Exploration in outbred mice covaries with general learning abilities irrespective of stress reactivity, emotionality, and physical attributes

Across multiple learning tasks (that place different sensory, motor, and information processing demands on the animals), we have found that the performance of mice is commonly regulated by a single factor ("general learning") that accounts for 30-40% of the variance across individuals and tasks. Furthermore, individuals' general learning abilities were highly correlated with their propensity to engage in exploration in an open field, a behavior that is potentially stress-inducing. This relationship between exploration in the open field and general learning abilities suggests the possibility that variations in stress sensitivity/responsivity or related emotional responses might directly influence individuals' general learning abilities. Here, the relationship of sensory/motor skills and stress sensitivity/emotionality to animals' general learning abilities were assessed. Outbred (CD-1) mice were tested in a battery of six learning tasks as well as 21 tests of exploratory behavior, sensory/motor function and fitness, emotionality, and stress reactivity. The performances of individual mice were correlated across six learning tasks, and the performance measures of all learning tasks loaded heavily on a single factor (principal component analysis), accounting for 32% of the variability between animals and tasks. Open field exploration and seven additional exploratory behaviors (including those exhibited in an elevated plus maze) also loaded heavily on this same factor, although general activity, sensory/motor responses, physical characteristics, and direct measures of fear did not. In a separate experiment, serum corticosterone levels of mice were elevated in response to a mild environmental stressor (confinement on an elevated platform). Stress-induced corticosterone levels were correlated with behavioral fear responses, but were unsystematically related to individuals' propensity for exploration. In total, these results suggest that although general learning abilities are strongly related to individuals' propensity for exploration, this relationship is not attributable to variations in sensory/motor function or the individuals' physiological or behavioral sensitivity to conditions that promote stress or fear.     

Brain network dysfunction in bipolar disorder

Bipolar disorder is a common psychiatric condition with significant associated morbidity and mortality. Despite its significance, the neurophysiology and neuropathology of this illness is incompletely understood. Recent advances in neuroimaging techniques have helped to begin clarifying these areas. Specifically, bipolar disorder appears to arise from abnormalities within discrete brain networks (eg, the anterior limbic network). The expression of the symptoms of bipolar disorder does not appear to result from single, localized brain lesions, but rather are emergent properties of dysfunction of these brain networks. As neuroimaging techniques continue to improve, the underlying neural basis of bipolar disorder will be clarified.     

Error-driven knowledge restructuring in categorization

Knowledge restructuring occurs when people shift to a new strategy or representation during learning. Although knowledge restructuring can frequently be experimentally encouraged, there are instances in which people resist restructuring and continue to use an expedient but imperfect initial strategy. The authors report 3 category learning experiments that reconciled those conflicting outcomes by postulating that, for restructuring to occur, learners must be dissatisfied with their knowledge and a usable alternative must be available. In line with expectation, restructuring was elicited only when an alternative strategy was pointed out and when people's initial expedient strategy entailed performance error. Neither error nor information about the alternative strategy by itself was sufficient to induce restructuring.     

Income inequality and risk of suicide in New York City neighborhoods: a multilevel case-control study

Evidence on the relationship between income inequality and suicide is inconsistent. Data from the New York City Office of the Chief Medical Examiner for all fatal injuries was collected to conduct a multilevel case-control study. In multilevel models, suicide decedents (n=374) were more likely than accident controls (n=453) to reside in neighborhoods with greater income inequality even after controlling for individual characteristics; this relation was modified by age with an effect overall and among decedents aged 15-34 but not among decedents 35-64. These data suggest that income inequality may contribute to the risk of suicide in younger adults.     

Superior performance of blind compared with sighted individuals on bimanual estimations of object size

Five preliminary experiments on sighted individuals revealed marked overestimation on an object size-estimation task using a bimanual response. These experiments ruled out the possibility that overestimation was due to the mode of visual presentation (whether two-dimensional or three-dimensional), the input modality (visual or kinesthetic), or the influence of other visual cues. The main experiment then investigated whether these distortions are due to visual experience by using a variant of the same task to test 24 blind and 24 sighted control participants. Remarkably, the sighted control participants overestimated object size, on average, but the blind participants did not. A follow-up experiment demonstrated that visual memory was the primary influence causing the size over-estimations. We conclude that blind individuals are more accurate than sighted individuals in representing the size of familiar objects because they rely on manual representations, which are less influenced by visual experience than are visual memory representations.     

A new model for sexual conditioning: the ring dove (Streptopelia risoria)

Sexual conditioning investigations have primarily used rats and domestic quail as subjects. Although much has been learned from such experiments, the relative simplicity of rat and quail reproductive behavior prohibits investigation of certain experimental questions about sexual conditioning. In contrast, the reproductive behavior of male and female ring doves (Streptopelia risoria) is complex, involving courtship, bonding, and parental care. In the present experiment, male ring doves that were presented with a visual conditioned stimulus paired with access to their pair-bonded mate (the unconditioned stimulus) showed sexual conditioned responding in the presence of the conditioned stimulus. These results represent the first evidence of sexual conditioning in ring doves and illustrate the potential of ring doves as a useful model for future sexual conditioning investigations.     

Attempts to control unwanted thoughts in the night: development of the thought control questionnaire-insomnia revised (TCQI-R)

The attempted control of intrusive, uncontrollable thoughts has been implicated in the maintenance of a range of psychological disorders. The current paper describes the refinement of the Thought Control Questionnaire Insomnia (TCQI; Behav. Cogn. Psychoth. 29 (2001)) through its administration to a sample (n=385) including good sleepers and individuals with insomnia. Several items with poor psychometric properties were discarded, resulting in a 35-item revised TCQI. Factor analysis revealed six factors; aggressive suppression, cognitive distraction, reappraisal, social avoidance, behavioural distraction, and worry. The attempted management of unwanted thoughts was compared across individuals with insomnia and good sleepers, and the impact of these strategies on sleep quality, anxiety and depression was investigated. With the exception of cognitive distraction, individuals with insomnia, relative to good sleepers, more frequently used every thought control strategy. The strategies of aggressive suppression and worry, in particular, appeared to be unhelpful, with the use of these strategies predicting sleep impairment, anxiety and depression. The strategy of cognitive distraction appeared to be helpful, with the use of this strategy predicting better sleep quality.