Fig. 6.

Brain activity correlating with the variance PE signal at the time of the offer. We found one cluster within the SN/VTA which BOLD signal correlated with the value of the variance PE. Using this cluster as a ROI we extracted the mean beta values for different binned-values of norm PEs (in $). Right plots show the relationship between brain activity expressed as beta values and the values of the norm PE. Error bars represent SEM. The SN/VTA cluster is displayed on the mean proton-density image. The SN (light grey) and VTA (dark grey) are outlined based on the Murty et al. (2014) atlas. Images were thresholded at P <0.005 uncorrected for display purposes. t-values were transformed into Z-scores because the total number of participants that had data for specific voxels could change due to the use of individually defined acquisition slabs. Statistics were only calculated on voxels that had at least 20 participants. SN/VTA: substantia nigra/ventral tegmental area; norm PE: norm PE SEM: standard error of the mean.