Conceptual and perceptual similarity between encoding and retrieval contexts and recognition memory context effects in older and younger adults

We examined the hypothesis that older adults' deficits in contextual memory result from difficulties in contending with partial encoding-to-retrieval changes in the context. We measured effects of contextual change and constancy on recognition memory for words, in older and younger adults. We assessed the ability to adjust to partial contextual changes by manipulating encoding-retrieval context similarity: identical, new and unrelated, conceptually similar, or perceptually similar. For both older and younger adults, identical and conceptually similar contexts benefited recognition of target words, whereas perceptually similar contexts did not. Older adults did not make more false alarms. In contrast, older adults' direct recognition of contextual stimuli was at chance. These results indicate that retrieval processes, rather than encoding or rigidity in the use of contextual cues, are implicated in older adults' difficulties in memory for contextual information.     

Concurrent validity of the Neurobehavioural Assessment for Pre-term Infants (NAPI) at term age

Background: Accurate measurement of neonatal neurological integrity is critical for early identification of pre-term and full-term infants at-risk for developmental disability. The Neurobehavioural Assessment for Pre-term Infants (NAPI) was developed to measure the progression of neurobehavioural development in pre-term infants born between 32 weeks post-conceptional age (PCA) and term. This instrument has many unique advantages; however, criterion validity is unknown and results are subsequently difficult to interpret. Objectives: This study examined the concurrent validity of the NAPI against a criterion instrument, the Einstein Neonatal Neurobehavioural Assessment Scale (ENNAS), which measures similar constructs and has demonstrated excellent reliability and validity. Methods: A sample of 41 pre-term and full-term infants (40?±?2 weeks) was assessed with the NAPI and ENNAS on the same day. Results: The findings demonstrated that correlations between similar NAPI clusters and ENNAS clusters ranged from 0.35–0.65 and correlations between many similar individual NAPI and ENNAS items ranged from 0.40–0.60. Two NAPI clusters also discriminated between normal, abnormal and suspect performance on the ENNAS. Conclusion: The NAPI has many unique advantages as a tool. It examines neonates serially, has established weekly normative data and requires minimal infant handling. This study provides new validation of the NAPI instrument.     

Dopaminergic Influences on Emotional Decision Making in Euthymic Bipolar Patients

We recently reported that the D2/D3 agonist pramipexole may have pro-cognitive effects in euthymic patients with bipolar disorder (BPD); however, the emergence of impulse-control disorders has been documented in Parkinson''s disease (PD) after pramipexole treatment. Performance on reward-based tasks is altered in healthy subjects after a single dose of pramipexole, but its potential to induce abnormalities in BPD patients is unknown. We assessed reward-dependent decision making in euthymic BPD patients pre- and post 8 weeks of treatment with pramipexole or placebo by using the Iowa Gambling Task (IGT). The IGT requires subjects to choose among four card decks (two risky and two conservative) and is designed to promote learning to make advantageous (conservative) choices over time. Thirty-four BPD patients completed both assessments (18 placebo and 16 pramipexole). Baseline performance did not differ by treatment group (F=0.63; p=0.64); however, at week 8, BPD patients on pramipexole demonstrated a significantly greater tendency to make increasingly high-risk, high-reward choices across the five blocks, whereas the placebo group''s pattern was similar to that reported in healthy individuals (treatment × time × block interaction, p<0.05). Analyses of choice strategy using the expectancy valence model revealed that after 8 weeks on pramipexole, BPD patients attended more readily to feedback related to gains than to losses, which could explain the impaired learning. There were no significant changes in mood symptoms over the 8 weeks, and no increased propensity toward manic-like behaviors were reported. Our results suggest that the enhancement of dopaminergic activity influences risk-associated decision-making performance in euthymic BPD. The clinical implications remain unknown.