Age-related differences in episodic feeling-of-knowing arise from differences in memory performance

Previous studies about the effects of ageing on the episodic feeling-of-knowing (FOK) accuracy and its underlying processes have yielded conflicting results. Recent work suggests that using alternative measures to gamma correlations might allow more accurate and informative interpretations of metamemory performance in ageing. We therefore investigated this issue with a large sample of 59 young and 61 older participants using alternative signal-detection theory (SDT) measures. These measures (receiver operating characteristic curves and Brier score) are recommended in the literature and able to reveal the characteristic profile of impairment in ageing. Our results suggest that the FOK accuracy deficit observed in the literature arises from differences in memory performance. This observation provides a convenient explanation to the previous discrepancies and furthermore supports the interest of the use of SDT-derived measures in the frame of metamemory.     

The Moral Insignificance of ``Bare' Personal Reasons

Common sense supports the idea that we can have morally significantreasons for giving priority to the interests of persons for whom wehave special concern. Yet there is a real question about the natureof such reasons. Many people seem to believe that there are biologicalor metaphysical special relations, such as family, race, religion orpersonal identity, which are in themselves morally important and thussupply reasons for special concern. I maintain that there are nogrounds for accepting this. What matters morally, I argue, is thesubstance of personal or wider social relationships. My ``substantivist'account of the source of morally salient reasons for special concernis positioned between nonreductionist and strong voluntarist views ofspecial responsibilities. Substantivism is more plausible than theseviews and has important implications for how we approach morallyweighing personal versus impartial reasons.     

The Rationale Behind Revision-Rule Semantics

According to Gupta and Belnap, the “extensional behavior” of ‘true’ matches that of a circularly defined predicate. Besides promising to explain semantic paradoxicality, their general theory of circular predicates significantly liberalizes the framework of truth-conditional semantics. The authors’ discussions of the rationale behind that liberalization invoke two distinct senses in which a circular predicate’s semantic behavior is explained by a “revision rule” carrying hypothetical information about its extension. Neither attempted explanation succeeds. Their theory may however be modified to employ a relativized notion of extension. The resulting contextualist semantics for ‘true’ construes circularity as a pragmatic phenomenon.     

mTOR signaling in the hippocampus is necessary for memory formation

It is widely accepted that the formation of long-term memory (LTM) requires mRNA translation, but little is known about the cellular mechanisms in the brain that regulate this process. Mammalian target of rapamycin (mTOR) is a key regulator of translational efficacy and capacity. Here, we show that LTM formation of one-trial inhibitory avoidance (IA) in rats, a hippocampus-dependent fear-motivated learning task, requires mTOR activation. IA training is specifically associated with a rapid increase in the phosphorylation state of mTOR and its substrate ribosomal S6 kinase (p70S6K). Bilateral intra-CA1 infusion of rapamycin, a selective mTOR inhibitor, 15 min before, but not immediately after training completely hinders IA LTM without affecting short-term memory (STM) retention. Therefore, our findings indicate that the regulation of hippocampal mRNA translation is a major control step in memory consolidation.