F(1,166) = 81.6, p < 0.001], Pe [Cz: 1.7 vs. 8.2 Vμ; F(1,166) = 127.1, p < 0.001], and Pc [FCz: 4.4 vs. 6.7 μV; F(1,166) = 13.9, p < 0.001] latency intervals. Smaller ERN and Pe ampli- tudes tended to be associated with slower mean hit RT (ERN: r = 0.15, p = 0.052; Pe: r = –0.14, p = 0.07), and amplitudes of all three error monitoring components were sig- nificantly associated with higher percent cor- rect go trials (ERN: r = –0.19, p = 0.02; Pe: r = 0.25, p = 0.001; Pc: r = 0.18, p = 0.02) and higher percent correct no-go trials (ERN: r = –0.23, p = 0.003; Pe: r = 0.25, p = 0.001; Pc: r = 0.16, p = 0.04). Results from the regression analyses test- ing for associations between contaminants and response-locked ERP parameters are pre- sented in Table 5. After statistical control for confounders, higher plasma PCB-153 con- centrations at time of testing are associated with reduced amplitude of the components Pe, elicited by false alarms, and Pc, elicited by correct hits. These effects are illustrated in Figure 3, which compares children from the bottom and top quartiles of current plasma PCB-153 concentrations (adjusted mean ± SD Pc amplitude, 5.5 ± 4.0 μV vs . 2.8 ± 4.8 Vμ, Cohen’s d = –0.61). Pb and Hg con- centrations in cord and child blood samples were not associated with any of the response- locked ERP measures in standard regression analyses (all p-values > 0.10). The effects of current plasma PCBs on response-locked ERPs did not interact with the other contaminants (all p-values > 0.15). Discussion In this study we examined the association of developmental exposure to Pb, PCBs, and MeHg with response inhibition in 11-year- old children using ERPs recorded during a visual go/no-go task. Blood Pb concentra- tions at time of testing were associated with higher rates of false alarms during the task and with reduced amplitude of the P3 wave elicited by go and no-go stimuli, suggesting reduced allocation of cognitive resources for task processing. Surprisingly, the effects of current Pb on P3 amplitudes were stronger in children with lower current MeHg and PCB exposures, which suggests that coexposure to the other contaminants may make the adverse Pb effects on these end points more difficult Table 5. Associations between contaminants and response-locked ERP amplitudes recorded during the go/no-go task (n = 166). Pb PCB-153 Cord blood Current blood Cord plasma Current plasma Cord blood Current blood ERP parameter ERN (FCz) Pe (Cz) Pc (FCz) r 0.03 –0.11 –0.19** β –0.02a,b,c,d –0.07a,e –0.12e r 0.09 –0.11 –0.10 β 0.11a,d –0.00a,e,f –0.00a,b,e,j r 0.07 0.07 –0.08 β –0.03a,c,d 0.11a,g,h –0.03a,b,f,g,j r 0.06 –0.18** –0.23* β 0.02a,b,c,d –0.16**i –0.20**g r 0.12 –0.09 –0.12 β 0.11a,c 0.05a,e,f,g 0.01a,e,g,j Values are Pearson correlation (r) and standardized regression (β) coefficients from multiple regression analyses. Negative (–) associations with ERN amplitude indicate greater (more negative) amplitude. Superscripts (a–j) indicate control variables included in the final model for each of the regression analyses. aChild sex. bAdoption status. cTransported from a remote village. dCord Hg. eChild PCB-153. fBreast-feeding duration. gCord Pb. hChild Hg. iChild Pb. jChild age. *p < 0.01. **p < 0.05. Environmental Health Perspectives • volume 120 | number 4 | April 2012 Pb, PCB, and MeHg effects on an ERP go/no-go task to detect. By contrast, plasma PCB-153 con- centrations at time of testing were associated with slower RTs to go trials and with reduced amplitude of the Pe/Pc components, which are believed to reflect postresponse brain activ- ity involved in error monitoring. Higher cord blood Pb concentrations were associated with poorer performance during the task (although not with any of ERP parameters), and the behavioral effects were markedly stronger in children with higher levels of prenatal expo- sure to MeHg and to PCBs. Cord PCB-153 levels were marginally associated with delayed latency of the N2 component in the go but not in the no-go condition. We previously assessed the relation of postnatal Pb exposure to ERPs recorded during a simple auditory oddball detection paradigm and found no effect of Pb on the P3 component recorded during this task at school age (Boucher et al. 2009b). The finding of decreased P3 amplitude to go and no-go stimuli as a function of current blood Pb con- centrations in the present analyses suggests –100 0 100 300 400 200 ms Figure 3. Grand average for response-locked go/no-go ERPs at midline electrodes comparing participants from the first quartile of plasma PCB-153 concentrations at time of testing (range, 3.5–26.0 μg/g fat; n = 46; thin lines) to those from the fourth quartile (range, 96.6–431.4 μg/g fat; n = 42; thick lines). Incorrect no-go trials (false alarms; dashed lines) elicit an early wave of negative voltage (ERN) followed by a large positive wave (Pe) maximal at the vertex (Cz). Correct go responses (solid lines) generate a frontocentral wave of positive voltage in the 100–300 msec (Pc) latency interval. Children with higher plasma PCB-153 concentrations show reduced activity during the Pe and Pc time windows compared with children with lower PCB-153 levels. +5 0 –5 +5 µV 0 –5 +5 0 –5 1st plasma PCB-153 quartile Go correct No-go incorrect 4th plasma PCB-153 quartile Go correct No-go incorrect Fz Cz Pz Hg r 0.10 –0.11 –0.10 β 0.07c –0.03a,e,f 0.01a,b,e,f,j 613