Kinematic study of reaching-grasping movements

The experiment was conducted to investigate, by using kinematic parameters, the influence of the type of prehension on the transportation component in reaching-grasping movements. The main question was whether the transportation component is influenced by the type of prehension besides the distance of the object. The experiment was carried out on eight subjects who performed reaching-grasping movements toward objects located at different distances. Two types of prehension were examined: whole hand prehension and precision grip. The following kinematic parameters of the transportation component (wrist movement) were studied: movement times, profiles of velocity and accelerations. Our results have shown that the transportation component is affected by the two factors. However the kinematic parameters were influenced differently by the distance and the type of prehension. Our conclusion is that, although distance and type of prehension affect the transportation component, they are computed separately in programming this component.     

Kinematic invariants during cyclical arm movements

It has been observed that the motion of the arm end-point (the hand, fingertip or the tip of a pen) is characterized by a number of regularities (kinematic invariants). Trajectory is usually straight, and the velocity profile has a bell shape during point-to-point movements. During drawing movements, a two-thirds power law predicts the dependence of the end-point velocity on the trajectory curvature. Although various principles of movement organization have been discussed as possible origins of these kinematic invariants, the nature of these movement trajectory characteristics remains an open question. A kinematic model of cyclical arm movements derived in the present study analytically demonstrates that all three kinematic invariants can be predicted from a two-joint approximation of the kinematic structure of the arm and from sinusoidal joint motions. With this approach, explicit expressions for two kinematic invariants, the two-thirds power law during drawing movements and the velocity profile during point-to-point movements are obtained as functions of arm segment lengths and joint motion parameters. Additionally, less recognized kinematic invariants are also derived from the model. The obtained analytical expressions are further validated with experimental data. The high accuracy of the predictions confirms practical utility of the model, showing that the model is relevant to human performance over a wide range of movements. The results create a basis for the consolidation of various existing interpretations of kinematic invariants. In particular, optimal control is discussed as a plausible source of invariant characteristics of joint motions and movement trajectories.     

Kinematic construction of the trajectory of sequential arm movements

A kinematic construction rule determining the trajectory of human sequential movements is formulated using minimum-jerk and minimum-angular-jerk trajectories. The kinematic construction rule states that the observed trajectory of sequential movements coincides with a weighted average of the minimum-jerk trajectory and the segmented minimum-angular-jerk trajectory. This rule covers not only point-to-point movements but also simple sequential movements. Five kinds of experiments that measure the trajectories in planar, multijoint sequential arm movements were conducted. The measured trajectories coincide with the predictions made on the basis of the kinematic construction rule presented here. Moreover, predictions of previous models such as the minimum-jerk, the equilibrium-trajectory, and the minimum-torque-change models are shown to be incompatible with our observations of sequential movements. Received: 31 October 1997 /Accepted in revised form: 18 November 1998     

Respiratory movements during vocalization in the squirrel monkey

Respiratory abdominal movements during vocalization were measured in awake squirrel monkeys during spontaneous and playback-induced vocal activity. Large vocalization-correlated respiratory movements (VCRM) starting before vocalization were observed during several call types, such as peeping, trilling, cackling and err-chuck. Purring, in contrast, was accompanied by only small VCRM that started late after vocal onset. VCRM during trilling, a call with marked frequency modulation, showed a modulation in the rhythm of the frequency changes. A correlation with amplitude modulation was also present but more variable. As high frequencies need a higher lung pressure for production than low frequencies, the modulation of VCRM seems to serve to optimize the lung pressure in relation to the vocalization frequency. The modulation, furthermore, may act as a mechanism to produce different trill variants. During err-chucks and staccato peeps, which show a large amplitude modulation, a non-modulated VCRM occurred. This indicates the existence of a laryngeal amplitude-controlling mechanism that is independent of respiration.Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

Kinematic study of the temporal coupling between the components of transport and manipulation during reaching and grasping movements

In this study the temporal coupling between transport and manipulation components of prehension movements was tested. For this purpose two experiments were carried out. In Experiment 1 six normal subjects were required to reach and grasp one of three spheres located at three different distances (Blocked trials). In Experiment 2 a visual perturbation paradigm was used in which the location of the object to be reached and grasped could change at onset of arm movement (Perturbed trials). The results of this study exclude a temporal coupling between events of transport and manipulation components. On the contrary they suggest that manipulation component organizes its time course having information about the time required to reach the object.     

Kinematic description of variability of fast movements: analytical and experimental approaches

Analysis of variability of fast aimed movements predicts the properties of trajectory variance. The analysis is based on a kinematic model with nonlinear changes in “internal time”. The purpose of the work was to identify different sources of variability and their influence on the trajectory variance. An analytical expression for the speed-accuracy trade-off is introduced. Experiments were performed with subjects making single-joint elbow flexion movements over different distances as fast as possible with their eyes closed to memorized targets. Standard deviation of movement trajectory increased during the first part of the movement and subsequently decreased. The variance peaked after the time of peak velocity, close to the time of peak deceleration. A dependence of the trajectory variance on movement distance (speed-accuracy trade-off) was seen during the movement (at times of peak velocity and peak deceleration) but not after the movement termination. We conclude that the previously reported drop in the variability of movement trajectory during the deceleration phase does not necessarily mean a compensation by the control system but may result from purely kinematic properties of the movement. The importance of the time of measurement for analysis of the speed-accuracy trade-offs is emphasized.     

Kinematic characteristics of the voluntary cyclic trunk movements in patients at the early stage of Parkinson's disease

Patients with the initial stage of Parkinson disease (PD) and matched controls performed repetitive bendings and turnings in standing position. Tasks included trunk movements in each of the anatomical planes: sagittal, frontal and axial. Electromagnetic system Flock of Birds was used for movement registration. Sensors were fixed at different segments of subject's body. Joint angles in the ankle, hip and torso as well as coordinates of the center of pressure served as output parameters. The amplitudes of joint angles were found to be lower in PD patients. Performance of the axial rotation revealed most pronounced differences. Thus, the amplitudes of joint angles of trunk movements in different anatomical planes reliably discriminate between PD patients and healthy subjects.     

Comparative study of the radiosensitivity of monkey chromosomes in cellular irradiation in vivo and in vitro]

Chromosome radiosensitivity was studied in the primary culture of peripheral blood lymphocytes and epithelial kidney cells of Macaca mulatta monkeys after gamma-irradiation in vivo and in vitro. The results of the experiments show that there are no differences in aberration yields produced in both types of somatic cells under gamma-irradiation in vivo and in vitro.     

Inheritance of pendulum movements in rats]

Inheritance of predisposition to pendulum movements (PMs) in rats was studied by two methods: segregation analysis of binary traits (on pedigrees recorded in the selection archives for cataleptic strain GC) and the classical Mendelian analysis of hybrids between strains PM+ and PM- selected for pronounced PMs and the absence of PMs, respectively. Both methods yields the same result: it was found that predisposition to PMs exhibited a monogenic dominant inheritance with incomplete penetrance.     

Kinematic features of continuous hand reaching movements under simple and complex rhythmical constraints

BackgroundAuditory cues are known to alter movement kinematics in healthy people as well as in people with neurological conditions (e.g., Parkinson’s disease or stroke). Pacing movement to rhythmical constraints is known to change both the spatial and temporal features of movement. However, the effect of complexity of pacing on the spatial and temporal kinematic properties is still poorly understood. The current study investigated spatial and temporal aspects of movement (path and speed, respectively) and their integration while subjects followed simple isochronous or complex non-isochronous rhythmical constraints. Spatiotemporal decoupling was expected under the latter constraint.MethodsTen subjects performed point-to-point hand movements towards visual targets on the surface of a hemisphere, while following continuous auditory cues of different pace and meter. The spatial and temporal properties of movement were compared to geodesic paths and unimodal bell-shaped speed profiles, respectively. Multiple two-way RM-ANOVAs (pace [1–2 Hz] × meter [duple–triple]) were performed on the different kinematic variables calculated to assess hand deviations from the model data (p ? 0.05).ResultsAs expected, increasing pace resulted in straighter hand paths and smoother speed profiles. Meter, however, affected only the path (shorter and straighter under triple) without significantly changing speed. Such an effect was observed at the slow pace only.ConclusionsUnder simple rhythmic cues, an increase in pace causes spontaneous adjustments in spatial features (straighter hand paths) while preserving temporal ones (maximally-smoothed hand speeds). Complex rhythmical cues in contrast perturb spatiotemporal coupling and challenge movement control. These results may have important practical implications in motor rehabilitation.     

Computer modeling of human movements]

A dynamic model for studying man's movements is proposed. Lagrange equations of the second order are used. Differential equations of the model are presented in the matrix form, and all the coefficients involved are calculated from recurrent formulae. The dynamic model described is easily algorythmized. Differentiating operations can be thus avoided which are realized on electron computers with difficulities.     

Kinematic and EMG characteristics of simple shoulder movements with proprioception and visual feedback.

The objective of this study was to determine if simple, shoulder movements use the dual control hypothesis strategy, previously demonstrated with elbow movements, and to see if this strategy also applies in the absence of visual feedback. Twenty subjects were seated with their right arm abducted to 90 degrees and externally rotated in the scapular plane. Subjects internally rotated to a target position using a custom shoulder wheel at three different speeds with and without visual feedback. Kinematics were collected with a motion analysis system and electromyographic (EMG) recordings of the pectoralis major (PECT), infraspinatus (INFRA), anterior and posterior (ADELT, PDELT) deltoid muscles were used to evaluate muscle activity patterns during movements. Kinematics changed as movement speed increased with less accuracy (p<0.01). Greater EMG activity was observed in the PECT, PDELT, and INFRA with shorter durations for the ADELT, PDELT and INFRA. Movements with only kinesthetic feedback were less accurate (p<0.01) and performed faster (p<0.01) than movements with visual feedback. EMG activity suggests no major difference in CNS control strategies in movements with and without visual feedback. Greater resolution with visual feedback enables the implementation of a dual control strategy, allowing greater movement velocity while maintaining accuracy.     

Method for simultaneous study of peristaltic and pendular movements of isolated rabbit ileum]

A method is described for studying simultaneously the peristalsis and the pendular movements in the isolated pieces of rabbit ileum. At the same time, using this method it is possible to analyse the actions of drugs on the mechanisms which ensure the pendular movements and the propulsive activity, as well as their relationship. The method is relatively simple and only classical and commercially available equipments are needed. With this method the records and the volume of fluid expelled are suitable for statistical analysis.     

The 4-dimensional spherical color space in the monkey]

Discrimination of colours by macaque rhesus was studied by the method of elaboration of differentiation inhibition of instrumental conditioned responses to colour stimuli. Matrix of probabilities of instrumental reactions to presentation of colour stimuli, the columns of which corresponded to the colours applied, and the lines--to series of experiments with definite reinforced colour--was processed by the method of factor analysis. Four factors describing the used colours in four-dimensional Euclidean space were singled out. Spatial structure of the seven used colours satisfies the equation of four-dimensional sphere. Two first factors are interpreted as colour-opponent red-green and yellow-blue and the third and fourth ones as achromatic light and dark neuronal channels. Perceptive space of colour stimuli based on the data of instrumental behaviour of the monkey corresponds to analogous results obtained by the method of multidimensional scaling of subjective evaluations of super-threshold colour differences for the man.     

The organization of instrumental food-procuring movements in rats]

The roles of the lateral hypothalamus, basolateral nucleus of the amygdalar complex, the second field of the frontal cortex, and ventromedial thalamic nucleus in organization of the fast ballistic food-procuring movements were studied in albino rats. Sequences of uni- and bilateral destruction of the brain structures were assessed by photorecording. Movement-related neuronal activity in these structures was recorded in freely moving animals. A specific involvement of each of the above listed structures in organization of food-procuring movements was shown. The lateral hypothalamus seems to participate in initiation of the motor program and its efficient realization, the basolateral amygdala appears to produce activatory, training, and stabilizing effects. The second field of the motor cortex leads in movement acquisition (i.e., in memorizing) and decision making about triggering the program. The idea about the relay role of the thalamic motor nucleus is supplemented by understanding of its more complex integrative function.