When averaging signals separately for trials with short, middle, and long CS-US intervals, the first and

Pfizer Licensed Compound Library last quarter of all time courses were classified as “early” and “late.” This resulted in borders at ∼5 s and ∼7 s for the CS-US interval. For plots of the average BOLD signal, only data points falling in the duration of the mean interval of all averaged time courses were included. We performed t tests and ANOVAs on the parameter estimates obtained from the first-level analyses for the VTA and VS ROI and the effects of interest (e.g., responses to CS and responses to the parametric regressors reflecting the predictions from the hazard functions). To test for an effect of expected reward, slopes were fitted to the estimates of www.selleckchem.com/products/frax597.html 0p, 20p, and 40p-predicting cues. Similarly

in the second GLM, the effect of waiting time was tested by fitting a slope to the estimates from the corresponding 0p, 20p, and 40p regressors. The t tests on slopes were one-tailed as a higher response was expected for higher expected rewards; all other t tests were two-tailed unless indicated otherwise. Where statistical tests involved comparisons against trials in which no event occurred (groupU, no reward trials), group comparisons were performed on the mean time courses as in Behrens et al. (2008). For the plots comparing predictions from the hazard functions with obtained BOLD responses, parameter estimates of the three resulting contrasts (constant RPE, linear hazard function, quadratic hazard function), multiplied by their parametric modulator, were linearly combined, to obtain the effect size of the RPE across different CS-US intervals (Figure 3C and Figure 4C). Note that these plots do not depict raw BOLD time courses. Peri-CS raw BOLD time courses are depicted elsewhere (Figures S3 and S4E), separately for short, middle, and long CS-US intervals and different CS conditions. We would like to thank Peter Dayan for helpful discussions on the study design and for his feedback on the data. This study was

supported by the Wellcome Trust (M.C.K.-F., L.T.H., R.J.D., and T.E.J.B.), and the Ergoloid MRC (T.E.J.B.). D.R.B. was supported by a Max Planck Award to R.J.D. “
“Advances in neuroimaging that facilitate the study of brain relationships in humans have stimulated an enormous amount of scientific and medical interest in recent years (Biswal et al., 1995, Bullmore and Sporns, 2009, Deco et al., 2011 and Dosenbach et al., 2010). Resting state functional connectivity MRI (rs-fcMRI), which measures spontaneous low-frequency fluctuations in blood oxygen level dependent (BOLD) signal in subjects at rest, has attracted particular attention for its ability to measure correlations in neural activity (via BOLD signal) between distant brain regions.