Not what u expect:Effects of prediction errors on item memory

The characterization of the relationship between predictions and one-shot episodic encoding poses an important challenge for memory research. On the one hand, events that are compatible with our previous knowledge are thought to be remembered better than incompatible ones. On the other hand, unexpected situations, by virtue of their novelty, are known to cause enhanced learning. Several theoretical accounts try to solve this apparent paradox by conceptualizing prediction error (PE) as a continuum ranging from low PE (for expectation-matching events) to high PE (for expectation-mismatching ones). Under such a framework, the relationship between PE and memory encoding would be described by a U-shape function with higher memory performance for extreme levels of PE and lower memory for middle levels of PE. In this study, we tested the framework by using a gradual manipulation of the strength of association between scenes and objects to render different levels of PE and then tested for item memory of the (mis)matching events. In two experiments, in contrast to what was anticipated, recognition memory for object identity followed an inverted U-shape as a function of PE, with higher performance for intermediate levels of PE. Furthermore, in two additional experiments, we showed the relevance of explicit predictions at encoding to reveal such an inverted U pattern, thus providing the boundary conditions of the effect. We discussed our findings in light of existing literature relating PE and episodic memory, pointing out the potential roles of uncertainty in the environment, and the importance of the cognitive operations underlying encoding tasks

Distinct multivariate structural brain profiles are related to variations in short- and long-delay memory consolidation across children and young adults

From early to middle childhood, brain regions that underlie memory consolidation undergo profound maturational changes. However, there is little empirical investigation that directly relates age-related differences in brain structural measures to memory consolidation processes. The present study examined memory consolidation of intentionally studied object-location associations after one night of sleep (short delay) and after two weeks (long delay) in normally developing 5-to-7-year-old children (n = 50) and young adults (n = 39). Behavioural differences in memory retention rate were related to structural brain measures. Our results showed that children, in comparison to young adults, retained correctly learnt object-location associations less robustly over short and long delay. Moreover, using partial least squares correlation method, a unique multivariate profile comprised of specific neocortical (prefrontal, parietal, and occipital), cerebellar, and hippocampal head and subfield structures in the body was found to be associated with variation in short-delay memory retention. A different multivariate profile comprised of a reduced set of brain structures, mainly consisting of neocortical (prefrontal, parietal, and occipital), hippocampal head, and selective hippocampal subfield structures (CA1-2 and subiculum) was associated with variation in long-delay memory retention. Taken together, the results suggest that multivariate structural pattern of unique sets of brain regions are related to variations in short-and long-delay memory consolidation across children and young adults

Functional effects of bilateral dorsolateral prefrontal cortex modulation during sequential decision-making: a functional near-infrared spectroscopy study with offline transcranial direct current stimulation

The ability to learn sequential contingencies of actions for predicting future outcomes is indispensable for flexible behavior in many daily decision-making contexts. It remains open whether such ability may be enhanced by transcranial direct current stimulation (tDCS). The present study combined tDCS with functional near-infrared spectroscopy (fNIRS) to investigate potential tDCS-induced effects on sequential decision-making and the neural mechanisms underlying such modulations. Offline tDCS and sham stimulation were applied over the left and right dorsolateral prefrontal cortex (dlPFC) in young male adults (N = 29, mean age = 23.4 years, SD = 3.2) in a double-blind between-subject design using a three-state Markov decision task. The results showed (i) an enhanced dlPFC hemodynamic response during the acquisition of sequential state transitions that is consistent with the findings from a previous functional magnetic resonance imaging (fMRI) study; (ii) a tDCS-induced increase of the hemodynamic response in the dlPFC, but without accompanying performance-enhancing effects at the behavioral level; and (iii) a greater tDCS-induced upregulation of hemodynamic responses in the delayed reward condition that seems to be associated with faster decision speed. Taken together, these findings provide empirical evidence for fNIRS as a suitable method for investigating hemodynamic correlates of sequential decision-making as well as functional brain correlates underlying tDCS-induced modulation. Future research with larger sample sizes for carrying out subgroup analysis is necessary in order to decipher interindividual differences in tDCS-induced effects on sequential decision-making process at the behavioral and brain levels

Short- and long-delay consolidation of memory accessibility and precision across childhood and young adulthood

Childhood is a period when memory consolidation and knowledge base undergo rapid changes. The present study examined short-delay (overnight) and long-delay (after a 2-week period) consolidation of new information either congruent or incongruent with prior knowledge in typically developing 6- to 8-year-old children (n = 32), 9- to 11-year-old children (n = 33), and 18- to 30-year-old young adults (YA; n = 39). Both memory accessibility (cued recall of objects) and precision (precision of object placement) of initially well-learned object–scene pairs were measured. Our results showed that overnight, memory accessibility declined similarly in all age groups; memory precision improved more in younger children (YC) compared to older children (OC) and even declined in YA. After a 2-week period, both memory accessibility and precision became worse. Specifically, while age groups showed similar decline in memory accessibility, precision decline was less in YC than in OC and YA. The accessibility and precision of congruent and incongruent information changed similarly with consolidation in all age groups. Taken together, our results showed that, for initially well-learned information, YC have robust memory consolidation, despite their overall lower mnemonic performance compared to OC and YA, which is potentially crucial for stable and precise knowledge accumulation early on in development

Not what U expect: Effects of Prediction Errors on Item Memory

In this project we aim at testing the effects of PE strength on episodic encoding. To do so, we manipulate prior strength to render different levels of PE and then test for item remembering of the (mis)matching events

Exp. 2B

- Experiment 2B: Four PE levels (.1, .5, .9) + categorization at encoding

Exp. 1

Experiment 1: Three PE levels (.2, .66, .8) + prediction at encoding

Exp. 2A

Experiment 2A: Four PE levels (.1, .3, .7, .9) + categorization at encoding