were no differences between the adolescent and young adult groups in the topography of the N450 during congruent and SC conditions. However during the RC condition the topography of the N450 was focused on the right scalp in adolescents

and on the left scalp in young adults. In adults a similar left hemisphere effect during the N450 has been found in previous Stroop studies (Chen et al., 2011, Jongen and Jonkman, 2008 and Lansbergen et al., 2007). Adleman et al. (2002) found increased left hemisphere activation in adults when compared to adolescents specifically in the left middle frontal gyrus during colour word Stroop conflict. The left middle frontal gyrus has been associated with both word generation (Thompson-Schill, D’Esposito, Aguirre, & Farah, 1997) and generating colour names (Martin, Haxby, Lalonde, Wiggs, & Ungerleider, 1995). The left scalp activation found find more in adults could represent the increased use of a verbal strategy to resolve conflict. In adolescents the topography of the N450 was focused on the right scalp. Right scalp activity has also been observed in adolescence during a Stop task and a Go-No/go task (Rubia et al., 2000 and Stevens et al., 2007) as well as during a Stroop task in children (previously unrecorded in adolescence) (Jongen & Jonkman, 2008). These authors have concluded that this right scalp activity is indicative of improved performance

strategy. Orotidine 5′-phosphate decarboxylase For example Stevens et al. (2007) found that in adolescents increased frontal–parietal circuit activity was related to good performance however this was not found in adults. Therefore increased right scalp activation may recruit frontal–parietal circuitry and allow for improved performance. In terms of middle age adults a stimulus conflict deficit was expected. However there were no differences in the topography of the N450 during stimulus conflict detection for young adults and middle age adults. Nevertheless topographical examination of the N450 during the RC condition reveals dispersed and increased negative amplitude with a right scalp shift. In a middle age group (41–61-year olds) Mager et al. (2007) similarly found increased amplitude of the N450. Mathis et al.