Contribution of NIRS to the study of prefrontal cortex for verbal fluency in aging

Healthy aging is characterized by a number of changes on brain structure and function. Several neuroimaging studies have shown an age-related reduction in hemispheric asymmetry on various cognitive tasks, a phenomenon captured by Cabeza (2002) in the Hemispheric Asymmetry Reduction in Older Adults (HAROLD) model. Although this phenomenon is supported by a range of neuroimaging data on memory and inhibitory processes, there is little evidence concerning changes in hemispheric asymmetry for language processing, and particularly word retrieval, which is assessed with verbal fluency task (VFT). This study aimed to investigate the age-related changes in cerebral oxygenation in the prefrontal cortex for both letter and category VFT, varying the complexity of the criteria (i.e., degree of productivity) and using near-infrared spectroscopy (NIRS). Sixteen younger and 16 older adults participated in this study. For both VF conditions, participants were instructed to pronounce as many nouns as possible as a function of high-productivity (e.g., “animals” or “L”) or low-productivity (e.g., “flowers” or “V”) criteria. Behavioral data (i.e., accuracy responses) showed comparable performance in younger and older adults for both VF conditions. However, NIRS data showed more reduced activation (i.e., significantly reduced increase in [O₂Hb] and reduced decrease in [HHb]) in older than younger adults for both VFT. In addition, a bilateral effect was found for both groups, suggesting that VFT requires both executive and language functions. The results are discussed in the context of the current theories of aging.     

Indonesian leadership styles: A mixed‐methods approach

Indonesian leadership characteristics were examined in three studies, using mixed methods. In the first, qualitative study 127 indigenous characteristics of Indonesian leadership were identified from interviews and focus group discussions with Indonesian managers and staff. In the second study, a questionnaire based on the characteristics found in the first study was administered to Indonesian managers to identify Indonesian leadership styles. Using factor analysis, two highly correlated dimensions were extracted, labelled benevolent paternalism and transformational leadership. In the third study, a questionnaire consisting of leadership characteristics from the GLOBE study, supplemented with a selection of 49 items from the Indonesian questionnaire, was administered to another sample of Indonesian managers. We found that Indonesian leadership has two components; the first involves a more local modernization dimension that ranges from (traditional) benevolent paternalism to (modern) transformational leadership, the second is a more universal person‐ versus team‐oriented leadership dimension. We conclude that Indonesian leadership has both emic and etic aspects.     

Enhanced corticospinal response to observed pain in pain synesthetes

Observing noxious injury to another’s hand is known to induce corticospinal inhibition that can be measured in the observer’s corresponding muscle. Here, we investigated whether acquired pain synesthetes, individuals who experience actual pain when observing injury to another, demonstrate less corticospinal inhibition than do controls during pain observation, as a potential mechanism for the experience of vicarious pain. We recorded motor-evoked potentials (MEPs) induced at two time points through transcranial magnetic stimulation while participants observed videos of a hand at rest, a hypodermic needle penetrating the skin, a Q-tip touching the skin, and a hypodermic needle penetrating an apple. We compared MEPs in three groups: 7 amputees who experience pain synesthesia, 11 nonsynesthete amputees who experience phantom limb pain, and 10 healthy controls. Results indicated that the pain synesthete group demonstrated significantly enhanced MEP response to the needle penetrating the hand, relative to the needle not having yet penetrated the hand, as compared with controls. This effect was not observed exclusively in the same muscle where noxious stimulation was applied. We speculate that our findings reflect a generalized response to pain observation arising from hyperactivity of motor mirror neurons not involved in direct one-to-one simulation but, rather, in the representation of another’s experience.     

Effectiveness of virtual reality for pediatric pain distraction during i.v. placement.

The objective of this study was to test the efficacy and suitability of virtual reality (VR) as a pain distraction for pediatric intravenous (i.v.) placement. Twenty children (12 boys, 8 girls) requiring i.v. placement for a magnetic resonance imaging/computed tomography (MRI/CT) scan were randomly assigned to two conditions: (1) VR distraction using Street Luge (5DT), presented via a head-mounted display, or (2) standard of care (topical anesthetic) with no distraction. Children, their parents, and nurses completed self-report questionnaires that assessed numerous health-related outcomes. Responses from the Faces Pain Scale-Revised indicated a fourfold increase in affective pain within the control condition; by contrast, no significant differences were detected within the VR condition. Significant associations between multiple measures of anticipatory anxiety, affective pain, i.v. pain intensity, and measures of past procedural pain provided support for the complex interplay of a multimodal assessment of pain perception. There was also a sufficient amount of evidence supporting the efficacy of Street Luge as a pediatric pain distraction tool during i.v. placement: an adequate level of presence, no simulator sickness, and significantly more child-, parent-, and nurse-reported satisfaction with pain management. VR pain distraction was positively endorsed by all reporters and is a promising tool for decreasing pain, and anxiety in children undergoing acute medical interventions. However, further research with larger sample sizes and other routine medical procedures is warranted.     

Age-related memory deficits in rats and mice: enhancement with peripheral injections of epinephrine

Epinephrine peripherally administered to rats and mice immediately following avoidance and/or appetitive training enhances later memory retention in both young and old animals. These findings suggest a possible involvement of peripheral adrenergic systems in memory dysfunctions which accompany aging.     

Cognitive functioning of older people in relation to social and personality variables

Age differences in performance on memory measures and in subjective ratings of memory adequacy were examined in the context of 12 social, personality, adjustment, and lifestyle measures. Participants were 285 men and women, aged 65 to 93, of middle- and working-class backgrounds. A series of multivariate and univariate analyses revealed that a large proportion of the age differences and virtually all of the social-class differences on memory measures could be accounted for by contextual variables, with education, intellectual activity, extroversion, neuroticism, and lie scores (on the Eysenck Personality Inventory) all accounting for more of the variance in memory performance than did age. Self-rated memory adequacy was not correlated with performance, and although the expected finding of lower ratings by older participants was obtained with the working-class group, the opposite was true for the middle-class group. Implications of these results for understanding age differences in memory are discussed.     

The socialization of sex-differentiated skills and academic performance: A mediational model

Using a multifactorial model, sex differences in academic performance were examined in a sample of 347 elementary school children. As expected, girls' academic performance averaged higher than boys'. Path analysis confirmed initial hypotheses that girls' advantage is partially due to their characteristic of greater responsiveness to social cues and compliance with adult direction. This advantage was partially offset in this model by boys' greater visual-spatial skill, which also was a predictor of academic success. Access to stereotypic masculine toys and activities at home was, for both sexes, a predictor of children's visual-spatial ability. As expected, socioeconomic variables, including mothers' occupation and fathers' level of education, also influenced the environmental, social, and cognitive factors predicting academic success. These results indicate that boys' and girls' differential development of specific cognitive and social skills may play an important role in establishing sex differences in academic performance.     

Relations between teachers' judgments of girls' and boys' compliance and intellectual competence

This study examined the relation between teachers' perceptions of children's compliance to them and their evaluations of the children's intellectual competence. One hundred and nine boys and 94 girls from 25 preschools participated in the study. Evaluations of the children's intellectual competence and their compliance to teachers were provided by teachers from each preschool. The children were given measures of intelligence and problem solving, which together with age and compliance to teachers were used to predict the teachers' evaluations of the children's intellectual competence. Only IQ and age significantly predicted teachers' evaluations of boys' competence. Teachers' evaluations of girls' intellectual competence were significantly predicted by age, compliance to teachers, and problem-solving scores, with the less compliant girls being perceived as less competent. The results were interpreted as indicating the possible influence of sex role bias on teachers' judgments of girls' intellectual competence.This research was funded by a grant from the Quebec Department of Education and was performed while the second author was supported by a scholarship from the Quebec Department of Education.     

Regional brain catecholamines and memory: effects of footshock, amygdala implantation, and stimulation

Previous findings have revealed a correlation between post-training release of whole brain norepinephrine (NE) and later retention performance. The present experiment examined changes after a training footshock in NE levels, as well as the levels of the major central NE metabolite, 3-methoxy-4-hydroxyphenylglycol (MHPG), dopamine (DA), and epinephrine (EPI) in eight brain regions. Brain levels of these amines and the metabolite were assessed 10 min after training in a one-trial inhibitory (passive) avoidance task. The results indicate that NE levels decreased significantly in neocortex, neostriatum, hypothalamus, frontal pole, septum, and brainstem, but not in hippocampus or thalamus. The decreases in NE levels were generally accompanied by increases in MHPG; the MHPG/NE ratio increased significantly in all areas in which decreases in NE were observed. DA levels decreased in neostriatum and increased in neocortex and brainstem. Epinephrine levels decreased only in the brainstem sample. Thus, the effects of training on NE are widespread, probably reflecting the release of the amine in most brain regions. Such findings are consistent with the view that posttraining release of brain NE may modulate the storage of new information in many brain regions. One especially potent treatment for modulating memory storage is electrical stimulation of the amygdala. Therefore, we also examined the effects of amygdala implantation and stimulation on brain catecholamine levels to determine whether such changes might be correlated with the effects of amygdala stimulation on memory. The results indicate that electrode implantation into the amygdala results in pervasive changes in NE levels in most brain regions tested. Against this modified baseline, the results of training and electrical stimulation were region specific and very difficult to interpret. The major conclusion which can be derived from this portion of the experiment is that the amygdala damage produced by electrode implantation produces a brain which is substantially different from that of intact animals.