Rational Actions and the Integration of Knowledge

Summary  The paper emphasizes the role of knowledge dimensions of an action which could be regarded as rational. Rational action usually results of specific decision – making process including selection, evaluation and acceptance of a preferred alternative. This process should integrate not only various types of knowledge but also the interdisciplinary or interdepartmental knowledge integration. The integration of knowledge may cover various forms, especially integration of knowledge relating to different domains, of different quality, of knowledge connected with different goal-orientations. The paper stresses the role of the hitherto known and recognized alternatives. The integration procedures should also include the integration of various spheres and types of knowledge with accepted and justified systems of values.     

Proprioception and Motor Control in Parkinson's Disease

ABSTRACT

Parkinson's disease (PD) is a neurodegenerative disorder that leads to a progressive decline in motor function. Growing evidence indicates that PD patients also experience an array of sensory problems that negatively impact motor function. This is especially true for proprioceptive deficits, which profoundly degrade motor performance. This review specifically address the relation between proprioception and motor impairments in PD. It is structured around 4 themes: (a) It examines whether the sensitivity of kinaesthetic perception, which is based on proprioceptive inputs, is actually altered in PD. (b) It discusses whether failed processes of proprioceptive-motor integration are central to the motor problems in PD. (c) It presents recent findings focusing on the link between the proprioception and the balance problems in PD. And (d) it discusses the current state of knowledge of how levodopa medication and deep brain stimulation affect proprioceptive and motor function in PD. The authors conclude that a failure to evaluate and to map proprioceptive information onto voluntary and reflexive motor commands is an integral part of the observed motor symptoms in PD.     

Multisensory integration in multiple reference frames in the posterior parietal cortex

Spatial information processing takes place in different brain regions that receive converging inputs from several sensory modalities. Because of our own movements—for example, changes in eye position, head rotations, and so forth—unimodal sensory representations move continuously relative to one another. It is generally assumed that for multisensory integration to be an orderly process, it should take place between stimuli at congruent spatial locations. In the monkey posterior parietal cortex, the ventral intraparietal (VIP) area is specialized for the analysis of movement information using visual, somatosensory, vestibular, and auditory signals. Focusing on the visual and tactile modalities, we found that in area VIP, like in the superior colliculus, multisensory signals interact at the single neuron level, suggesting that this area participates in multisensory integration. Curiously, VIP does not use a single, invariant coordinate system to encode locations within and across sensory modalities. Visual stimuli can be encoded with respect to the eye, the head, or halfway between the two reference frames, whereas tactile stimuli seem to be prevalently encoded relative to the body. Hence, while some multisensory neurons in VIP could encode spatially congruent tactile and visual stimuli independently of current posture, in other neurons this would not be the case. Future work will need to evaluate the implications of these observations for theories of optimal multisensory integration.Edited by: Marie-Hélène Giard and Mark Wallace     

Spatial Coupling in the Coordination of Complex Actions

The majority of investigations on coordinated action have focused on temporal constraints in movements. Recent studies have demonstrated spatial constraints when the hands produce different trajectory shapes simultaneously. The focus of the current study was to determine whether spatial coupling occurs in individual parameters of the actions, or whether the shapes per se undergo accommodation. Subjects were tested on a bimanual paradigm to investigate the nature of spatial constraints in complex tasks. Shape and size of the required trajectories were varied for the two limbs. When trajectories that require different shapes were assigned to the two hands,disruption in the spatial characteristics of the trajectories was observed. Disruption in the global patterns of the trajectories could be described on the basis of coupling in individual parameters of action, direction, and amplitude, which could be inferred by decomposing the trajectories into orthogonal components. Amplitude accommodation in these orthogonal components of motion increased linearly with the difference in required amplitude for the two limbs. Interpretations of these effects suggest that directional coupling is a result of interference between two different response plans, whereas amplitude coupling may be related to either planning or execution variables. These results strongly suggest the need for further investigation of the spatial domain of complex coordinated action.     

The role of visible persistence for perception of visual bilateral symmetry1

Abstract: Although the detection of visual bilateral symmetry has been claimed to be highly efficient, the possible involvement and function of visual memory in such efficient mechanisms has rarely been examined. We hypothesized that symmetry perception is rapid, as it can be achieved from rapidly decaying information of visible persistence. To test this hypothesis, we employed a temporal integration paradigm. A symmetric dot pattern was randomly divided into two asymmetric patterns and presented successively with a blank screen presented between patterns. Observers could detect symmetry when the two patterns were presented close in time (Experiment 1), indicating that observers perceived symmetry presumably utilizing visible persistence. In addition, the inverse‐intensity effect of visible persistence (Di Lollo & Bischof, 1995) was evident in our temporal integration task of symmetry (Experiment 2). The results of the current study clearly demonstrate that the detection of symmetry can be achieved based on the visible persistence. The large capacity and high spatial precision of visible persistence might be adequate for the rapid and spatially global encoding of visual symmetry.     

Evidence Supporting the Importance of Peripheral Visual Information for the Directional Control of Aiming Movement

The focus of the present study was on determining whether the high level of directional accuracy found in aiming studies in which the subjects can see their hand in the visual periphery supports the existence of a kinetic visual channel or, rather, the advantage of binocular over monocular vision for movement directional control. The limits of this kinetic visual channel were also explored. The results of the 1st experiment indicated that seeing one's hand in the visual periphery is sufficient to ensure optimal directional aiming accuracy. Further, no differences in aiming accuracy were noted between monocular and binocular vision. These results supported the existence of a visual kinetic channel. In the 2nd experiment, whether this kinetic visual channel would operate with movements slower (55°/s) than those usually used in studies that had proved its existence (over 110°/s) was determined. The results indicated that this visual kinetic channel was operative even at relatively slow movement velocities. Central vision of the hand seemed to be used for on-line directional control of relatively slow movements.     

Afferent Information for Motor Control: The Role of Visual Information in Different Portions of the Movement

The question addressed in the present study was whether subjects (N = 24) can use visual information about their hand, in the first half of an aiming movement, to ensure optimal directional accuracy of their aiming movements. Four groups of subjects practiced an aiming task in either a complete vision condition, a no-vision condition, or in a condition in which their hand was visible for the first half [initial vision condition (IV)] or the second half of the movement [final vision condition (FV)]. Following 240 trials of acquisition, all subjects were submitted to a transfer test that consisted of 40 trials performed in a no-vision condition. The results indicated that seeing the hand early in movement did not help subjects to optimize either directional or amplitude accuracy. On the other hand, when subjects viewed their hand closer to the target, movements resulted that were as accurate as those performed under a complete vision condition. In transfer, withdrawing vision did not cause any increase in aiming error for the IV or the no-vision conditions. These results replicated those of Carlton (1981) and extended those of Bard and colleagues (Bard, Hay, & Fleury, 1985) in that they indicated that the kinetic visual channel hypothesized by Paillard (1980; Paillard & Amblard, 1985) appeared to be inoperative beyond 40deg of visual angle.     

Roles of Visual Information for Control of Reaching Movements in Children

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.     

The Influence of Contraction Types on the Relationship Between the Intended Force and the Actual Force

Abstract

It has been demonstrated that the intended force (subjective estimation of force) does not always match to actual force without external feedback. The purpose of this study was to compare the influence of ballistic and tonic contractions on the relationship between the intended and actual force. Subjects produced isometric force at requested percentages of their MVC (20, 40, 60 and 80%) based on subjective estimation of force under two conditions (tonic and ballistic conditions). The tonic condition was to maintain force production, whereas the ballistic condition was to produce force as fast as possible. As a result, the actual force amplitude, the coefficient of variance and EMG amplitude were larger under the ballistic contraction compared with the tonic condition, even the same intended force levels. These results suggest that different motor unit activity and control systems in the ballistic and tonic contractions could alter the relationship between the intended force and the actual force.     

Perceptual Integration of Timing and Intensity Variations in the Perception of Musical Accents

The author investigated the detection of timing and intensity variations in tone sequences within the framework of perceptual independence or integration. The participants listened to sequences of tones that contained variations in timing, intensity, or both. Each participant tried to detect variations in the dimension that was declared relevant, which was either timing or intensity. The irrelevant dimension was held constant, or varied in a manner uncorrelated with the relevant dimension, or varied in a correlated manner. When the variations in the 2 dimensions were correlated, the correlation could be either positive (i.e., timing and intensity created accents in the same sequences) or negative (i.e., timing and intensity created accents in different sequences). Uncorrelated variation in the irrelevant dimension interfered with the detection of variations in the relevant dimension. In the case of a positive correlation between the 2 dimensions, the detection of variations was better than it was with the absence of variation in the irrelevant dimension only for participants who attended to timing. In the case of a negative correlation, the effect was the opposite. The results showed that timing and intensity accents were not processed by completely independent channels. Rather, information from the 2 dimensions combined at a late stage of processing.     

Brain Mechanisms for Interpreting the Actions of Others From Biological-Motion Cues

ABSTRACT— Humans are an intensely social species. Our social abilities depend upon specialized brain systems for rapidly recognizing the faces of others, for interpreting the actions of others through an analysis of biological-motion cues, and for determining the emotional states of others via inspection of facial expression. Recent work has implicated the superior temporal sulcus (STS) region as an important component of the social brain. Functional neuroimaging studies have provided clues about how this region is involved in the visual analysis and interpretation of other people's actions. STS activity is modulated by the context within which the actions of biological entities are observed. Such a contextual influence is consistent with a broader tradition within social psychology emphasizing the powerful influences of situational and contextual factors on behavior and perception. The STS region also shows promise as a region of importance in the investigation of both typical and impaired social-cognitive development. Future work should aim to inform us better of the development of interrelationships between the STS region and other regions of the social brain, including the amygdala and the fusiform gyrus.     

Plane of Motion Mediates the Coalition of Constraints in Rhythmic Bimanual Coordination

The authors hypothesized that the modulation of coordinative stability and accuracy caused by the coalition of egocentric (neuromuscular) and allocentric (directional) constraints varies depending on the plane of motion in which coordination patterns are performed. Participants (N = 7) produced rhythmic bimanual movements of the hands in the sagittal plane (i.e., up-and-down oscillations resulting from flexion—extension of their wrists). The timing of activation of muscle groups, direction of movements, visual feedback, and across-trial movement frequency were manipulated. Results showed that both the egocentric and the allocentric constraints modulated pattern stability and accuracy. However, the allocentric constraint played a dominant role over the egocentric. The removal of vision only slightly destabilized movements, regardless of the effects of directional and (neuro)muscular constraints. The results of the present study hint at considering the plane in which coordination is performed as a mediator of the coalition of egocentric and allocentric constraints that modulates coordinative stability of rhythmic bimanual coordination.     

Cognitive empathy modulates the visual perception of human-like body postures without imitation

To examine the mechanism of visual perception of human-like body postures, we conducted a posture recognition task, a questionnaire survey, and the Interpersonal Reactivity Index (IRI). The majority of participants perceived the pseudo-posture as a human posture in the early stage (78%), but only approximately half of them reported the imagination of bodily movement (66%). These results suggest that the majority of observers perceive pseudo-postures as human postures in the early stage of perception, but this human posture perception does not necessarily lead to the visualisation of bodily movement. In a group of who received the pseudo posture as a human-posture regardless of the perception stages, the participants who imagined bodily movement (64%) showed significantly higher scores than those who did not on the Fantasy subscale of the IRI. Highly empathic participants are more likely to detect a kinematic relation between the pseudo-postures.     

The role of perception, language, and preference in the developmental acquisition of basic color terms

When learning basic color vocabulary, young children show a selective delay in the acquisition of brown and gray relative to other basic color terms. In this study, we first establish the robustness of this finding and then investigate the extent to which perception, language, and color preference may influence color conceptualization. Experimental tasks were designed to measure different aspects of perceptual color processing (discrimination and saliency), color preference and objective counts of color term frequency in preschool-directed language (books and mothers' speech) were used to compare the acquisition of three groups of colors: primary colors, secondary colors (orange, pink, and purple) that appear at the same time as the primary colors, and secondary colors (brown and gray) that appear late. Although our results suggest that perception does not directly shape young children's color term acquisition, we found that children prefer brown and gray significantly less than basic colors and that these color terms appear significantly less often in child-directed speech, suggesting that color preference, linguistic input, and developing color cognition may be linked.     

Visual Information and the Control of Reaching in Children: A Comparison Between Children With and Without Developmental Coordination Disorder

Three experiments were performed on reach and grasp in 9- to 10-year-old children (8 controls and 8 with developmental coordination disorder [DCD]). In normal reaching, children in the DCD group were less responsive to the accuracy demands of the task in controlling the transport component of prehension and spent less time in the deceleration phase of hand transport. When vision was removed as movement began, children in the control group spent more time decelerating and reached peak aperture earlier. Children in the DCD group did not do that, although, like the control group, they did increase grip aperture in the dark. When depth cues were reduced and only the target or only the target and hand were visible, children in the control group used target information to maintain the same grip aperture in all conditions, but DCD children behaved as if the target was not visible. Throughout the studies, the control group of 9- to 10-year-olds did not produce adult-like adaptations to reduced vision, suggesting that they had not yet attained adult-like integration of sensory input. Compared with control children, children with DCD did not exhibit increased dependence on vision but showed less recognition of accuracy demands, less adaptation to the removal of vision, and less use of minimal visual information when it was available.     

心理差异量对儿童青少年分类活动影响的研究

本研究选择自制的、被试从前未看过的墨渍图为实验材料,探讨心理差异量对分类活动的影响。以４０名１１－２０岁儿童青少年为被试,一方面使用速示仪测量墨渍图之间的心理差异量,一方面要求被试对墨渍图进行自由分类,并说明理由。结果发现：①心理差异量直接影响分类结果。②心理差异量在１１岁、１４岁与１７岁、２０岁之间存在着非常显著的差异（Ｐ〈０．０１）。③分类标准的选择的年龄差异主要表现在分类标准的复杂性方面。