第一和第二语言Stroop任务中EEG同步化分析

采用基于多元自回归的瞬时EEG相干方法研究了十位汉英双语者执行Stroop任务时脑神经电活动及其功能皮层区的协同作用。结果显示：在β1(13-18Hz)频段,无论是汉语(第一语言,L1)还是英语(第二语言,L2)呈现的刺激,不一致条件的EEG相干值明显大于一致条件的EEG相干值,表明β1频段对刺激类型敏感;与L2相比,L1的Stroop任务中,额一顶区的相干值显著增强。EEG相干值反映了不同脑皮层间的相互作用强度。因此研究结果表明：判断和处理冲突信息(如Stroop的不一致条件)时脑功能皮层区之间的协同作用增强;相对于第二语言,第一语言处理过程中额一顶区之间的通信协作增加。     

Association of lucid dreaming frequency with Stroop task performance.

Lucid dreaming involves the attentional skill of having metacognition about the dreamer's state of consciousness at the same time as being engaged in the dream scenario. A combination of two levels of cognition also occurs in the incongruent condition of the Stroop task, where there is interference between the attentional demands of a relatively difficult (color naming) and an easy (reading) task. It was thus hypothesized that frequent lucid dreamers would perform better on the Stroop task than would nonlucid dreamers. Individuals who reported having lucid dreams more than once per month (n = 15) were found to be significantly faster on the incongruent condition of the Stroop task than were occasional lucid dreamers (n = 15) or nonlucid dreamers (n = 15). The groups did not differ on the standard colored nonword control condition. Continuity in attentional ability between waking and dreaming cognition was thus found. This continuity may counteract the psychophysiologically dominant and possibly evolutionarily selected lack of self-awareness in dreams. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The emotional counting Stroop: a task for assessing emotional interference during brain imaging

The emotional counting Stroop (ecStroop) is an emotional variant of the counting Stroop. Both of these tasks require a motor response instead of a spoken response for the purpose of minimizing head movement during functional MRI (fMRI). During this task, subjects report, by button press, the number of words (1-4) that appear on a screen, regardless of word meaning. Neutral word-control trials contain common words (e.g., 'cabinet' written three times), while interference trials contain emotional words (e.g., 'murder' written three times). The degree to which this task represents a true 'Stroop' interference task, in the sense that emotional words will increase motor-response times compared with neutral words, depends upon the subjects of the study and the words that are presented. Much research on the emotional Stroop task demonstrates that interference effects are observed in psychopathological groups in response to words that are specific to their disorder, and in normal subjects when the words are related to current concerns endorsed by them. The ecStroop task described here will produce reaction time-interference effects that are comparable to the traditional color-naming emotional Stroop. This protocol can be completed in approximately 20 min per subject. The protocol described here employs neutral words and emotional words that include general-negative words, as well as words specific to combat-related trauma. However, this protocol is amenable to any emotional word lists.     

Leaf scorch symptoms are not correlated with bacterial populations during Pierce's disease

Xylella fastidiosa (Xf) is a xylem-limited bacterium that lives as a harmless endophyte in most plant species but is pathogenic in several agriculturally important crops such as coffee, citrus, and grapevine (Vitis vinifera L.). In susceptible cultivars of grapevine, Xf infection results in leaf scorch, premature leaf senescence, and eventually vine death; a suite of symptoms collectively referred to as Pierce's disease. A qPCR assay was developed to determine bacterial concentrations in planta and these concentrations were related to the development of leaf-scorch symptoms. The concentration of Xf in leaves of experimental grapevines grown in the greenhouse was similar to the concentration of Xf in leaves of naturally infected plants in the field. The distribution of Xf was patchy within and among leaves. Some whole leaves exhibited severe leaf-scorch symptoms in the absence of high concentrations of Xf. Despite a highly sensitive assay and a range of Xf concentrations from 10(2) to 10(9) cells g(-1) fresh weight, no clear relationship between bacterial population and symptom development during Pierce's disease was revealed. Thus, high and localized concentrations of Xf are not necessary for the formation of leaf-scorch symptoms. The results are interpreted as being consistent with an atiology that involves a systemic plant response.     

Alpha-Theta Effects Associated with Ageing during the Stroop Test

The Stroop effect is considered as a standard attentional measure to study conflict resolution in humans. The response of the brain to conflict is supposed to change over time and it is impaired in certain pathological conditions. Neuropsychological Stroop test measures have been complemented with electroencephalography (EEG) techniques to evaluate the mechanisms in the brain that underlie conflict resolution from the age of 20 to 70. To study the changes in EEG activity during life, we recruited a large sample of healthy subjects of different ages that included 90 healthy individuals, divided by age into decade intervals, which performed the Stroop test while recording a 14 channel EEG. The results highlighted an interaction between age and stimulus that was focused on the prefrontal (Alpha and Theta band) and Occipital (Alpha band) areas. We concluded that behavioural Stroop interference is directly influenced by opposing Alpha and Theta activity and evolves across the decades of life.     

Mitochondria and Wolbachia titers are positively correlated during maternal transmission

Mothers provide their offspring with symbionts. Maternally transmitted, intracellular symbionts must disperse from mother to offspring with other cytoplasmic elements, like mitochondria. Here, we investigated how the intracellular symbiont Wolbachia interacts with mitochondria during maternal transmission. Mitochondria and Wolbachia may interact antagonistically and compete as each population tries to ensure its own evolutionary success. Alternatively, mitochondria and Wolbachia may cooperate as both benefit from ensuring the fitness of the mother. We characterized the relationship between mitochondria and Wolbachia titers in ovaries of Drosophila melanogaster. We found that mitochondria and Wolbachia titers are positively correlated in common laboratory genotypes of D. melanogaster. We attempted to perturb this covariation through the introduction of Wolbachia variants that colonize at different titers. We also attempted to perturb the covariation through manipulating the female reproductive tract to disrupt maternal transmission. Finally, we also attempted to disrupt the covariation by knocking down gene expression for two loci involved in mitochondrial metabolism: NADH dehydrogenase and a mitochondrial transporter. Overall, we find that mitochondria and Wolbachia titers are commonly positively correlated, but this positive covariation is disrupted at high titers of Wolbachia. Our results suggest that mitochondria and Wolbachia have likely evolved mechanisms to stably coexist, but the competitive dynamics change at high Wolbachia titers. We provide future directions to better understand how their interaction influences the maintenance of the symbiosis.     

Specific peroxidase isoenzymes are correlated with organogenesis

We have examined isoperoxidase patterns obtained from buffer-, salt-, and enzyme-extractable fractions and correlated them with histological changes in tobacco (Nicotiana tabacum L., cv Wisc. 38) `epidermal' explants induced to produce either callus, vegetative buds, or floral buds. By utilizing a combination of extraction and electrophoretic procedures different from any hitherto used for this kind of investigation, we were able to resolve 47 isoperoxidases distributed between the three types of fractions. The majority of these isoperoxidases were common to all explants regardless of their developmental fate. Correspondingly, a number of histological changes were observed in all explants (e.g. the initiation of cell division by day 2, lignin deposition by day 4, and the formation of clustered tracheary elements by day 8). We have made correlations between 25 isoperoxidases and specific developmental events based on the time when certain isoperoxidases were detected relative to observed histological changes: 3 were correlated with desuppressed/sustained cell division, 3 to 6 with lignification/tracheary element maturation, 7 with callus formation, 1 with localized suppression of growth, 3 with determinate axial organization, 4 with leaf development, and 1 with stamen development. These results suggest that a continued investigation using this system could lead to a better understanding of the role of specific isoperoxidases in different developmental processes.     

Inflection points of cardiovascular responses and oxygenation are correlated in the distal but not the proximal portions of muscle during incremental exercise.

To test whether there is a regional difference in the exercise pressor reflex within a given muscle, we investigated the relationship between the inflection points of cardiovascular responses and muscle oxygenation during exercise. Seven subjects performed incremental exercise, which consisted of incremental 30-s static knee extensions, each separated by 30 s of recovery. The workload started at 5% maximal voluntary contraction (MVC) and increased by 5% MVC for each increment until exhaustion. Changes (Delta) in the concentrations (denoted by brackets) of oxygenated Hb (O2Hb) and deoxygenated Hb (HHb) were monitored in proximal and distal portions of the vastus lateralis by near-infrared spectroscopy. The inflection points of mean arterial pressure (MAP), calf vascular resistance (CVR), and muscle deoxygenation index (Delta[O2Hb-HHb]) were calculated as the intersection point of two regression equations obtained at lower and higher workloads. The inflection point of Delta[O2Hb-HHb] differed significantly between proximal and distal portions (28.5 +/- 3.0 vs. 39.5 +/- 3.0%MVC, P < 0.05). Linear regression analysis showed significant correlations between the inflection point of Delta[O2Hb-HHb] in the distal portion and MAP (r = 0.89; P < 0.01) and CVR (r = 0.89; P < 0.05), but no significant relationship between the inflection point in the proximal portion and MAP or CVR. These data show that the inflection point of muscle deoxygenation differs between proximal and distal portions within the vastus lateralis during incremental exercise and suggest that the distal portion of the vastus lateralis contributes more to the pressor response than does the proximal portion.     

Group testing for case identification with correlated responses

This article examines group testing procedures where units within a group (or pool) may be correlated. The expected number of tests per unit (i.e., efficiency) of hierarchical- and matrix-based procedures is derived based on a class of models of exchangeable binary random variables. The effect on efficiency of the arrangement of correlated units within pools is then examined. In general, when correlated units are arranged in the same pool, the expected number of tests per unit decreases, sometimes substantially, relative to arrangements that ignore information about correlation.     

Foot structure is correlated with performance in a single-joint jumping task

Variability in musculoskeletal structure has the potential to influence locomotor function. It has been shown, for example, that sprinters have smaller Achilles tendon moment arms and longer toes than non-sprinters, and toe length has been found to correlate with toe flexor work in running humans. These findings suggest that interindividual variation in human foot structure allows for function that is adapted to various motor tasks. The purpose of this study was to test for correlations between foot anthropometry and single-joint maximal-height jumping performance. Ten male subjects performed static jumps using only their ankles for propulsion. Several anthropometric measures were taken. Bivariate correlation analyses were performed between all anthropometric variables and the average jump height for each subject. Results showed that the best jumpers had longer lateral heel lengths (r = 0.871; p = 0.001) and longer toes (r = 0.712; p = 0.021). None of the other anthropometric variables (stature, mass, lower extremity lengths) measured were found to correlate significantly with jump height. A factor analysis was performed to investigate whether some underlying feature related to body stature could explain jumping performance. Taller subjects did not necessarily jump higher. Specific variations in foot structure, unrelated to other general stature measures, were associated with performance in this single-joint jumping task.     

Rates of protein evolution are positively correlated with developmental timing of expression during mouse spermatogenesis

Male reproductive genes often evolve very rapidly, and sexual selection is thought to be a primary force driving this divergence. We investigated the molecular evolution of 987 genes expressed at different times during mouse spermatogenesis to determine if the rate of evolution and the intensity of positive selection vary across stages of male gamete development. Using mouse-rat orthologs, we found that rates of protein evolution were positively correlated with the developmental timing of expression. Genes expressed early in spermatogenesis had rates of divergence similar to the genome median, while genes expressed after the onset of meiosis were found to evolve much more quickly. Rates of protein evolution were fastest for genes expressed during the dramatic morphogenesis of round spermatids into spermatozoa. Late-expressed genes were also more likely to be specific to the male germline. To test for evidence of positive selection, we analyzed the ratio of nonsynonymous to synonymous changes using a maximum likelihood framework in comparisons among mouse, rat, and human. Many genes showed evidence of positive selection, and most of these genes were expressed late in spermatogenesis and were testis specific. Overall, these data suggest that the intensity of positive selection associated with the evolution of male gametes varies considerably across development and acts primarily on phenotypes that develop late in spermatogenesis.     

Biologically constrained action selection improves cognitive control in a model of the Stroop task

The Stroop task is a paradigmatic psychological task for investigating stimulus conflict and the effect this has on response selection. The model of Cohen et al. (Cohen et al. 1990 Psychol. Rev. 97, 332-361) has hitherto provided the best account of performance in the Stroop task, but there remains certain key data that it fails to match. We show that this failure is due to the mechanism used to perform final response selection-one based on the diffusion model of choice behaviour (Ratcliff 1978 Psychol. Rev. 85, 59-108). We adapt the model to use a selection mechanism which is based on the putative human locus of final response selection, the basal ganglia/thalamo-cortical complex (Redgrave et al. 1999 Neuroscience 89, 1009-1023). This improves the match to the core human data and, additionally, makes it possible for the model to accommodate, in a principled way, additional mechanisms of cognitive control that enable better fits to the data. This work prompts a critique of the diffusion model as a mechanism of response selection, and the features that any response mechanism must possess to provide adaptive action selection. We conclude that the consideration of biologically constrained solutions to the action selection problem is vital to the understanding and improvement of cognitive models of response selection.     

Basic chitinases are correlated with the morphogenic response of flax cells

Flax ( Linum usitatissimum ) hypocotyl protoplasts immobilized in a calcium‐alginate matrix give rise to embryo‐like structures. A direct correlation was established between the presence of a set of ionically‐bound cell wall proteins, which includes the basic polypeptides P184 and P183 with an apparent molecular mass of 25 kDa, and this morphogenic response. Microsequencing of tryptic fragments from P184 and P183 indicated homologies with the chitinase family. These homologies were confirmed by demonstrating that, after renaturation, such proteins express a potential chitinase activity in SDS‐PAGE gel containing glycol chitin as synthetic substrate. Using degenerate primers from P184 internal sequences, we isolated one partial genomic sequence of a chitinase of 626 bp from which a putative 74‐amino acid sequence, disrupted by one intron, was deduced. High degrees of homology with several plant chitinases, including those expressed during somatic embryogenesis or in seeds, were observed. P184 microsequences match the corresponding sequence deduced from the chitinase PCR‐fragment perfectly.     

Mtu1 defects are correlated with reduced osteogenic differentiation

Accumulating evidence has revealed that mitochondria dynamics and function regulation is essential for the successful mesenchymal stem cell (MSC) differentiation. In the present study, the researchers reported for the first time that Mtu1 defects are correlated with reduced osteogenic differentiation. Using in vitro cultured bone marrow MSCs and stromal cell line MS5, we demonstrated that depressed Mtu1 expression was associated with reduced 2-thiouridine modification of the U34 of mitochondrial tRNA^Gln, tRNA^Glu, and tRNA^Lys, which led to respiratory deficiencies and reduced mitochondrial ATP production, and finally suppressed osteogenic differentiation. As expected, these Mtu1-deficient mice exhibited obvious osteopenia. Therefore, our findings in this study provide new insights into the pathophysiology of osteopenia.Subject terms: Cell biology, Post-translational modifications, Mesenchymal stem cells