The role of alpha oscillations in deriving and maintaining spatial relations in working memory

Previous research has demonstrated distinct neural correlates for maintenance of abstract, relational versus concrete, sensory information in working memory (WM). Storage of spatial relations in WM results in suppression of posterior sensory regions, which suggests that sensory information is task-irrelevant when relational representations are maintained in WM. However, the neural mechanisms by which abstract representations are derived from sensory information remain unclear. Here, using electroencephalography, we investigated the role of alpha oscillations in deriving spatial relations from a sensory stimulus and maintaining them in WM. Participants encoded two locations into WM, then after an initial maintenance period, a cue indicated whether to convert the spatial information to another sensory representation or to a relational representation. Results revealed that alpha power increased over posterior electrodes when sensory information was converted to a relational representation, but not when the information was converted to another sensory representation. Further, alpha phase synchrony between posterior and frontal regions increased for relational compared to sensory trials during the maintenance period. These results demonstrate that maintaining spatial relations and locations in WM rely on distinct neural oscillatory patterns.     

Individual differences in language lateralisation,schizotypy and the remote-associate task

We tested the hypothesis that the level of reduced laterality in language is correlated with the degrees of schizotypal personality in healthy individuals and with their performance in the remote-associate task (RAT). A total of 53 healthy participants completed a schizotypal personality measure of the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE; a questionnaire measuring the level of psychotic proneness), a consonant–vowel–consonant (CVC; requiring the identification of letter trigrams presented tachistoscopically in the left/right visual fields or both), measuring reduced language laterality and a remote-associate task (RAT; requiring to report a word, weakly associated with three cue words). Analysis revealed correlations between CVC and O-LIFE, as well as between CVC and RAT performance. The results suggest that reduced language lateralisation (reduced hemispheric integration) may play a role in schizophrenic language disorganization, as reflected in highly schizotypal individuals, and that hemispheric integration plays a role in the remote-associate task.     

Force Control of Ankle Dorsiflexors in Young Adults: Effects of Bilateral Control and Leg Dominance

Abstract

We investigated whether bilateral lower-limb control and leg dominance affect force control ability in 15 healthy young adults (9 males and 6 females, age =26.8?±?4.1 years). Participants performed isometric ankle dorsiflexion force control tasks, matching a visual target (10% of maximal effort) as quickly and precisely as possible in ballistic and tonic tasks. Performance was evaluated using force error, force steadiness, amount of muscle activity of the tibialis anterior, and response time characteristics. Results showed no significant effects of leg dominance during both ballistic and tonic tasks, while bilateral condition resulted in significantly larger error, less force steadiness, compared to unilateral condition, and only during the tonic task. Consequently, bilateral control, specifically in tasks utilizing feedback control (i.e., tonic task) might affect force control ability, possibly because of the interhemispheric inhibition to meet bilateral task complexity and integrate afferent bilateral sensory information from both right and left legs.     

Trends and monthly variations in the historical record of suicide in Japan from 1976 to 1994

Monthly suicide rates in Japan were analyzed for the period from 1976 to 1994 to clarify trends and recurring effects. The data were separated by sex, and the least-squares method was used. The major findings were (1) a significant positive correlation between unemployment rate and suicide rate for both sexes, (2) the suicide rate was highest in April for both sexes, and (3) an upsurge in male suicide mortality was noted from 1983 to 1990. These findings may well be associated with socioeconomic factors as well as neurobehavioral variables.     

Development of a Japanese version of the Positive and Negative Affect Schedule for Children

In this paper, the Positive and Negative Affect Schedule for Children originally developed in 1999 by Laurent, et al. was adapted for use in Japan. In Study 1, a total of 763 children in Grades 4 to 6 completed this Schedule, and 103 of them completed it again about three months later. Principal factor analysis with promax rotation identified two factors, positive and negative affect, in the Japanese version, whose alphas (over .80) and test-retest correlations (over .50) were sufficient to indicate internal consistency and stability over time. In Study 2, a total of 328 children completed the Japanese version, the Depression Self-rating Scale for Children, and the Trait Form of the State-Trait Anxiety Inventory for Children. Intercorrelations showed convergent and discriminant validity using these self-report measures of depression and anxiety. Overall these data support the reliability and validity of this Japanese version.     

Language-dependent access to autobiographical memory in Japanese-English bilinguals and US monolinguals

Japanese bilinguals retrieved autobiographical memories in response to 20 English and 20 Japanese cue words. US monolinguals were cued with 40 English words. All participants reported one earliest memory. Japanese bilinguals retrieved more memories and earlier memories when cued with Japanese words. They also retrieved more memories when the cue language matched either the language of memory encoding or the language of first thought. Although English cues elicited equivalent numbers of English and Japanese memories in the more fluent speakers of English, Japanese words elicited significantly larger numbers of Japanese memories in all Japanese-English bilinguals. The average age of cued autobiographical memories was significantly earlier for US than for Japanese students but age of the earliest memory did not differ.     

Gravity bias in young and adult chimpanzees (Pan troglodytes): tests with a modified opaque-tubes task

Young human children at around 2 years of age fail to predict the correct location of an object when it is dropped from the top of an S-shape opaque tube. They search in the location just below the releasing point (Hood, 1995). This type of error, called a 'gravity bias', has recently been reported in dogs and monkeys. In the present study, we investigated whether young and adult chimpanzees also show such a gravity bias in a modified version of the original opaque-tube task. The original task by Hood and colleagues required the subject to search in a location after the object had fallen, while in the task reported here, subjects were required to predict the location before the object was dropped. Thus the present procedure does not involve explicit invisible displacement operations, one of the important components of the original procedure. In Experiment 1 both young (1.5-2.5-year-old) and adult chimpanzees predicted the location of falling food items below the releasing point even when crossed tubes were used. These gravity errors remained after the extensive experience of using the tubes themselves. Experiment 2 further tested adult and 4-year-old chimpanzees under the set-up in which the straight and crossed tubes were simultaneously presented. The results were the same as those in the previous test, suggesting that developmental changes and learning effect do not affect the gravity bias in chimpanzees.     

Sexually dimorphic preference for altruism in the opposite sex according to recipient

Sexual selection may affect human altruistic behaviour. Evolutionary psychology predicts that human mate preference reflects sexual selection. We investigated sex differences in preference for opposite‐sex altruism according to recipient because the reasons for altruistic behaviour differ according to the relationship between actor and recipient. We employed the Self‐Report Altruism Scale Distinguished by the Recipient, which was newly developed to evaluate altruism among Japanese undergraduates. We asked participants to evaluate preferences for each item based on the recipient of the altruistic behaviour (family members, friends or acquaintances, and strangers). Preference for opposite‐sex altruism differed according to recipient, gender of the participant, and relationship type, and several significant interactions were observed among these factors. We suggest that whereas women use a potential partner's altruism towards strangers as a costly signal of their resource‐holding potential when choosing a mate, they consider altruism towards family when they are in a long‐term relationship to ensure that resources are not allocated to non‐relatives.     

Longitudinal relations among maternal behaviors, effortful control and young children's committed compliance

In a sample (n = 235) of 30-, 42-, and 54-month-olds, the relations among parenting, effortful control (EC), impulsivity, and children's committed compliance were examined. Parenting was assessed with mothers' observed sensitivity and warmth; EC was measured by mothers' and caregivers' reports, as well as a behavioral task; impulsivity was assessed by mothers' and caregivers' reports; and committed compliance was observed during a cleanup and prohibition task, as well as measured by adults' reports. Using path modeling, there was evidence that 30-month parenting predicted high EC and low impulsivity a year later when the stability of the outcomes was controlled, and there was evidence that 30- and 42-month EC, but not impulsivity, predicted higher committed compliance a year later, controlling for earlier levels of the outcomes. Moreover, 42-month EC predicted low impulsivity a year later. Fixed effects models, which are not biased by omitted time-invariant variables, also were conducted and showed that 30-month parenting still predicted EC a year later, and 42-month EC predicted later low impulsivity. Findings are discussed in terms of the importance of differentiating between effortful control and impulsivity and the potential mediating role of EC in the relations between parenting and children's committed compliance.