Article Figures & Data
Figures
- Figure 1.
A, Experimental paradigm. One example trial is shown. First, subjects were presented with a mapping cue (2000 ms) that indicated the current association of tasks and rewards. In this trial, parity is associated with a low reward and magnitude is associated with a high reward. After a long delay (delay 1, 6000 ms) subjects were presented with a task cue (1500 ms) indicating which task is to be performed this trial. Note that only by combining information from both cues could subjects determine the current reward condition, in this case a high reward. Before the onset of the task cue, subjects could neither prepare the execution of the instructed task nor could they expect a high or a low reward, leaving only the mapping information to be represented before the task cue onset. After a second delay (delay 2, 1500 ms) the task screen was presented (2000 ms). A single digit was shown together with four response symbols (from left to right: odd, even, larger than 5, and smaller than 5), and subjects were instructed to press the correct button as quickly and accurately as possible. After a third short delay (delay 3, 300 ms), subjects received a reward feedback (500 ms), indicating whether they were correct and fast enough to receive a reward (green for high reward, yellow for low reward), were correct but too slow to receive a reward (magenta), were wrong (red), or did not press any button (red). After a variable intertrial interval (ITI, 2000–7000 ms), the next trial started. B, Analysis overview. Depicted are the three main MVPAs performed in this experiment. In the task–reward mapping analysis (left), task–reward mapping 1 (light gray) was contrasted with task–reward mapping 2 (dark gray). In the reward analysis (middle), the high-reward (light gray) and low-reward (dark gray) conditions were contrasted. In the task analysis (right), the parity task (light gray) was contrasted with the magnitude task (dark gray). In all analyses, we used cross-classification across visual cues to decorrelate the conditions of interest from the visual identity of the cues presented to the subjects.
- Figure 2.
Depicted are the results from all decoding analyses. A, Task–reward mapping decoding. It can be seen that two clusters in the bilateral inferior parietal cortex represented task–reward mappings during the presentation of mapping cues and delay 1. B, Task decoding. The left inferior parietal cortex and left premotor cortex represented tasks during the presentation of the task cue, delay 2, task execution, and reward feedback. C, Above, results from the reward-effects decoding analysis are shown. It can be seen that a large cortical and subcortical network shows reward effects during the presentation of the task cue, delay 2, task execution, and reward feedback. This network included striatal, medial prefrontal, and parietal regions. Below, brain regions showing a univariate signal increase in high reward trials during the same period in the trial are shown for comparison.
- Figure 3.
A, Time course of information for the two brain regions identified in the task–reward mapping analysis (left parietal cortex and right parietal cortex). The left gray line shows the onset of the mapping cue and the duration of the delay 1. The right gray line shows the onset of the task cue, and the duration of the delay 2, task execution, and reward feedback periods. The two black lines represent the same events with a hemodynamic lag of 4 s factored in. Error bars represent SEs. Four independent decoding analyses were performed, each correcting for a different possible confounding variable. The plot shows the minimum accuracy value of those four analyses at each time point. Because the mapping analysis has been used to define the ROIs, data from that analysis are not shown to avoid circularity. Task and reward accuracy time courses are independent of the data used to define the ROIs. B, Time course of information for the two brain regions identified in the task decoding analysis (left parietal cortex, left premotor cortex). Because the task analysis has been used to define the ROIs, data from that analysis are not shown to avoid circularity. Mapping and reward accuracy time courses are independent of the data used to define the ROIs.
- Figure 4.
Overlap of all three MVPAs. Regions informative about the mapping during delay 1 are shown in red, regions informative about the task during task execution are shown in blue, and regions informative about the reward during task execution are shown in green. The informative regions of all three analyses overlap in the left inferior parietal cortex, whereas regions informative about mappings and rewards overlap in the right inferior parietal cortex. This shows that brain areas that represent an association between tasks and rewards early in the trial represent actual tasks and rewards or their effects at a later stage in the trial.
Tables
Brain region Side Cluster size MNI coordinates (peak voxel) x y z Task–reward associations Left inferior parietal cortex Left 67 −48 −52 37 Right inferior parietal cortex Right 73 57 −64 34 Tasks Ventral premotor cortex Left 80 −42 2 19 Inferior parietal cortex Left 134 −54 −43 22 Rewards Inferior parietal cortex Left 300 −45 −43 19 Inferior parietal cortex Right 56 57 −40 28 Medial cortex Bilateral 7736 6 −4 67 Precentral gyrus Left 305 −30 −19 49 Midfrontal gyrus Left 74 −36 14 43 Superior temporal gyrus Right 31 60 −19 −5 Anterior midfrontal gyrus Right 35 42 47 13 Anterior midfrontal gyrus Left 59 −27 44 22 Inferior frontal gyrus, pars triangularis Left 28 −30 35 7 Inferior frontal gyrus, operculum Right 26 48 14 1 Cerebellum Right 231 27 −52 −32 Results are shown for a statistical threshold of p < 0.001, corrected for multiple comparisons at the cluster level (p < 0.05). The regions shown for the task–reward association results encoded these associations before the onset of the task cue. The regions shown for the task and reward results encoded these variables after the onset of the task cue. All clusters larger than 20 voxels are reported.
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