Left frontal aslant tract and lexical selection: Evidence from frontal lobe lesions
The frontal aslant tract (FAT) is a white-matter tract connecting the inferior frontal gyrus (IFG) and the supplementary motor complex (SMC). Damage to either component of the network causes spontaneous speech dysfluency, indicating its critical role in language production. However, spontaneous speech dysfluency may stem from various lower-level linguistic deficits, precluding inferences about the nature of linguistic processing subserved by the IFG-SMC network. Since the IFG and the SMC are attributed a role in conceptual and lexical selection during language production, we hypothesized that these processes rely on the IFG-SMC connectivity via the FAT. We analysed the effects of FAT volume on conceptual and lexical selection measures following frontal lobe stroke. The measures were obtained from the sentence completion (SC) task, tapping into conceptual and lexical selection, and the picture-word interference (PWI) task, providing a more specific measure of lexical selection. Lower FAT volume was not associated with lower conceptual or lexical selection abilities in our patient cohort. Current findings stand in marked discrepancy with previous lesion and neuroimaging evidence for the joint contribution of the IFG and the SMC to lexical and conceptual selection. A plausible explanation reconciling this discrepancy is that the IFG-SMC connectivity via the FAT does contribute to conceptual and/or lexical selection but its disrupted function undergoes reorganisation over the course of post-stroke recovery. Thus, our negative findings stress the importance of testing the causal role of the FAT in lexical and conceptual selection in patients with more acute frontal lobe lesions.
Currently there is a need for standardized language assessment test in Russian. Our group has developed Russian Aphasia Test (RAT) based on modern psycholinguistic models and psychometric principles, taking into account existing standardized tests in other languages. RAT allows to separately assess each level of linguistic processing: from phonemic perception to discourse. Here we present the design of the test and the first results of its approbation in groups of neurologically healthy participants and individuals with aphasia. Preliminary results demonstrated that the test is sensitive to language deficits and their severity. Thus, RAT is a practical instrument for language assessment in aphasia which can be used both in clinical practice and for research purposes. At present test standardization in a large group of participants with and without aphasia is on-going with the goal of developing appropriate clinical and age norms.
Cognitive control is a set of processes that are responsible for flexible goal-directed behaviour. We did a series of electroencephalographic experiments during the auditory condensation task. The findings obtained allow distinguishing three brain networks that carry out adaptive processes after error commission. We also show that increased response time is associated with lower level of attention and higher level of uncertainty.
Adequate assessment of individual functional motor potentials is important for developing appropriate rehabilitation strategies in ischemic stroke . Microstructural changes in corticospinal tract (CST) and corpus callosum (CC) were repeatedly correlated to post-stroke outcome [2, 3]. However, relationship between them and functional recovery remains unclear. Here we investigated relationship between integrity of CST and CC assessed with diffusion tensor imaging (DTI) and brain functional state assessed with navigated transcranial magnetic stimulation (nTMS) in chronic ischemic supratentorial stroke.
The present work is dedicated to the role of gestures in overcoming lexical access problems in patients with motor aphasia. The study is based on a corpus of narratives by brain-damaged individuals – «Russian CliPS» (Clinical Pear Stories), the videos from which were annotated in the linguistic annotator «ELAN», with the gestural layout included in the analysis. The results suggest that most often the difficulties with lexical access were related to the search for nouns and verbs, and gestures (deictic and rhythmic gestures, beats) facilitated lexical access in patients.
Age-related changes in language processing have not yet been as well-studied as those in perception, memory, attention or cognition. Specifically with regard to syntactic processing, it is still debatable whether only the processing speed or also accuracy decreases with age. The present study investigated the effect of age and individual differences on syntactic processing in healthy adults. Specifically, we tested the effect of age on the speed of reading syntactically complex sentences and the accuracy of their comprehension, and explored the neural correlates of individual differences in speed and accuracy when taking age into account. The analysis was limited to white matter and used diffusion tensor imaging and tract-based spatial statistics to analyze fractional anisotropy of white-matter tracts. The reading speed was found to become slower with age; however, sentence comprehension accuracy was unaffected by age. Thus, similar to the processing speed decrease in many other cognitive domains, a decrease in sentence processing speed seems to be a compensatory mechanisms that ensures that processing accuracy is maintained. The study did not find any significant correlates of individual differences in syntactic processing accuracy, which is likely due to small sample size.
The aim of the current study was to provide an empirical evidence of an emotional state’s influence on the updating of affective information in working memory. The emotional congruence effect was expected: participants in a happy emotional state would be more successful in updating positive information compared to negative and neutral information. It was also expected that participants in a negative emotional state would show the opposite pattern of results. The sample included 66 subjects (age: M = 18.56; SD = 1.02). To measure updating, an affective n-back task was applied with positive, negative and neutral words as stimuli. To induce an emotional state, a combination of autobiographical memories and music listening was used. No emotional congruence effect has been obtained. The pattern of results for reaction times and accuracy was similar in both groups; most likely, it was partially caused by the sequence effect. In all types of trials, participants responded faster after emotion induction. The accuracy of responses to negative (M = 0.83; SD = 0.12) was significantly different compared to positive (M = 0.78; SD = 0.16) and neutral trials (M = 0.73; SD = 0.21). The results show that the updating of emotional stimuli is more effective compared to neutral stimuli; among emotional stimuli, updating negative stimuli is more effective compared to positive stimuli.
Studying how the healthy human brain develops is important to understand early pathological mechanisms and to assess the influence of fetal or perinatal events on later life. Brain development relies on complex and intermingled mechanisms especially during gestation and first post-natal months, with intense interactions between genetic, epigenetic and environmental factors. Although the baby's brain is organized early on, it is not a miniature adult brain: regional brain changes are asynchronous and protracted, i.e. sensory-motor regions develop early and quickly, whereas associative regions develop later and slowly over decades. Concurrently, the infant/child gradually achieves new performances, but how brain maturation relates to changes in behavior is poorly understood, requiring non-invasive in vivo imaging studies such as magnetic resonance imaging (MRI). Two main processes of early white matter development are reviewed: (1) establishment of connections between brain regions within functional networks, leading to adult-like organization during the last trimester of gestation, (2) maturation (myelination) of these connections during infancy to provide efficient transfers of information. Current knowledge from post-mortem descriptions and in vivo MRI studies is summed up, focusing on T1- and T2-weighted imaging, diffusion tensor imaging, and quantitative mapping of T1/T2 relaxation times, myelin water fraction and magnetization transfer ratio.
Students' internet usage attracts the attention of many researchers in different countries. Differences in internet penetration in diverse countries lead us to ask about the interaction of medium and culture in this process. In this paper we present an analysis based on a sample of 825 students from 18 Russian universities and discuss findings on particularities of students' ICT usage. On the background of the findings of the study, based on data collected in 2008-2009 year during a project "A сross-cultural study of the new learning culture formation in Germany and Russia", we discuss the problem of plagiarism in Russia, the availability of ICT features in Russian universities and an evaluation of the attractiveness of different categories of ICT usage and gender specifics in the use of ICT.
The distractive effects on attentional task performance in different paradigms are analyzed in this paper. I demonstrate how distractors may negatively affect (interference effect), positively (redundancy effect) or neutrally (null effect). Distractor effects described in literature are classified in accordance with their hypothetical source. The general rule of the theory is also introduced. It contains the formal prediction of the particular distractor effect, based on entropy and redundancy measures from the mathematical theory of communication (Shannon, 1948). Single- vs dual-process frameworks are considered for hypothetical mechanisms which underpin the distractor effects. Distractor profiles (DPs) are also introduced for the formalization and simple visualization of experimental data concerning the distractor effects. Typical shapes of DPs and their interpretations are discussed with examples from three frequently cited experiments. Finally, the paper introduces hierarchical hypothesis that states the level-fashion modulating interrelations between distractor effects of different classes.
The results of cross-cultural research of implicit theories of innovativeness among students and teachers, representatives of three ethnocultural groups: Russians, the people of the North Caucasus (Chechens and Ingushs) and Tuvinians (N=804) are presented. Intergroup differences in implicit theories of innovativeness are revealed: the ‘individual’ theories of innovativeness prevail among Russians and among the students, the ‘social’ theories of innovativeness are more expressed among respondents from the North Caucasus, Tuva and among the teachers. Using the structural equations modeling the universal model of values impact on implicit theories of innovativeness and attitudes towards innovations is constructed. Values of the Openness to changes and individual theories of innovativeness promote the positive relation to innovations. Results of research have shown that implicit theories of innovativeness differ in different cultures, and values make different impact on the attitudes towards innovations and innovative experience in different cultures.