Working memory deficits, increased anxiety-like traits, and seizure susceptibility in BDNF overexpressing mice

BDNF regulates components of cognitive processes and has been implicated in psychiatric disorders. Here we report that genetic overexpression of the BDNF mature isoform (BDNF-tg) in female mice impaired working memory functions while sparing components of fear conditioning. BDNF-tg mice also displayed reduced breeding efficiency, higher anxiety-like scores, high self-grooming, impaired prepulse inhibition, and higher susceptibility to seizures when placed in a new empty cage, as compared with wild-type (WT) littermate controls. Control measures of general health, locomotor activity, motor coordination, depression-related behaviors, and sociability did not differ between genotypes. The present findings, indicating detrimental effects of life-long increased BDNF in mice, may inform human studies evaluating the role of BDNF functional genetic variations on cognitive abilities and vulnerability to psychiatric disorders.     

Plasticity associated with escalated operant ethanol self-administration during acute withdrawal in ethanol-dependent rats requires intact matrix metalloproteinase systems

Repeated cycles of ethanol intoxication and withdrawal associated with dependence induce neuroadaptations in a variety of brain systems. Withdrawal-induced negative emotional states can be ameliorated by ethanol consumption; a learned process termed negative reinforcement. Accordingly, a dependence-induced phenotype is escalated ethanol self-administration. Matrix metalloproteinases (MMPs) are proteolytic enzymes which degrade the extracellular matrix to allow for synaptic reorganization and plasticity. To test the hypothesis that an intact MMP system is required for animals to learn about the negative reinforcing effects of ethanol and display escalated self-administration during acute withdrawal when ethanol-dependent, male Wistar rats were trained to self-administer ethanol and then assigned to either acute or chronic MMP inhibition treatment groups. The chronic treatment group received intracerebroventricular (ICV) infusions of the broad spectrum MMP inhibitor FN-439 or artificial cerebrospinal fluid (aCSF) via osmotic minipumps during a 1 month ethanol dependence induction period and subsequent post-dependence induction self-administration sessions that occurred during acute withdrawal. The acute treatment group only received ICV FN-439 or aCSF on the day of self-administration sessions following dependence induction during acute withdrawal. The results showed that inhibition of MMPs attenuated escalated ethanol self-administration following chronic and acute exposure conditions. Furthermore, once learning (i.e., plasticity) had occurred, MMP inhibition had no impact on escalated response patterns and animals previously subjected to MMP inhibition that did not escalate evidenced normal escalations in operant ethanol self-administration once FN-439 treatments were terminated. Thus, the present data identified that an intact MMP system is required for the escalated responding that occurs during acute withdrawal in dependent animals and implicate such escalation as a learned response.     

Pre-K attendance and social development: The moderating role of kindergarten classroom experiences

Many studies have established that there are important life-long benefits of attending pre-K. At the same time, recent research suggests that pre-K attenders may enter and exit kindergarten exhibiting less optimal social and learning behaviours than their non-attending peers, and little attention has been paid to what factors may contribute to these patterns of development after children enter kindergarten. The current study will address these gaps in knowledge using nationally representative data from the Early Childhood Longitudinal Study Kindergarten Class of 2011 to examine the social and learning behaviours of pre-K attenders and nonattenders at kindergarten entry and exit. Moreover, we will determine the extent to which children's social and behavioural skills change at differential rates across the kindergarten year as a function of pre-K attendance and their kindergarten classroom experiences, with a focus on the academic rigour, activity settings and teacher-student relationships.     

Online mental health treatment: concerns and considerations.

Concerns and considerations have emerged as mental health professionals contemplate the provision of mental health treatment over the Internet. This paper identifies perceptions of online mental health treatment among a national sample of 2,098 social workers, psychologists, and other professionals. These professionals were unlikely to provide online mental health treatment, although some used the Internet as an adjunct to clinical practice. They noted specific concerns related to the provision of mental health treatment online, including confidentiality of client information and liability issues. We explore these issues and discuss implications for professionals who provide mental health treatment.     

Persistent structural priming from language comprehension to language production

To examine the relationship between syntactic processes in language comprehension and language production, we compared structural persistence from sentence primes that speakers heard to persistence from primes that speakers produced. [Bock, J. K., & Griffin, Z. M. (2000). The persistence of structural priming: transient activation or implicit learning? Journal of Experimental Psychology: General, 129, 177-192.] showed that the production of target priming structures increased the probability of spontaneously using the same structures to describe events in subsequent pictures that were semantically unrelated to the primes. These priming effects persisted across as many as ten intervening filler trials. The present studies replicated these results using auditorily presented primes to which participants only listened. The results indicated persistence of priming across all lags, with relative magnitudes of priming as large as those observed by Bock and Griffin. The implication is that structural priming is persistent regardless of the modality in which language structures are experienced, underscoring the power of priming as an implicit learning mechanism.     

A metric for the cognitive map: found at last?

A network of brain areas collectively represent location, but the underlying nature of this "cognitive map" has remained elusive. A recent study reports that the activity patterns of some entorhinal cortical neurons form a remarkably regular array of evenly spaced peaks across the surface of the environment. These "grid cells" might be the basis of a metric used for calculating position, and their discovery could greatly advance our understanding of how navigational computations are performed.     

Birthweight-discordance and differences in early parenting relate to monozygotic twin differences in behaviour problems and academic achievement at age 7

This longitudinal monozygotic (MZ) twin differences study explored associations between birthweight and early family environment and teacher-rated behaviour problems and academic achievement at age 7. MZ differences in anxiety, hyperactivity, conduct problems, peer problems and academic achievement correlated significantly with MZ differences in birthweight and early family environment, showing effect sizes of up to 2%. As predicted by earlier research, associations increased at the extremes of discordance, even in a longitudinal, cross-rater design, with effect sizes reaching as high as 12%. As with previous research some of these non-shared environmental (NSE) relationships appeared to operate partly as a function of SES, family chaos and maternal depression. Higher-risk families generally showed stronger negative associations.     

Predictors of Premature Match Closure in Youth Mentoring Relationships

Although mentoring is a popular and effective means of intervention with youth, the positive effects of mentoring can be diminished by premature match closure of relationships. Program, mentor, and mentee characteristics were examined as predictors of premature match closure. Secondary data analyses were conducted on a large national database of mentoring programs consisting of match and youth risk information from 170 mentoring programs and 6468 matches from across the U.S. Premature closure was associated with mentee age at match inception and 19 individual mentee characteristics. The set of mentee characteristics were examined as part of a cumulative risk index encompassing seven conceptually combined categories including family background characteristics, school functioning problems, engagement in risky health behaviors, self‐regulation difficulties, engagement in illegal or criminal activities, and internalizing and externalizing behavior problems. Both the age of mentees when matched and the cumulative risk index score significantly predicted premature closure. Results are discussed in terms of directions for future research and suggestions for enhancing mentoring program practices.