Premovement activity of the pre-supplementary motor area and the readiness for action: studies of time-resolved event-related functional MRI

The supplementary motor area (SMA) is thought to play in important role in the preparation and organisation of voluntary movement. It has long been known that cortical activity begins to increase up to 2s prior to voluntary self-initiated movement. This increasing premovement activity measured in EEG is known as the Bereitschaftspotential or readiness potential. Modern functional brain imaging methods, using event-related and time-resolved functional MRI techniques, are beginning to reveal the role of the SMA, and in particular the more anterior pre-SMA, in premovement activity associated with the readiness for action. In this paper we review recent studies using event-related time-resolved fMRI methods to examine the time-course of activation changes within the SMA throughout the preparation, readiness and execution of action. These studies suggest that the pre-SMA plays a common role in encoding or representing actions prior to our own voluntary self-initiated movements, during motor imagery, and from the observation of others' actions. We suggest that the pre-SMA generates and encodes motor representations which are then maintained in readiness for action.     

Time for action versus action in time: time estimation differs between motor preparation and execution

Theories relating to time perception and motor performance predict very different temporal distortions depending on the synchronisation or succession of temporal processing and motor behaviour. However, our knowledge about the temporal difference between motor preparation and execution is still scarce. In order to expand on prior studies, two different time reproduction tasks were utilised to measure motor preparation and motor execution. We found that motor preparation of a planned action allows participants to complete the time reproduction task more accurately and, in short duration trials, less variably than for motor execution. Furthermore, under-reproduction was found in motor preparation compared to motor execution, which may be caused by increased temporal information processing. According to the attentional gate theory, more attention allocated to time processing and reduced motor distraction leads to less temporal distortion in the motor preparation. The findings are also important for designing to study consciousness, temporal and visual processing.     

Colateralization of Broca's area and the visual word form area in left-handers: fMRI evidence

Language production has been found to be lateralized in the left hemisphere (LH) for 95% of right-handed people and about 75% of left-handers. The prevalence of atypical right hemispheric (RH) or bilateral lateralization for reading and colateralization of production with word reading laterality has never been tested in a large sample. In this study, we scanned 57 left-handers who had previously been identified as being clearly left (N = 30), bilateral (N = 7) or clearly right (N = 20) dominant for speech on the basis of fMRI activity in the inferior frontal gyrus (pars opercularis/pars triangularis) during a silent word generation task. They were asked to perform a lexical decision task, in which words were contrasted against checkerboards, to test the lateralization of reading in the ventral occipitotemporal region. Lateralization indices for both tasks correlated significantly (r = 0.59). The majority of subjects showed most activity during lexical decision in the hemisphere that was identified as their word production dominant hemisphere. However, more than half of the sample (N = 31) had bilateral activity for the lexical decision task without a clear dominant role for either the LH or RH, and three showed a crossed frontotemporal lateralization pattern. These findings have consequences for neurobiological models relating phonological and orthographic processes, and for lateralization measurements for clinical purposes.     

运动技能水平与躯体感觉输入对运动表象的影响

运动表象质量与运动技能水平有关,运动表象质量随着运动技能水平的提高而上升。器械使用可使人脑产生可塑性改变,使用者会将器械纳入身体图式。然而,两者影响运动表象的神经心理机制还不清楚。本研究采用功能性磁共振成像探析篮球运动员与新手在不同持球条件下表象投篮时脑功能活动的差异。结果表明运动员表象质量较好,镜像神经系统激活高于新手;持球条件下运动员表象质量显著高于不持球条件下,镜像神经系统激活程度显著低于不持球条件下。研究说明持器械可以显著提高运动员的表象质量,器械使用带来镜像神经系统的可塑性变化。     

Motor timing deficits in community and clinical boys with hyperactive behavior: the effect of methylphenidate on motor timing

In a previous paper we showed that community children with hyperactive behavior were more inconsistent than controls in the temporal organization of their motor output. In this study we investigated: (1) various aspects of motor timing processes in 13 clinically diagnosed boys with attention deficit hyperactivity disorder (ADHD) who were compared to 11 community boys with hyperactive behavior and to a control group and (2) the effect of methylphenidate on the motor timing processes in the clinical group with ADHD in a double blind, cross-over, medication-placebo design, including 4 weeks of medication. The clinical group with ADHD, like the community group with hyperactivity, showed greater variability in sensorimotor synchronization and in sensorimotor anticipation relative to controls. The clinical group was also impaired in time perception, which was spared in the community group with hyperactivity. The persistent, but not the acute dose, of methylphenidate reduced the variability of sensorimotor synchronization and anticipation, but had no effect on time perception. This study shows that motor timing functions are impaired in both clinical and community children with hyperactivity. It is the first study to show the effectiveness of persistent administration of methylphenidate on deficits in motor timing in ADHD children and extends the use of methylphenidate from the domain of attentional and inhibitory functions to the domain of executive motor timing.     

Alterations in error-related brain activity and post-error behavior over time

This study examines the relation between the error-related negativity (ERN) and post-error behavior over time in healthy young adults (N=61). Event-related brain potentials were collected during two sessions of an identical flanker task. Results indicated changes in ERN and post-error accuracy were related across task sessions, with more negative ERN associated with greater improvements in post-error accuracy. This relationship was independent of any cross-sectional relationships between overall task performance, individual difference factors, including personality and self-efficacy, and indices of self-regulatory action monitoring. These results indicate that the relation between ERN and post-error accuracy remains intact and consistent regardless of variation in this set of individual difference factors previously associated with both of these indices of self-regulatory action monitoring, providing support for the strength, robustness, and persistence of this relationship in the process of adaptively controlling behavior to enhance task performance.     

Early processing of emotional faces in children with autism: An event-related potential study

Social deficits are one of the most striking manifestations of autism spectrum disorders (ASDs). Among these social deficits, the recognition and understanding of emotional facial expressions has been widely reported to be affected in ASDs. We investigated emotional face processing in children with and without autism using event-related potentials (ERPs). High-functioning children with autism (n = 15, mean age = 10.5 ± 3.3 years) completed an implicit emotional task while visual ERPs were recorded. Two groups of typically developing children (chronological age-matched and verbal equivalent age-matched [both ns = 15, mean age = 7.7 ± 3.8 years]) also participated in this study. The early ERP responses to faces (P1 and N170) were delayed, and the P1 was smaller in children with autism than in typically developing children of the same chronological age, revealing that the first stages of emotional face processing are affected in autism. However, when matched by verbal equivalent age, only P1 amplitude remained affected in autism. Our results suggest that the emotional and facial processing difficulties in autism could start from atypicalities in visual perceptual processes involving rapid feedback to primary visual areas and subsequent holistic processing.     

The study of early emotion processing in the frontal area using a two-dipole source model

The present study explored early emotion processing in the frontal area using the two-dipole source model. The 21-channel recordings of event-related potentials (ERPs) produced by a pure tone were analyzed in order to assess information processing. In the test conditions, the pure tone followed the presentation of one of two unpleasant sounds to enhance anxiety. In the control condition, only the pure tone was presented. There were two groups of eight subjects, one with low scores for trait anxiety and one with high scores. The ERPs were separately averaged for the groups, as well as for the high- and low-anxiety sound and control session. A negative peak around 120 ms (C2) and a positive peak around 280 ms (C5) after stimulus onset were identified in all the sessions. The two-dipole source model was applied to these two components. In the C2 component, dipole sources were located in the left frontal area in the control sessions, and in the right frontal area in the high-anxiety sessions. This activation pattern was clearer in the group with low trait anxiety. In contrast, with the C5 component, lateralization of the dipole source in the frontal area was not seen. These findings suggest that the frontal area is involved in early emotion processing. A dual-stage model of emotion processing is therefore proposed.     

Individual differences in ERPs during mental rotation of characters: Lateralization,and performance level

The cognitive process of imaging an object turning around is called mental rotation. Many studies have been put forward analyzing mental rotation by means of event-related potentials (ERPs). Event-related potentials (ERPs) were measured during mental rotation of characters in a sample (N = 82) with a sufficient size to obtain even small effects. A bilateral ERP amplitude modulation as a function of angular displacement was observed at parietal leads without any lateralization. Sex had no effect on mental rotation of characters, neither with respect to performance nor with respect to brain potentials. When the sample was split into groups of high- and low-performers, however, the results indicated (a) in line with the idea of neural efficiency substantially larger amplitudes for low-performers; (b) that the smaller amplitudes of the high-performers involved larger parietal networks; and (c) a left-parietal disengagement of neural activity for high-performers but a right-parietal disengagement for low-performers. The latter finding became evident through an analysis of internal consistencies of ERP amplitudes across conditions and performance levels, showing that internal consistencies were reduced at all three leads in the high-performance group for the biggest rotation angle, relative the other conditions and the low-performing group.     

General and supplementary factors of personality in genetic and environmental correlation matrices

Genetic and environmental correlation matrices among 7 personality scales were estimated, using samples of adult and young adult twins from Australia (2081 and 1178 pairs, respectively). A general factor of personality and two supplemental factors were obtained in each. The supplemental factors were tentatively identified as Social conformity and Other-dependence. Factors from the genetic and environmental correlations replicated well across samples, and they were similar in both the genetic and environmental covariation. It was concluded that the structure of personality is inherent in the evolved phenotype, and is not the immediate consequence of either genetic or environmental organizing factors.     

Neurophysiology and neuroanatomy of reflexive and volitional saccades: evidence from studies of humans

This review provides a summary of the contributions made by human functional neuroimaging studies to the understanding of neural correlates of saccadic control. The generation of simple visually guided saccades (redirections of gaze to a visual stimulus or pro-saccades) and more complex volitional saccades require similar basic neural circuitry with additional neural regions supporting requisite higher level processes. The saccadic system has been studied extensively in non-human (e.g., single-unit recordings) and human (e.g., lesions and neuroimaging) primates. Considerable knowledge of this system’s functional neuroanatomy makes it useful for investigating models of cognitive control. The network involved in pro-saccade generation (by definition largely exogenously-driven) includes subcortical (striatum, thalamus, superior colliculus, and cerebellar vermis) and cortical (primary visual, extrastriate, and parietal cortices, and frontal and supplementary eye fields) structures. Activation in these regions is also observed during endogenously-driven voluntary saccades (e.g., anti-saccades, ocular motor delayed response or memory saccades, predictive tracking tasks and anticipatory saccades, and saccade sequencing), all of which require complex cognitive processes like inhibition and working memory. These additional requirements are supported by changes in neural activity in basic saccade circuitry and by recruitment of additional neural regions (such as prefrontal and anterior cingulate cortices). Activity in visual cortex is modulated as a function of task demands and may predict the type of saccade to be generated, perhaps via top-down control mechanisms. Neuroimaging studies suggest two foci of activation within FEF - medial and lateral - which may correspond to volitional and reflexive demands, respectively. Future research on saccade control could usefully (i) delineate important anatomical subdivisions that underlie functional differences, (ii) evaluate functional connectivity of anatomical regions supporting saccade generation using methods such as ICA and structural equation modeling, (iii) investigate how context affects behavior and brain activity, and (iv) use multi-modal neuroimaging to maximize spatial and temporal resolution.     

The Relative Dominance of Schemata in a Manual Tracking Task: Input Patterns,System Dynamics,and Movement Patterns

As subjects repeatedly track the same spatiotemporal pattern, they learn to anticipate the pattern and thereby to reduce their effective time delay. The successive organization of perception hypothesis suggests that subjects progress from an error-nulling mode to a pursuit mode, in which they respond to the estimated instantaneous input pattern, and then to a precognitive mode, in which they rely on memory of the input pattern or movement pattern. We used a transfer of training experiment involving position and rate control systems to distinguish among these strategies by determining the relative dominance of schemata for the input pattern, system dynamics, and movement pattern. Results indicated that subjects relied on a memorized movement pattern, which is characteristic of the precognitive mode. Adaptations of this transfer methodology may be useful in testing other theories that postulate multiple schemata for the control of perceptual-motor behavior.     

The relationship between motor development,gestures and language production in the second year of life: A mediational analysis

This longitudinal study investigated the relationships between motor, gestural and linguistic abilities using two parent report instruments. Motor skills at 12 months significantly correlated with language production at 16, 20 and 23 months, but these associations were mediated by the use of representational gestures.     

Developmental changes in memory: The effects of processing time and rehearsal instructions

An overt rehearsal procedure was used to investigate the relationship between children's rehearsal strategies and free recall performance. Previous work has shown that developmental differences in rehearsal content, rather than rehearsal frequency, affect recall performance. This experiment investigated the effects of increased processing time and rehearsal training upon recall. Third-grade girls (age 8) were able to use additional processing time to increase the activity of their rehearsal, and they showed corresponding improvement in recall. In contrast, third-grade boys (age 8) and sixth-grade boys and girls (age 12) did not take advantage of a slower presentation rate to rehearse more actively, and their recall did not change. Further, even without additional processing time, both the third-grade boys and girls were able to use an instructed active rehearsal strategy to facilitate their recall. The direct manipulation of rehearsal activity and the resulting improvement in recall provide experimental support for the proposed relationship between rehearsal content and recall from long-term memory store.     

Sex task and processing strategy effects in hemispheric alpha asymmetries for the recall and recognition of arousal words: results from perceptual and motor tasks in males and females

Hemispheric alpha asymmetries of males and females were observed during perceptual and motor tasks requiring recall and recognition of words controlled for level of arousal (positive, negative, and neutral). Verbal reports of individual processing strategy were collected and analyzed relative to hemispheric alpha ratios. Results showed greater alpha suppression in the left relative to right hemisphere for recall as compared to recognition tasks and for word presentation when contrasted with motor conditions. High positive correlations were found between narrative report of processing strategy and hemispheric alpha data. A separate analysis revealed that seven subjects identified as highly analytic processors showed greater alpha suppression in the left relative to right hemisphere across tasks, conditions, and stimuli than did seven highly visual processors who, in contrast, demonstrated greater right hemispheric alpha suppression. Task difficulty and individual differences in processing style that modify cerebral laterality effects are discussed.     

Placing inspection time, reaction time, and perceptual speed in the broader context of cognitive ability: The VPR model in the Lothian Birth Cohort 1936

The idea that information processing speed is related to cognitive ability has a long history. Much evidence has been amassed in its support, with respect to both individual differences in general intelligence and developmental trajectories. Two so-called elementary cognitive tasks, reaction time and inspection time, have been used to compile this evidence, but most studies have used either one or the other. Relations between speed and fluid intelligence have tended to be stronger than those between speed and crystallized intelligence, but studies testing this have confounded verbal abilities with crystallized intelligence and spatial/perceptual abilities with fluid intelligence. Questions have also been raised regarding whether speed contributes directly to general intelligence or to more specific cognitive abilities to which general intelligence also contributes. We used 18 ability and speed measures in the Lothian Birth Cohort 1936, assessed at approximately age 70, to construct alternative versions of the Verbal-Perceptual-Image Rotation (Johnson & Bouchard, 2005a) model of cognitive ability to test different hypotheses regarding these issues. Though differences in the extents to which our models fit the data were relatively small, they suggested that reaction and inspection time tasks were comparable indicators of information processing speed with respect to general intelligence, that verbal and spatial abilities were similarly related to information processing speed, and that spatial, verbal, and perceptual speed abilities were more directly related to information processing speed than was general intelligence. We discuss the theoretical implications of these results.     

Cognitive control of language production in bilinguals involves a partly independent process within the domain-general cognitive control network: evidence from task-switching and electrical brain activity

In highly proficient, early bilinguals, behavioural studies of the cost of switching language or task suggest qualitative differences between language control and domain-general cognitive control. By contrast, several neuroimaging studies have shown an overlap of the brain areas involved in language control and domain-general cognitive control. The current study measured both behavioural responses and event-related potentials (ERPs) from bilinguals who performed picture naming in single- or mixed-language contexts, as well as an alphanumeric categorisation task in single- or mixed-task context. Analysis of switch costs during the mixed-context conditions showed qualitative differences between language control and domain-general cognitive control. A 2 × 2 ANOVA of the ERPs, with domain (linguistic, alphanumeric) and context (single, mixed) as within-participant factors, revealed a significant interaction, which also suggests a partly independent language-control mechanism. Source estimations revealed the neural basis of this mechanism to be in bilateral frontal-temporal areas.     

The effects of music exposure and own genre preference on conscious and unconscious cognitive processes: a pilot ERP study

Did Beethoven and Mozart have more in common with each other than Clapton and Hendrix? The current research demonstrated the widely reported Mozart Effect as only partly significant. Event-related brain potentials (ERPs) were recorded from 16 professional classical and rock musicians during a standard 2 stimulus visual oddball task, while listening to classical and rock music. During the oddball task participants were required to discriminate between an infrequent target stimulus randomly embedded in a train of repetitive background or standard stimuli. Consistent with previous research, the P3 and N2 ERPs were elicited in response to the infrequent target stimuli. Own genre preference resulted in a reduction in amplitude of the P3 for classical musicians exposed to classical music and rock musicians exposed to rock music. Notably, at the pre-attentive stage of processing (N2) beneficial effects of exposure to classical music were observed for both groups of musicians. These data are discussed in terms of short and long-term music benefits on both conscious and unconscious cognitive processes.     

领导行为:企业并购整合研究的新方向

过去一个世纪以来,国际性兼并、收购和战略联盟急剧增多,然而大部分并购案例均以失败告终,无法达到其原定目标,有的甚至使企业陷入困境.导致并购失败的最主要原因是并购后的整合失败,并非战略与财政不当.领导行为在组织变革和组织再造过程中起着关键性作用,但其在组织并购整合过程中的作用却一直被研究者忽视.全球范围内并购浪潮的持续增长要求领导者迅速提升自身的应对能力,但领导在组织并购整合中的作用机制尚待深入研究.本文介绍了企业并购整合过程中所需的基本领导模式、相关研究的理论基础与方向,以期为提高并购整合活动的领导效力及深入研究提供参考.     

The golem: Uncertainty and communicating science

This paper elaborates on the golem metaphor as a way of understanding uncertainty in science. Its implications for the ethics of communicating science are explored.