Septal driving of the hippocampal theta rhythm produces a long-term, proactive and non-associative increase in resistance to extinction

Previous experiments employing electrical or pharmacological induction, or instrumental reinforcement, of hippocampal theta rhythm in rats have reported subsequent performance changes in a number of learning situations. In all these studies theta induction took place either concurrent with or following the behaviour under investigation. In the present two experiments, a treatment phase of electrically-induced hippocampal theta (by septal stimulation at 7·7 Hz) preceded acquisition of a discrete trial, barpress response on a fixed ratio 5 reinforcement schedule. In one of three treatment conditions animals received electrical stimulation (1) on its own, or (2) in a classical conditioning relationship with food delivery as unconditioned stimulus, or (3) temporally uncorrelated with food delivery; controls were implanted with electrodes but not stimulated. After 15 days' acquisition of barpressing, all animals were extinguished over the subsequent 12 days. Results indicated that theta-driving stimulation, independent of any association with food, resulted in increased resistance to extinction of barpressing. In addition, conditions (1) and (3) enhanced the speed of response during early acquisition. These findings cast doubt on a “memory consolidation” hypothesis of hippocampal theta function and demonstrate a non-associative, long-lasting, proactive effect of theta induction on behaviour.     

Few Preschool Boys and Girls with ADHD are Well-Adjusted During Adolescence

To estimate the prevalence of being well-adjusted in adolescence, boys and girls with (n = 96) and without (n = 126) attention-deficit/hyperactivity disorder (ADHD) were assessed seven times in eight years starting when they were 4–6 years of age. Symptoms of ADHD, ODD/CD, and depression/anxiety in addition to social skills and social preference were gathered using multiple methods and informants. Being well-adjusted was defined by surpassing thresholds in at least four of the five domains. At the 7- and 8-year follow-up, when youth were 11–14 years old, probands were significantly less likely to be well-adjusted relative to age- and ethnicity-matched control children. Only a minority of children with ADHD was well-adjusted in adolescence when emotional, behavioral, and social domains were considered simultaneously. Even when their ADHD symptoms improved over time, most probands exhibited significant impairment 7–8 years after their initial assessment.     

Academic Achievement Over 8 Years Among Children Who Met Modified Criteria for Attention-deficit/Hyperactivity Disorder at 4–6 Years of Age

The predictive validity of symptom criteria for different subtypes of ADHD among children who were impaired in at least one setting in early childhood was examined. Academic achievement was assessed seven times over 8 years in 125 children who met symptom criteria for ADHD at 4–6 years of age and in 130 demographically-matched non-referred comparison children. When intelligence and other confounds were controlled, children who met modified criteria for the predominantly inattentive subtype of ADHD in wave 1 had lower reading, spelling, and mathematics scores over time than both comparison children and children who met modified criteria for the other subtypes of ADHD. In some analyses, children who met modified criteria for the combined type had somewhat lower mathematics scores than comparison children. The robust academic deficits relative to intelligence in the inattentive group in this age range suggest either that inattention results in academic underachievement or that some children in the inattentive group have learning disabilities that cause secondary symptoms of inattention. Unexpectedly, wave 1 internalizing (anxiety and depression) symptoms independently predicted deficits in academic achievement controlling ADHD, intelligence, and other predictors.     

The Moderating Effect of Cognitive Flexibility in the Relationship Between Work Stress and Psychological Symptoms in Korean Air Force Pilots

Stress is closely associated with not only physical illness but also with indices of psychological maladjustment. However, such negative mental health outcomes may vary depending on the individual’s cognitive style, or perception of stress. Air force pilots are particularly vulnerable to experience a high degree of stress as they are required to conduct missions while simultaneously monitoring for safety in complex and uncertain flight situations. It can thus be posited that appropriate use of cognitive stress management strategies is one of the crucial competency requirements for pilots. As such, the present study examined the effects of stress on psychological symptoms of Korean Air Force pilots and further investigated the moderating role of cognitive flexibility in this relationship. A total of 192 air force pilots participated in the present study. The results indicated that degree of stress was positively correlated with indices of psychological maladjustment, while cognitive flexibility was negatively associated with psychological symptoms. Furthermore, cognitive flexibility demonstrated a significant moderating effect on the relationship between stress and psychological symptoms. Such results suggest that cognitive flexibility may serve as a protective factor in the potential effects of stress on psychological adjustment. Implications and suggestions for future research are discussed.     

The nature of correlation perception in scatterplots

For scatterplots with gaussian distributions of dots, the perception of Pearson correlation r can be described by two simple laws: a linear one for discrimination, and a logarithmic one for perceived magnitude (Rensink & Baldridge, 2010). The underlying perceptual mechanisms, however, remain poorly understood. To cast light on these, four different distributions of datapoints were examined. The first had 100 points with equal variance in both dimensions. Consistent with earlier results, just noticeable difference (JND) was a linear function of the distance away from r = 1, and the magnitude of perceived correlation a logarithmic function of this quantity. In addition, these laws were linked, with the intercept of the JND line being the inverse of the bias in perceived magnitude. Three other conditions were also examined: a dot cloud with 25 points, a horizontal compression of the cloud, and a cloud with a uniform distribution of dots. Performance was found to be similar in all conditions. The generality and form of these laws suggest that what underlies correlation perception is not a geometric structure such as the shape of the dot cloud, but the shape of the probability distribution of the dots, likely inferred via a form of ensemble coding. It is suggested that this reflects the ability of observers to perceive the information entropy in an image, with this quantity used as a proxy for Pearson correlation.