Sleep enhances memory consolidation in the hippocampus-dependent object-place recognition task in rats

The positive impact of sleep on memory consolidation has been shown for human subjects in numerous studies, but there is still sparse knowledge on this topic in rats, one of the most prominent model species in neuroscience research. Here, we examined the role of sleep in the object-place recognition task, a task closely comparable to tasks typically applied for testing human declarative memory: It is a one-trial task, hippocampus-dependent, not stressful and can be repeated within the same animal. A test session consisted of the Sample trial, followed by a 2-h retention interval and a Test trial, the latter examining the memory the rat had for the places of two objects presented at the Sample trial. In Experiment 1, each rat was tested twice, with the retention interval taking place either in the morning or evening, i.e., in the inactive or active phase, respectively. Rats showed significantly (p<0.01) better memory for object place after the Morning session. To control for confounding circadian factors, in Experiment 2 rats were tested four times, i.e., in the morning or in the evening while sleep was or was not deprived. Sleep during the retention interval was recorded polysomnographically. Rats only showed significant memory for the target object place in the Test trial after the Morning retention interval in the absence of sleep deprivation, and recognition performance in this condition was significantly superior to that in the three other conditions (p<0.05). EEG recordings during spontaneous morning sleep revealed increased slow oscillation (0.85-2.0 Hz) and upper delta (2.0-4.0 Hz), but reduced spindle band (10.5-13.5 Hz) activity, as compared to evening sleep. However, spindle band power was increased in the Morning retention interval in comparison to a Morning Baseline period (p<0.05). We conclude that consolidation of object-place memory depends on sleep, and presumably requires NonREM sleep rich in both slow wave and spindle activity.     

Empathy, Shared Intentionality, and Motivation by Moral Reasons

Internalists about reasons generally insist that if a putative reason, R, is to count as a genuine normative reason for a particular agent to do something, then R must make a rational connection to some desire or interest of the agent in question. If internalism is true, but moral reasons purport to apply to agents independently of the particular desires, interests, and commitments they have, then we may be forced to conclude that moral reasons are incoherent. Richard Joyce (2001) develops an argument along these lines. Against this view, I argue that we can make sense of moral reasons as reasons that apply to, and are capable of motivating, agents independently of their prior interests and desires. More specifically, I argue that moral agents, in virtue of their capacities for empathy and shared intentionality, are sensitive to reasons that do not directly link up with their pre-existing ends. In particular, they are sensitive to, and hence can be motivated by, reasons grounded in the desires, projects, commitments, concerns, and interests of others. Moral reasons are a subset of this class of reasons to which moral agents are sensitive. Thus, moral agents can be motivated by moral reasons, even where such reasons fail to link up to their own pre-existing ends.     

Preschool‐aged children's understanding of gratitude: Relations with emotion and mental state knowledge

Developmental precursors to children's early understanding of gratitude were examined. A diverse group of 263 children was tested for emotion and mental state knowledge at ages 3 and 4, and their understanding of gratitude was measured at age 5. Children varied widely in their understanding of gratitude, but most understood some aspects of gratitude‐eliciting situations. A model‐building path analysis approach was used to examine longitudinal relations among early emotion and mental state knowledge and later understanding of gratitude. Children with a better early understanding of emotions and mental states understand more about gratitude. Mental state knowledge at age 4 mediated the relation between emotion knowledge at age 3 and gratitude understanding at age 5. The current study contributes to the scant literature on the early emergence of children's understanding of gratitude.