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PubMed2000

Congenitally blind individuals rapidly adapt to coriolis force perturbations of their reaching movements.

Reaching movements made to visual targets in a rotating room are initially deviated in path and endpoint in the direction of transient Coriolis forces generated by the motion of the arm relative to the rotating environment. With additional reaches, movements become progressively straighter and more accurate. Such adaptation can occur even in the absence of visual feedback about movement progression or terminus. Here we examined whether congenitally blind and sighted subjects without visual feedback would demonstrate adaptation to Coriolis forces when they pointed to a haptically specified target location. Subjects were tested pre-, per-, and postrotation at 10 rpm counterclockwise. Reaching to straight ahead targets prerotation, both groups exhibited slightly curved paths. Per-rotation, both groups showed large initial deviations of movement path and curvature but within 12 reaches on average had returned to prerotation curvature levels and endpoints. Postrotation, both groups showed mirror image patterns of curvature and endpoint to the per-rotation pattern. The groups did not differ significantly on any of the performance measures. These results provide compelling evidence that motor adaptation to Coriolis perturbations can be achieved on the basis of proprioceptive, somatosensory, and motor information in the complete absence of visual experience.

Adaptation, Physiological↗
PubMed2004

Motivation-dependent responses in the human caudate nucleus.

Motivation is a complex process that leads to completion or avoidance of a behavior. Past research strongly implicates the basal ganglia in a circuit integral for the control of motivation. Specifically, the human striatum has been shown to process reward information, differentiating between monetary rewards and punishments in recent neuroimaging experiments. It is unclear, however, how the dorsal striatum, particularly the caudate nucleus, responds to changes in the motivational context of a task. Using an event-related design, where participants were given positive and negative feedback upon guessing the value of an unknown card, we manipulated the motivational context of the task by dividing trials into periods of high incentive (where visual feedback indicated monetary rewards and punishments) and low incentive (where visual feedback indicated only accuracy). We found that activity in the caudate nucleus was strongly influenced by the different incentive periods. The hemodynamic response was characterized by a larger rise at the onset of trials and larger differences between positive and negative feedback during periods of high incentive. These results suggest that changes in motivation are capable of modulating basal ganglia activity, and further support an important role for the caudate nucleus in affective processing.

Adult↗
PubMed1984

Maximum phonation time for children with normal voices.

Maximum phonation time (MPT) data were collected for 286 male and female children between the ages 3-6 and 17-11. Subjects sustained phonation of the vowel/a/for 14 consecutive trials. The influence of sex, age, and multiple trials on MPT was studied. The group mean MPT for the male subjects was significantly longer than for the female subjects. Generally, phonation time increased with age for both sexes. A definite monotonic increase in length of sustained phonation was not apparent across all age levels. Optimum MPT performance can be enhanced by using repeated trials, and by providing visual feedback and encouragement regarding depth of inhalation, verbal instructions and encouragement regarding increased phonation time, and visual feedback regarding length of sustained phonation prior to and during each trial. The large intra- and intersubject variability in MPT performance reported in this study prevents valid individual-group mean MPT comparisons. A more discriminatory clinical interpretation of MPT is necessary.

Adolescent↗
PubMed2003

Three-year follow-up for virtual reality exposure for fear of flying.

Thirty participants who had been treated for aviophobia with virtual reality graded exposure therapy with physiological monitoring and visual feedback (VRGETpm), virtual reality graded exposure therapy with physiological monitoring only (VRGETno), or imaginal exposure therapy (visualization) with physiological monitoring only (IET) between January 1998 and January 1999 were contacted in January 2002 for a 3-year posttreatment follow-up assessment. Of the participants in the VRGETpm group who had flown successfully by the end of treatment, all had maintained their ability to fly at follow-up. Of the participants in the VRGETno group who had flown successfully by the end of treatment, two were no longer able to fly. Of the participants in the IET group who had flown successfully, all were still able to fly. It appears that the addition of teaching self-control via visual feedback of physiological signals may serve to maintain treatment gains in long-term follow-up.

Adult↗
PubMed2001

Human large-scale oscillatory brain activity during an operant shaping procedure.

The present study aimed at examining the oscillatory brain-electric correlates of human operant learning using high-density electroencephalography (EEG). Induced gamma-band activity (GBA) was studied using a fixed-interval reinforcement schedule with a variable limited hold period, which was decreased depending on response accuracy. Thus, participants' behavior was shaped during the course of the learning session. After each response, numbers indicating the money value of that response served as reinforcing stimuli. Random reinforcement and self-paced button pressing without reinforcement were added as control conditions. GBA around 40 Hz was enhanced at posterior electrodes in response to visual feedback stimuli during shaping and random reward compared to the self-paced pressing condition where no visual feedback was provided. Furthermore, shaping was associated with a pronounced left frontal lower gamma (20-30 Hz) increase in response to feedback stimuli, whereas this pattern was not observed in the random reinforcement and self-paced pressing conditions. The present findings are in line with the notion that macroscopic high-frequency dynamics of neuronal cell assemblies may be regarded as a mechanism involved in learning and memory formation.

Adult↗
PubMed1994

Spatial bias in visually-guided reaching and bisection following right cerebral stroke.

Groups of patients with left or right unilateral cerebral stroke were tested for their ability to reach either toward a single visual target or midway between 2 targets. The tasks were performed both in free vision and in conditions preventing visual feedback from the hand. It was found that only the right CVA patients were inaccurate in reaching, and only when visual feedback was absent. This effect of right hemisphere lesions took the form of a rightward bias, present throughout the trajectory of the hand during the reach. It was present regardless of the hand used in reaching and whichever of the two tasks was performed, and was of a similar magnitude irrespective of target location. It is suggested that this rightward bias might reflect the 'premotor' effects that have been proposed to contribute to line-bisection errors in certain patients with visuospatial neglect.

Aged↗
PubMed2006

Impaired dimensional selection but intact use of reward feedback during visual discrimination learning in Parkinson's disease.

It has been suggested that Parkinson's disease (PD) impairs the ability to learn on the basis of reward or reinforcing feedback i.e., by trial-and-error. In many learning tasks, particular 'dimensions' of stimulus information are relevant whilst others are irrelevant; therefore, efficient performance depends on identifying the dimensions of these 'compound' stimuli and selecting the relevant dimension for further processing. We investigated the ability of patients with PD, as well as patients with Huntington's disease and patients with frontal or temporal lobe lesions, to learn visual discriminations which required either a number of associations to be learned concurrently (the 'eight-pair' task) or the selection of information from compound stimuli (the 'five-dimension' task), both tasks being learned by trial-and-error. None of the basal ganglia disorder patient groups was impaired on the eight-pair task, militating against a crucial role for these brain structures in trial-and-error learning per se. Patients with mild, medicated PD, but not unmedicated PD patients, were impaired at identifying all five feature dimensions in the five-dimension task, implying dopaminergic 'overdosing' of the ability to analyse compound stimuli in terms of their component dimensions. Temporal lobe lesion patients performed similarly, suggesting that the temporal lobe may be the site of the medication overdose effect. Patients with severe, medicated PD were impaired at compound discrimination learning on the five-dimension task in the absence of an underlying impairment in identifying component stimulus dimensions; this pattern resembled that seen in Huntington's disease and frontal lobe lesion patients, implying that fronto-striatal circuitry is involved in the formation of rules based upon selected stimulus dimensions.

Adult↗
PubMed1976

The instructional effect of verbal/visual feedback in visualized instruction.

This study was designed to measure the instructional effect of verbal/visual beedback in facilitating S achievement and to determine whether the amount of realistic detail contained in the visualization influences S achievement. Two hundred sixty-seven university students were randomly assigned to one of three presentation method. Ss received a pretest, participated in their respective instructional presentation, and received four individual criterion measures. Results indicate that all feedback strategies are not equally effective in facilitating student achievement of different educational objectives and that specific feedback techniques may be so elaborate as to interfere with rather than facilitate achievement.

Achievement↗
PubMed1975

Effect of exteroceptive feedback in controlling electrodermal activity in pre-conditioned fears.

Ss with a strong fear of snakes were taught to increase and decrease their skin resistance during practice sessions with a continuous visual display. Ss were not aware that they were increasing or decreasing their levels of skin resistance and attempted only to influence the magnitude of the multimeter display, the polarity of which was controlled by the experimenter. The study used a within-subjects reversal design to investigate whether bidirectional control could be acquired over skin resistance level. To investigate whether this acquired control could affect the magnitude of elicited pre-conditioned autonomic responses, a pre- and post-training comparison was made between the GSRs elicited during test sessions in which Ss viewed slides of snakes while attempting to influence their electrodermal activity with the assistance of the visual display. The results suggest that Ss are able to acquire voluntarily bidirectional control of their level of skin resistance with continuous visual feedback and that this control can either depress or facilitate the magnitude of pre-conditioned emotional responses as a function of visual feedback.

Adolescent↗
PubMed2002

Modeling head tracking of visual targets.

Control of the head involves somatosensory, vestibular, and visual feedback. The dynamics of these three feedback systems must be identified in order to gain a greater understanding of the head control system. We have completed one step in the development of a head control model by identifying the dynamics of the visual feedback system. A mathematical model of human head tracking of visual targets in the horizontal plane was fit to experimental data from seven subjects performing a visual head tracking task. The model incorporates components based on the underlying physiology of the head control system. Using optimization methods, we were able to identify neural processing delay, visual control gain, and neck viscosity parameters in each experimental subject.

Algorithms↗
PubMed1990

Subjective awareness of abnormal involuntary movements in chronic schizophrenic patients.

The authors examined the effects of verbal and visual feedback on subjective awareness of involuntary movements in 20 chronic schizophrenic patients. At initial evaluation only 25% of the patients were fully aware of their movement disorder. Both verbal and visual feedback resulted in significant immediate enhancement of awareness. However, assessment of awareness 2 weeks later showed a return to prefeedback baseline levels. Lack of awareness of involuntary movements was associated with a lack of awareness of psychiatric disorder, and both were associated with a longer duration of illness.

Adult↗
PubMed2000

Vision and laterality: does occlusion disclose a feedback processing advantage for the right hand system?

The main purpose of this study was to examine whether manual asymmetries could be related to the superiority of the left hemisphere/right hand system in processing visual feedback. Subjects were tested when performing single (Experiment 1) and reciprocal (Experiment 2) aiming movements under different vision conditions (full vision, 20 ms on/180 ms off, 10/90, 40/160, 20/80, 60/120, 20/40). Although in both experiments right hand advantages were found, manual asymmetries did not interact with intermittent vision conditions. Similar patterns of results were found across vision conditions for both hands. These data do not support the visual feedback processing hypothesis of manual asymmetry. Motor performance is affected to the same extent for both hand systems when vision is degraded.

Adolescent↗
PubMed2003

'Side-effects': intrinsic and task-induced asymmetry in bimanual rhythmic coordination.

Multifrequency coordination studies have shown the importance of hand-role in addition to hand-preference in bimanual rhythmic coordination. In these studies, hand-role has been defined by the task of the individual hands (moving fast or slow). In the present study, the hands were coordinated at the same frequency and hand-role was defined by the asymmetry of the coordination pattern. Eleven consistent left-handers and 13 consistent right-handers tapped three patterns (anti-phase, left-gallop, right-gallop) in four visual feedback conditions (no feedback, left-hand feedback, right-hand feedback, full feedback). The analysis focused on phase shifts, phase variability, intertap interval variability, and correlations between intertap intervals. The manipulation of visual feedback had only minor effects. In the anti-phase pattern, a symmetric coupling mechanism was found. The results support the idea that coordination in the gallop pattern is governed by a hierarchical control mechanism. In contrast to the multifrequency studies, however, successful control in the gallop is not dependent on a hand arrangement that accommodates the preferred hand as the leading hand. An adjustment to the model of Summers et al. (1993, J Exp Psychol Hum Percept Perform 19:416-428) is presented for the case of the gallop pattern.

Adult↗
PubMed1991

[Quantitative evaluation of disorders of upright posture using stabilometry].

The authors examined, using the stabilometric method, 14 patients with lesions of the cerebellum, vestibular system and cerebral hemispheres (hemiparetics). Quantitative evaluation of the stability of posture was done using 7 parameters under four conditions: with open eyes, with closed eyes, with additional visual feedback and standing on a 10 cm foam rubber with closed eyes. In patients with a vestibular lesion the authors observed more frequent elevated values in a lateral direction, a marked destabilization of the posture on the foam rubber and effective use of the added visual feedback. Cerebellar patients were unable to use effectively the visual biofeedback for stabilization of posture. They were characterized by an obvious increase of stabilometric parameters in both directions and under all circumstances. The visual biofeedback had a different effect on maintenance of the upright position in hemiparetic patients. Stabilometry enables the authors to quantify posture and to record different characteristics of postural ataxias.

Adolescent↗
PubMed2005

Frontal cortical areas of the monkey brain engaged in reaching behavior: a (14)C-deoxyglucose imaging study.

The ((14)C)-deoxyglucose method was employed to study whether different areas of the primate frontal lobe are involved in different aspects of reaching behavior. To this end, we mapped the functional activity of the frontal motor cortical areas in three monkeys performing reaching movements with one forelimb. The first monkey had to capture a peripheral visual target with a saccade and a forelimb-reach together, the second monkey had to reach a peripheral visual target with one forelimb while fixating a central target, and the third one had to reach a peripheral memorized target with one forelimb in complete darkness while the eyes maintained a straight ahead direction. The extent and intensity of activations were compared to those of three respective control monkeys: a saccade-control, a fixation-control, and a dark-control. The primary somatosensory (S1) and motor (F1) forelimb representation, the S1- and F1-trunk representation, the F2-dimple region, areas F3-forelimb, F4, F5-bank of arcuate sulcus, F7-ridge, the dorsal bank of cingulate sulcus, and 24 c were activated in all reaching monkeys regardless of accompanying visual stimulation and oculomotor behavior. Interestingly, the S1-forelimb activation in the monkey reaching to memorized targets in complete darkness was more pronounced than that in the monkeys reaching to visual targets in the light, indicating that increased somatosensory processing compensates for the absence of visual feedback. On the other hand, areas F2-periarcuate, F5-convexity, F6, and 23 were preferentially activated by reaching to visual targets and remained unaffected during reaching to memorized targets when no visual feedback was available.

Animals↗
PubMed2001

Impaired motor learning in children with hydrocephalus.

Hydrocephalic (n = 19) and normal (n = 20) children in two age groups (averaged at 10 and 14 years old) were asked to learn 5 predetermined timing rhythm interval tasks (including timing duration and relative timing pattern) by pressing keys on a computer keyboard. In the acquisition phase, visual and auditory goal timing intervals, as well as visualized feedback were presented to all participants before and after their key presses, respectively. A retention test without the auditory information and visualized feedback was administered 1 day later. By using the computerized timing test, we demonstrated in this study that the hydrocephalic group had significantly (ANOVA analysis) increased relative timing errors; this function depends on the formation of an internal model or a motor program related to long-term memory disorders. These findings could lead to the formulation of training procedures with simplified movements that may help hydrocephalic children improve their motor skill learning.

Adolescent↗