Comparison of semantic and phonological false memories in short- and long-term tests.

The Deese-Roediger-McDermott (DRM) paradigm has been at the centre of false memory research. Whereas most work with this paradigm has examined memory at the long term and with semantically associated lists, the present study examines phonological and semantic false memories at both short- and long-term delays. In two experiments, participants studied short lists containing six (Experiment 1) or four (Experiment 2) items, either semantically or phonologically related to the same non-studied critical items (CI). Following each list, participants completed 36 trials of an immediate recognition task (short-term memory [STM]-only condition) only or they also completed a surprise recognition test after a 1-min delay after all 36 STM trials (STM + long-term memory [LTM] condition). In STM, false alarms were higher in phonological lists, whereas after the delay, false alarms were higher in semantic lists, reflecting differential sensitivity to the type of association as a function of delay. A third experiment examined LTM performance after controlling for prior testing and yielded highly similar results. Both the activation-monitoring framework (AMF) and fuzzy-trace theory (FTT) can explain the majority of the findings, with some remaining issues. These results confirm that information from the knowledge base (LTM) does influence accuracy in an STM task, albeit less so than perceptual level similarity.

Voluntary wheel running access produces opposite effects in male and female rats on both palatable diet consumption and associated ventral striatal opioid- and dopamine-related gene expression.

The relationship between physical activity levels and feeding behaviors has been a focus of preclinical research for decades, yet this interaction has only recently been explored for potential sex differences. The aim of the present study was to isolate sex-dependent effects of voluntary wheel running (RUN) vs. sedentary locked wheel (SED) home cage conditions on palatability-driven feeding behavior using a 2-diet choice task between standard chow and a high-fat diet. The sex-dependent effects of physical activity on feeding behavior were examined following a within-subject novel reversal design of physical activity conditions (i.e., RUN > SED > RUN), to assess temporal sensitivity of the interaction. Following the final 2 weeks of reestablished and sustained RUN vs. SED conditions in separate groups of both males and females, reward-related opioid and dopamine gene expression within the nucleus accumbens (Acb) brain region were analyzed. Results demonstrated that the initial RUN > SED transition led to sex-dependent effects of SED condition, as males increased, and females decreased their high fat consumption, compared to their respective high fat consumption during previous RUN condition phase. Following reintroduction to the RUN condition, males decreased, and females increased their high fat consumption, compared to their separate SED control group. Last, sex-dependent shifts in ventral striatal opioid- and dopamine-related gene expression were observed to parallel the behavioral effects. The major findings of the study reveal that SED and RUN home cage conditions shift palatability-driven feeding in the opposite direction for males and females, these effects are sensitive to reversal, and these sex-dependent feeding behaviors track sex-dependent changes to critical reward-related gene expression patterns in the Acb. Considering the present high rates of sedentary behavior and obesity, furthering our understanding of the interaction between physical activity (or lack thereof) and feeding behavior should be a priority, especially in the context of these divergent sex-dependent outcomes.