Brief bimanual force pulses: Correlations between the hands in force and time.

Three experiments assessed coupling phenomena in the coordination of bimanual force pulses. Experiment 1 required symmetric force pulses (equal target forces and rise times for both hands) using the index finger of each hand. As the authors expected, on the basis of bimanual pointing movement results, this experiment revealed positive correlations between both the force rise times and the force amplitudes of the two hands. Experiments 2 and 3 included asymmetric conditions with different target force amplitudes (Experiment 2) or target rise times (Experiment 3). In Experiment 2 force amplitudes but not rise times were fully decoupled in the asymmetric condition. In the asymmetric condition of Experiment 3, however, neither rise times nor force amplitudes were fully decoupled. The results suggest a hierarchical control structure with temporal control dominating nontemporal control of bimanual force coordination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interference effects in bimanual coordination are independent of movement type.

Simultaneously executed limb movements interfere with each other. Whereas the interference between discrete movements is examined mostly from a cognitive perspective, that between rhythmic movements is studied mainly from a dynamical systems perspective. As the tools and concepts developed by both communities are limited in their applicability to the other domain, it remains unclear if a common cause underlies motor interference in both domains. We investigated the interference between simultaneously executed discrete and rhythmic wrist movements. The discrete movements' reaction time and movement time decreased with increasing rhythmic movement frequency. The discrete movements accelerated or decelerated the rhythmic movements in a manner that depended on movement frequency and the discrete movement's initiation phase. The acceleration/deceleration profile was bimodal at low frequencies and unimodal at high frequencies, mimicking the hallmark feature of rhythmic-rhythmic coordination, thus suggesting that interference between movements may be invariant across different movement types. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Target selection during bimanual reaching to direct cues is unaffected by the perceptual similarity of the targets.

Investigations of bimanual movements have shed considerable insight on the constraints underlying our ability to perform coordinated actions. One prominent limitation is evident when people are required to produce reaching movements in which the two trajectories are of different amplitudes and/or directions. This effect, however, is only obtained when the movements are cued symbolically (e.g., letters indicate target locations); these planning costs are absent when the target locations are directly cued (J. Diedrichsen, E. Hazeltine, S. Kennerley, & R. B. Ivry, 2001). The present experiments test whether the absence of planning costs under the latter condition is due to the perceptual similarity of the direct cues. The results demonstrate that measures of response planning and execution do not depend on the perceptual similarity of the direct cues. Limitations in our ability to perform distinct actions with the two hands appear to reflect interactions related to response selection involving the translation of symbolic cues into their associated movements rather than arise from interactions associated with perception, motor programming, and motor execution. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coordination of grip and load forces during vertical point-to-point movements with a grasped object in Parkinson's disease.

Thirteen patients with Parkinson's disease and 13 age-matched control subjects performed vertical point-to-point arm movements with an instrumented object, starting and ending with the object being held stationary. All Parkinsonian patients were tested on medication. Parkinsonian patients retained all aspects of predictive grip force control. Compared with healthy controls, they generated similar static grip forces during stationary holding and similar force ratios between maximum grip and load force, reflecting effective grip force adjustments in relation to movement-induced inertial loads. Grip and load force maximums coincided very closely, indicating that temporal aspects of predictive grip force regulation were also unaffected. However, Parkinsonian subjects showed additional oscillations in acceleration and grip force due to tremor and produced significantly slower arm accelerations due to bradykinesia. The results suggest that Parkinson's disease does not significantly impair the anticipation of movement-induced load fluctuations during voluntary arm movements with a grasped object performed on medication. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bimanual motor coordination in agenesis of the corpus callosum.

The nature and extent of deficiencies in bimanual motor coordination in individuals with agenesis of the corpus callosum (ACC) was studied using the computerized Bimanual Coordination Test (cBCT). Compared with previous bimanual tasks, the cBCT is more specifically reliant on interhemispheric interactions of lateralized motor control, allows more precise measurement, and permits examination of performance over a wider range of bimanual challenges. The cBCT performance of 13 high-functioning individuals with complete ACC was compared to 21 age- and IQ-matched controls. The groups did not differ in unimanual response speed. On trials involving angled paths that require bimanual coordination, the ACC group performed significantly slower and less accurately across all angles. The largest group differences in speed occurred on trials where the hands must respond symmetrically, while mirror-image (vs. parallel) responding produced the greatest deficits in accuracy. These data confirm previous findings of deficits in bimanual coordination in callosal absence, but using significantly improved measurement technology. Deficits in bimanual coordination in ACC are present across different demands for interhand interactions in the speed and direction of movement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A test of motor (not executive) planning in developmental coordination disorder and autism.

Grip selection tasks have been used to test “planning” in both autism and developmental coordination disorder (DCD). We differentiate between motor and executive planning and present a modified motor planning task. Participants grasped a cylinder in 1 of 2 orientations before turning it clockwise or anticlockwise. The rotation resulted in a comfortable final posture at the cost of a harder initial reaching action on 50% of trials. We hypothesized that grip selection would be dominated by motoric developmental status. Adults were always biased towards a comfortable end-state with their dominant hand, but occasionally ended uncomfortably with their nondominant hand. Most 9- to 14-year-olds with and without autism also showed this “end-state comfort” bias but only 50% of 5- to 8-year-olds. In contrast, children with DCD were biased towards selecting the simplest initial movement. Our results are best understood in terms of motor planning, with selection of an easier initial grip resulting from poor reach-to-grasp control rather than an executive planning deficit. The absence of differences between autism and controls may reflect the low demand this particular task places on executive planning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Motor fluency deficits in the sequencing of actions in schizophrenia.

Many everyday activities depend on the capacity to organize and smoothly execute motor sequences. The authors tested the hypothesis that a sequencing deficit is associated with schizophrenia. They used a new method to distinguish between lower and higher order mechanisms for the impairment. The 1st task involved triggered sequences in which sensory information from 1 movement was the cue for initiation of the following movement. Results showed that the motor sequences were performed as fluently in patients as in controls. The 2nd and 3rd tasks involved sequences in which the entire movement sequence could be preplanned. Patients executed the sequences less fluently than controls but only under the condition where action sequences were required. Furthermore, the patients' fluency deficit increased with sequence complexity. The high discrimination power of Task 3 gave the authors a means to control for a potential psychometric confound involving differential discriminating power and to argue in favor of a specific higher order motor fluency deficit in patients with schizophrenia. It is suggested that basic lower order mechanisms that integrate sensory information with outgoing motor commands are preserved in schizophrenia, whereas higher order integrative mechanisms that are required for the smooth coordination of motor sequences are impaired. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The use of bouts and frequencies in the evaluation of hand preferences for a coordinated bimanual task in chimpanzees (Pan troglodytes): An empirical study comparing two different indices of laterality.

Hand preferences for a coordinated bimanual task were assessed in 109 chimpanzees (Pan troglodytes). Hand preference was evaluated for 4 test sessions using bouts and frequencies of hand use to compare the sensitivity of each level of analysis in evaluating individual variation in handedness. Overall, significant population-level right-handedness was found using several different measures of hand use. Handedness indices based on bouts and frequencies were highly and significantly correlated. Moreover, hand preferences were consistent across tests despite efforts to situationally bias preference during each test. Taken together, these data do not support the view that bouts are a better level of analysis for evaluating hand preference. The results further suggest that hand preferences for coordinated bimanual actions are not influenced by situational factors and may reflect an inherent specialization of the left hemisphere for motor skill. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Cinderella of Psychology: The Neglect of Motor Control in the Science of Mental Life and Behavior.

One would expect psychology--the science of mental life and behavior--to place great emphasis on the means by which mental life is behaviorally expressed. Surprisingly, however, the study of how decisions are enacted--the focus of motor control research--has received little attention in psychology. This article documents the neglect and considers possible reasons for it. The hypotheses considered include three that are raised and then rejected: (a) no famous psychologists have studied motor control, (b) cognitive psychologists are mainly interested in uniquely human functions, and (c) motor control is simply too hard to study. Three other hypotheses are more viable: (d) cognitive psychologists have been more interested in epistemology than in action, (e) psychologists have disfavored motor control because overt responses were the only admissible measure in behaviorism, and (f) psychologists have felt that neuroscientists have the market cornered when it comes to motor control research. There are signs that motor control's Cinderella status is changing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Grip morphology and hand use in chimpanzees (Pan troglodytes): Evidence of a left hemisphere specialization in motor skill.

Three experiments on grip morphology and hand use were conducted in a sample of chimpanzees. In Experiment 1, grip morphology when grasping food items was recorded, and it was found that subjects who adopted a precision grip were more right-handed than chimpanzees using other grips. In Experiment 2, the effect of food type on grasping was assessed. Smaller food items elicited significantly more precision grips for the right hand. In Experiment 3, error rates in grasping foods were compared between the left and right hands. Significantly more errors were made for the left compared with the right hand. The cumulative results indicate that chimpanzees show a left-hemisphere asymmetry in motor skill that is associated with the use of precision grips. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Activity of common marmosets (Callithrix jacchus) in limited spaces: Hand movement characteristics.

The increasing popularity of marmoset monkeys (Callithrix jacchus) in anatomical, behavioral, and electrophysiological studies has called for a detailed analysis of their natural behavior within limited spaces. In the present study, the authors analyzed hand movements during horizontal and vertical progressions in a cylinder. The trajectory of each hand covered the entire cylinder floor during horizontal progressions and the entire cylinder wall during vertical progressions. Different marmosets have different patterns of hand movement. The average maximum angle of hand movements for all marmosets during horizontal and vertical progressions oscillates, although the average over time is constant and similar for both hands, whereas head movements during horizontal progressions become smaller with successive progressions. Another observed difference between rats and monkeys was in the size of head and hand movements at the beginning of each experimental session. During the 1st horizontal progression, all marmosets moved their heads to a greater extent than their hands. This sequential head and hand movement is referred as bistable behavior. The bistable pattern of motor behavior, which was also observed in successive progressions, may be derived from an inherent fear of predators or exploratory interest of a novel environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hand path priming in manual obstacle avoidance: Evidence that the dorsal stream does not only control visually guided actions in real time.

According to a prominent theory of human perception and performance (M. A. Goodale & A. D. Milner, 1992), the dorsal, action-related stream only controls visually guided actions in real time. Such a system would be predicted to show little or no action priming from previous experience. The 3 experiments reported here were designed to determine whether priming exists for visually guiding the hand to targets with obstacles sometimes in the way. In all 3 experiments, priming was observed in the curvature of hand paths. Hand paths when no obstacles were present were more curved if obstacles had recently appeared than if obstacles had not recently appeared. The results also show that hand path priming was not the result of active prediction, persisted for many trials, and generalized over the workspace. The times to initiate movements also reflected the use of a sophisticated visual search strategy that took obstacle likelihood into account. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Handedness in Chimpanzees (Pan troglodytes) Is Associated With Asymmetries of the Primary Motor Cortex but Not With Homologous Language Areas.

The neurobiology of hand preferences in nonhuman primates is poorly understood. In this study, the authors report the first evidence of an association between hand preference and precentral gyrus-morphology in chimpanzees (Pan troglodytes). Hand preferences did not significantly correlate with other asymmetric brain regions associated with language functions in humans including the planum temporale and frontal operculum. The overall results suggest that homologous regions of the motor cortex control hand preferences in humans and apes and that these functions evolved independently of left-hemisphere specialization for language and speech. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The plasticity of human maternal brain: Longitudinal changes in brain anatomy during the early postpartum period.

Animal studies suggest that structural changes occur in the maternal brain during the early postpartum period in regions such as the hypothalamus, amygdala, parietal lobe, and prefrontal cortex and such changes are related to the expression of maternal behaviors. In an attempt to explore this in humans, we conducted a prospective longitudinal study to examine gray matter changes using voxel-based morphometry on high resolution magnetic resonance images of mothers' brains at two time points: 2–4 weeks postpartum and 3–4 months postpartum. Comparing gray matter volumes across these two time points, we found increases in gray matter volume of the prefrontal cortex, parietal lobes, and midbrain areas. Increased gray matter volume in the midbrain including the hypothalamus, substantia nigra, and amygdala was associated with maternal positive perception of her baby. These results suggest that the first months of motherhood in humans are accompanied by structural changes in brain regions implicated in maternal motivation and behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Complexity in object manipulation by Japanese macaques (Macaca fuscata): A cross-sectional analysis of manual coordination in stone handling patterns.

Defined as a spontaneous stone-directed noninstrumental manipulative behavior, and comprised of multiple one-handed and (a)symmetrical/(un)coordinated two-handed patterns, stone handling (SH) is a good candidate for the study of complexity in object manipulation. We present a cross-sectional developmental analysis of SH complexity in Japanese macaques (Macaca fuscata), through the combined investigation of bimanuality, coordination, and symmetry in hand use. Bimanual SH patterns were more frequent than unimanual patterns. Among bimanual patterns, coordinated actions were more frequent than uncoordinated ones. We recorded five asymmetrical coordinated SH patterns with manual role differentiation, a form of hand use reminiscent of complex actions involving the use of tools in monkeys and apes. Bimanuality in SH was affected by body posture. Aging individuals performed less bimanual and less coordinated SH patterns than younger individuals. Our result on senescent males performing less bimanual patterns than senescent females was consistent with sex differences found in the late deterioration of complex manual movements in other species. Although some SH patterns represent a high degree of behavioral complexity, our results suggest that SH behavior is not as complex as tool-use or tool-manufacture in other nonhuman primates and hominids. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Neuroanatomical localization of the motor hand area with magnetic resonance imaging: The left hemisphere is larger in great apes.

Magnetic resonance images of the brain were obtained from 2 gorillas (Gorilla gorilla gorilla), 4 orangutans (Pongo pygmaeus), 14 chimpanzees (Pan troglodytes), and 4 bonobos (Pan paniscus), The region on the motor cortex of humans identified as responsible for motor skill of the hand (the "knob") was identified in this sample on consecutive 1-mm axial scans. The shape of the knob area was traced on each scan from both hemispheres, and the area from all scans was summed to calculate the knob volume. The width of the knob was also measured and correlated highly with knob volume. A significant population-level leftward asymmetry in the volume and width of the knob was revealed (p?     

Structure formation during sintering in the presence of a liquid phase in Cr-Cu-metal of the iron family systems. II. Systems Cr-Cu-Ni(Co, Fe)

Features of structure and phase formation in Cr-Cu-Ni(Co, Fe) systems during liquid-phase sintering in a vacuum of (2–4) · 10⁻³ Pa at 1200 and 1270°C are studied. It is shown that with introduction of elements of the iron family into molten copper there is dispersion of refractory particles and formation at the boundary with the readily melting component of a transition layer whose structure and composition are determined by the nature of the addition. Growth of refractory particles during liquid-phase sintering of composites of the system Cr-Cu-Ni is controlled by diffusion of elements into the solid phase of the transition layer. __________ Translated from Poroshkovaya Metallurgiya, Nos. 7–8(450), pp. 19–25, July–August, 2006.     

Health stresses and depressive symptomatology in the elderly: The importance of health engagement control strategies.

The study presents cross-sectional (N=127) and longitudinal (n=111) analyses examining relations between health engagement control strategies (HECSs), depressive symptoms, and health stresses in elderly individuals. HECS was measured as people's behavioral and cognitive investments toward attaining health goals. HECS was related to low levels of depressive symptoms, particularly among people experiencing acute physical symptoms. Moreover, HECS predicted reduction of depressive symptoms over time, and depressive symptomatology predicted negative change in HECS. The findings show that active investments of HECSs significantly moderate the negative affective consequences of health threats. Individuals who are characterized by low levels of HECS and high levels of depressive symptoms may be at increased risk of accelerated decline in their physical and mental health. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A meta-analytic investigation of conscientiousness in the prediction of job performance: Examining the intercorrelations and the incremental validity of narrow traits.

Researchers of broad and narrow traits have debated whether narrow traits are important to consider in the prediction of job performance. Because personality-performance relationship meta-analyses have focused almost exclusively on the Big Five, the predictive power of narrow traits has not been adequately examined. In this study, the authors address this question by meta-analytically examining the degree to which the narrow traits of conscientiousness predict above and beyond global conscientiousness. Results suggest that narrow traits do incrementally predict performance above and beyond global conscientiousness, yet the degree to which they contribute depends on the particular performance criterion and occupation in question. Overall, the results of this study suggest that there are benefits to considering the narrow traits of conscientiousness in the prediction of performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)