The effects of life stress and neural learning signals on fluid intelligence

Abstract

Fluid intelligence (fluid IQ), defined as the capacity for rapid problem solving and behavioral adaptation, is known to be modulated by learning and experience. Both stressful life events (SLES) and neural correlates of learning [specifically, a key mediator of adaptive learning in the brain, namely the ventral striatal representation of prediction errors (PE)] have been shown to be associated with individual differences in fluid IQ. Here, we examine the interaction between adaptive learning signals (using a well-characterized probabilistic reversal learning task in combination with fMRI) and SLES on fluid IQ measures. We find that the correlation between ventral striatal BOLD PE and fluid IQ, which we have previously reported, is quantitatively modulated by the amount of reported SLES. Thus, after experiencing adversity, basic neuronal learning signatures appear to align more closely with a general measure of flexible learning (fluid IQ), a finding complementing studies on the effects of acute stress on learning. The results suggest that an understanding of the neurobiological correlates of trait variables like fluid IQ needs to take socioemotional influences such as chronic stress into account.

Fig. 1

Probabilistic reversal task. Subjects first saw two abstract stimuli for up to 2 s (or reaction time). After selecting one with a button press, a blue frame surrounded the chosen target along with either positive (reward) or negative (loss) feedback. Feedback was displayed for 1 s, followed by a fixation cross for 1–6.5 s

Fig. 2

Stressful life events were significantly and positively correlated with the BOLD PE signal in the left VS (x/y/z = −16/3/−8, T = 3.02; p _{FWE corrected for VS VOI} = 0.047). Color Scale represents T Values

Fig. 3

Effects of stressful life events and VS BOLD PE signal on fluid IQ. Subjects reporting stressful life events above the median are depicted in red solid triangles (R ² = 0.759). Subjects reporting below the median in blue transparent circles (R ² = 0.287). The interaction term is significant (β = 1.19, T = 2.53, p < 0.05), indicating that in subjects reporting more stressful life events, the VS BOLD PE signal correlates more strongly with fluid IQ. An outlier analysis was performed for each included data point (n = 16) revealing no relevant leverage effects (z value < 3, Cook’s distance < 1, max = 0.218, SD = 0.061)