What Are the Brain Areas that Support Curiosity?

Adcock et al., 2006 Adcock R.A.

Thangavel A.

Whitfield-Gabrieli S.

Knutson B.

Gabrieli J.D.E. Reward-motivated learning: mesolimbic activation precedes memory formation. Knutson et al., 2001 Knutson B.

Adams C.M.

Fong G.W.

Hommer D. Anticipation of increasing monetary reward selectively recruits nucleus accumbens. Shohamy and Adcock, 2010 Shohamy D.

Adcock R.A. Dopamine and adaptive memory. Kang et al., 2009 Kang M.J.

Hsu M.

Krajbich I.M.

Loewenstein G.

McClure S.M.

Wang J.T.-Y.

Camerer C.F. The wick in the candle of learning: epistemic curiosity activates reward circuitry and enhances memory. Our first analyses identified brain areas that are recruited during states of high curiosity. Based on studies of extrinsic reward anticipation (), we hypothesized that activity in the SN/VTA and nucleus accumbens ROIs should be enhanced during states of high curiosity. We were less certain about effects of curiosity in the hippocampal ROI, as it is unclear from prior studies whether hippocampal activity is generally reward-sensitive or if it more specifically reflects motivational influences on learning (). To quantify the positive relationship between curiosity and brain activity (cf.), we ran an analysis testing for parametric modulation of activation during each trial as a function of curiosity ratings (see Experimental Procedures for details). Because of directed hypotheses, we performed one-tailed t tests (note that this is the approach routinely used in voxel-based fMRI analyses). As we did not have strong predictions about whether effects would be seen in the left or right hemispheres, we corrected for multiple comparisons across hemispheres by using a Bonferroni-adjusted alpha level of 0.025 per analysis.

(18) = 3.16, p = 0.003; right: t (18) = 2.60, p = 0.009) and the left SN/VTA (left: t (18) = 2.23, p = 0.020; right: t (18) = 1.52, p = 0.073) increased linearly with curiosity ratings ( (18) = 0.54, and t (18) = 0.73, respectively; left and right SN/VTA: t (18) = 0.23 and t (18) = −0.06, respectively; p > 0.05). Activity in the hippocampal ROIs was not significantly modulated by curiosity during presentation of trivia questions (left: t (18) = 0.31; right: t (18) = −0.28; p > 0.05) or answers (left: t (18) = −0.61; right: t (18) = −0.43; p > 0.05). Figure 2 Curiosity-Modulated Activity in the Dopaminergic Circuit Show full caption Curiosity ratings were associated with activity increases in the bilateral nucleus accumbens ROI (A) and left SN/VTA ROI (B). On the left, ROIs are shown in red on the average, normalized anatomical image in our group of participants. On the right, to depict the effects modeled by the parametric modulation analysis, mean BOLD parameter estimates related to the onset of the trivia questions are plotted on the y axis against the curiosity rating given during the screening phase on the x axis. Error bars represent ±1 SEM. During presentation of trivia questions (when curiosity was elicited), activity in the bilateral nucleus accumbens (left: t= 3.16, p = 0.003; right: t= 2.60, p = 0.009) and the left SN/VTA (left: t= 2.23, p = 0.020; right: t= 1.52, p = 0.073) increased linearly with curiosity ratings ( Figures 2 A and 2B ). In contrast, no significant modulation was seen in these regions during presentation of trivia answers, when curiosity was satisfied (left and right nucleus accumbens: t= 0.54, and t= 0.73, respectively; left and right SN/VTA: t= 0.23 and t= −0.06, respectively; p > 0.05). Activity in the hippocampal ROIs was not significantly modulated by curiosity during presentation of trivia questions (left: t= 0.31; right: t= −0.28; p > 0.05) or answers (left: t= −0.61; right: t= −0.43; p > 0.05).

In addition to the parametric modulation analysis, we also performed a simpler analysis in which we directly contrasted activation following the presentation of questions associated with high (4–6) and low (1–3) curiosity ratings. Consistent with findings from the parametric modulation analyses, we found significantly increased question-related activation for high compared to low curiosity conditions in the left SN/VTA (left: t (18) = 2.53, p = 0.010; right: t (18) = 0.95, p = 0.177), and similar trends in the bilateral nucleus accumbens that did not exceed the Bonferroni-corrected threshold (left: t (18) = 2.05, p = 0.027; right: t (18) = 1.70, p = 0.053). Again, no significant effects were seen in the hippocampal ROIs (left: t (18) = −0.91; right: t (18) = −0.68; p > 0.05). As in the parametric modulation analysis, no significant effects of curiosity were seen during presentation of the trivia answers (left nucleus accumbens: t (18) = 1.68, p = 0.055; all other ROIs: t values ≤ 1.22, p > 0.05).

Kang et al., 2009 Kang M.J.

Hsu M.

Krajbich I.M.

Loewenstein G.

McClure S.M.

Wang J.T.-Y.

Camerer C.F. The wick in the candle of learning: epistemic curiosity activates reward circuitry and enhances memory. Knutson et al., 2001 Knutson B.

Adams C.M.

Fong G.W.

Hommer D. Anticipation of increasing monetary reward selectively recruits nucleus accumbens. Kang et al. (2009) Kang M.J.

Hsu M.

Krajbich I.M.

Loewenstein G.

McClure S.M.

Wang J.T.-Y.

Camerer C.F. The wick in the candle of learning: epistemic curiosity activates reward circuitry and enhances memory. To characterize activation outside of the a priori ROIs and enable comparison to prior fMRI studies of motivation (e.g.,), we performed whole-brain, voxel-based analyses testing for parametric modulation of activity following presentation of trivia questions as a function of curiosity. This analysis revealed suprathreshold clusters of the bilateral striatum (i.e., dorsal and ventral), left inferior frontal gyrus, left superior gyrus, and the cerebellum (for details, see Table S1 and Figure S2 ). These results are highly consistent with the work of, who also showed curiosity-related activation in the dorsal striatum, inferior frontal gyrus, and superior frontal gyrus.

In summary, the results described above suggest that curiosity modulates activity in the nucleus accumbens and SN/VTA, along with a possible set of SN/VTA afferents across the striatum and prefrontal cortex.