Exposure to repetitive tasks induces motor changes related to skill acquisition and inflammation in rats

The authors elucidate exposure-response relationships between repetitive tasks, inflammation, and motor changes with work-related musculoskeletal disorders. Using a rat model of reaching and handle pulling, they examined effects of performing a high-repetition, low-force (HRLF); low-repetition, high-force (LRHF); or high-repetition, high-force (HRHF) task (2 hr/day, 3 days/week, 12 weeks) on reach rate and force, percentage of successful reaches, duration of participation, and grip strength. Reach rate and reach force improved with HRLF, and percentage success increased in all groups in Week 9, and in HRLF and HRHF in Week 12, indicative of skill acquisition. Duration and grip strength showed force-dependent declines with task performance. A subset of HRHF rats received ibuprofen in Weeks 5-12. Ibuprofen significantly improved reach rate, reach force, and duration in treated rats, indicative of an inflammatory influence on reach performance. Ibuprofen improved percentage of successful reaches in Week 9, although this increase was not sustained. However, declines in grip strength, a nocifensive behavior, were not prevented by ibuprofen. Examination of cervical spinal cords of untreated and ibuprofen treated HRHF rats showed increased IL-1beta, an inflammatory cytokine, in neurons. These findings suggest that only a preventive intervention could have addressed all motor declines.     

Potentiation in young infants: The origin of the prior knowledge effect?

In two experiments with 6-month-old infants, we found that prior learning of an operant task (remembered for 2 weeks) mediated new learning of a modeling event (remembered for only 1 day) and increased its recall. Infants first learned to associate lever pressing with moving a toy train housed in a large box. One or 2 weeks later, three target actions were modeled on a hand puppet while the train box (a retrieval cue) was in view. Merely retrieving the train memory strengthened it, and simultaneously pairing its retrieved memory with the modeled actions potentiated their learning and recall. When paired 1 week later, deferred imitation increased from 1 day to 4 weeks; when paired 2 weeks later, it increased from 1 day to 6 weeks. The striking parallels between potentiated learning in infants and the prior knowledge effect in adults suggests that the prior knowledge effect originates in early infancy.     

Social Discounting and Externalizing Behavior Problems in Boys

Social discounting refers to the fact that most people assign more value to the welfare of close affiliates than they do to the welfare of distant affiliates—they discount the latter compared to the former. We report the first study to apply a social discounting paradigm to boys. We were particularly interested in investigating the relations between social discounting, age, and externalizing behavior problems (antisocial behavior). Results showed that (1) preadolescent boys were more likely than adolescent boys to show atypical response patterns in allocating rewards to affiliates; (2) task behavior was well represented as social discounting once boys with atypical response patterns were deleted from the sample, and (3) boys functioning in the clinical range on indices of externalizing behavior problems demonstrated steeper social discounting compared to controls. We conclude that social discounting as a measure of perceived social closeness is feasible for use in adolescent samples. Social discounting may operate similarly to other forms of discounting in impulsive individuals. Copyright © 2011 John Wiley & Sons, Ltd.     

BRIEF REPORT Set‐shifting and sensitivity to reward: A possible dopamine mechanism for explaining disinhibitory disorders

The objective of this study was to investigate personality correlates of set‐shifting behaviour using a task sensitive to dopaminergic activity. As expected, set‐shifting behaviour was positively correlated with scores on the Sensitivity to Reward scale, a measure of Gray's impulsivity. Discussion is focused on the relationship between this greater ability for set‐shifting and the proneness to disinhibition.     

A Study of the Use and Interpretation of Standardized Suicide Risk Assessment: Measures within a Psychiatrically Hospitalized Correctional Population

The reliability, validity, and utility of the Adult Suicidal Ideation Questionnaire (ASIQ), Beck Hopelessness Scale (BHS), Beck Scale for Suicide Ideation (BSS), and Reasons for Attempting Suicide Questionnaire (RASQ) with correctional mental health populations was evaluated. Evidence was found indicating good to excellent reliability for all measures. Each of the measures significantly differentiated multiple attempters from single attempters and nonattempters, providing evidence of convergent and divergent validity. Logistic regression and receiver operating characteristic analyses revealed strong associations between multiple attempts and the ASIQ, BSS, and RASQ, but not the BHS. Implications for suicide risk assessment processes in correctional settings are discussed.     

Infant imitation from television using novel touch screen technology

Infants learn less from a televised demonstration than from a live demonstration, the video deficit effect. The present study employs a novel approach, using touch screen technology to examine 15‐month olds' transfer of learning. Infants were randomly assigned either to within‐dimension (2D/2D or 3D/3D) or cross‐dimension (3D/2D or 2D/3D) conditions. For the within‐dimension conditions, an experimenter demonstrated an action by pushing a virtual button on a 2D screen or a real button on a 3D object. Infants were then given the opportunity to imitate using the same screen or object. For the 3D/2D condition, an experimenter demonstrated the action on the 3D object, and infants were given the opportunity to reproduce the action on a 2D touch screen (and vice versa for the 2D/3D condition). Infants produced significantly fewer target actions in the cross‐dimension conditions than in the within‐dimension conditions. These findings have important implications for infants' understanding and learning from 2D images and for their using 2D media as the basis of actions in the real world.