Motor Programming

In many activities, the human being must quickly decide on the response to be produced following a change in the environment. In some of these situations, the limb that the individual chooses to carry out a response seems to be a significant element in performance. Thus, if the individual carries out the response with the limb closest to the target, the performance can improve because it will take less time to achieve the goal. However, it seems that in these situations, the human being does not take this decrease in movement time into consideration and that the response is carried out with the dominant hand. Why is this so? It may be because the reaction is faster when there doesn’t have to be a choice as to which limb will carry out the response. The goal of this study was to check this possibility. In order to do so, the subjects performed a two choice reaction-time task. For this task, some subjects knew beforehand which hand they had to use to carry out the response while other subjects were unaware of this fact. The results of two experiments indicate that the choice of the limb which is to carry out the response requires no particular delay when the movement to be produced is externally guided.     

Continuous Cognitive Tasks Improve Postural Control Compared to Discrete Cognitive Tasks

Research suggests that postural control synergies are sensitive to cognitive manipulations; however, the impact of different types of cognitive tasks on postural control remains inconclusive. The authors examined the effect of discrete and continuous tasks on postural control. Sixteen healthy young adults (M age = 22.7 ± 2.2 years) stood with feet together on a force platform while performing randomly assigned discrete and continuous cognitive tasks. Results demonstrated marked improvements in the area of 95% confidence ellipse and the standard deviation of the center of pressure in the anterior-posterior and medial-lateral directions for continuous compared to discrete tasks. This reinforces the notion that continuous tasks are sufficient in providing less opportunity to consciously attend to postural control, thereby facilitating automatic postural control.     

Effect of thermoelectric magnetic force on the array of dendrites during directional solidification of Al–Cu alloys in a high magnetic field

By eliminating the effect of the magnetic moment arising from the magnetic crystalline anisotropy, the effect of the thermoelectric magnetic force on the array of dendrites during directional solidification of Al–35?wt%Cu and Al-40?wt%Cu alloys in a high magnetic field has been investigated experimentally. The results indicate that the dendrite array is essentially destroyed, a result that could have general significance for understanding the processes involved in the solidification of alloys in a magnetic field.     

High magnetic field induction of the formation of twinned dendrites during directional solidification of Al–4.5wt%Cu alloy

It is reported that the application of a high magnetic field is capable of inducing the formation of twinned dendrites during directional solidification of Al–4.5wt%Cu alloy. Numerical results reveal that a unidirectional thermoelectric magnetic force acts on tilted dendrites during directional solidification under a magnetic field. This force should be responsible for the formation of twinned dendrites. The work may initiate a new method for inducing twinned dendrites in Al-based alloys via an applied high magnetic field during directional solidification.     

Processing the emotions in words: The complementary contributions of the left and right hemispheres

A dual-process model is suggested for the processing of words with emotional meaning in the cerebral hemispheres. While the right hemisphere and valence hypotheses have long been used to explain the results of research on emotional stimulus processing, including nonverbal and verbal stimuli, data on emotional word processing are mostly inconsistent with both hypotheses. Three complementary lines of research data from behavioral, electrophysiological, and neuroimaging studies seem to suggest that both hemispheres have access to the meanings of emotional words, although their time course of activation may be different. The left hemisphere activates these words automatically early in processing, whereas the right hemisphere gains access to emotional words slowly when attention is recruited by the meaning of these words in a controlled manner. This processing dichotomy probably corroborates the complementary roles the two hemispheres play in data processing.     

Contribution of NIRS to the study of prefrontal cortex for verbal fluency in aging

Healthy aging is characterized by a number of changes on brain structure and function. Several neuroimaging studies have shown an age-related reduction in hemispheric asymmetry on various cognitive tasks, a phenomenon captured by Cabeza (2002) in the Hemispheric Asymmetry Reduction in Older Adults (HAROLD) model. Although this phenomenon is supported by a range of neuroimaging data on memory and inhibitory processes, there is little evidence concerning changes in hemispheric asymmetry for language processing, and particularly word retrieval, which is assessed with verbal fluency task (VFT). This study aimed to investigate the age-related changes in cerebral oxygenation in the prefrontal cortex for both letter and category VFT, varying the complexity of the criteria (i.e., degree of productivity) and using near-infrared spectroscopy (NIRS). Sixteen younger and 16 older adults participated in this study. For both VF conditions, participants were instructed to pronounce as many nouns as possible as a function of high-productivity (e.g., “animals” or “L”) or low-productivity (e.g., “flowers” or “V”) criteria. Behavioral data (i.e., accuracy responses) showed comparable performance in younger and older adults for both VF conditions. However, NIRS data showed more reduced activation (i.e., significantly reduced increase in [O₂Hb] and reduced decrease in [HHb]) in older than younger adults for both VFT. In addition, a bilateral effect was found for both groups, suggesting that VFT requires both executive and language functions. The results are discussed in the context of the current theories of aging.     

COVERT ORIENTING IN THE SPLIT BRAIN REVEALS HEMISPHERIC SPECIALIZATION FOR OBJECT-BASED ATTENTION

Abstract— Theones in cognitive science have debated whether visual selective attention is a space-based or object-based process To investigate this issue, we applied a new experimental paradigm that permits the simultaneous measurement of both space-based and object-based attention to a split-brain patient with disconnected cerebral hemispheres The data demonstrate both space-based and object-based components to the allocation of attention, and reveal that the two processes have different neural substrates These findings are related to previous research on split-brain and unilateral parietal patients     

Expanding MEL response box to accommodate up to 16 external buttons

Micro Experimental Laboratory (MEL) is a widely used software package developed for the automation of psychological experiments. This report presents a simple way to implement and use an expanded MEL response box that accommodates up to 16 external switches. Hardware and software considerations are reviewed, and relevant MEL code is provided. This includes a simple algorithm that permits the reading of multiple responses within a single trial.     

Improvement of mental imagery after prism exposure in neglect: a case study

Previous work has shown that various symptoms of unilateral neglect, including the pathological shift of the subjective midline to the right, may be improved by a short adaptation period to a prismatic shift of the visual field to the right. We report here the improvement of imagined neglect after prism exposure in a patient with a left unilateral neglect. Despite a strong neglect observed for mental images as well as for conventional tests, the mental evocation of left-sided information from an internal image of the map of France map was fully recovered following prism adaptation to the right. This improvement could not be explained by the alteration of visuomotor responses induced by the prism adaptation. Prism adaptation may therefore act not only on sensory-motor levels but also on a higher cognitive level of mental space representation and/or exploration.