Ocular motility and visuo-spatial attention in children with periventricular leukomalacia

Periventricular leukomalacia (PVL) is known to cause visual, motor, and cognitive impairments varying in their severity. Most studies focused on impairment at early ages. Little is known about the PVL's later outcome. Effects of neural plasticity are for instance insufficiently known to prognose precisely their behavioral outcome. It is even hard to determine the consequence of one defect on global development over time. Because of the established neural link between eye motion and space perception, 5-to-9 year-old PVL's were tested in visual detection, postural control, and space attention tasks. In this paper, discussion will focus on behavioral asymmetry, developmental outcome, and brain injury.     

The impact of lesion laterality on neuropsychological change following posterior pallidotomy: a review of current findings

This paper reviews seven studies evaluating the impact of lesion laterality on the neuropsychological sequelae of posterior pallidotomy for treatment of Parkinson's disease. Left lesions of the internal globus pallidus (GPi) were associated with subtle deficits on measures sensitive to frontal lobe function. The findings of a randomized clinical trial including a patient control group indicated that many of these deficits were transient, resolving by 6 months following surgery. Right GPi lesions were not consistently associated with neuropsychological deficit, except in one study that included a significant proportion of demented patients. It is hypothesized that when neuropsychological decline is present following surgery, this reflects impingement of posterior GPi lesions into proximal regions such as anterior GPi or the external pallidum that participate in cognitive basal ganglia-thalamocortical circuits. The findings from neuroimaging will be important for elucidating the relationship between lesion locus and neuropsychological sequelae.     

Effects of spatial and symbolic precues on localization performance

One of the fundamental properties of spatial vision is the ability to localize objects in space. According to a recent proposal, accurate localization performance involves the operation of two systems: the attention system and the eye movement system. Upon stimulus presentation, attention is shifted to the target area: this provides coarse location information. Subsequently, a saccadic eye movement is executed: this provides fine location information. In this study we tested predictions derived from this model concerning the effects of precue information on localization performance. In a series of five experiments we manipulated duration of precue (71, 400, and 1,000 ms) and type of precue (spatial versus symbolic). Results showed that very short duration (i.e., 71 ms) spatial precues improved localization performance whereas very short duration symbolic precues did not. In contrast, the 1,000 ms duration precue condition showed similar amounts of precuing benefit for the spatial and symbolic precues. This pattern of differential precuing effects corroborated the two-process model of localization performance. Received: 24 June 1999 / Accepted: 28 January 2000     

Lateralization of speech processing in the brain as indicated by mismatch negativity and dichotic listening

The goal of the present study was to evaluate the differences between dichotic listening and mismatch negativity as measures of speech lateralization in the human brain. For this purpose, we recorded the magnetic equivalent of the mismatch negativity, elicited by consonant-vowel syllable change, and tested the same subjects in the dichotic listening procedure. The results showed that both methods indicated left-hemisphere dominance in speech processing. However, the mismatch negativity, as compared to the right-ear advantage, suggested slightly stronger left-hemisphere dominance in speech processing. No clear correlation was found between the laterality indexes of mismatch negativity and right-ear advantage calculated from dichotic listening results. The possible explanation for this finding would be that these two measures reflect different stages of speech processing in the human brain.     

Introduction to this issue: international perspectives on psychopathic disorders

The importance of characterological disturbances, that contribute towards individual patterns of law breaking behavior, to legal systems in all countries should be self-evident. Contributors to this international perspective issue represent Canada, Germany, Great Britain, and the United States, and data from several additional European countries were included in Hare's article. This issue addresses emotional deficiency, molecular genetics, construct and predictive validity of the PCL-R, psychosocial predictors and treatment. Critical analyses of current models for civil commitment and criminal responsibility vis-à-vis psychopathic disorders contribute towards informed dialectic on these compelling public policy issues. We hope that readers will find that these articles collectively advance our understanding of the nature of these disorders, currently available therapeutic interventions, and today's critical social issues.     

The centercept: an estimable and meaningful regression parameter

Linear regression is a mathematical model that is employed broadly throughout all of social science research. The choice of parameterization for linear models has important substantive and statistical implications. This article examines the typical parameterization chosen, which includes a parameter for slope and a parameter for the y -intercept. The article demonstrates that the centercept has an interpretive advantage over the traditionally used y -intercept and that the centercept is typically estimated more accurately.     

Sex differences in mathematical reasoning ability at age 13: their status 20 years later

Reported is the 20-year follow-up of 1,975 mathematically gifted adolescents (top 1%) whose assessments at age 12 to 14 revealed robust gender differences in mathematical reasoning ability. Both sexes became exceptional achievers and perceived themselves as such; they reported uniformly high levels of degree attainment and satisfaction with both their career direction and their overall success. The earlier sex differences in mathematical reasoning ability did predict differential educational and occupational outcomes. The observed differences also appeared to be a function of sex differences in preferences for (a) inorganic versus organic disciplines and (b) a career-focused versus more-balanced life. Because profile differences in abilities and preferences are longitudinally stable, males probably will remain more represented in some disciplines, whereas females are likely to remain more represented in others. These data have policy implications for higher education and the world of work.