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Results for “Goal-directed control”

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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

Visual stability with goal-directed eye and arm movements toward a target displaced during saccadic suppression.

This experiment tested whether the perceived stability of the environment is altered when there is a combination of eye and visually open-loop hand movements toward a target displaced during the eye movements, i.e., during saccadic suppression. Visual-target eccentricity randomly decreased or increased during eye movements and subjects reported whether they perceived a target displacement or not, and if so, the direction of the displacement. Three experimental conditions, involving different combinations of eye and arm movements, were tested: (a) eye movements only; (b) simultaneous eye and rapid arm movements toward the target; and (c) simultaneous eye and arm movements with a restraint blocking the arm as soon as the hand left the starting position. The perceptual threshold of target displacements resulting in an increased target eccentricity was greater when subjects combined eye and arm movements toward the target object, specially for the no-restraint condition. Subjects corrected most of their arm trajectory toward the displaced target despite the short movement times (average MT = 189 ms). After the movements, the null error feedback of the hand's final position presumably overlapped the retino-oculomotor signal error and could be responsible for the deficient perception of target displacements. Thus, subjects interpreted the terminal hand positions as being within the range of the endpoint variability associated with the production of rapid arm movements rather than as a change of the environment. These results suggest that a natural strategy adopted for processing spatial information, especially in a competing situation, could favour a constancy tendency avoiding systematic perception of a change of environment for any noise or variability at the central or peripheral levels.

Adult↗

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↗

PubMed1996

Opposite asymmetries in blind locomotor orientation of patients with panic agoraphobia compared to those with generalized anxiety.

Panic agoraphobic subjects constantly struggle with the accurate registration of everyday space-time dimension. They are hindered in the exploration of their surroundings by constant self-directed attention. In our investigations we examined whether during experimental goal-directed locomotion orientation insecurity would appear. The accuracy of target-directed motion, i.e. the degree of lateral deviation, was recorded in three diagnostic groups, panic agoraphobics (15 subjects), generalized anxiety patients (15 subjects), and normal controls (15 subjects), and normal controls (15 subjects). According to our results the approach vector of the panic agoraphobics deviated to the right, while in the case of generalized anxiety patients it deviated to the left, while normal controls did not deviate significantly from the middle line. Results are compatible with previous literature which associated panic with an overactivity of left-sided functions, and generalised anxiety with an overactivity of right-sided functions.

Adult↗

PubMed1997

Changes in initiation of orienting gaze shifts after muscimol inactivation of the caudal fastigial nucleus in the cat.

1. The production of a goal-directed saccadic gaze shift involves the specification of movement amplitude and direction, and the decision to trigger the movement. Behavioural and neurophysiological data suggest that these two functions involve separate processes which may interact. 2. The medio-posterior cerebellar areas are classically assigned a major contribution to the control of saccade metrics, and previous cerebellar lesion studies have revealed marked dysmetria of visually triggered gaze shifts. In contrast, these studies did not provide evidence for a cerebellar role in saccadic initiation. 3. In the present study, we investigated in the head-unrestrained cat the deficits in both the initiation and the metrics control of saccadic gaze shifts following pharmacological inactivation of the caudal part of the fastigial nucleus (cFN). 4. After cFN inactivation, latencies for contraversive gaze shifts increased to about 137 +/- 28% of normal, and latencies for ipsiversive gaze shifts decreased to about 84 +/- 8% of normal. Similar changes in head movement latency were observed, such that the temporal coupling between eye and head components remained largely unaffected. 5. Contraversive gaze shifts were more hypometric as their latency increased. In contrast, the degree of hypermetria in ipsiversive gaze shifts was unrelated to latency. 6. These results suggest a functional role of the medio-posterior cerebellum in gaze shift initiation and in storing information about the target location and/or the desired gaze shift amplitude.

Animals↗

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↗

PubMed1994

Pictorial support for discourse comprehension.

Discourse comprehension often involves the construction of a mental model of a situation and its updating as the discourse progresses. Theory suggests that a picture which depicts the initial physical situation in a story could help young children construct a functional mental model which they might maintain as the story progresses, thereby supporting comprehension. This was tested with young children, 4 to 6 years of age. The ability of those who saw the picture to model the final story event was enhanced and, even though the picture did not depict the main character's goal directly, recall of the goal was increased. This could be explained in terms of the creation of a functional mental model and the increased opportunity that it provides for linking goal-directed events with the goal as the model is updated. Mental representation theory was found useful here for predicting how to support comprehension in ways which could translate readily into practice in the classroom. Some potential applications of the findings in teaching young children are described.

Child Development↗

PubMed1993

Control of goal-oriented, rapid arm movements by individuals with diabetes mellitus.

Diabetic subjects completed a series of rapid, goal-directed arm movements under two conditions of unexpected external loading. Evaluation of electromyographic (EMG) patterns revealed that cocontraction and triphasic activity were predominantly associated with inertial and spring loading, respectively. During inertial load responses some EMG patterns indicated a modified cocontraction pattern. Response accuracy was unaffected by type of load but movement time was greater for the inertial load condition.

Arm↗

PubMed1994

Correlates of temporal perspective.

The present study examined both dispositional and behavioral indices of future and present temporal perspective as measured by the 1985 Gonzalez and Zimbardo scale. To examine the behavioral consequences of individual temporal perspective, the 1988 Robinson method of time diaries was used. Four dispositional indices and their association with individual temporal perspective were examined, need for achievement, work ethic orientation, self-monitoring, and evaluation anxiety. Individuals with a future time perspective placed a strong emphasis on success via goal-directed behavior, paid attention to environmental cues, and engaged in a large number of activities to achieve these goals. Implications for research are discussed.

Activities of Daily Living↗

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↗