Lateralized Increases in Cerebral Blood Flow during Performance of Verbal and Spatial Tasks: Relationship with Performance Level

Physiologic neuroimaging studies have shown lateralized regional increase in brain activity during cognitive tasks, but the hypothesis that such changes are correlated with task performance has not been tested directly. We examined cerebral blood flow (CBF) changes induced by cognitive tasks in relation to performance. CBF was measured with the ¹³³Xenon clearance method in 34 normal right-handed young (age < 30) volunteers during resting baseline and during the performance of a verbal analogies and a spatial line orientation test. Performance measures included "speed" and "power" estimates of both activation tasks. Resting CBF was moderately correlated with performance. The correlations were slightly higher with activated CBF for verbal but not spatial performance. The degree of increase (task-baseline) did not correlate with performance for either task. The highest and topographically specific correlations were obtained between laterality of CBF and verbal performance. Higher left hemispheric activation was correlated with verbal performance, and this correlation was significantly higher in the angular gyrus region. For the spatial task the correlations were with relatively higher right hemispheric activation but without regional specificity. The results underscore the importance of integrating behavioral performance data with physiologic measures in neuroimaging activation studies.     

A bright side of sadness: The depolarizing role of sadness in intergroup conflicts

Intractable conflicts constitute violent and threatening environments that lead to intense emotions and polarized attitudes. Sadness is one emotion frequently elicited by the price of such conflicts. This investigation characterized the effects of sadness on conflict‐related information processing and attitudes in the Israeli–Palestinian conflict. Findings from four experimental studies suggest that both incidental and integral sadness can induce a depolarization of political attitudes. In Study 1 (N = 163), sadness reduced the effect of political ideology on conflict‐related decisions. Sadness reduced the effect of political ideology on in‐group bias in resource allocation in Studies 2 (N = 213) and 4 (N = 274), willingness to negotiate in Studies 1 and 3 (N = 174), and openness to information supporting the out‐group's perspective (Study 4). Overall, in addition to its more negative implications, these results suggest that sadness (compared to both the non‐emotional and anger conditions) may have a bright side, since it may induce depolarization of political attitudes in intractable conflicts.     

An fMRI study of sex differences in regional activation to a verbal and a spatial task

Sex differences in cognitive performance have been documented, women performing better on some phonological tasks and men on spatial tasks. An earlier fMRI study suggested sex differences in distributed brain activation during phonological processing, with bilateral activation seen in women while men showed primarily left-lateralized activation. This blood oxygen level-dependent fMRI study examined sex differences (14 men, 13 women) in activation for a spatial task (judgment of line orientation) compared to a verbal-reasoning task (analogies) that does not typically show sex differences. Task difficulty was manipulated. Hypothesized ROI-based analysis documented the expected left-lateralized changes for the verbal task in the inferior parietal and planum temporal regions in both men and women, but only men showed right-lateralized increase for the spatial task in these regions. Image-based analysis revealed a distributed network of cortical regions activated by the tasks, which consisted of the lateral frontal, medial frontal, mid-temporal, occipitoparietal, and occipital regions. The activation was more left lateralized for the verbal and more right for the spatial tasks, but men also showed some left activation for the spatial task, which was not seen in women. Increased task difficulty produced more distributed activation for the verbal and more circumscribed activation for the spatial task. The results suggest that failure to activate the appropriate hemisphere in regions directly involved in task performance may explain certain sex differences in performance. They also extend, for a spatial task, the principle that bilateral activation in a distributed cognitive system underlies sex differences in performance.     

Conjugate lateral eye movements as an index of hemispheric activation.

Right handers moved their eyes leftward when solving spatial problems and rightward for verbal problems when the questioner sat behind them. When facing the questioner, the same subjects moved their eyes predominantly in only one direction, either right or left, regardless of problem type. The results indicate that the cerebral hemispheres, though specialized for problem type, are also preferentially activated within the same individuals.     

The nature of schizotypy among multigenerational multiplex schizophrenia families

Identification of endophenotypes (Gottesman & Gould, 2003; Gottesman & Shields, 1972) that genetically correlate with schizophrenia and are genetically homogeneous is an important strategy for detecting genes that affect schizophrenia risk. Symptoms of schizotypy may familially correlate with schizophrenia; however, there are critical limitations of the current literature concerning this association. The present study examined the genetic architecture and genetic associations between schizotypy and schizophrenia among multigenerational, multiplex schizophrenia families. Genetic schizotypy factor scales were developed that genetically correlated with schizophrenia, although some relations were unexpected in direction suggesting minimization of "psychotic-like" symptoms. These genetic schizotypy factor scales did not genetically correlate with major depressive disorder or substance dependence indicating specificity to schizophrenia. The results highlight the possibility of significant response bias in schizophrenia families, particularly among close relatives, and suggest an important consideration when acquiring self-report information. This is a topic that deserves future study as the origins of this putative bias in relatives are unclear. In addition, the results support the identification of genetic schizotypy factors as a promising technique for maximizing genetic correlation of endophenotypes with schizophrenia.