Bimanual coordination dynamics in poststroke hemiparetics

Poststroke hemiparetic individuals (n = 9) and a control group (n = 9) completed a frequency-scaled circle-drawing task in unimanual and bimanual conditions. Measures of intralimb spatial and temporal task accuracy and interlimb coordination parameters were analyzed. Significant reductions in task performance were seen in both limbs of the patients and controls with the introduction of bimanual movement. Spatial performance parameters suggested that the 2 groups focused on different hands during bimanual conditions. In the controls, interlimb coordination variables indicated predictable hand dominance effects, whereas in the patient group, dominance was influenced by the side of impairment and prior handedness of the individual. Therefore, in this particular bimanual task, performance improvements in the hemiplegic side could not be elicited. Intrinsic coupling asymmetries between the hands can be altered by unilateral motor deficits.     

Amplitude scaling in a bimanual circle-drawing task: pattern switching and end-effector variability

The authors manipulated movement amplitude in a bimanual circle-tracing task performed by 11 participants. With pacing frequency fixed, the systematic increase and decrease of circle diameter within a trial induced phase transitions from the asymmetric (33% of trials) to the symmetric bimanual circle-tracing pattern; the transitions resulted from a loss of stability in the asymmetric pattern. Tracing frequency varied inversely with circle diameter so that end-effector variability was minimized in a set of self-paced trials in which the circle diameter in a trial was fixed. In the amplitude-scaling trials, end-effector variability varied directly with circle diameter, a consistent speed-accuracy tradeoff. The results support the conclusion that movement amplitude is a nonspecific control parameter. The findings are discussed with reference to several factors, e.g., tactile feedback, the recruitment and suppression of biomechanical degrees of freedom, and the role those factors may play in stabilizing bimanual coordination patterns     

EMG activity as a function of the performer's focus of attention

In previous studies of attentional focus effects, investigators have measured performance outcome. Here, however, the authors used electromyography (EMG) to determine whether difference between external and internal foci would also be manifested at the neuromuscular level. In 2 experiments, participants (N=11, Experiment 1; N=12, Experiment 2) performed biceps curls while focusing on the movements of the curl bar (external focus) or on their arms (internal focus). In Experiment 1, movements were performed faster under external than under internal focus conditions. Also, integrated EMG (iEMG) activity was reduced when performers adopted an external focus. In Experiment 2, movement time was controlled through the use of a metronome, and iEMG activity was again reduced under external focus conditions. Those findings are in line with the constrained action hypothesis (G. Wulf, N. McNevin, & C. H. Shea, 2001), according to which an external focus promotes the use of more automatic control processes.     

Reciprocal influences of attentional focus on postural and suprapostural task performance

The authors examined the influence that attentional focus on either a postural or a suprapostural task had on the performance of each task. Participants (N = 32) stood on an inflated rubber disk and held a pole horizontally. All participants performed under 4 attentional focus conditions: external (disk) or internal (feet) focus on the postural task, and external (pole) or internal (hands) focus on the suprapostural task. Compared with internal focuses, external focuses on either task resulted in similar and reduced postural sway. Response frequency on each task increased when participants focused on the respective task. Finally, an external focus on either task produced higher frequencies of responding on the suprapostural task. The authors conclude that suprapostural task goals have a stronger influence on postural control than vice versa, reflecting the propensity of the motor system to optimize control processes on the basis of the desired movement effect.     

Healthy and unhealthy emotion regulation: personality processes, individual differences, and life span development

Abstract Individuals regulate their emotions in a wide variety of ways. Are some forms of emotion regulation healthier than others? We focus on two commonly used emotion regulation strategies: reappraisal (changing the way one thinks about a potentially emotion‐eliciting event) and suppression (changing the way one responds behaviorally to an emotion‐eliciting event). In the first section, we review experimental findings showing that reappraisal has a healthier profile of short‐term affective, cognitive, and social consequences than suppression. In the second section, we review individual‐difference findings, which show that using reappraisal to regulate emotions is associated with healthier patterns of affect, social functioning, and well‐being than is using suppression. In the third section, we consider issues in the development of reappraisal and suppression and provide new evidence for a normative shift toward an increasingly healthy emotion regulation profile during adulthood (i.e., increases in the use of reappraisal and decreases in the use of suppression).     

The effects of cooperation and competition on intrinsic motivation and performance

The authors examined the effects of competition and cooperation on intrinsic motivation and performance in 4 studies. Across 3 behavioral studies that involved shooting a basketball, no differences were observed between competition and cooperation on task enjoyment or performance. However, the combination of competition and cooperation (intergroup competition) consistently led to higher levels of intrinsic motivation, and in 2 of the 3 studies, performance. In a questionnaire study, the authors replicated the positive effects of intergroup competition on enjoyment and examined process measures that might account for these effects. These findings suggest that competition and cooperation both have positive aspects and that structuring recreational activities to include both can facilitate high levels of both intrinsic motivation and performance.     

The effects of motor neurone disease on language: further evidence

It might sound surprising that Motor Neurone Disease (MND), regarded still by many as the very example of a neurodegenerative disease affecting selectively the motor system and sparing the sensory functions as well as cognition, can have a significant influence on language. In this article we hope to demonstrate that language dysfunction is not only a pronounced and well documented symptom in some MND patients but also that the study of language in MND can address interesting theoretical questions about the representation of language and conceptual knowledge in the brain. After a brief introduction delineating clinical and pathological features of the disease we discuss the evidence available in the literature for language dysfunction in MND. We then present linguistic data from our own study of seven patients with MND/dementia/aphasia syndrome focusing on the dissociation between noun and verb processing. To illustrate the clinical, neuropsychological and linguistic aspects of MND we describe in more detail the patient E.N., a pathologically confirmed case of MND/dementia. Finally, we attempt to characterise the nature of the linguistic impairment in MND in the light of current debates about the mechanisms underlying noun/verb dissociation.     

Size of the neocerebellar vermis is associated with cognition in healthy elderly men

Cerebellar volumes show small positive correlations with cognitive ability in young adults, but no studies have examined this relationship in older adults. Furthermore, no studies have examined relationships between sizes of subareas of the cerebellum and cognitive ability. We hypothesized that size of the two areas of the neocerebellar vermis would correlate with a battery of eight cognitive tests in 50 men aged 65-70. Size of the neocerebellar areas of the vermis correlated positively with several cognitive tests (r's=.29-.37, p<.05), whilst sizes of other parts of the vermis did not correlate with any cognitive tests. Total cerebellar volumes correlated significantly with a test of nonverbal reasoning (r=.030, p=.42). These findings suggest a specific association of neocerebellar vermis size with variations in cognitive ability in older adults.     

Modeling the effects of prior knowledge on learning incongruent features of category members

The authors conducted 3 experiments addressing the issue of how observations and multiple sources of prior knowledge are put together in category learning. In Experiments 1 and 2, learning was faster for critical features, which were predictable on the basis of prior knowledge, than for filler features, and this advantage increased as more observations were made. In addition, learning was fastest for incongruent features that could only be predicted using knowledge from other domains. In Experiment 3, presenting contradictory features that violated prior knowledge led to rote learning rather than use of prior knowledge. The results were simulated with the Baywatch model, which addresses how observations of category members lead to recruitment and selection of sources of prior knowledge.