Alexithymia and Somatization in Agenesis of the Corpus Callosum

Deficient communication between the cerebral hemispheres is one of several prevailing neurobiological explanations for alexithymia and has been strongly supported by research on patients with commissurotomy. We examined self-reported symptoms of alexithymia in adults with agenesis of the corpus callosum (AgCC), a condition characterized by more subtle reductions in interhemispheric transfer than in commissurotomy. 16 adults with AgCC and FSIQ > 80 were compared with 15 age- and IQ-matched neurotypical controls. The AgCC group endorsed greater difficulty identifying and describing feelings and more vague physical symptoms than controls, but similar levels of emotional experience and emotional coping. This finding of impaired emotional interpretation with intact emotional experience is consistent with findings in callosotomy patients, implicating the critical role of the corpus callosum in cognitive dimensions of emotion processing. Further study of alexithymia in AgCC using task-based measures may help clarify the nature of this relationship.

Motives and Laterality: Exploring the Links

Objectives We explored associations between the needs for power, achievement, and affiliation and functional cerebral asymmetries (FCAs), guided by three established hypotheses about the nature of these associations. Methods One-hundred-and-seven participants completed picture-story measures of dispositional motives and activity inhibition (AI), a frequent moderator of motive-behavior associations, tasks measuring FCAs (line bisection, chimeric emotional face judgments, turning bias, perceptual and response asymmetries on the Poffenberger task), self-reported laterality preferences (handedness, footedness, ear and eye preference), and interhemispheric interaction (crossed-uncrossed difference). They also completed an experiment manipulating hand contractions (left, right, both, neither) while they worked on a second picture-story motive measure. Results Dispositional power motivation was associated with stronger rightward asymmetry and less interhemispheric transfer in high-AI and stronger leftward asymmetry and more interhemispheric transfer in low-AI individuals. For the affiliation motive, findings were fewer and in the opposite direction of those for the power motive. These findings emerged for men, but not for women. Left- or right-hand contractions led to increases in power and achievement motivation, but not affiliation motivation. Only left-hand contractions led to decreased AI. Conclusions We discuss these findings in the context of sex-dimorphic organizing and activating effects of steroids on motives and laterality.

Music Playing and Interhemispheric Communication: Older Professional Musicians Outperform Age-Matched Non-Musicians in Fingertip Cross-Localization Test

Objective: Numerous investigations have documented that age-related changes in the integrity of the corpus callosum are associated with age-related decline in the interhemispheric transfer of information. Conversely, there is accumulating evidence for more efficient white matter organization of the corpus callosum in individuals with extensive musical training. However, the relationship between making music and accuracy in interhemispheric transfer remains poorly explored. Methods: To test the hypothesis that musicians show enhanced functional connectivity between the two hemispheres, 65 professional musicians (aged 56–90 years) and 65 age- and sex-matched non-musicians performed the fingertip cross-localization test. In this task, subjects must respond to a tactile stimulus presented to one hand using the ipsilateral (intra-hemispheric test) or contralateral (inter-hemispheric test) hand. Because the transfer of information from one hemisphere to another may imply a loss of accuracy, the value of the difference between the intrahemispheric and interhemispheric tests can be utilized as a reliable measure of the effectiveness of hemispheric interactions. Results: Older professional musicians show significantly greater accuracy in tactile interhemispheric transfer than non-musicians who suffer from age-related decline. Conclusions: Musicians have more efficient interhemispheric communication than age-matched non-musicians. This finding is in keeping with studies showing that individuals with extensive musical training have a larger corpus callosum. The results are discussed in relation to relevant data suggesting that music positively influences aging brain plasticity.

Relation of success in study of foreign language with speed of interhemispheric transfer of information

Bilingual speakers seem to outreach monolingual speakers in performing non-verbal tasks for testing executive functions, such as Simon, Flanker and Stroop tasks, as well as in capacity of working memory. Other researchers have doubts about these cognitive benefits of bilinguals and multilinguals. The study used a combined test with the tasks of the Stroop, Poffenberger, Sperry in native (Ukrainian) and foreign (English) languages. Schoolboys of lyceum were the subjects surveyed (14-15 years old). Stimuli (the word "Green" or "Red", "Blue" or "Yellow" written in relevant or irrelevant color) were exposed on the right or left from the center of the screen. In the case of congruence the word and its semantic meaning should press one button by the ipsilateral hand ("yes"), while in the case of mismatch – the other button by the contralateral one ("no"). Latent periods of response to stimuli, which reflect the speed of the interhemispheric transfer of information, were taken into account. Correlation analysis of the success in study in the nine subjects of the three blocks (humanities, natural and formal disciplines) reveal a direct correlation of speed of reaction when performing the complex Stroop test in both the native and English languages with the success in the learning English language, what may indicate on special dependence of the success from interhemispheric interaction. In order for the foreign language to be automated and become "all the more native", it is need the fast access of the executive structures of the brain, such as the front-parietal neural network, to the linguistic neural networks, presented in both hemispheres. According to literature, the inhibitory control mechanism from the dorsolateral prefrontal cortex as the key structure of the front-parietal brain system may be one of several mechanisms underlying bilingual superiority. The results obtained by us complement this conception, indicating the importance of the speed of interhemispheric interaction.