Number conservation is related to children's prefrontal inhibitory control: an fMRI study of a piagetian task

Although young children can accurately determine that two rows contain the same number of coins when they are placed in a one-to-one correspondence, children younger than 7 years of age erroneously think that the longer row contains more coins when the coins in one of the rows are spread apart. To demonstrate that prefrontal inhibitory control is necessary to succeed at this task (Piaget's conservation-of-number task), we studied the relationship between the percentage of BOLD signal changes in the brain areas activated in this developmental task and behavioral performance on a Stroop task and a Backward Digit Span task. The level of activation in the right insula/inferior frontal gyrus was selectively related to inhibitory control efficiency (i.e., the Stroop task), whereas the activation in the left intraparietal sulcus (IPS) was selectively related to the ability to manipulate numerical information in working memory (i.e., the Backward Digit Span task). Taken together, the results indicate that to acquire number conservation, children's brains must not only activate the reversibility of cognitive operations (supported by the IPS) but also inhibit a misleading length-equal-number strategy (supported by the right insula/inferior frontal gyrus).     

Functional Brain Asymmetry and Individual Differences in Hand Preference in Early Ontogeny

This work was aimed at studying the brain mechanisms of hand preference in 10- to 11-month-old infants. According to the results of neuropsychological investigations, the preference for the right hand in children of this age (at the populational level) primarily arises in actions that demand involvement of the functions of planning and motor control of reaching (functions of the motor control of reaching: FMCR) for an object. The stage of development of the FMCR in each child was scored on the Diamond scale. Total numbers of movements performed by the right and left hands and a coefficient of the manual asymmetry (AC) were calculated. On the basis of quartile analysis of the AC distribution, groups of right-handers, left-handers, and ambidextrals were formed. The EEG was recorded in the state of visual focused attention, and the spectral absolute amplitude density (AAD) of the sensorimotor rhythm and other infant EEG rhythms in the frequency band was analyzed. In order to estimate the statistical correlation of manual asymmetry, gender, and stage of development of the FMCR with functional asymmetry of the AAD of the -band rhythms in different cortical derivations, analysis of variance with factors of repeated measurements and analysis of multiple regression were used. The main results showed that 10- to 11-month-old children with different types of manual asymmetry differed in interhemispheric asymmetry of the visual attention-related EEG -band rhythms (including asymmetry of the sensorimotor rhythm). The maximum differences were observed in the lateral frontal and posterotemporal areas of the brain cortex. The leftward amplitude asymmetry was characteristic of right-handers; in left-handers and ambidextrals, the EEG amplitude was distributed over the brain hemispheres in a more symmetric way. The correlation between the brain and manual asymmetries was stronger in boys than in girls. There was a strict linear correlation between the degree of manual asymmetry and interhemispheric asymmetry of the EEG sensorimotor rhythm in the precentral and lateral frontal brain areas. On the whole, the close correlation of the manual asymmetry with functional asymmetry of the EEG sensorimotor rhythm suggests that it is determined by the formation of the brain FMCR lateralization.     

A study of correlates of hand preferences in squirrel monkeys (Saimiri sciureus)

The purpose of this study was to test the influence of sex, age, social rank, matriline membership, posture, and visual and tactual motor control on manual preferences inSaimiri sciureus. A well-established social group of 12 squirrel monkeys, aged 2 to 14 yrs and consisting of two matrilines with social rank known for each animal, was presented with four different food-reaching tasks and assessed for hand preferences with a minimum of 100 reaches per animal. Frequency of occurrence of hand preferences at the group level and degree of hand preferences at the individual level depended on posture and on whether the reaching act took place under visual or tactual guidance. Sex, age, social rank, and matriline membership were not found to determine frequency of occurrence, direction or degree of hand preferences with the exception of one task in which a significant negative correlation between the degree of hand preference and age was found. Nine out of 12 monkeys showed task-dependent changes in the hand they used preferentially while only three animals preferred the same hand in all four tasks. Significant preferences for the use of right or left hand on a given task were distributed almost equally between individuals. Thus, the results of this study suggest task-specific demands like posture and/or whether reaching was visually or tactually guided to be the major correlates of hand preferences in food-reaching tasks in squirrel monkeys.     

Black lemur (Lemur macaco) hand preference in food reaching

The present study assessed the hand preferences exhibited by 33 black lemurs during routine feeding. Individual animals displayed hand preferences that were consistent across observations separated by as much as seven months. Within this population, 20 were left hand preferent, 12 right preferent, and 1 was ambidextrous. Correlational analysis of age and percentage left hand use indicated an inverse relationship in which younger animals tended towards the preferential use of the left hand and older animals the preferential use of the right hand. Similar analysis found no relationship between either sex and hand preference or familial relationship and hand preference. The skewed distribution of age in this sample renders tentative conclusions regarding age-related variations in hand preference. It is suggested that if the hand preferences of the black lemur are not age-related, then this species may be characterized as having a bias towards the preferential use of the left hand for food reaching.     

Hand preference in capuchin monkeys varies with age

The purpose of this research was to examine the influence of age on hand preference in capuchin monkeys (Cebus apella). Twenty-two capuchins, aged 6 months to 30 years, were presented with a task that involved reaching for food and a task that involved using sponging tools to absorb juice. Adults exhibited a greater percentage of right-handed actions in each task than did immature subjects. Adults also exhibited a stronger lateral bias than did immature subjects in the sponging task. These results are consistent with hypotheses: a) adult capuchin monkeys are biased toward use of their right hand for reaching; b) adult capuchins exhibit a greater incidence of right-hand preference than do immature capuchins; and c) primates exhibit age-related differences in the strength and direction of hand preference in tasks that involve the use of tools.     

Hand Preference for a Novel Bimanual Coordinated Task During Termite Feeding in Wild Western Gorillas (<Emphasis Type="Italic">Gorilla gorilla gorilla</Emphasis>)

Although the level of handedness in humans varies cross-culturally, humans are generally described as right-handed, which has been considered a uniquely human trait. Recently, captive chimpanzees (Pan troglodytes) have been shown to exhibit right-hand preference when performing bimanual but not unimanual tasks. Less clear is whether this pattern also occurs in wild chimpanzees and other African apes. Using videos (N = 49) of six wild western gorillas (Gorilla gorilla gorilla) feeding on termites at the Mondika Research Center (Republic of Congo), we tested whether they exhibit hand preference when performing unimanual, i.e., reaching for termite mound pieces; bimanual, i.e., “termite tapping”: rhythmically shaking a piece of termite mound with the dominant hand and collecting the termites in the other hand tasks; or hand transfer prior to bimanual tasks, i.e., transferring a piece of termite mound from one hand to the other. All individuals exhibited exclusive hand preference when performing the bimanual tasks, with five of six gorillas preferring the right hand. Conversely, most individuals did not show any manual preference during the unimanual task. In addition, hand preference during hand transfer revealed clear hand dominance of similar strength and direction of those shown for the bimanual task, suggesting that this measure is as sensitive as the bimanual task itself. Thus, we propose “termite feeding” as a novel task to be considered in future hand-preference studies in wild western gorillas. Our results are in concordance with those for chimpanzees and captive gorillas showing hemispheric specialization for bimanual actions in apes.     

Hand preferences of captive chimpanzees (Pan troglodytes) in simple reaching for food

We examined chimpanzee hand preference in simple reaching for food, with special reference to manipulative patterns and the developmental shift. We observed 80 captive chimpanzees, ranging from 1 to 25 years old. We also studied the manipulative patterns (grip- types) of 70 individuals as they reached for raisins scattered randomly on the floor. We employed LQ score as a measure of hand preference and designated the subjects right- handers (or left- handers) if they used their right hands (left hands) above chance level. Although the numbers of right- handers and left- handers are almost equal, the distribution of the strength is not symmetrical in both groups. Strong preference was exhibited by more left- handers than right- handers. Subjects > 9 years old exhibited greater hand preference, whereas subjects < 9 years old were ambidextrous. We classified manipulative patterns for reaching into five basic grip- types and analyzed them vis- à- vis age. There is no significant correlation between preferred hand and manipulative patterns. However, adult subjects tended to use an index- and - middle- finger grip with the left hand and to use imprecise grips with the right hand more often than other patterns regardless which hand they preferred. These data demonstrate a developmental shift in hand preference and manipulative patterns and also reveal functional asymmetries between the right and the left hand in Pan troglodytes.     

Hand preferences of captive chimpanzees (Pan troglodytes) in simple reaching for food

We examined chimpanzee hand preference in simple reaching for food, with special reference to manipulative patterns and the developmental shift. We observed 80 captive chimpanzees, ranging from 1 to 25 years old. We also studied the manipulative patterns (grip- types) of 70 individuals as they reached for raisins scattered randomly on the floor. We employed LQ score as a measure of hand preference and designated the subjects right- handers (or left- handers) if they used their right hands (left hands) above chance level. Although the numbers of right- handers and left- handers are almost equal, the distribution of the strength is not symmetrical in both groups. Strong preference was exhibited by more left- handers than right- handers. Subjects > 9 years old exhibited greater hand preference, whereas subjects < 9 years old were ambidextrous. We classified manipulative patterns for reaching into five basic grip- types and analyzed them vis- à- vis age. There is no significant correlation between preferred hand and manipulative patterns. However, adult subjects tended to use an index- and - middle- finger grip with the left hand and to use imprecise grips with the right hand more often than other patterns regardless which hand they preferred. These data demonstrate a developmental shift in hand preference and manipulative patterns and also reveal functional asymmetries between the right and the left hand in Pan troglodytes.     

Lateral bias in feeding and brachiation inHylobates

Lateralized hand use in gibbons was assessed for both food reaching and leading limb in brachiation. Sex and age effects were found in hand preference for food reaching. Adult females were all very strongly right hand preferent, whereas adult males had no across group consistent preference. Within the female group there was a strong correlation between age and strength of right handedness. When compared in terms of absolute strength of hand preference, females were found to be more strongly lateralized than males. Leading limb preference in brachiation was scored into vocal and non-vocal categories. Three subjects had a shift in preferred leading limb from the non-vocal brachiation condition to the vocal brachiation condition. This shift may be influenced by the arousal effects of species typical vocalization. The results of this study underline the importance of consideration of such factors as sex and age when interpreting behavioral lateralization data. The exploration of laterality in many different response measures is important to the achievement of a complete understanding of behavioral lateralization in primates.     

Effects of upright posture on hand preference for reaching vs. the use of probing tools by tufted capuchins (Cebus apella)

This research examined the effects of task (reaching vs. Tool use) and posture (quadrupedal vs. bipedal) on hand preference in tufted capuchins (Cebus apella). Regarding direction of hand preference, we found a significant main effect of posture, as the bipedal stance elicited greater use of the right hand than did the quadrupedal stance, and a significant posture × task interaction, as bipedal reaching elicited greater use of the right hand than did other postural and task conditions. Further, we found a significant main effect of task on strength of hand preference, as tool use elicited more consistent use of one hand over the other than did reaching. Our findings indicate that bipedal reaching facilitates a mild right-hand bias in intensely manipulative primates. We speculate that this moderate bias may have been pushed in the direction of nearly exclusive right-hand preference in most humans with the development of complex tool use. Am. J. Primatol. 44:147–153, 1998. © 1998 Wiley-Liss, Inc. This article is a US Government work and, as such, is in the public domain in the United States of America.     

Bodily Illusions in Young Children: Developmental Change in Visual and Proprioceptive Contributions to Perceived Hand Position

We examined the visual capture of perceived hand position in forty-five 5- to 7-year-olds and in fifteen young adults, using a mirror illusion task. In this task, participants see their left hand on both the left and right (by virtue of a mirror placed at the midline facing the left arm, and obscuring the right). The accuracy of participants’ reaching was measured when proprioceptive and visual cues to the location of the right arm were put into conflict (by placing the arms at different distances from the mirror), and also when only proprioceptive information was available (i.e., when the mirror was covered). Children in all age-groups (and adults) made reaching errors in the mirror condition in accordance with the visually-specified illusory starting position of their hand indicating a visual capture of perceived hand position. Data analysis indicated that visual capture increased substantially up until 6 years of age. These findings are interpreted with respect to the development of the visual guidance of action in early childhood.     

Age-related features of the organization of motor activity in 6- to 16-year-old children

The use of the KID-3 diagnostic set for a large-scale examination of 6- to 16-year-old children helped reveal substantial age-related differences in the mechanisms of the regulation of motor activity on the basis of correlation of the specified parameters: velocity, precision, smoothness, velocity of readjustment of motor tasks, etc. The study confirmed the leading role of visual control in the realization of the motor function in 6- to 9-year olds. The mechanisms of movement regulation, i.e., a transition from a primarily monitoring mechanism of control to one based on a preliminarily formed motor program, is changed substantially by nine–ten years. These changes are possible only at this age, since it is in this period that substantial shifts take place in the morphofunctional development of the frontal cortical areas, and they become more important in the control of the activation processes, which determine and regulate motor activity. The age of nine-ten years is transitional in the formation of the mechanisms of central commands. This efficient movement control mechanism only begins to form at this age, and its formation is completed at age 14.     

川金丝猴摄食过程中“手”的选择使用

本文对20只川金丝猴(Rhinopithecus roxellana) 摄食过程中左右“手”的使用频次进行了观察和分析。在样本较小的条件下, 尽管被研究动物中有一半个体明显地倾向于使用右手, 但没有发现统计学上明显的种群水平的单手利现象。虽然本研究中成体金丝猴使用右手的比例在数量上高于幼体, 但在统计学上, 单手利行为不存在明显的年龄差别; 同样, 单手利用行为也不存在统计学上明显的性别差异。建议在未来的研究中采用大样本在解决复杂问题过程中对单手利行为做进一步的探讨。     

Hand preferences for a haptic searching task by tufted capuchins (Cebus apella)

We tested the effects of a haptic search task on hand preferences in capuchins(Cebus apella) and compare this situation to a visual by guided reaching task. In the haptic task, 21 monkeys searched for sunflower seeds on the top or side surfaces of 12 objects. A left-hand preference emerged at the group level, suggesting a greater involvement of the right hemisphere. The percentage of preferred hand usage and the direction of the preference were influenced by both sex and age of the subjects: adult males tended to be less lateralized than the other groups of subjects were. Shape had an insignificant effect on the direction of hand preferences or on the percentage of preferred hand use. No lateral bias emerge in the visually guided reaching task, and the percentage of left-hand usage fell significantly across tasks, demonstrating that the haptic demands of the task enhance the use of the left hand at the group level. We discuss these results with regard to current theories on manual lateralization in nonhuman primates.     

Complex Visual Search in Children and Adolescents: Effects of Age and Performance on fMRI Activation

Complex visuospatial processing relies on distributed neural networks involving occipital, parietal and frontal brain regions. Effects of physiological maturation (during normal brain development) and proficiency on tasks requiring complex visuospatial processing have not yet been studied extensively, as they are almost invariably interrelated. We therefore aimed at dissociating the effects of age and performance on functional MRI (fMRI) activation in a complex visual search task. In our cross-sectional study, healthy children and adolescents (n = 43, 19 females, 7-17 years) performed a complex visual search task during fMRI. Resulting activation was analysed with regard to the differential effects of age and performance. Our results are compatible with an increase in the neural network''s efficacy with age: within occipital and parietal cortex, the core regions of the visual exploration network, activation increased with age, and more so in the right than in the left hemisphere. Further, activation outside the visual search network decreased with age, mainly in left inferior frontal, middle temporal, and inferior parietal cortex. High-performers had stronger activation in right superior parietal cortex, suggesting a more mature visual search network. We could not see effects of age or performance in frontal cortex. Our results show that effects of physiological maturation and effects of performance, while usually intertwined, can be successfully disentangled and investigated using fMRI in children and adolescents.     

屯堡人7项不对称行为特征

在贵州省安顺市对359例屯堡人(男145例,女214例)中学生的7项不对称行为特征(扣手、利手、叠臂、叠腿、利足、起步类型和优势眼)进行了调查。研究结果显示:1)屯堡人除叠臂左型率高于右型率外,其他6项不对称行为特征均为右型率高于左型率;2)屯堡人7项不对称行为特征的出现率均无性别差异;3)与其他族群比较,屯堡人利足右型率和叠臂右型率中等,叠腿右型率和扣手右型率高;4)屯堡人两两不对称行为中,扣手与利手、扣手与叠臂、扣手与叠腿、叠腿与起步相关,利手、利足、起步三种行为彼此相关。     

Three-dimensional tomography of event-related potentials during response inhibition: evidence for phasic frontal lobe activation

Objectives: Spatial analysis of the evoked brain electrical fields during a cued revealed an extremely robust anteriorization of the positivity of a P300 microstate in the NoGo compared to the Go condition (NoGo-anteriorization in a prevailing study). To allow a neuroanatomical interpretation the NoGo-anteriorization was investigated with a new three-dimensional source tomography method (LORETA) was applied.Methods: The test contains subsets of stimuli requiring the execution (Go) or the inhibition (NoGo) of a cued motor response which can be considered as mutual control conditions for the study of inhibitory brain functions. 21-channel ERPs were obtained from 10 healthy subjects during a cued CPT, And analyzed with LORETA.Results: Topographic analyses revealed significantly different scalp distributions between the Go and the NoGo conditions in both P100 and P300 microstates, indicating that already at an early stage different neural assemblies are activated. LORETA disclosed a significant hyperactivity located in the right frontal lobe during the NoGo condition in the P300 microstate.Conclusions: The results indicate that right frontal sources are responsible for the NoGo-anteriorization of the scalp P300 which is consistent with animal and human lesion studies of inhibitory brain functions. Furthermore, it demonstrates that frontal activation is confined to a brief microstate and time-locked to phasic inhibitory motor control. This adds important functional and chronometric specificity to findings of frontal activation obtained with PET and Near-Infrared-Spectroscopy studies during the cued CPT, and suggests that these metabolic results are not due to general task demands.     

Development of Lateralization of Unconditional Motor Reactions in Early Ontogenesis of White Rats

The problem of development of lateralization of motor systems in the course of early ontogenesis is important for understanding regularities of formation of functional characteristics of motor control. To solve these tasks, in the 8–74-day old rat pups the presence of lateralization was studied in two motor tests: the choice of the preferable rotation direction at holding the rat by the tail and the choice of one of the forelimbs in the test of initiation of the limb placement onto a support. It has been shown that in early ontogenesis, until the age of the sexual maturation, no constant lateralization is observed in realization of the unconditional motor reactions in any of the performed tests. The turning point of the establishment of the lateral preference has been revealed to correspond to the three-week age (the 21–23rd days), while the final lateralization both for individual animals and for the entire sample takes place at the age of 1.5–2 months. It is suggested that development of lateralization of the limb placement on a support occurs with the approximately two-week delay as compared with the process of formation of the preference in the choice of the rotation direction.     

Alien hand syndrome: neural correlates of movements without conscious will

Background

The alien hand syndrome is a striking phenomenon characterized by purposeful and autonomous movements that are not voluntarily initiated. This study aimed to examine neural correlates of this rare neurological disorder in a patient with corticobasal degeneration and alien hand syndrome of the left hand.

Methodology/Principal Findings

We employed functional magnetic resonance imaging to investigate brain responses associated with unwanted movements in a case study. Results revealed that alien hand movements involved a network of brain activations including the primary motor cortex, premotor cortex, precuneus, and right inferior frontal gyrus. Conscious and voluntary movements of the alien hand elicited a similar network of brain responses but lacked an activation of the inferior frontal gyrus. The results demonstrate that alien and unwanted movements may engage similar brain networks than voluntary movements, but also imply different functional contributions of prefrontal areas. Since the inferior frontal gyrus was uniquely activated during alien movements, the results provide further support for a specific role of this brain region in inhibitory control over involuntary motor responses.

Conclusions/Significance

We discuss the outcome of this study as providing evidence for a distributed neural network associated with unwanted movements in alien hand syndrome, including brain regions known to be related to movement execution and planning as well as areas that have been linked to inhibition control (inferior frontal gyrus) and experience of agency (precuneus).     

The potential effects of sex,posture and living condition on lateralized behaviors in ring-tailed lemurs (<Emphasis Type="Italic">Lemur catta</Emphasis>)

This research explores the effects of posture, sex, and living condition on hand and side preferences of semi-free-ranging, adult ring-tailed lemurs (Lemur catta) housed at the Duke University Primate Center in Durham, NC. Data were collected on 11 adult individuals (five females and six males) during normal daily activities over a ten-week period from May–July 2001. Variables analyzed in this study include unimanual behaviors (i.e., reach, hold, and limb used to start locomotion) and other potentially lateralized behaviors that do not involve handuse (i.e., whole-body turning and tail position). The data were analyzed to investigate potential individual and population level side biases for each behavior; potential sex biases in side preference for each behavior; and for ‘reach’, potential effects of posture (sitting, tripedal stance, or bipedal stance) on individual hand preferences. Additionally, to investigate potential effects of living condition on lateral biases, the data from this study were compared to data collected on the same individual Lemurs living under more restrictive living conditions during the previous year. Largely, as predicted based on available literature, we found that there was a significant sex difference across all hand-use categories and for whole-body turning, and that posture was a significant factor in the expression of hand preference for reaching. Contrary to previous research, the effect of living condition on lateral preferences was minimal, and no side preferences were found at the population level for any of the behaviors analyzed.