Exploration-related activity in frontopolar cortex. a, Regions of left and right frontopolar cortex (lFP, rFP) showing significantly increased activation on exploratory compared with exploitative trials. Activation maps (yellow, P < 0.001; red, P < 0.01) are superimposed on a subject-averaged structural scan. The coordinates of activated areas are [−27,48,4, peak z = 3.49] for lFP and [27,57,6, peak z = 4.13] for rFP. b, rFP BOLD time courses averaged over 1,515 exploratory (red line) and 2,646 exploitative (blue line) decisions. Black dots indicate the sampling frequency (although, because sample alignment varied from trial to trial, time courses were upsampled). Coloured fringes show error bars (representing s.e.m.).