Instrumental learning and cognitive flexibility processes are impaired in children exposed to early life stress

Children who experience severe early life stress show persistent deficits in many aspects of cognitive and social adaptation. Early stress might be associated with these broad changes in functioning because it impairs general learning mechanisms. To explore this possibility, we examined whether individuals who experienced abusive caregiving in childhood had difficulties with instrumental learning and/or cognitive flexibility as adolescents. Fifty‐three 14–17‐year‐old adolescents (31 exposed to high levels of childhood stress, 22 control) completed an fMRI task that required them to first learn associations in the environment and then update those pairings. Adolescents with histories of early life stress eventually learned to pair stimuli with both positive and negative outcomes, but did so more slowly than their peers. Furthermore, these stress‐exposed adolescents showed markedly impaired cognitive flexibility; they were less able than their peers to update those pairings when the contingencies changed. These learning problems were reflected in abnormal activity in learning‐ and attention‐related brain circuitry. Both altered patterns of learning and neural activation were associated with the severity of lifetime stress that the adolescents had experienced. Taken together, the results of this experiment suggest that basic learning processes are impaired in adolescents exposed to early life stress. These general learning mechanisms may help explain the emergence of social problems observed in these individuals.     

Extinction of appetitive learning is disrupted by cycloheximide and propranolol in the sand maze in rats

The present study investigated whether memory for extinction in an appetitive task (the sand maze) could be attenuated by administration of cycloheximide (protein synthesis inhibitor) or propranolol (β-adrenergic receptor antagonist). Ninety-day-old male Long-Evans rats were trained to retrieve a sweet cereal reinforcer from an open container in the sand maze. One day following this non-spatial training, rats received three extinction trials in which they were placed in the maze with the reinforcer present, but unattainable. Thirty minutes prior to the first extinction trial, rats received an intraperitoneal injection of cycloheximide (1mg/kg), propranolol (25mg/kg), or vehicle (1mg/kg distilled water). Twenty-four hours later, rats were tested in the sand maze with the reinforcer again available. Results from the test trial showed that both cycloheximide and propranolol groups found the reinforcer more quickly than controls. Two weeks later, rats were trained on a spatial version of the sand maze in which they had to search for a buried reinforcer using extramaze cues. Cycloheximide and propranolol groups learned this task significantly faster than the control group, demonstrating the long-lasting effect of cycloheximide and propranolol on the blocking of memory for extinction.     

NICHD research initiative in newborn screening

Recent changes in genetics research have created new opportunities to improve the scope and quality of newborn screening services. Changes in newborn screening should be supported and directed by an organized program of research. The NICHD Research Initiative in Newborn Screening includes the development of systematic methods to identify additional conditions appropriate for newborn screening; development and testing innovative interventions and treatments to improve outcomes; education of the provider workforce; development and implementation of appropriate information and communication systems for parents and providers; and, sponsoring an ongoing program of research and research training. Future needs will include the development of a national translational research infrastructure, prevention research and research into behavioral and social sciences issues. The NICHD Research Initiative in Newborn Screening is expected to be an ongoing and vital initiative that adapts itself to new scientific findings, technological developments, changes in the public and personal health care system, and our evolving understanding of the needs of affected individuals, families and the community.     

A New Representation Theorem for Contranegative Deontic Logic

The logic of an ought operator O is contranegative with respect to an underlying preference relation if it satisfies the property Op & (¬p)(¬q) Oq. Here the condition that is interpolative ((p (pq) q) (q (pq) p)) is shown to be necessary and sufficient for all -contranegative preference relations to satisfy the plausible deontic postulates agglomeration (Op & OqO(p&q)) and disjunctive division (O(p&q) Op Oq).     

Interactions among chronic cold, corticosterone and puberty on energy intake and deposition

We have shown that chronic cold stress strongly interacts with corticosterone (B) to determine subsequent regulation of the hypothalamo-pituitary-adrenal (HPA) axis responses to novel stress. These studies, using the same 2 sets of rats, show that chronic cold also interacts with B and testosterone on signals of energy balance. The two groups of rats differed in weight by 20% and in age by 2 weeks (44-59 days of age). Adrenalectomized rats, replaced with varying doses of B, were exposed to cold or served as controls. Food intake and body weight during the experiments and hormones, metabolites and fat depots were measured on day 5. B, but not cold, affected food intake in the younger rats; by contrast, cold, but not B, affected food intake in the older rats. Testosterone was higher in older control rats and was markedly depressed by cold; younger rats had lower testosterone that was minimally affected by cold. Weight gain decreased in all rats at room temperature with increasing B, whereas they all lost weight in cold independently of B. Cold stimulated and B inhibited interscapular brown adipose tissue DNA content (reflecting sympathetic stimulation of thermogenesis). B stimulated insulin, whereas cold inhibited leptin and insulin; B also increased white adipose tissue weight gain in controls and inhibited its loss in cold. Leptin was unrelated to white adipose tissue depots in older control rats but was strongly related to these stores in younger rats and in all rats in cold. We conclude that: 1. By decreasing signals that act centrally to inhibit food intake (insulin, leptin and testosterone) cold allows B to stimulate food intake; 2. B inhibits weight gain although it causes accrual of fat; 3. Cold, probably through sympathetic stimulation of white adipose tissue, causes fat loss which is modulated by the inhibitory effect of B on sympathetic outflow; and, 4. The slope of the relationship between fat depot size and leptin becomes flatter in cold, possibly because of increased sympathetic outflow to these depots.     

Ray on Tarski on Logical Consequence

In Logical consequence: A defense of Tarski (Journal of Philosophical Logic, vol. 25, 1996, pp. 617–677), Greg Ray defends Tarski"s account of logical consequence against the criticisms of John Etchemendy. While Ray"s defense of Tarski is largely successful, his attempt to give a general proof that Tarskian consequence preserves truth fails. Analysis of this failure shows that de facto truth preservation is a very weak criterion of adequacy for a theory of logical consequence and should be replaced by a stronger absence-of-counterexamples criterion. It is argued that the latter criterion reflects the modal character of our intuitive concept of logical consequence, and it is shown that Tarskian consequence can be proved to satisfy this criterion for certain choices of logical constants. Finally, an apparent inconsistency in Ray"s interpretation of Tarski"s position on the modal status of the consequence relation is noted.     

Cultural Similarity, Foreign Policy Actions, and Regime Perception: An Experimental Study of International Cues and Democratic Peace

This study examines previous explanations of democratic peace in light of sociocultural factors and foreign policy actions that influence public perceptions of another country. Two experiments assessed the effects of relevant sociocultural and foreign policy action cues on perception of the regime type of a target nation and on public approval of the use of force. The findings suggest that sociocultural cues affect regime perception. Moreover, perceived similarity of a target nation and foreign policy actions are significant determinants of the public approval of the use of force in addition to perceptions of regime type.     

Correlations of glucose metabolism and structural damage to language function in aphasia

Studies of aphasic patients using [18F]fluorodeoxyglucose positron computed tomographs have shown areas of metabolic depression in the left hemisphere larger than the area of infarction noted on CT. To evaluate these metabolic differences in relationship to language abnormalities, 11 patients had metabolic scans, CT, and were administered the Boston Diagnostic Aphasia Battery and the Porch Index of Communicative Ability. Correlation analyses were computed between metabolic, CT, and language data. CT demonstrated reliable correlations of speaking, oral reading, and repetition to Wernicke' area, consistent with current anatomic language models, while metabolic data from areas posterior, inferior, and superior to the traditional Wernicke's area and the head of the caudate nucleus also had reliable correlations with aphasic language function. The utilization of both structural and metabolic brain measures may improve our understanding of the anatomy of language as related to aphasia.     

A shortened version of the Southern Illinois university speech situation checklist for the identification of speech-related anxiety

This study investigated the ability of the 51-item Southern Illinois University Speech Situation Checklist (SSC) to differentiate stutterers known to have high levels of speech-related anxiety from nonstutterers with normal levels of speech- related anxiety. Checklist responses of 65 randomly selected subjects (33 stutterers and 32 nonstutterers) were subjected to a stepwise discriminant analysis. The analysis identified a combination of 21 SSC items that had significant discriminative power. Subsequently, the derived discriminant equation achieved 93% accuracy in correctly classifying a hold-out sample of 29 subjects (14 stutterers and 15 nonstutterers). These results strongly suggest that the 21 items of the SSC identified by discriminant analysis may provide an effective screening device for identifying disfluent speakers who experience an abnormal amount of speech-related anxiety.     

Achievement motivation for males and females as a determinant of attributions for success and failure

Male and female college students, divided according to levels of achievement motivation, were asked to do an anagram task at which their success or failure was determined by experimental manipulation of the problems they were given. Their ratings of ability, effort, task difficulty, and luck as possible causes for success or failure indicated that those with high achievement motivation of both sexes made relatively higher ratings for ability and lower ratings for task difficulty. Females tended to employ higher ratings for luck, and females with high achievement motivation made maximal use of effort as a causal factor. Theoretical implications and potential applications of these data are discussed.