“右好左坏”和“左好右坏”——利手与左右空间情感效价的关联性

人们会将“右”和“左”与积极或消极的事物相关联,这称为左右空间的情感效价.以具身认知理论和躯体特异性假设为基础的研究发现,右利手会将右侧空间与积极事物相关联,而左利手则会将左侧空间与积极事物相关连;左右空间情感效价是由利手与非利手的运动经验塑造的;利手与非利手运动经验的改变则会反转左右空间情感效价;趋近动机脑功能偏侧化与利手是一致的.未来的研究应进一步澄清利手运动与趋近动机在神经机制上的关联性,并探索文化因素与身体经验如何共同塑造左右空间情感效价.     

From the left to the right: How the brain compensates progressive loss of language function

In normal right-handed subjects language production usually is a function oft the left brain hemisphere. Patients with aphasia following brain damage to the left hemisphere have a considerable potential to compensate for the loss of this function. Sometimes, but not always, areas of the right hemisphere which are homologous to language areas of the left hemisphere in normal subjects are successfully employed for compensation but this integration process may need time to develop. We investigated right-handed patients with left hemisphere brain tumors as a model of continuously progressive brain damage to left hemisphere language areas using functional neuroimaging and transcranial magnetic stimulation (TMS) to identify factors which determine successful compensation of lost language function. Only patients with slowly progressing brain lesions recovered right-sided language function as detected by TMS. In patients with rapidly progressive lesions no right-sided language function was found and language performance was linearly correlated with the lateralization of language related brain activation to the left hemisphere. It can thus be concluded that time is the factor which determines successful integration of the right hemisphere into the language network for compensation of lost left hemisphere language function.     

Neurology of affective prosody and its functional-anatomic organization in right hemisphere

Unlike the aphasic syndromes, the organization of affective prosody in brain has remained controversial because affective-prosodic deficits may occur after left or right brain damage. However, different patterns of deficits are observed following left and right brain damage that suggest affective prosody is a dominant and lateralized function of the right hemisphere. Using the Aprosodia Battery, which was developed to differentiate left and right hemisphere patterns of affective-prosodic deficits, functional-anatomic evidence is presented in patients with focal ischemic strokes to support the concepts that (1) affective prosody is a dominant and lateralized function of the right hemisphere, (2) the intrahemispheric organization of affective prosody in the right hemisphere, with the partial exception of Repetition, is analogous to the organization of propositional language in the left hemisphere and (3) the aprosodic syndromes are cortically based as part of evolutionary adaptations underlying human language and communication.     

Neurodevelopmental differences in emotional prosody in normal children and children with left and right temporal lobe epilepsy

Emotional prosody, which has been defined as the emotional aspects of speech which communicate pleasure, fear, sorrow, anger, etc., has been demonstrated to be primarily a function of the nondominant hemisphere (typically, the right hemisphere) in adult populations. However, few researchers have addressed the developmental or lateralized nature of emotional prosody in children. In this study, an instrument was developed to measure the receptive aspects of emotional prosody in pediatric populations and administered to normal children ages 6 to 11 years old. An analysis of variance revealed significant age-related differences. Additionally, the instrument was administered to 12 children with right temporal lobe epilepsy and 11 children with left temporal lobe epilepsy. Analysis of variance indicated that there was no significant difference in scores between the left temporal and right temporal lobe groups. However, right temporal epileptic patients scored significantly lower than normal children on all sections of the instrument, suggesting that in children like adults, the right temporal lobe may be dominant with respect to the receptive aspects of emotional prosody.     

Neural correlates of feigned memory impairment are distinguishable from answering randomly and answering incorrectly: an fMRI and behavioral study

Previous functional magnetic resonance imaging (fMRI) studies have identified activation in the prefrontal-parietal-sub-cortical circuit during feigned memory impairment when comparing with truthful telling. Here, we used fMRI to determine whether neural activity can differentiate between answering correctly, answering randomly, answering incorrectly, and feigned memory impairment. In this study, 12 healthy subjects underwent block-design fMRI while they performed digit task of forced-choice format under four conditions: answering correctly, answering randomly, answering incorrectly, and simulated feigned memory impairment. There were three main results. First, six areas, including the left prefrontal cortex, the left superior temporal lobe, the right postcentral gyrus, the right superior parietal cortex, the right superior occipital cortex, and the right putamen, were significantly modulated by condition type. Second, for some areas, including the right superior parietal cortex, the right postcentral gyrus, the right superior occipital cortex, and the right putamen, brain activity was significantly greater in feigned memory impairment than answering randomly. Third, for the areas including the left prefrontal cortex and the right putamen, brain activity was significantly greater in feigned memory impairment than answering incorrectly. In contrast, for the left superior temporal lobe, brain activity was significantly greater in answering incorrectly than feigned memory impairment. The results suggest that neural correlates of feigned memory impairment are distinguishable from answering randomly and answering incorrectly in healthy subjects.     

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.     

From hand to mouth in the evolution of language: the influence of vocal behavior on lateralized hand use in manual gestures by chimpanzees (Pan troglodytes)

Studies in human subjects indicate that manual gestures accompanied by speech are produced more often by the right compared to the left hand. Additional studies indicate that the production of sign language is controlled by the same brain areas as speech, suggesting similar neurobiological substrates for language that are not modality specific. We report evidence that chimpanzees exhibit preferential use of the right hand in gestural communication. Moreover, use of the right hand in gestural communication is significantly enhanced when accompanied by a vocalization, particularly among human‐reared chimpanzees. Taken together, the data suggest that the lateralization of manual and speech systems of communication may date back as far as 5 million years ago.     

Right-handers' reaching in contralateral hemispace: a kinematic observation

C. Gabbard and C. Helbig (2004) found, when examining seated participants' limb selection for reaching and grasping in hemispace, that right-handers preferred to switch to the nondominant left arm for objects located approximately 20 degrees horizontally from body midline (90 degrees) in left hemispace. In the present study, the authors examined 13 strongly lateralized seated right-handers' kinematics of reaching to object positions ranging from body midline to 40 degrees horizontally in left hemispace. Participants executed faster reaches with the left arm than with the right arm to objects placed 20 degrees-40 degrees from midline, whereas they did not change the proportion of time they spent accelerating the hands when the position of the object changed. A 2nd main finding was an increase in the left hand's trajectory curvature as object position moved farther from midline, with a corresponding decrease in the contribution of upper-arm motion to the reach. Those observations suggest that the switch from dominant right-arm reaching to nondominant left-arm reaching in left hemispace reported in the aforementioned study may have emerged from a shift from a shoulder-driven reach to an elbow-driven action.     

Understanding the dorsal and ventral systems of the human cerebral cortex: beyond dichotomies

Traditionally, characterizations of the macrolevel functional organization of the human cerebral cortex have focused on the left and right cerebral hemispheres. However, the idea of left brain versus right brain functions has been shown to be an oversimplification. We argue here that a top-bottom divide, rather than a left-right divide, is a more fruitful way to organize human cortical brain functions. However, current characterizations of the functions of the dorsal (top) and ventral (bottom) systems have rested on dichotomies, namely where versus what and how versus what. We propose that characterizing information-processing systems leads to a better macrolevel organization of cortical function; specifically, we hypothesize that the dorsal system is driven by expectations and processes sequences, relations, and movement, whereas the ventral system categorizes stimuli in parallel, focuses on individual events, and processes object properties (such as shape in vision and pitch in audition). To test this hypothesis, we reviewed over 100 relevant studies in the human neuroimaging and neuropsychological literatures and coded them relative to 11 variables, some of which characterized our hypothesis and some of which characterized the previous dichotomies. The results of forward stepwise logistic regressions supported our characterization of the 2 systems and showed that this model predicted the empirical findings better than either the traditional dichotomies or a left-right difference.     

双侧梭状回面孔区在面孔加工中的功能分工与协作

梭状回面孔区(fusiform face area,FFA)是视觉皮层上专门加工面孔的区域。然而,双侧FFA在面孔加工中的功能分工与协作还存在争议。在特异性刺激的加工上,右侧FFA主要负责人类面孔类别的知觉,而左侧FFA的功能与面孔精细特征的感知有关;在皮层可塑性上,右侧FFA主要参与青少年的社会适应学习,而左侧FFA负责成年人的知觉学习;在面孔网络中,二者与不同区域的连接用以适应不同的认知需求;他们之间的有向协作具有任务特定性。未来研究需要回答三个问题:左侧FFA的可塑性程度及这一可塑性是否是认知特定的、左侧FFA及其形成的网络连接的认知意义,双侧FFA在面孔网络中的连接有向性等问题。     

听觉障碍人群的言语机制

对听觉障碍人群言语机制的研究,提供了独特的视角来探讨人脑内语言专门化系统的组织。该回顾了近年来在该领域内进行的损伤研究及功能性成像研究,着重综述了三个问题：(1)左右半球损伤造成的手语失语症的特点;(2)手语加工过程中左右半球的激活模式;(3)先天聋被试在阅读唇语过程中的脑内激活模式及后部扣带皮层在唇语阅读过程中的可能作用。     

Language acquisition following hemidecortication: Linguistic superiority of the left over the right hemisphere

The language development of three 9- and 10-year-old children possessing only a right or a left hemisphere was studied. Surgical removal of one brain half antedated the beginning of speech, so each child has acquired speech and language with only one hemisphere. Different configurations of language skill have developed in the two isolated hemispheres: phonemic and semantic abilities are similarly developed but syntactic competence has been asymmetrically acquired. In relation to the left, the right brain half is deficient in understanding auditory language, especially when meaning is conveyed by syntactic diversity; detecting and correcting errors of surface syntactic structure; repeating stylistically permuted sentences; producing tag questions which match the grammatical features of a heard statement; determining sentence implication; integrating semantic and syntactic information to replace missing pronouns; and performing judgments of word interrelationships in sentences. Language development in an isolated right hemisphere, even under seizure-free conditions, results in incomplete language acquisition.     

Selective loss of complex-pitch or speech discrimination after unilateral lesion

Twenty-eight right-handed patients who suffered a single cerebrovascular accident in the distribution of either the left or right middle cerebral artery were tested on their ability to discriminate complex-pitch and speech stimuli presented dichotically. Whereas the left hemisphere lesion group was impaired in dichotic speech but not in dichotic complex-pitch discrimination, the right hemisphere lesion group was impaired in dichotic complex pitch but not in dichotic speech discrimination. Complex-pitch phenomena may provide a useful model for the study of auditory function in the nondominant hemisphere.     

Asymmetric control of force and symmetric control of timing in bimanual finger tapping

An experiment was conducted to examine the control of force and timing in bimanual finger tapping. Participants were trained to produce both unimanual (left or right hand) and bimanual finger-tapping sequences with a peak force of 200 g and an intertap interval (ITI) of 400 ms. During practice, visual force feedback was provided pertaining to the hand performing the unimanual tapping sequences and to either the dominant or the nondominant hand in the bimanual tapping sequences. After practice, the participants produced the learned unimanual and bimanual tapping sequences in the absence of feedback. In those trials the force produced by the dominant (right) hand was significantly larger than that produced by the nondominant (left) hand, in the absence of a significant difference between the ITIs produced by both hands. Furthermore, after unilateral feedback had been provided of the force produced by the nondominant hand, the force output of the dominant hand was significantly more variable than that of the nondominant hand. In contrast, after feedback had been provided of the force produced by the dominant hand, the variability of the force outputs of the two hands did not differ significantly. These results were discussed in the light of both neurophysiological and anatomical findings, and were interpreted to imply that the control of timing (in bimanual tasks) may be more tightly coupled in the motor system than the control of force.     

Asymmetrical brain activity induced by voluntary spatial attention depends on the visual hemifield: a functional near-infrared spectroscopy study

The effect of the visual hemifield to which spatial attention was oriented on the activities of the posterior parietal and occipital visual cortices was examined using functional near-infrared spectroscopy in order to investigate the neural substrates of voluntary visuospatial attention. Our brain imaging data support the theory put forth in a previous psychophysical study, namely, the attentional resources for the left and right visual hemifields are distinct. Increasing the attentional load asymmetrically increased the brain activity. Increase in attentional load produced a greater increase in brain activity in the case of the left visual hemifield than in the case of the right visual hemifield. This asymmetry was observed in all the examined brain areas, including the right and left occipital and parietal cortices. These results suggest the existence of asymmetrical inhibitory interactions between the hemispheres and the presence of an extensive inhibitory network.     

Personality and the neural efficiency theory

The neural efficiency theory was formulated in the field of intelligence research and it posits that better performers require less brain activity to successfully perform a task of a given difficulty level. Here we suggest that in the field of personality research, the neural efficiency concept could be reformulated so that habitual behavior requires less brain activity. To test this hypothesis, 46 participants were presented with a social interactions task, in which they had to choose one out of three ways of interaction with a virtual ‘person’: ‘attack’, ‘avoid’, or ‘make friends’, while EEG was recorded simultaneously. Personality was assessed using the Eysenck Personality Profiler. Extraverts made more friendly choices and these choices were accompanied by smaller event-related theta synchronization in the left prefrontal cortex. Neuroticism did not show significant behavioral effects, but in high neuroticism scorers, the choice of avoidance was accompanied by smaller theta synchronization in the right prefrontal cortex. Psychoticism was positively associated with the number of aggressive choices and in high psychoticism scorers, these choices were accompanied by smaller theta synchronization in the left precentral cortex. These results are consistent with the extension of the neural efficiency concept for personality.     

Inter-individual variability in metacognitive ability for visuomotor performance and underlying brain structures

Metacognition refers to the ability to discriminate between one’s own correct and incorrect decisions. The neurobiological underpinnings of metacognition have mainly been studied in perceptual decision-making. Here we investigated whether differences in brain structure predict individual variability in metacognitive sensitivity for visuomotor performance. Participants had to draw straight trajectories toward visual targets, which could unpredictably deviate around detection threshold, report such deviations when detected, and rate their confidence level for such reports. Structural brain MRI analyses revealed that larger gray-matter volume (GMV) in the left middle occipital gyrus, left medial parietal cortex, and right postcentral gyrus predicted higher deviation detection sensitivity. By contrast, larger GMV in the right prefrontal cortex but also right anterior insula and right fusiform gyrus predicted higher metacognitive sensitivity. These results extend past research by linking metacognitive sensitivity for visuomotor behavior to brain areas involved in action agency (insula), executive control (prefrontal cortex) and vision (fusiform).     

The effects of musical practice on structural plasticity: The dynamics of grey matter changes

Intensive training and the acquisition of expertise are known to bring about structural changes in the brain. Musical training is a particularly interesting model. Previous studies have reported structural brain modifications in the auditory, motor and visuospatial areas of musicians compared with nonmusicians. The main goal of the present study was to go one step further, by exploring the dynamic of those structural brain changes related to musical experience. To this end, we conducted a regression study on 44 nonmusicians and amateur musicians with 0–26 years of musical practice of a variety instruments. We sought first to highlight brain areas that increased with the duration of practice and secondly distinguish (thanks to an ANOVA analysis) brain areas that undergo grey matter changes after only limited years of musical practice from those that require longer practice before they exhibit changes. Results revealed that musical training results a greater grey matter volumes in different brain areas for musicians. Changes appear gradually in the left hippocampus and right middle and superior frontal regions, but later also include the right insula and supplementary motor area and left superior temporal, and posterior cingulate areas. Given that all participants had the same age and that we controlled for age and education level, these results cannot be ascribed to normal brain maturation. Instead, they support the notion that musical training could induce dynamic structural changes.     

The left: lateral eye movements and ideology.

The lateral eye movements of 24 college students were videotaped as they reflected on spatial and analytical questions. As predicted, participants with more initial movements to the left had significantly higher scores on the leftist (or humanistic) index of the Tomkin's Polarity Scale. The direction of this relationship was reversed for the rightist index (right movers scoring higher) but this difference was not significant. Results are interpreted as additions to evidence which suggests a connection between the left and right sides of the human body and more global dichotomies of ideology or personality.     

The Use of Non-invasive Brain Stimulation Techniques to Facilitate Recovery from Post-stroke Aphasia

Aphasia is a common symptom after left hemispheric stroke. Neuroimaging techniques over the last 10–15 years have described two general trends: Patients with small left hemisphere strokes tend to recruit perilesional areas, while patients with large left hemisphere lesions recruit mainly homotopic regions in the right hemisphere. Non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) have been employed to facilitate recovery by stimulating lesional and contralesional regions. The majority of these brain stimulation studies have attempted to block homotopic regions in the right posterior inferior frontal gyrus (IFG) to affect a presumed disinhibited right IFG (triangular portion). Other studies have used anodal or excitatory tDCS to stimulate the contralesional (right) fronto-temporal region or parts of the intact left IFG and perilesional regions to improve speech-motor output. It remains unclear whether the interhemispheric disinhibition model, which is the basis for motor cortex stimulation studies, also applies to the language system. Future studies could address a number of issues, including: the effect of lesion location on current density distribution, timing of the intervention with regard to stroke onset, whether brain stimulation should be combined with behavioral therapy, and whether multiple brain sites should be stimulated. A better understanding of the predictors of recovery from natural outcome studies would also help to inform study design, and the selection of clinically meaningful outcome measures in future studies.