scholarly journals The influence of saccades in shaping curved hand movement trajectory

2017 ◽  
Author(s):  
Sumitash Jana ◽  
Aditya Murthy
Keyword(s):  
Hand Movement ◽  
Hand Movements ◽  
Avoidance Task ◽  
Movement Trajectory ◽  
Hand Trajectory ◽  
Movement Trajectories ◽  
Spatial Coupling ◽  
End Point ◽  
Temporal Coupling ◽  
Made In

Eye and hand movements are often made in isolation but for reaching movements they are usually coupled together. While previous studies have demonstrated aspects of both kinematic and spatial coupling between eye and hand, few studies have investigated the influence of saccades on shaping a more complex curved hand movement trajectory profile. Here, using a novel obstacle avoidance task where the obstacle appeared in an infrequent number of trials, we try to establish the link between the saccade and hand trajectory. In the first part of the paper, we illustrate that the hand trajectory direction is influenced by the end location of the saccade, despite little temporal coupling between the two effectors. The x-position of the saccade end-point was related to whether the hand trajectory followed a straight or a curved path, while the y-position of the saccade end-point was related to whether the hand took a path passing from over or below the obstacle. In the second part of the paper, we establish the link between the saccade locations and hand sub-movements and observed that the number and timing of saccades and number of hand velocity peaks were related. Taken together these results indicate that saccades can influence complex hand movement trajectories.

scholarly journals A common control signal and a ballistic stage can explain the control of coordinated eye-hand movements

2016 ◽  
Vol 115 (5) ◽  
pp. 2470-2484 ◽  
Author(s):  
Atul Gopal ◽  
Aditya Murthy
Keyword(s):  
Hand Movement ◽  
Race Model ◽  
Control Signal ◽  
Hand Movements ◽  
Model Framework ◽  
Common Control ◽  
Performance Curves ◽  
Hand Coordination ◽  
Single Effector ◽  
Made In

Voluntary control has been extensively studied in the context of eye and hand movements made in isolation, yet little is known about the nature of control during eye-hand coordination. We probed this with a redirect task. Here subjects had to make reaching/pointing movements accompanied by coordinated eye movements but had to change their plans when the target occasionally changed its position during some trials. Using a race model framework, we found that separate effector-specific mechanisms may be recruited to control eye and hand movements when executed in isolation but when the same effectors are coordinated a unitary mechanism to control coordinated eye-hand movements is employed. Specifically, we found that performance curves were distinct for the eye and hand when these movements were executed in isolation but were comparable when they were executed together. Second, the time to switch motor plans, called the target step reaction time, was different in the eye-alone and hand-alone conditions but was similar in the coordinated condition under assumption of a ballistic stage of ∼40 ms, on average. Interestingly, the existence of this ballistic stage could predict the extent of eye-hand dissociations seen in individual subjects. Finally, when subjects were explicitly instructed to control specifically a single effector (eye or hand), redirecting one effector had a strong effect on the performance of the other effector. Taken together, these results suggest that a common control signal and a ballistic stage are recruited when coordinated eye-hand movement plans require alteration.

scholarly journals Context effects on smooth pursuit and manual interception of a disappearing target

2017 ◽  
Vol 118 (1) ◽  
pp. 404-415 ◽  
Author(s):  
Philipp Kreyenmeier ◽  
Jolande Fooken ◽  
Miriam Spering
Keyword(s):  
Eye Movements ◽  
Smooth Pursuit ◽  
Context Effects ◽  
Hand Movement ◽  
Hand Movements ◽  
Hand Position ◽  
Visual Context ◽  
End Points ◽  
Movement Trajectories ◽  
Trial Basis

In our natural environment, we interact with moving objects that are surrounded by richly textured, dynamic visual contexts. Yet most laboratory studies on vision and movement show visual objects in front of uniform gray backgrounds. Context effects on eye movements have been widely studied, but it is less well known how visual contexts affect hand movements. Here we ask whether eye and hand movements integrate motion signals from target and context similarly or differently, and whether context effects on eye and hand change over time. We developed a track-intercept task requiring participants to track the initial launch of a moving object (“ball”) with smooth pursuit eye movements. The ball disappeared after a brief presentation, and participants had to intercept it in a designated “hit zone.” In two experiments ( n = 18 human observers each), the ball was shown in front of a uniform or a textured background that either was stationary or moved along with the target. Eye and hand movement latencies and speeds were similarly affected by the visual context, but eye and hand interception (eye position at time of interception, and hand interception timing error) did not differ significantly between context conditions. Eye and hand interception timing errors were strongly correlated on a trial-by-trial basis across all context conditions, highlighting the close relation between these responses in manual interception tasks. Our results indicate that visual contexts similarly affect eye and hand movements but that these effects may be short-lasting, affecting movement trajectories more than movement end points. NEW & NOTEWORTHY In a novel track-intercept paradigm, human observers tracked a briefly shown object moving across a textured, dynamic context and intercepted it with their finger after it had disappeared. Context motion significantly affected eye and hand movement latency and speed, but not interception accuracy; eye and hand position at interception were correlated on a trial-by-trial basis. Visual context effects may be short-lasting, affecting movement trajectories more than movement end points.

Context-dependent relationship in high-resolution micro-ECoG studies during finger movements

2020 ◽  
Vol 132 (5) ◽  
pp. 1358-1366
Author(s):  
Chao-Hung Kuo ◽  
Timothy M. Blakely ◽  
Jeremiah D. Wander ◽  
Devapratim Sarma ◽  
Jing Wu ◽  
...  
Keyword(s):  
High Resolution ◽  
Sensorimotor Cortex ◽  
Index Finger ◽  
Hand Movement ◽  
Cortical Activation ◽  
Hand Movements ◽  
Finger Movements ◽  
Thumb Movement ◽  
Neurosurgical Patients ◽  
The Relationship

OBJECTIVEThe activation of the sensorimotor cortex as measured by electrocorticographic (ECoG) signals has been correlated with contralateral hand movements in humans, as precisely as the level of individual digits. However, the relationship between individual and multiple synergistic finger movements and the neural signal as detected by ECoG has not been fully explored. The authors used intraoperative high-resolution micro-ECoG (µECoG) on the sensorimotor cortex to link neural signals to finger movements across several context-specific motor tasks.METHODSThree neurosurgical patients with cortical lesions over eloquent regions participated. During awake craniotomy, a sensorimotor cortex area of hand movement was localized by high-frequency responses measured by an 8 × 8 µECoG grid of 3-mm interelectrode spacing. Patients performed a flexion movement of the thumb or index finger, or a pinch movement of both, based on a visual cue. High-gamma (HG; 70–230 Hz) filtered µECoG was used to identify dominant electrodes associated with thumb and index movement. Hand movements were recorded by a dataglove simultaneously with µECoG recording.RESULTSIn all 3 patients, the electrodes controlling thumb and index finger movements were identifiable approximately 3–6-mm apart by the HG-filtered µECoG signal. For HG power of cortical activation measured with µECoG, the thumb and index signals in the pinch movement were similar to those observed during thumb-only and index-only movement, respectively (all p > 0.05). Index finger movements, measured by the dataglove joint angles, were similar in both the index-only and pinch movements (p > 0.05). However, despite similar activation across the conditions, markedly decreased thumb movement was observed in pinch relative to independent thumb-only movement (all p < 0.05).CONCLUSIONSHG-filtered µECoG signals effectively identify dominant regions associated with thumb and index finger movement. For pinch, the µECoG signal comprises a combination of the signals from individual thumb and index movements. However, while the relationship between the index finger joint angle and HG-filtered signal remains consistent between conditions, there is not a fixed relationship for thumb movement. Although the HG-filtered µECoG signal is similar in both thumb-only and pinch conditions, the actual thumb movement is markedly smaller in the pinch condition than in the thumb-only condition. This implies a nonlinear relationship between the cortical signal and the motor output for some, but importantly not all, movement types. This analysis provides insight into the tuning of the motor cortex toward specific types of motor behaviors.

scholarly journals Perceptual uncertainty and action consequences independently affect hand movements in a virtual environment

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Martin Giesel ◽  
Anna Nowakowska ◽  
Julie M. Harris ◽  
Constanze Hesse
Keyword(s):  
Virtual Environments ◽  
Virtual Environment ◽  
Motor Skills ◽  
Hand Movements ◽  
Perceptual Information ◽  
Avoidance Task ◽  
Natural Environments ◽  
Motor Behaviour ◽  
Virtual And Augmented Reality

AbstractWhen we use virtual and augmented reality (VR/AR) environments to investigate behaviour or train motor skills, we expect that the insights or skills acquired in VR/AR transfer to real-world settings. Motor behaviour is strongly influenced by perceptual uncertainty and the expected consequences of actions. VR/AR differ in both of these aspects from natural environments. Perceptual information in VR/AR is less reliable than in natural environments, and the knowledge of acting in a virtual environment might modulate our expectations of action consequences. Using mirror reflections to create a virtual environment free of perceptual artefacts, we show that hand movements in an obstacle avoidance task systematically differed between real and virtual obstacles and that these behavioural differences occurred independent of the quality of the available perceptual information. This suggests that even when perceptual correspondence between natural and virtual environments is achieved, action correspondence does not necessarily follow due to the disparity in the expected consequences of actions in the two environments.

Hand Movements and Nondominant Fluency in Bilinguals

1979 ◽  
Vol 48 (1) ◽  
pp. 207-214 ◽  
Author(s):  
Luis R. Marcos
Keyword(s):  
Cognitive Processes ◽  
Motor Behavior ◽  
Hand Movement ◽  
Movement Behavior ◽  
Hand Movements ◽  
Language Fluency ◽  
Movement Activity

16 subordinate bilingual subjects produced 5-min. monologues in their nondominant languages, i.e., English or Spanish. Hand-movement activity manifested during the videotape monologues was scored and related to measures of fluency in the nondominant language. The hand-movement behavior categorized as Groping Movement was significantly related to all of the nondominant-language fluency measures. These correlations support the assumption that Groping Movement may have a function in the process of verbal encoding. The results are discussed in terms of the possibility of monitoring central cognitive processes through the study of “visible” motor behavior.

scholarly journals Eye movements do not play an important role in the adaptation of hand tracking to a visuomotor rotation

2019 ◽  
Vol 121 (5) ◽  
pp. 1967-1976 ◽  
Author(s):  
Niels Gouirand ◽  
James Mathew ◽  
Eli Brenner ◽  
Frederic R. Danion
Keyword(s):  
Eye Movements ◽  
Time Course ◽  
Motor Behavior ◽  
Hand Movement ◽  
Visuomotor Adaptation ◽  
Online Control ◽  
Hand Movements ◽  
Hand Tracking ◽  
Gaze Fixation ◽  
The Gaze

Adapting hand movements to changes in our body or the environment is essential for skilled motor behavior. Although eye movements are known to assist hand movement control, how eye movements might contribute to the adaptation of hand movements remains largely unexplored. To determine to what extent eye movements contribute to visuomotor adaptation of hand tracking, participants were asked to track a visual target that followed an unpredictable trajectory with a cursor using a joystick. During blocks of trials, participants were either allowed to look wherever they liked or required to fixate a cross at the center of the screen. Eye movements were tracked to ensure gaze fixation as well as to examine free gaze behavior. The cursor initially responded normally to the joystick, but after several trials, the direction in which it responded was rotated by 90°. Although fixating the eyes had a detrimental influence on hand tracking performance, participants exhibited a rather similar time course of adaptation to rotated visual feedback in the gaze-fixed and gaze-free conditions. More importantly, there was extensive transfer of adaptation between the gaze-fixed and gaze-free conditions. We conclude that although eye movements are relevant for the online control of hand tracking, they do not play an important role in the visuomotor adaptation of such tracking. These results suggest that participants do not adapt by changing the mapping between eye and hand movements, but rather by changing the mapping between hand movements and the cursor’s motion independently of eye movements. NEW & NOTEWORTHY Eye movements assist hand movements in everyday activities, but their contribution to visuomotor adaptation remains largely unknown. We compared adaptation of hand tracking under free gaze and fixed gaze. Although our results confirm that following the target with the eyes increases the accuracy of hand movements, they unexpectedly demonstrate that gaze fixation does not hinder adaptation. These results suggest that eye movements have distinct contributions for online control and visuomotor adaptation of hand movements.

Hand Movement Training in Braille Reading

1981 ◽  
Vol 75 (8) ◽  
pp. 327-331 ◽  
Author(s):  
Diane P. Wormsley
Keyword(s):  
Character Recognition ◽  
Hand Movement ◽  
Movement Pattern ◽  
Hand Movements ◽  
Dramatic Decrease ◽  
Movement Training ◽  
Perceptual Ability ◽  
Tracking Movements

Twenty-one children ages 6 though 13 were taught to use their hands independently when reading braille to determine how this pattern of hand movements affected reading variables, excluding character recognition. Although all the children learned this pattern of hand movements during the 20 days scheduled for training, only nine children exhibited a dramatic decrease in inefficient tracking movements such as pauses and scrubbing motions. Because these children were younger and more intelligent than the others, read braille more slowly, and had received less training in braille at school, the results strongly suggested that skill in tracking and use of an efficient hand movement pattern is closely tied to perceptual ability. Thus when teaching children to read braille, the motor aspects of the task should be combined with the perceptual aspects from the beginning.

Modified Resazurin Test for Estimating Bacterial Counts in Maple Sap: Color Standards

1972 ◽  
Vol 55 (1) ◽  
pp. 119-120
Author(s):  
J C Kissinger
Keyword(s):  
Test Solution ◽  
Bacterial Counts ◽  
Graphic Form ◽  
Color Standard ◽  
End Point ◽  
Nonfat Milk ◽  
Maple Sap ◽  
Made In ◽  
Munsell System

Abstract An end point color standard based on reflectance, which can be described by the Munsell system of color notation, was developed for the modified resazurin test used to estimate bacterial counts in maple sap. In order to secure a reflected color, a sterile, nonfat milk solution was added to the clear sap-dye test solution to render it opaque. Results of tests made in accordance with this method are presented in graphic form.

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