Figure 3.
Effects of inactivation or overactivation of specific PFC sub-regions during contingency degradation
(A) In area 24, inactivation and over-activation blunted the sensitivity of marmosets to contingency degradation (treatment × degradation: F2,15 = 4.429, p = 0.0308). There was a significant difference between degraded and non-degraded sessions only following saline infusion (p = 0.0065) but not after inactivation (p = 0.331) or overactivation (p = 0.601). This lack of difference after inactivation occurred due to a selective increase in responding in degraded sessions (p = 0.001) but not in non-degraded sessions (p = 0.912) when compared to saline. Responding across degraded and non-degraded sessions following overactivation was less than that of inactivation (p = 0.0005; see Figure 5A).
(B) Area 11 (antOFC) inactivation apparently enhanced the sensitivity of marmosets to contingency degradation, while overactivation impaired it (treatment × degradation: F2,13.287 = 7.213, p = 0.00757). Marmoset responding in degraded sessions was significantly reduced, compared to non-degraded sessions, under both saline (p = 0.0407) and inactivation infusions (p = 0.0004), but no significant difference was observed after overactivation (p = 0.363). Further analysis revealed a significant increase in the difference in responding between degraded and non-degraded conditions after inactivation when compared to saline infusion (p = 0.0158). This effect was driven by a significant increase in responding in the non-degraded condition after inactivation when compared to saline (p = 0.0032) but not in the degraded condition (p = 0.248).
(C) In area 32 (mPFC), marmoset responding in non-degraded sessions was significantly greater than that of degraded sessions across all treatment conditions (p = 0.0016). There were significant effects of degradation when saline data were considered alone (F1,3 = 21.176, p = 0.0193).
(D) A significant difference between degraded and non-degraded sessions was observed following saline infusion (p = 0.0011) and inactivation (p = 0.0012) of area 14 (rostral vmPFC/mOFC). There were also significant effects of degradation when saline data were considered alone (F1,3 = 12.137, p = 0.04). Although no significant differences occurred between degraded and non-degraded sessions after overactivation (p = 0.445), this effect was most likely a non-specific drug effect (see Figure 5B). Responding during the non-degraded session after overactivation was significantly lower than that after inactivation (p = 0.0107) and trended lower than after saline (p = 0.0834). Conversely, the responding of marmosets during the degraded session after overactivation was not significantly different from that of inactivation (p = 0.848) or saline (p = 0.815). A similar pattern was observed in the baseline sessions, which tested the effects of drugs on marmoset responding without the presence of free rewards (see Figure 5B).
(E) In area 14-25 (caudal vmPFC), marmoset responding in non-degraded sessions was significantly greater than that of degraded sessions across all drug conditions (p = 0.0016). There were significant effects of degradation when saline data were considered alone (F1,2 = 24.409, p = 0.0386).
Relevant graphs show 2 × SED for degraded versus non-degraded comparisons (area 24: n = 4; area 11: n = 4; area 32: n = 4; area 14: n = 4; area 14-25: n = 3). Deg, degraded session. Nondeg, non-degraded session. Asterisk (∗) indicates a significant effect of the degradation × treatment interaction, # indicates a significant effect between treatments, ˆ indicates a significant effect between degradations. ∗/#/ˆp < 0.05, ∗∗/##/ˆˆp < 0.01, ∗∗∗/###/ˆˆˆp < 0.001.