SEARCH · PubMed Health

Results for “Goal-directed control”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

PubMed1991

Visuomotor performance of normal and clumsy children. I: Fast goal-directed arm-movements with and without visual feedback.

The mechanisms underlying accuracy in fast goal-directed arm-movements were investigated in normal and clumsy children in two age-groups, six to seven and 10 to 11 years. Clumsy children in both age-groups had a longer movement time than normal children; this difference increased slightly when there was visual feedback. For both normal and clumsy children, the relative variability of the total distance moved was smaller than that of the distance moved during acceleration, indicating a variability reduction mechanism in the course of a movement. In the six- to seven-year-old group, the relative variability of the distance moved during acceleration and of the total distance was larger for clumsy than for normal children; this did not reach significance in the 10- to 11-year-old group. It is suggested that motor difficulties are linked to inaccuracy in open-loop control processes and to less efficient use of visual feedback.

Age Factors↗

PubMed1986

Effects of eye position on saccades evoked electrically from superior colliculus of alert cats.

Electrical stimulation was carried out in the intermediate and deep gray layers of the superior colliculus in alert cats. The heads of the animals were fixed, and their eye movements were recorded with the scleral search coil method. Stimulation in the anterior two-thirds of the colliculus with long-duration pulse trains produced multiple saccades, as in the primate (45, 51), but their directions and amplitudes were influenced significantly by the initial position of the eye. Stimulation in the posterior part of the colliculus evoked saccades that appeared to be "goal-directed," whereas stimulation at the extreme caudal edge of the colliculus yielded centering saccades. These observations confirm previous reports of Roucoux and Crommelinck (48) and Guitton et al. (24). Saccades evoked during bilateral simultaneous stimulation of the superior colliculi were also dependent on the initial position of the eye. At certain relative intensities of stimulation on the two sides, saccades failed to occur when the eye was within a particular part of the oculomotor range. When the eye was outside this region, the same stimuli triggered an eye movement that drove the eye toward the zone of saccade failure. These findings indicate that saccadic commands resulting from focal collicular stimulation in the cat can be modified by information about current eye position. It is not certain where in the brain this occurs or by what neural mechanisms, but a local feedback model of the saccadic control system (46) can account for the main observations. The functional significance of these findings depends in large measure on the degree to which focal collicular stimulation reproduces naturally occurring patterns of neural activity.

Animals↗

PubMed1988

Human saccadic eye movements in the absence of the geniculocalcarine projection.

This paper describes the results of an investigation into the spatial and temporal properties of the saccadic eye-movement system in a subject with a 'blind' hemifield caused by accidental damage to the left geniculostriate projection. The results show that blind hemifield stimulation can elicit goal-directed saccades of short latency provided the contrast of the visual stimulus is above the threshold required for saccade generation at the corresponding stimulus eccentricity. Signal processing associated with blind hemifield pathways shows reduced sensitivity by comparison with the normal hemifield and greater dependence on stimulus size, eccentricity and mode of presentation. Higher contrast levels are always needed for blind field stimulation and larger variance in mean saccadic amplitudes and latencies is normally observed. Large stimulus eccentricities which would normally require corrective saccades exhibit a different response pattern to that observed in normal vision. The results show that the centre of gravity effect and the generation of rapid, 'express-saccades' observed in normal vision are not inevitable outcomes of midbrain processing of visual information. The subject's performance reveals strategic patterns of eye-movement responses which maximize the use of his normal hemifield. Visual performance in the control of saccadic eye-movement responses appears to be optimum when the detection of the visual stimulus is associated with both the geniculostriate and the midbrain pathways. Experiments designed to test for the effects of light scatter into the normal hemifield show that the subject's saccadic eye-movement performance following visual stimulation of the blind hemifield cannot be attributed either to the amount or the pattern of light scatter into the normal hemifield. The implications of present findings on the results of other studies of eye-movements in subjects with scotomas associated with cortical lesions are also examined.

Adult↗

PubMed1995

Children's memory for emotional events: the importance of emotion-related retrieval cues.

Preschool children's memory for real life emotion episodes was assessed by first having their parents generate descriptions of recent events where they had actually observed their children experience happiness, sadness, anger, and fear. The 77 preschool children, 42 boys and 33 girls, were then presented with their parents' recollection of each precipitating event and asked to recall everything they could remember about the emotion episode. Instructions for facilitating retrieval varied across four conditions. In the Control Condition, children were presented with a precipitating event and were asked to recall the entire episode, without being given any emotion cue. In the Emotion Label Condition, children were presented with a precipitating event, were asked to generate a verbal label(s) that corresponded to their emotional reaction to the event, and were asked to recall the entire episode. In the Emotion Face Condition, children generated a verbal label for their emotional reaction, made a face that corresponded to their emotional reaction, and were asked to recall the entire episode. In the Emotion Reinstatement Condition, children labeled their emotional reaction, made a face, and were then asked to reinstate their original emotional reaction as though it were happening in the present. Almost all children recognized and agreed that the precipitating events described by their parents had occurred. Across all emotions, children instructed to use all three emotion cues generated the most detailed, goal-directed, and causally structured accounts, and also recalled more additional experiences associated with each emotion episode. These results show that the quantity, content, and organization of memory for emotional events are affected significantly by reinstatement of the original emotional reaction.

Child↗

PubMed1988

Spared-root deafferentation of a cat's hindlimb: hierarchical regulation of pathways mediating recovery of motor behavior.

Previous studies showed that after complete hindlimb deafferentation in cats, the ipsilateral descending pathways mediated recovery of overground, goal-directed locomotion and accurate placement of the deafferented limb. In the present study deafferentations sparing one dorsal root (L6) were performed to see if the descending systems would still be responsible for the recovery. The partially deafferented hindlimb is initially impaired in postural reflexes and accurate placement during locomotion but considerable recovery occurs. A similar pattern of severe impairment and subsequent recovery is observed in cats in which the only lesion is L1 hemisection. When a hemisection is added 6 months later to chronic spared-root deafferentation the recovery (from the latter lesion) is temporarily reversed but the animals recover again in a fashion similar to that after hemisection alone. Since there is no recovery of overground locomotion when hemisection is added to complete deafferentation but there is when deafferentation is incomplete, the descending pathways apparently are not responsible for maintaining the recovery when one dorsal root is spared as they are when all are cut. The results suggest that a competitive or hierarchical control over residual systems may regulate recovery of motor function.

Animals↗

PubMed1992

Effects of weak antagonist on fast elbow flexion movements in man.

By using a mathematical model and experiments involving electrical simulation of antagonistic muscles, we have formed the hypothesis (Wierzbicka et al. 1986) that in one-joint movements the antagonist muscle not only provides braking torque but also controls movement time. To get additional experimental support for this hypothesis, we studied elbow flexion movements performed by patients with spinal cord injury at the C5-6 level who had relatively normal strength in their biceps muscle and little or no voluntary control of the triceps. Seven quadriplegic patients and six control subjects performed elbow flexion movements of 10 degrees, 20 degrees, and 30 degrees "as fast and accurately as possible". Despite the lack of antagonist, patients used the same "pulse height" strategy as control subjects to scale their responses with movement amplitude. However, patients' movement time was on average twice that of control subjects, and durations of both accelerative and decelerative phases of movement were increased. Movement speed and acceleration were reduced to 20-50% of the corresponding values of control subjects. Patients tended to overshoot the target to a larger extent than control subjects, particularly 10 degrees targets, with nearly twice the error. We performed the same experiments using an external torque motor to assist the weak triceps. When a constant extensor torque of 2.5 or 5 Nm was provided by the motor, patients were able to move faster, and movement accuracy improved to within the normal range. These results provide direct evidence that the lack of an antagonist has an important effect on completion time and accuracy of fast goal-directed movements.

Adult↗

PubMed1984

Source density analysis of scalp potentials during evaluated action. I. Coronal distribution.

The distribution of source densities (the "Laplacean") of event related potentials (ERPs) over the scalp during a goal-directed task has been derived by a novel method which presents seven samples in a hexagonal array, using an economical computing technique that affords much freedom from artefactual contamination. The task had four phases: waiting for a ball to appear, observing its coordinates and estimating action needed to get it through a goal-mouth, acting and awaiting the outcome, and finally evaluating the outcome as success or failure. Different phases of the task were characterized by significantly different distributions of sources. Failures were distinguished from success to consistent features of the last phase of the ERP. All locations within the reference hexagon (spanning a circle of approximately 12 cm diameter on the scalp) showed the latter features. In control experiments, the effects of response mode and of different cognitive interpretations of the input/output situation were studied. A check showed that with monopolar recording involuntary tongue movements can totally vitiate conclusions in such investigations. The Laplacean derivations proved relatively free of such artefactual contamination.

Arousal↗

PubMed1995

The experiential meaning of eating, handicap, adaptedness, and confirmation in living with esophageal dysphagia.

This article is mainly based on interview studies of pensioners' (n = 62), patients' (n = 19), and students' (n = 87) experiences of living with longstanding esophageal dysphagia. The aim is to describe the experiential meaning of dysphagic patients' lives by interpreting their experiences, problems, and emotions and by specifying these into scales according to the model of goal-directed action by Pörn [43-49]. The experiential meaning will be articulated in terms of attainment or nonattainment of goals in relation to eating, handicap, adaptedness, and confirmation. In the experiential meaning of eating, the emphasis is on the attainment of nourishing goals or goals attained by means of food with desired hedonistic qualities and linked with feelings of hope or no hope of a shared life. The experiential meaning of handicap is interpreted as the dysphagic individual's experiences of an actual nonattainment of eating goals due to swallowing disabilities and with experiences of nonattainment of other important goals and related emotions; for example, shame for human incompetence. The experiential meaning of adaptedness is understood as the dysphagic individual's experiences of actual capacity for goal attainments interpreted as a sense of control in the daily living with dysphagia and linked with security, or in the negative case, reduced self-esteem and feelings of panic or fear. The experiential meaning of confirmation is interpreted as the dysphagic individual's experiences of actual or potential repertoire for goal attainment, i.e., self-assessment strengthened by evidence obtained in relationships linked with emotions of hope of self-realization. In conclusion, a specific model for understanding the dysphagic patient's concealment of dysphagia in the medical encounter has been developed.

Adaptation, Physiological↗

PubMed1986

The role of fixation and visual attention in the occurrence of express saccades in man.

The differential influence of fixation and directed visual attention on reaction times of goal-directed saccades and especially on the occurrence of express saccades was investigated. In all the experiments the subjects were instructed first to keep their direction of gaze at the center of a translucent screen with or without a central fixation point. When a new stimulus appeared, the subjects had to look at it as soon as possible. In some control experiments the subjects had to direct their gaze to the screen center and simultaneously direct their attention to a peripheral light spot before the target for the saccade appeared. Many express saccades occurred when either active fixation of a central fixation point or attention directed to a peripheral visual target (regardless of its position) was interrupted 200 ms before the target for the saccade appeared. Express saccades were almost completely abolished in the presence of fixation and/or directed visual attention at the moment in which the saccade target appeared. We conclude that express saccades occur if visual attention has already been released at the moment when the target for the saccade appears. This disengagement needs some time which adds to the reaction time.

Adult↗

PubMed1992

Intention and outcome: key components of causal structure facilitating mapping in children's analogical transfer.

The consequences of two key features of causal structure in source stories, intention and positive outcome, for analogical transfer were examined in kindergarten and second graders. In Experiment 1, children received either structure-complete, structure-incomplete, or irrelevant source stories. Structure-incomplete stories lacked either the intention to solve a problem (a goal-directed component), evidence of a successful consequence (an outcome-related component), or both as part of the solution activity described in source stories. Evidence for transfer was obtained for second graders when a goal-directed component, and to a lesser extent, an outcome-related component were connected to the solution action in source stories. Differences among conditions for kindergartners were less evident, although they revealed a pattern of performance similar to the second graders. A second experiment was conducted to determine whether memory and an orientation to use the source story information might account for these findings. Efforts to ensure memory for and hints to use information in the source stories, however, did not benefit solution transfer when intention and positive outcome were absent. These results suggest that a complete causal structure, including goal and outcome, in source stories augments transfer in young children by promoting mapping of the analogical relationship between source stories and the target problem.

Achievement↗

PubMed1990

Dynamic properties of human goal-directed arm movements.

In the present study, the velocity of pointing movements towards visual targets was analyzed. In accordance with the literature, tangential velocity was found to exhibit rather smooth, single-peaked profiles. In contrast, however, the profiles of the velocity components in the Cartesian coordinates of space were conspicuously multi-peaked, and suggestive of sums of a smooth curve and an oscillation. Oscillation frequency was 4-6 Hz, and its amplitude 200-600 mm/s; the phase shift between horizontal and vertical oscillation was about 180 degrees. The oscillation remained unaltered when the external load of the arm, the size of the visual target, or the required movement direction were changed. The relationship between the present findings and previously documented rhythmic properties of motor control is discussed, and it is concluded that the oscillations may have been generated by neural circuits with inherent oscillatory properties.

Acceleration↗

PubMed1987

The properties of goal-directed eye movements evoked by microstimulation of the cerebellar vermis in the cat.

The properties of eye movements evoked by microstimulation of the cerebellar vermis, lobules V VII, were investigated in encéphale isolé cats. The evoked eye movements tended to reach the same final goal in the orbit irrespective of initial eye position. The goal position depended on stimulus intensity. In contrast with the monkey, the goal of the eye movement lay within the oculomotor range. The goal position of the eye movements evoked by simultaneous stimuli delivered to two sites corresponded with the point which was obtained by the vectorial addition of the two eye movements evoked by the stimulation of each site. These findings suggest that the cat vermal lobules V VII play an important role in the control of horizontal and vertical eye position in the orbit.

Animals↗

PubMed2026

The effects of visuomotor training and tDCS stimulation on visuomotor integration and visual processing: an electrophysiological approach.

BACKGROUND: Visuomotor integration coordinates visual and motor cortical activity to produce goal-directed responses and can be indexed by Rolandic Mu-rhythm suppression and visual evoked potential (VEP) P100 parameters. Perceptual-motor training improves visuomotor performance, and transcranial direct current stimulation (tDCS) over primary motor cortex (M1) has been reported to enhance motor learning when paired with training. This study examined whether anodal M1 tDCS augments the effects of Senaptec visuomotor training in healthy adults. METHODS: Sixty participants were randomized to active anodal tDCS (five 10-minute sessions, 1 mA; n = 31) or sham (n = 29) over M1 immediately before each Senaptec training session; 53 completed all sessions and post-testing. Outcomes were Mu-suppression ratios, VEP P100 latency and amplitude, and Senaptec measures of visual sensitivity and visuomotor control. RESULTS: Active tDCS produced no augmentation of any outcome, with no significant group × time interaction for any measure, consistent across composite and task-level analyses. Training alone produced no change in Mu suppression or visuomotor control. By contrast, both groups showed significant training-related gains in visual sensitivity, including near-far quickness and stereopsis, accompanied by shorter P100 latencies and larger amplitudes, indicating more efficient early visual processing. CONCLUSIONS: A clear dissociation emerged: training produced robust improvements in early visual processing, whereas neither tDCS nor training altered sensorimotor (Mu) or visuomotor-control measures. The tDCS results should be interpreted cautiously given the modest dose and limited power to detect small effects, rather than as evidence of inefficacy. Tablet-based perceptual training enhanced visual processing independent of neuromodulation.

Humans↗

PubMed1981

Different effects involved in the interaction of saccades and the vestibulo-ocular reflex.

The accuracy of human goal-directed saccades during passive sinusoidal whole-body rotation is the same as that of normal saccades with the head still. Two mechanisms contribute to this accuracy: 1. There is an incomplete summation (70% on the average) of saccade and VOR velocities. 2. The duration of saccades during head rotation is lengthened if VOR and saccade velocities have the same direction, and is shortened if their direction is opposite. The latter finding supports the hypothesis that saccades are controlled by local feedback.

Eye Movements↗

PubMed1992

Goal-directed care: caring for aggressive nursing home residents with dementia.

1. Aggressive behavior in elders with dementia occurs most often during personal care. It is often a response to invasion of private space and may be prevented or reduced by interpersonal approaches that reflect a set of individualized goals for the resident. 2. Five resident goals for preventing or reducing aggressive behavior are to feel safe, to feel physically comfortable, to experience a sense of control, to experience optimal stress, and to experience pleasure. 3. These goals provide a framework for humane care that respects the personhood of the individual and minimizes the need for psychotropic medications and physical restraints.

Aged↗

PubMed1991

The effects of task preference on performance during purposeful and nonpurposeful activities.

This study examined the number of repetitions, increase in heart rate, increase in blood pressure, and rating of perceived exertion of subjects performing the most-preferred and least-preferred tasks from a predetermined list under purposeful and nonpurposeful conditions. Twenty healthy women completed the four experimental tests in random order for a period of 10 min each. The results indicated that there was no significant interaction (p greater than .05) between task choice and condition, thus implying that the subjects' performance was not influenced by task preference regardless of whether the activity was purposeful or nonpurposeful. Comparisons between the purposeful and nonpurposeful conditions revealed that the increase in heart rate and rating of perceived exertion were significantly higher (p less than .05) during nonpurposeful activity for both the most-preferred and the least-preferred tasks. On the basis of these results, it is recommended that therapists use purposeful, or goal-directed, activities in their practice, even if they are unable to provide their patients with a choice of therapeutic tasks.

Adult↗

PubMed1991

Compensatory muscle activity for sitting posture during upper extremity task performance in paraplegic persons.

Compensation for the loss of postural activity of the erector spinae (ES) muscle in spinal cord injured (SCI) subjects was investigated. All SCI subjects had clinically complete lesions below the T3 level. Body disbalance was invoked by requiring sitting subjects to execute reaching movements over individually predetermined distances in a horizontal plane. Myoelectric activity of the latissimus dorsi (LD) muscle and the trapezius pars ascendens (TPA) muscle both in the SCI subjects and in controls was recorded. The body disbalance was measured in terms of changes in the position of the body centre of gravity. The effects of anticipation for body displacement were examined by cuing the direction of the reaching movement. Our results indicate that paraplegic subjects use both LD and TPA to stabilize their sitting posture, in contrast to non-disabled persons. Secondly, the movement anticipation is in general slower in persons with paraplegia. Furthermore, the paraplegic subjects showed considerable impairments concerning the processing of precued information prior to a goal-directed upper extremity movement.

Adolescent↗

PubMed1986

Adaptive gain control of saccadic eye movements.

Properties of gain adaptivity in the saccadic system were studied. Subjects had to track a target which moved in single or double steps. The first target step which elicited the primary saccade had an amplitude in the range of 8-16 deg. The primary saccade triggered a further target displacement of 4 deg either in the same or--in different experimental sessions--in the opposite direction of the first target step. These consistent intrasaccadic target displacements lead to adaptive changes of saccadic amplitudes. The experimental data show that the saccadic system adapts to the stimulus sequence in a simple, parametric manner, namely by changing its gain. Consequently, it is assumed that a single gain element determines saccade sizes for all target eccentricities. Further, it is shown that adaptation has different time courses for gain increase and decrease, and its performance is close to completeness. The results are discussed with respect to the undershooting behaviour of goal-directed saccades and the functional demands to the saccadic system.

Adaptation, Ocular↗