Timing is essential for rapid effects of corticosterone on synaptic potentiation in the mouse hippocampus

Stress facilitates memory formation, but only when the stressor is closely linked to the learning context. These effects are, at least in part, mediated by corticosteroid hormones. Here we demonstrate that corticosterone rapidly facilitates synaptic potentiation in the mouse hippocampal CA1 area when high levels of the hormone and high-frequency stimulation coincide in time, but not when corticosterone is given either before or after repetitive stimulation. This effect could not be blocked by antagonists of the mineralocorticoid receptor and glucocorticoid receptor (spironolactone and RU 38486, respectively). These data provide a biological substrate for the important behavioral observation that stress and corticosteroid hormones can facilitate learning and memory processes.     

Sleep deprivation impairs object recognition in mice

Many studies in animals and humans suggest that sleep facilitates learning, memory consolidation, and retrieval. Moreover, sleep deprivation (SD) incurred after learning, impaired memory in humans, mice, rats, and hamsters. We investigated the importance of sleep and its timing in an object recognition task in OF1 mice subjected to 6h SD either immediately after the acquisition phase (0-6 SD) or 6h later (7-12 SD), and in corresponding undisturbed controls. Motor activity was continuously recorded with infrared sensors. All groups explored two familiar, previously encountered objects to a similar extent, both at the end of the acquisition phase and 24h later during the test phase, indicating intact familiarity detection. During the test phase 0-6 SD mice failed to discriminate between the single novel and the two familiar objects. In contrast, the 7-12 SD group and the two control groups explored the novel object significantly longer than the two familiar objects. Plasma corticosterone levels determined after SD did not differ from time-matched undisturbed controls, but were significantly below the level measured after learning alone. ACTH did not differ between the groups. Therefore, it is unlikely that stress contributed to the memory impairment. We conclude that the loss of sleep and the activities the mice engaged in during the SD, impaired recognition memory retrieval, when they occurred immediately after acquisition. The delayed SD enabled memory consolidation during the 6h when the mice were allowed to sleep, and had no detrimental effect on memory. Neither SD schedule impaired object familiarity processing, suggesting that only specific cognitive abilities were sensitive to the intervention. Sleep may either actively promote memory formation, or alternatively, sleep may provide optimal conditions of non-interference for consolidation.     

Inter- and intra-group variability in perceptions of behavior among Asian Americans and European Americans

Between-group and within-group differences in perceptions of behavior were examined among 74 Asian Americans and 111 European Americans. Participants rated videotaped interactions of Asian American mothers and daughters. Asian Americans, and a more homogeneous sample of Chinese Americans, perceived less maternal control and more reciprocity than did European Americans. Intra-cultural variations in perceptions were also evident, as within-group analyses revealed differences in perceptions based on the generational status of Asian Americans and the degree of multicultural experience of European Americans. Overall, findings suggest that perceptions of behavior are shaped as much by within-group differences in familiarity and experience with the target culture as by between-group differences in ethnicity. Implications for theories of child socialization, multicultural counseling, and observational research are discussed.     

Do humans and baboons use the same information when categorizing human and baboon faces?

What information is used for sorting pictures of complex stimuli into categories? We applied a reverse correlation method to reveal the visual features mediating categorization in humans and baboons. Two baboons and 6 humans were trained to sort, by species, pictures of human and baboon faces on which random visual noise was superimposed. On ambiguous probe trials, a human-baboon morph was presented, eliciting "human" responses on some trials and "baboon" responses on others. The difference between the noise patterns that induced the two responses made explicit the information mediating the classification. Unlike the humans, the baboons based their categorization on information that closely matched that used by a theoretical observer responding solely on the basis of the pixel similarities between the probe and training images. We show that the classification-image technique and principal components analysis provide a method to make explicit the differences in the information mediating categorization in humans and animals.     

The singularity of being: Lacan and the immortal within

Drawing on the work of Eric Santner, Slavoj ?i?ek, and Alenka Zupan?i?, this paper constructs a theory of subjective singularity from a Lacanian perspective. It argues that, unlike the "subject" (who comes into existence as a result of symbolic prohibition), or the "person" (who is aligned with the narcissistic conceits of the imaginary), the singular self emerges in response to a galvanizing directive arising from the real. This directive summons the individual to a "character" beyond his or her social and intersubjective investments. Consequently, singularity expresses the individual's nonnegotiable distinctiveness, eccentricity, or idiosyncrasy at the same time as it prevents both symbolic and imaginary closure. It opens to layers of rebelliousness that indicate that there are components of human life that exceed the realm of normative sociality. Indeed, insofar as singularity articulates something about the "undead" pulse of jouissance, it connects the individual to a paradoxical kind of immortality. This does not mean that the individual will not die, but rather that he or she is capable of "transcendent" experiences, such as heightened states of creativity, that (always momentarily) reach "outside" the parameters of mortal life. Such experiences allow the individual to feel "real" in ways that fend off symbolic abduction and psychic death.     

Symbolic and nonsymbolic number comparison in children with and without dyscalculia

Developmental dyscalculia (DD) is a pervasive difficulty affecting number processing and arithmetic. It is encountered in around 6% of school-aged children. While previous studies have mainly focused on general cognitive functions, the present paper aims to further investigate the hypothesis of a specific numerical deficit in dyscalculia. The performance of 10- and 11-year-old children with DD characterised by a weakness in arithmetic facts retrieval and age-matched control children was compared on various number comparison tasks. Participants were asked to compare a quantity presented in either a symbolic (Arabic numerals, number words, canonical dots patterns) or a nonsymbolic format (noncanonical dots patterns, and random sticks patterns) to the reference quantity 5. DD children showed a greater numerical distance effect than control children, irrespective of the number format. This favours a deficit in the specialised cognitive system underlying the processing of number magnitude in children with DD. Results are discussed in terms of access and representation deficit hypotheses.