Colonic sensitivity in irritable bowel syndrome and normal subjects according to their hemispheric preference and cognitive style.

According to our earlier results, non-painful, weak afferent visceral signals may exert a steady influence on brain processes, including cognitive functions. In the present series colonic impulses of irritable bowel syndrome (IBS) subjects served as a model of chronic impact from the gut. Hemispheric preference, as well as cognitive style of information processing served as indicators of covert changes in brain functions. In twenty-one IBS patients and in ten control subjects of both sexes, the thresholds of minimal colonic distension sensitivity has been measured following the determination of hemispheric preference and of advantage in verbal or spatial information processing of the subjects. In IBS patients distension thresholds proved to be higher in verbals than in spatials, whereas in healthy controls the relationship of colonic thresholds and verbal versus spatial advantage was reversed. Among the normal controls with left hemisphere preference a significantly higher distension threshold has been observed than in those with right hemisphere preference, whereas in the IBS group such threshold-differences were not observable.     

Cerebral lateralization of spatial abilities: a meta-analysis

There is a substantial disagreement in the existing literature regarding which hemisphere of the brain controls spatial abilities. In an attempt to resolve this dispute, we conducted a meta-analysis to decipher which hemisphere truly dominates and under what circumstances. It was found that across people and situations, the right hemisphere is the more dominant for spatial processing. However, consideration of specific moderator variables yielded a more complex picture. For example, females showed no hemisphere preference while males showed a right hemisphere advantage. Also, no hemisphere preference was indicated for spatial visualization tasks while subjects performing spatial orientation and manual manipulation tasks displayed a predictable right hemisphere preference. These findings are discussed in terms of their implications for exiting theoretical positions as well as future empirical research.     

Individual differences in spatial relation processing: effects of strategy, ability, and gender

Numerous studies have focused on the distinction between categorical and coordinate spatial relations. Categorical relations are propositional and abstract, and often related to a left hemisphere advantage. Coordinate relations specify the metric information of the relative locations of objects, and can be linked to right hemisphere processing. Yet, not all studies have reported such a clear double dissociation; in particular the categorical left hemisphere advantage is not always reported. In the current study we investigated whether verbal and spatial strategies, verbal and spatial cognitive abilities, and gender could account for the discrepancies observed in hemispheric lateralization of spatial relations. Seventy-five participants performed two visual half field, match-to-sample tasks (Van der Ham, van Wezel, Oleksiak, & Postma, 2007; Van der Ham, Raemaekers, van Wezel, Oleksiak, and Postma, 2009) to study the lateralization of categorical and coordinate relation processing. For each participant we determined the strategy they used in each of the two tasks. Consistent with previous findings, we found an overall categorical left hemisphere advantage and coordinate right hemisphere advantage. The lateralization pattern was affected selectively by the degree to which participants used a spatial strategy and by none of the other variables (i.e., verbal strategy, cognitive abilities, and gender). Critically, the categorical left hemisphere advantage was observed only for participants that relied strongly on a spatial strategy. This result is another piece of evidence that categorical spatial relation processing relies on spatial and not verbal processes.     

Position Location on Topographical Maps: Effects of Task Factors,Training, and Strategies

There is little research on the ways people go about the very common task of extracting information from various forms of maps. In this study, we examined task factors, cognitive processes, and individual differences as determinants of performance differences when locating a position on a topographical map from a given position on the ground. Subjects for the study were 188 Australian Army personnel. Both spatial visualization ability and a visual learning style preference were found to be effective predictors of performance, whereas a form of verbal strategy training produced significantly improved performance. When no effective strategy was supplied, those subjects with a strong visual learning style preference performed dramatically better than their low-preference counterparts, suggesting that this form of processing preference may have a powerful impact on untrained performance. These results indicate that most subjects usually approach the task of map reading in a relatively passive way, without any coherent strategy, and then attempt to encode information using inefficient spatial codes. When a simple and effective verbal strategy was supplied, most subjects were able to adopt it, with uniformly beneficial, results. This suggests that performance on many spatial tasks could be improved by verbal strategy training.     

Look over there! Unilateral gaze increases geographical memory of the 50 United States

Based on their specialized processing abilities, the left and right hemispheres of the brain may not contribute equally to recall of general world knowledge. US college students recalled the verbal names and spatial locations of the 50 US states while sustaining leftward or rightward unilateral gaze, a procedure that selectively activates the contralateral hemisphere. Compared to a no-unilateral gaze control, right gaze/left hemisphere activation resulted in better recall, demonstrating left hemisphere superiority in recall of general world knowledge and offering equivocal support for the hemispheric encoding asymmetry model of memory. Unilateral gaze- regardless of direction- improved recall of spatial, but not verbal, information. Future research could investigate the conditions under which unilateral gaze increases recall. Sustained unilateral gaze can be used as a simple, inexpensive, means for testing theories of hemispheric specialization of cognitive functions. Results support an overall deficit in US geographical knowledge in undergraduate college students.     

Individual differences in cognitive strategy and personality traits as measured by the Sixteen Personality Factor Questionnaire

The relationship between personality and preference for use of the right or left hemisphere of the brain in cognitive processing was investigated. Lateral eye movements were recorded as 50 female and 20 male right-handed subjects considered questions requiring reflection. The questions were not obviously "verbal" or "spatial" in nature but did require differing levels of reflection. Questions requiring higher levels of reflection produced a higher rate of lateral eye movement responses. Percent right eye movement for individual subjects was then correlated with scores on the Sixteen Personality Factor Questionnaire, using both first-order factors and the second-order factor Cortertia, which has some face validity as describing the personality generally ascribed to those who produce mostly right lateral eye movements. No correlation was found between the preferred directions of eye movements and 16 PF factors, which suggests that the lateral eye movements reflect thinking and problem-solving strategies but are not associated with personality styles.     

An fMRI study of phonological and spatial working memory using identical stimuli

The aim of the present fMRI study was to localize brain areas that were uniquely activated for phonological versus spatial working memory. Previous studies have reported inconsistent results, most likely because of methodological heterogeneity varying both stimuli and instructions in the same study. Here, identical consonant-vowel-consonant non-words were visually presented to the subjects in a 2-back paradigm under two different instructions; the subjects either had to memorize the non-words per se or their location. The results give evidence for a hemispheric organization of working memory, with dominance for processing of phonological information in the left hemisphere and frontal cortex, and spatial information in the right hemisphere and parietal cortex. The results also reflect a certain overlap between the neuronal network for working memory and processing of verbal and spatial material. These findings are discussed with regard to processing specificity and the extent that activated areas also may reflect perceptual processes.     

人类工作记忆的某些神经影像研究

采用神经影像技术研究人类工作记忆的脑机理是目前一个十分活跃的研究领域。研究表明存在负责不同信息加工的工作记忆系统 ,如词语工作记忆、空间工作记忆等 ,其中词语工作记忆主要由大脑左半球参与 ,空间工作记忆主要由大脑右半球参与。前额叶在工作记忆中的作用相当复杂 ,包括对记忆信息的注意和抑制、管理、整合等功能。合理巧妙的实验设计、多种研究手段的综合应用必将使人类工作记忆的脑机理得到充分阐明。     

Seeing either the forest or the trees: dissociation in visuospatial processing

Traditionally, visuospatial processing has resisted fractionation into functional substrates. Recently, however, it has been shown that the brain honors the distinction between global and local processing of hierarchical visual stimuli: unilateral left hemisphere brain-damaged subjects were impaired in their ability to draw the local forms of a hierarchical design, whereas right hemisphere-damaged patients demonstrated the opposite pattern (Delis, Robertson, & Efron, 1986; Delis, Kiefner, & Fridlund, 1988). The present study reports a similar pronounced dissociation in hierarchical visual processing but in quite different populations and in the absence of focal structural brain damage. Mentally retarded subjects with Williams Syndrome are considerably more impaired in global relative to local analysis, whereas subjects with Down Syndrome display the opposite pattern. These results, in concert with other neuropsychological data, are provocative because they suggest that certain cognitive deficits may cluster even in the absence of frank cerebral damage, just as they cluster following insult to one hemisphere. These findings should provide clues to the interrelationship of components of visuospatial processing and other cognitive functions.     

Discourse deficits following right hemisphere damage in deaf signers

Previous findings have demonstrated that hemispheric organization in deaf users of American Sign Language (ASL) parallels that of the hearing population, with the left hemisphere showing dominance for grammatical linguistic functions and the right hemisphere showing specialization for non-linguistic spatial functions. The present study addresses two further questions: first, do extra-grammatical discourse functions in deaf signers show the same right-hemisphere dominance observed for discourse functions in hearing subjects; and second, do discourse functions in ASL that employ spatial relations depend upon more general intact spatial cognitive abilities? We report findings from two right-hemisphere damaged deaf signers, both of whom show disruption of discourse functions in absence of any disruption of grammatical functions. The exact nature of the disruption differs for the two subjects, however. Subject AR shows difficulty in maintaining topical coherence, while SJ shows difficulty in employing spatial discourse devices. Further, the two subjects are equally impaired on non-linguistic spatial tasks, indicating that spared spatial discourse functions can occur even when more general spatial cognition is disrupted. We conclude that, as in the hearing population, discourse functions involve the right hemisphere; that distinct discourse functions can be dissociated from one another in ASL; and that brain organization for linguistic spatial devices is driven by its functional role in language processing, rather than by its surface, spatial characteristics.     

HEMISPHERE FUNCTION AND SPATIAL ABILITY: AN EXPLORATORY STUDY OF SEX AND CULTURAL DIFFERENCES

Three experiments investigated performance as a function of the visual hemifield to which verbal and spatial stimuli were presented tachistoscopically. The aim was to relate laterality effects to individual, sex and cultural differences in spatial ability within the framework of a model of hemispheric specialisation. A left-hemisphere advantage for verbal materials was obtained but no advantage for right-hemisphere presentation of visuospatial information occurred in the following samples: British and Ghanaian (experiment 1), high and low spatial ability groups (experiment 2) and males and females (experiment 3). Traditional spatial ability tests had no predictive value for performance on the tachistocopic tasks and an interaction between presentation field and responding hand was interpreted as implying equivalent processing of spatial information in either hemisphere.     

Simultaneity in Processing of Verbal and Spatial Information

Recent studies involving recall of verbal and spatial information produced conflicting results. In some cases investigators found males recalled verbal and spatial information equally well whereas females did less well on spatial than verbal information, but in other cases no sex differences were found. They also differed in that one study found processing of verbal and spatial information to be independent whereas others suggested trade-offs might occur. Using college-age subjects (17-25 yrs) with equal numbers of males and females (total n = 186) two experiments were performed to examine these differences. Although overall differences were found favoring verbal recall, females’ recall of spatial information was relatively poorer than males. Using a procedure designed to avoid possible artifactual depression of combined performance, we concluded that processing of spatial and verbal information is simultaneous in nature.

     

Writing induces a right hemisphere linguistic advantage in dysphonetic dyslexic children: implications for attention and capacity models of laterality

An experiment demonstrated a complete hemispheric processing reversal in 10 male, dysphonetic dyslexic children that occurred during a dichotic listening test of their verbal working memory. Requiring a written response to dichotic digits produced a right hemisphere/left ear superiority in the dysphonetic dyslexics whereas normal subjects and other dyslexics maintained a left hemisphere/right ear advantage. This reversal was unaffected by changes in task difficulty. A second experiment assessed the influence on producing the reversal of concurrent manual interference with left hemisphere verbal processing (responding orally vs. manually) and selective right hemisphere priming (Forward Writing vs. Backward Writing). The dysphonetic children reverted to a strong left hemisphere superiority when recalling the dichotic digits orally. Backward writing produced no ear advantage in either direction. The findings suggest that dysphonetic dyslexia may be related to (1) left hemisphere processing demands that exceed capacity, (2) easily activated right hemisphere processing strategies and (3) failure to coordinate linguistic processing interhemispherically. The results supported a novel hybrid conceptualization of dyslexia consisting of a synthesis of selective activation, and dual processor-limited capacity, theories.     

The role of instruction preference in analogy learning: Brain activity and motor performance

This study examined the role of verbal instruction preference when learning motor skills by analogy. During skill learning, analogies are a useful tool for providing knowledge about how to move. It has been argued that analogy instructions reduce reliance on verbal information processes during motor planning, compared to traditional forms of instruction (i.e., explicit rules about how to move). This may be reflected by reduced verbal activity in the brain, measured by EEG alpha power at the temporal region, as well as reduced verbal-motor cross-communication (EEG T7-Fz coherence) during the preparation phase of a movement. Preference for using verbal or visual instructions is likely to influence the efficacy of analogy instructions. This study investigated whether preference for verbal instructions was related to a) changes in performance and b) changes in verbal-cognitive information processing during performance of an adapted basketball task after instruction by analogy. Basketball novices with a high preference for verbal instructions (n = 15) showed significantly decreased activation of verbal brain regions when they used the analogy (high-alpha power), but their performance remained stable. Novices with a low preference for verbal instructions (n = 13) did not show a significant decrease in activation of verbal regions, and their performance deteriorated significantly after introduction of the analogy instruction. It is likely that both cognitive and performance changes after analogy instruction depend on personal aspects of information processing, such as verbal preference.     

熟练双语者负性情绪干扰下的认知优势效应:来自2-back的证据

熟练双语者在空间工作记忆中存在认知优势,但是在负性情绪干扰下熟练双语者在空间工作记忆中是否存在认知优势尚不清楚。空间工作记忆和负性情绪均以大脑右半球为优势脑区,加工效能理论认为空间工作记忆和负性情绪的加工使用同样的认知资源。研究采用情绪空间2-back任务,探究在负性情绪刺激干扰下的空间工作记忆任务中熟练双语者是否存在认知优势。结果表明,熟练双语者在该任务中表现出比非熟练双语者更高的正确率和更短的反应时。这一结果说明,尽管存在负性情绪刺激的干扰,相比非熟练双语者,熟练双语者在空间工作记忆中仍然表现出了认知优势。     

认知风格影响框架效应的ERP研究

采用ERP方法,考察了不同认知风格被试在决策过程中的框架效应。分析的脑电成分为N200和P300成分。结果发现：场依存者的反应时显著高于场独立者;场依存者诱发的N200和P300平均波幅均显著低于场独立者;大脑右半球的N200和P300平均波幅均显著高于左半球。这些结果表明,场独立者在决策过程中更具有理性,基本不受决策问题表述方式的影响,且该决策过程主要发生在大脑的右半球。     

Perceptual asymmetry for chimeric stimuli in children with early unilateral brain damage

The present study used a chimeric stimuli task to assess the magnitude of the left-hemispace bias in children with congenital unilateral brain damage (n = 46) as compared to typically developing matched controls (n = 46). As would be expected, controls exhibited a significant left-hemispace bias. In the presence of left hemisphere (LH) damage, the left-hemispace preference was found to be present, but attenuated, whereas right hemisphere (RH) damage resulted in a less lateralized process. Examination of lesion severity revealed that large lesions in the RH were associated with a reversal of the typical left-hemispace bias, while small lesions resulted in a left bias approximating that of controls. In contrast, the left-hemispace preference in children with LH damage was similar across lesion size. We conclude that damage to either hemisphere early in brain development may alter hemispheric preference for processing of nonverbal stimuli, and that at least in the case of RH damage, alteration of the normal perceptual asymmetry may depend on the interaction between lesion side and severity.     

Concurrent Verbal and Emotion Laterality Effects Exhibited by Normally Achieving and Learning Disabled Children

This study assessed both left- and right-hemisphere functions simultaneously when two-syllable words differing only in the initial stop consonant and spoken in different emotional tones were paired dichotically. Seventy-two right-handed normally achieving children, 12 boys and 12 girls at each of grades 1, 3, and 5, were instructed to detect either the presence of a specific word or of a specific emotion. In addition, 30 right-handed learning disabled (LD) children (age-matched to the normal controls) were assessed to determine whether LD children distribute verbal and nonverbal functions to different hemispheres. Results indicated that although both control and LD children demonstrated an overall REA for word stimuli and an LEA for emotional stimuli, and that emotional stimuli were easier to process than word stimuli, LD children were less accurate in processing both types of stimuli than their control counterparts. ‘Complementary specialization,’ as assessed through distribution of laterality effects, was found to be greater for control children than for LD children. However, the lack of consistency in complementary specialization found among the three developmental grade levels may be indicative that independent brain mechanisms underlying verbal and emotional processing have yet to be fully established in children. Further, in contrast to adult findings, a larger LEA was obtained for the emotion ‘happy’ than for the emotion ‘sad.’ It was concluded that whereas independent hemisphere processing for words and emotions is somewhat prevalent for control children, LD children might not be as strongly lateralized for opposite hemisphere processing of these functions.     

Concurrent verbal and emotion laterality effects exhibited by normally achieving and learning disabled children.

This study assessed both left- and right-hemisphere functions simultaneously when two-syllable words differing only in the initial stop consonant and spoken in different emotional tones were paired dichotically. Seventy-two right-handed normally achieving children, 12 boys and 12 girls at each of grades 1, 3, and 5, were instructed to detect either the presence of a specific word or of a specific emotion. In addition, 30 right-handed learning disabled (LD) children (age-matched to the normal controls) were assessed to determine whether LD children distribute verbal and nonverbal functions to different hemispheres. Results indicated that although both control and LD children demonstrated an overall REA for word stimuli and an LEA for emotional stimuli, and that emotional stimuli were easier to process than word stimuli, LD children were less accurate in processing both types of stimuli than their control counterparts. 'Complementary specialization,' as assessed through distribution of laterality effects, was found to be greater for control children than for LD children. However, the lack of consistency in complementary specialization found among the three developmental grade levels may be indicative that independent brain mechanisms underlying verbal and emotional processing have yet to be fully established in children. Further, in contrast to adult findings, a larger LEA was obtained for the emotion 'happy' than for the emotion 'sad.' It was concluded that whereas independent hemisphere processing for words and emotions is somewhat prevalent for control children, LD children might not be as strongly lateralized for opposite hemisphere processing of these functions.     

The influence of cognitive styles and strategies in the digit span backwards task: Effects on performance and neuronal activity

The way information is processed in the brain varies strongly between individuals. A prominent distinction is made between visual and verbal processing in everyday-life as well as concrete tasks at hand. To investigate the role of routinely-used cognitive styles and task-specific cognitive strategies, n = 40 participants were presented with the digit span backwards task - which is widely used as a measure of working memory capacity - with acoustically or optically presented stimuli. In a dual task condition, the participants had to remember both an acoustically and an optically presented digit series. The task specific cognitive strategy was predictive for dual task performance, while the habitual cognitive style was not. Also, the preference for a verbal or visual cognitive style was not associated with the task specific strategy, indicating that a visual or verbal strategy can be adapted deliberately in order to perform the task at hand. Functional magnetic resonance imaging showed that a verbal processing style is associated with higher activation in the middle frontal gyrus, which is crucial for working memory performance. The results indicate that a verbal processing style is associated with more effort, possibly due to the adaptation of a task-specific strategy.