Rostral Cingulate Zone andcorrect response monitoring

Keeping our behavior adapted to an ever changing environment requires a constant evaluationof one’s own performance. In this respect, errors play an essential role in this evaluation, since they strongly signal the need for adaptation. In the early 90’s, Falkenstein et al. (1991) reported the existence of an EEG component peaking just after error commission in reaction time (RT) tasks (see also Gehring et al., 1993) : This fronto-central negative wave starts just before the response, and peaks between 50 and 100 ms later. With conventional monopolar recordings, this activity has originally been observed only on errors and was hence interpreted as re ectin ga n\Erro rDetection « mechanism .Accordingly ,i twa sname d\Erro rNegativity « (Ne ,Falkenstei ne tal. ,1991 )o r\Error Related Negativity » (ERN, Gehring et al., 1993). Source localization approaches (Dehaene et al., 1994; Herrmann et al., 2004; Van Veen et Carter, 2002) and fMRI data (Debener et al., 2005; Ullsperger et von Cramon, 2001) have pointed to a Rostral Cingulate Zone (RCZ, Ridderinkhof et al., 2004a) generator of this activity. This generator would be more likely located within the anterior cingulate cortex (ACC) and/or the supplementary motor area (SMA) (Dehaene et al., 1994; Ullsperger et von Cramon, 2001). This Ne was later included in more general models of response monitoring, and was re-interpreted as re ectin gcon i ctmonitori ng(Yeu ng etal .,200 4,s eehowev erBur le etal .

The specicity of the Ne to errors was disputed by Vidal et al. (2000). These authors computed the Current Source Density (by applying the Laplacian operator), which has been shown to dra- matically improve the spatial resolution of monopolar recordings (Babiloni et al., 2001). Thanks to this methodological improvement, Vidal et al. (2000) evidenced that a similar activity was also ob- served on correct trials, albeit with smaller amplitude. They rst analyzed some particular correct trials in which partial errors occurred : On such trials, although the correct response was given, electromyographic (EMG) recordings allow to reveal a small EMG burst on the muscles involved in the incorrect response (Burle et al., 2002b; Coles et al., 1985; Eriksen et al., 1985). Vidal and colleagues observed a negative wave just after the onset of such partial errors with comparable latency and topography as the wave reported on errors (see Scheers et al., 1996 for similar data in a go/nogo task). More importantly, they also reported a similar negativity, of smaller amplitude though, just after the EMG leading to the correct response on pure correct trials (i.e. trials without any sign of incorrect EMG activation). The negative activities obtained on errors, partial errors and pure correct trials had similar topographies, similar time-courses (after Laplacian transform), and their amplitude was shown to monotonically decrease from errors to pure correct, with partial errors in between. Based on these similarities, Vidal et al. (2000) argued that the Nerror trials re ec tth esam efunctiona lan dphysiologica lmechanism smodulate di namplitud eo rwhethe rthe yar ecompletel ydieren tprocesses.

While the proposition that the negativities observed on pure correct, partial errors and errors re ec tth esame ,modulated ,mechanis m(Vida le tal. ,2000 ,2003a) ,i ssupporte db yth efac ttha tth enegativit yo ncorrec ttrial si sals osensitiv et oth esubject’ sperformanc e(Lu ue tal. ,2000b ;Ridderinkho fe tal. ,2003 ;Allai ne tal. ,2004c ;Hajca ke tal. ,2005b) ,thi svie wwa sdispute db yYordanov ae tal .(2004) .Thes eauthor sreporte dtha to ncorrec ttrial sth enegativit ytende dt ob elateralize dtowar dth ehemispher econtrolatera lt oth erespondin ghan dwherea sth etopograph ywa smor ecentra lfo rerrors .Base do nth edierenc ei ntopograph yan di nth etime-frequenc ypatter no fnegativitie so ncorrec tan derroneou strials ,the yconclude dtha tth etw onegativitie sre e ctdiere ntprocesse s.T helateralizati onreport ed byYordano va eta l.(200 4)mig htwe ll bedu e,howeve r, to anindepende ntsourc e.Indee d,followi ngt hemot orlateralizati oninduc ed byrespon seexecuti onprocess es(Vid al etal .,2003 b,s eeBur le etal .,200 4bf o rareview ),t helateralizati on oft hobserved by Yordanova et al. (2004) could be due to the propagation of the primary motor activity towards premotor areas (see Tandonnet et al., 2005, Fig. 1) : If this pre-motor activity is of same amplitude for correct and errors trials, it may contribute more to the topography when the amplitude of the medial activity is lower, that is for correct trials. This may give the false impression of a lateralization limited to correct trials, although the same lateralized activity could also be present on errors, but less visible. In agreement with this view, a critical look at the gures 1 and 6 of Yordanova et al. (2004) shows that, even on errors, the iso-contour lines present a lateralization.