Figure 5.

Main Neural Decision Signals

(A) Whole-brain effects of prospective value (green, Ai) and myopic value (red, Aii) when the initial search decision is made. Parts of dACC and dlPFC and posterior cingulate cortex are sensitive to both aspects of value (p < 0.001, cluster-corrected; see also Table 1).

(B) Time course of the regression weights for prospective (green) and myopic (red) value on brain activity in dACC and dlPFC.

(C) Connectivity between dACC and dlPFC is increased when prospective value is high as opposed to low (Ci) (see Figure S6A for regression instead of split). Although both dACC and dlPFC are also activated by myopic value, this form of value does not lead to the same connectivity effects; there is no difference between dACC-dlPFC connectivity when myopic value is high or low (Cii).

(D) Value-related activity in dACC is not due to difficulty. A whole-brain analysis time-locked to decision onset and using the same statistical significance thresholds as used in analyses of value-related signals found no evidence that a choice uncertainty-based metric of difficulty activated dACC at the time of decision (Di). Subsequent dACC time course analyses (ROI based on the peak of prospective value effect shown in crosshair [x = −10, y = 34, z = 18], but using anatomical ROI of rostral cingulate zone yields very similar results) found activity at the end of the trial reflected choice uncertainty (Dii) and reaction time (Diii); dACC activity was only protracted when it was difficult to select a response and reaction times were long. (Div) Although the number of alternatives might intuitively be thought to make a trial difficult, they were not associated with an increase in dACC activity (whole-brain result in Figure S5C). Time courses show means and standard error of the mean (shaded area). Vertical black line in all plots illustrates average reaction time across all participants. Horizontal ranges (in black) show the mean SD around the mean median reaction time across participants.