Acetylcholine modulation of neural systems involved in learning and memory

Extensive evidence supports the view that cholinergic mechanisms modulate learning and memory formation. This paper reviews evidence for cholinergic regulation of multiple memory systems, noting that manipulations of cholinergic functions in many neural systems can enhance or impair memory for tasks generally associated with those neural systems. While parallel memory systems can be identified by combining lesions with carefully crafted tasks, most—if not all—tasks require the combinatorial participation of multiple neural systems. This paper offers the hypothesis that the magnitude of acetylcholine (ACh) release in different neural systems may regulate the relative contributions of these systems to learning. Recent studies of ACh release, obtained with in vivo microdialysis samples during training, together with direct injections of cholinergic drugs into different neural systems, provide evidence that release of ACh is important in engaging these systems during learning, and that the extent to which the systems are engaged is associated with individual differences in learning and memory.     

Adolescents' emotion expectancies regarding aggressive and nonaggressive events: connections with behavior problems

A total of 50 behaviorally disruptive (conduct-disordered or oppositional defiant-disordered) adolescents and 50 comparison adolescents assessed how they expected to feel following both aggressive and nonaggressive situations. Compared with their peers, behaviorally disruptive adolescents expected fewer normative emotions and exhibited somewhat more of an anger emphasis in their nonaggressive emotion attributions, and they expected to feel happier following acts of instrumental/proactive aggression. These patterns of emotion expectancies were linked more closely with teacher ratings of adolescents' proactive aggression than with ratings of reactive aggression. Regression analyses indicated that both nonaggression emotion expectancies and proactive aggression happiness made independent contributions to predicting adolescents' externalizing tendencies. Discussion focused on the contributions of different types of self-attributed emotion expectancies to adolescents' social understanding and behavior.     

Three stress groups on their stressors and reactions to stressors in five studies

A comparison of means and SDs for responses from three stress groups on the Student-life Stress Inventory in five studies over 13 years.     

Who chooses a pSTEM academic major? Using social psychology to predict selection and persistence over the freshman year

Many social psychological variables, in addition to knowledge-based factors such as academic preparedness, have been investigated individually as sources of the persistent gender gap in pSTEM (physical science, technology, engineering, and mathematics) fields. The present work tested all of these factors simultaneously and longitudinally, in a sample drawn from an incoming freshman class measured at three timepoints over the course of their first year. One thousand nine hundred and twenty-nine students completed a survey with items assessing eleven social psychological constructs and were asked for permission to obtain institutional data regarding their academic preparedness and choice of academic major before matriculation, after the first semester, and at the end of freshman year. These social psychological and academic variables were used to predict pSTEM major status. Across multiple timepoints, and over and above academic preparedness, greater Math and Science Self-Efficacy, rejection of the stereotype that scientist careers are unsociable in nature, having a pSTEM role model in high school, and lower endorsement of communal goals were consistently related to the selection of a pSTEM major. Students who endorsed entity theories of math and science abilities were also less likely to select a pSTEM over life and social sciences major. As a set, the factors accounted for roughly half of the gender difference in pSTEM major selection. Interventions aimed at reducing the gender gap in pSTEM major selection might do well to focus on these more psychological factors as well as academic ones.     

The neural circuitry supporting goal maintenance during cognitive control: a comparison of expectancy AX-CPT and dot probe expectancy paradigms

Goal maintenance is an aspect of cognitive control that has been identified as critical for understanding psychopathology according to criteria of the NIMH-sponsored CNTRICS (Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia) and Research Domain Criteria (RDoC) initiatives. CNTRICS proposed the expectancy AX-CPT, and its visual-spatial parallel the dot probe expectancy (DPX), as valid measures of the cognitive and neural processes thought to be relevant for goal maintenance. The goal of this study was to specifically examine the functional neural correlates and connectivity patterns of both goal maintenance tasks in the same subset of subjects to further validate their neural construct validity and clarify our understanding of the nature and function of the neural circuitry engaged by the tasks. Twenty-six healthy control subjects performed both the letter (AX) and dot pattern (DPX) variants of the CPT during fMRI. Behavioral performance was similar between tasks. The 2 tasks engaged the same brain networks including dorsolateral prefrontal cortex (DLPFC) and dorsal parietal regions, supporting their validity as complementary measures of the goal maintenance construct. Interestingly there was greater engagement of the frontal opercular insula region during the expectancy AX-CPT (letter) and greater functional connectivity between the PFC and medial temporal lobe in the DPX (dot pattern). These differences are consistent with differential recruitment of phonological and visual-spatial processes by the two tasks and suggest that additional long-term memory systems may be engaged by the dot probe version.     

Enhanced release of norepinephrine in rat hippocampus during spontaneous alternation tests

Recent evidence suggests that release of acetylcholine (ACh) in the hippocampus is associated with performance on a spontaneous alternation task and with enhancement of that performance by systemic and central injections of glucose. The present study extended these findings by examining norepinephrine (NE) release in the hippocampus using in vivo microdialysis while rats were tested for spontaneous alternation performance with and without prior injections (ip) of glucose. Microdialysis samples were collected every 12 min and assayed for NE content by HPLC-ECD. Like ACh, NE release in hippocampus increased during spontaneous alternation testing. As in past experiments, administration of glucose (250 mg/kg) significantly enhanced alternation scores. However, glucose did not influence NE release either during behavioral testing or at rest. These findings contrast with prior evidence showing that glucose augments testing-related increases in ACh release. The findings suggest that norepinephrine is released within the hippocampus while rats are engaged in alternation performance. However, increased release of norepinephrine apparently does not contribute to the enhancement of alternation scores produced by glucose.