Evidence of Incomplete Motor Programming in Parkinson's Disease

One of the essential questions regarding movement deficits in Parkinson's disease (PD) is whether they stem from impaired selecting and switching among movements, impaired use of predictive information to prepare movement, or impaired execution of movement. PD subjects (n = 9) and age-matched control subjects (n = 8) performed a cued, sequential-response RT task. The cue provided either no information, accurate information, or inaccurate information about the upcoming response. PD subjects used predictive information to prepare and to switch among movement sequences normally, but second and third key press latencies were prolonged in comparison with the first key press latency. In Experiments 2 and 3, the effects of choice set and sequence length on key press latencies were examined. These results provide evidence that PD subjects initiate movement before the entire response sequence is prepared. PD does not impair motor programming or execution processes themselves but impairs the smooth coordination of those processes.     

Rapid Aimed Limb Movements: Differential Effects of Practice on Component Submovements

Three experiments are reported in which subjects practiced rapid aimed limb movements (arm pointing and wrist rotation) toward a visible target region. Subjects were required to minimize their movement durations while still landing in the target. The movement trajectories were examined to assess the effects of practice on separate component submovements of the limb movements. The results revealed that practice improved primarily temporal, not spatial, aspects of performance. Practice reduced the overall movement durations, but had different effects on the individual submovements: Practice allowed subjects to reduce the amount of time spent performing final corrective submovements, but actually increased slightly the time needed to produce the initial ballistic submovement. The results suggest that practice in the present task primarily enhanced the ability to use feedback information, but there was also some evidence of changes in the ballistic, preprogrammed portion of the movements. The results demonstrate that analysis of submovements can reveal important details of the underlying motor control processes.     

Gross Motor Performance in Minimally Brain Injured Children

As a pre-requisite to curriculum development, the characteristics of the gross motor performance of special education classes of minimally brain injured boys and girls were described. In general, age changes in mean performance were linear, the scores of the boys being the superior. The level of performance very closely resembled that of comparison groups of educable mentally retarded children from the same school districts.     

The Effect of Rest Following Massed Practice of Continuous and Discrete Motor Tasks

Theories of the rest-related phenomena of reminiscence and warm-up decrement regard them as independent, being due to different factors. In this study it was found that rest following massed practice of a continuous task increased performance (reminiscence) and rest following massed practice of a discrete task lowered performance (warm-up decrement). The near-zero correlation found between the phenomena indicates that they are indeed independent and task-specific. Implications of the findings for the prediction of the effect of rest, and the fact that much motor learning and performance is task-specific, is discussed.     

Bimanual and Unimanual Convergent Goal-Directed Movement Times

Three experiments are reported, investigating the effects of using 1 or 2 hands when making convergent low index of difficulty (ID) and visually controlled movements (2 hands meeting together). The experiments involved movements in four different cases—a probe held in the right hand and moved to a target held in the stationary left hand, vice versa of this arrangement, both hands moving with the probe in the right hand and target in the left hand, and vice-versa of this arrangement. Experiments were the standard Fitts’ paradigm, moving a pin into a hole and a low-ID task. In Fitts’ task, 2-hand movements were faster than 1 hand only at higher IDs; this was also the case in the pin-to-hole transfer task and the movement times were lower when the pin was held in the preferred hand. Movements made with low ID showed a small effect of 1- or 2-handed movements, with the effective amplitude of the movement being reduced by about 20% when 2 hands were used.     

Control of Integrated Task Sequences Shapes Components of Reaching

Reaching toward an object usually consists of a sequence of elemental actions. Using a reaching task sequence, the authors investigated how task elements of that sequence affected feedforward and feedback components of the reaching phase of the movement. Nine right-handed adults performed, with their dominant and nondominant hands, 4 tasks of different complexities: a simple reaching task; a reach-to-grasp task; a reach-to-grasp and lift object task; and a reach-to-grasp, lift, and place object task. Results showed that in the reach-to-grasp and lift object task more time was allocated to the feedforward component of the reach phase, while latency between the task elements decreased. We also found between-hand differences, supporting previous findings of increased efficiency of processing planning-related information in the preferred hand. The presence of task-related modifications supports the concept of contextual effects when planning a movement.     

Fitts’ Theorem in Oculomotor Control: Dissociable Movement Times for Amplitude and Width Manipulations

The authors examined whether movement times (MT) for discrete saccades are constant given equivalent index of difficulty (ID) values (i.e., unitary nature of Fitts’ theorem). To that end, we contrasted ID/MT relations for saccades equated for ID but differing with respect to their target amplitudes and widths. Results showed that MT increased with increasing ID within amplitude and width conditions; however, the ID/MT slope was markedly steeper in the former condition. Thus, the amplitude condition imposed greater information processing demands than the width condition—a result indicating that the constituent elements of Fitts’ theorem are dissociable (i.e., nonunitary). Further, examination of saccade kinematics demonstrated that the optimal MT for a given target amplitude was largely independent of target width.     

Keys to the development of the role of grandparents in current Spanish society / Claves para el desarrollo del rol de abuelo y abuela en la sociedad española actual

Abstract

Current demographic changes and work-family reconciliation difficulties in Spain have resulted in an increase in the arrangement of grandparents caring for their grandchildren. However, in order to ensure that the relationship between both generations is a privileged interaction that promotes successful ageing, furthering our knowledge of the challenges that this field of study faces is necessary. On this basis, the purpose of this article is to review the theories regarding this family relationship, which, together with the empirical research into this area, comprise the basis of a three-pronged proposal that includes the keys or challenges to studying the role of grandparents: (1) the heterogeneity and multidimensionality in the study of this role; (2) the complex interaction of positive and negative aspects that produce significant ambivalence in grandparents as a reaction to their experiences in this role; and (3) the influence of the baby boom generation grandparents’ new characteristics.     

Disequilibrium in the mind,disharmony in the body

Although it is generally acknowledged that experiences of frustration, confusion, and anxiety are embodied phenomena, very little is known about how these processes modulate presumably unconscious, but constantly present, subtle bodily movement. We addressed this problem by tracking the low-level dynamics of body movement, using 1/f noise, pink noise, or “fractal scaling”, during naturalistic experiences of affect in two studies involving deep learning and effortful problem-solving. Our results indicate that body movement fluctuations of individuals experiencing cognitive equilibrium was characteristic of correlated pink noise, but there was a whitening of the signal when participants experienced states that are diagnostic of cognitive distress such as anxiety, confusion, and frustration. We orient our findings within theories that emphasise the embodied nature of cognition and affect and with perspectives that view affective and cognitive processes as emergent products of a self-organising dynamical system (the brain) that is inextricably coupled to the body.     

Buddhist prajÑĀ and Greek sophia

The present review examines five books, one by a non-Baha'i, three by a Baha'i academic, and one by a Baha'i non-academic. The non-Baha'i volume, which is very short, is by a Danish sociologist of religion, Margit Warburg. It forms a solid explanatory text informed by a lengthy experience of the Baha'is both in Denmark and abroad. This review discusses, inter alia, three volumes by a Baha'i sociologist, Peter Smith. While the three titles are very different books, taken together they form an intelligent presentation of the religion from the perspective of a thoughtful insider. Finally, the article looks at a completely different sort of book, an intelligent portrayal of Baha'ism from its spiritual and moral perspectives by Moojan Momen. This last brings readers closest to typical fare for believers and new converts.