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Agnes M F Wong - One of the best experts on this subject based on the ideXlab platform.
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effects of strabismic amblyopia and strabismus without amblyopia on visuomotor behavior iii temporal eye Hand Coordination during reaching
Investigative Ophthalmology & Visual Science, 2014Co-Authors: Ewa Niechwiejszwedo, Manokaraananthan Chandrakumar, Herbert C Goltz, Agnes M F WongAbstract:PURPOSE To examine the effects of strabismic amblyopia and strabismus only, without amblyopia, on the temporal patterns of eye-Hand Coordination during both the planning and execution stages of visually-guided reaching. METHODS Forty-six adults (16 with strabismic amblyopia, 14 with strabismus only, and 16 visually normal) executed reach-to-touch movements toward targets presented randomly 5° or 10° to the left or right of central fixation. Viewing conditions were binocular, monocular viewing with the amblyopic eye, and monocular viewing with the fellow eye (dominant and nondominant viewing for participants without amblyopia). Temporal Coordination between eye and Hand movements was examined during reach planning (interval between the initiation of saccade and reaching, i.e., saccade-to-reach planning interval) and reach execution (interval between the initiation of saccade and reach peak velocity [PV], i.e., saccade-to-reach PV interval). The frequency and dynamics of secondary reach-related saccades were also examined. RESULTS The temporal patterns of eye-Hand Coordination prior to reach initiation were comparable among participants with strabismic amblyopia, strabismus only, and visually normal adults. However, the reach acceleration phase of participants with strabismic amblyopia and those with strabismus only were longer following target fixation (saccade-to-reach PV interval) than that of visually normal participants (P < 0.05). This effect was evident under all viewing conditions. The saccade-to-reach planning interval and the saccade-to-reach PV interval were not significantly different among participants with amblyopia with different levels of acuity and stereo acuity loss. Participants with strabismic amblyopia and strabismus only initiated secondary reach-related saccades significantly more frequently than visually normal participants. The amplitude and peak velocity of these saccades were significantly greater during amblyopic eye viewing in participants with amblyopia who also had negative stereopsis. CONCLUSIONS Adults with strabismic amblyopia and strabismus only showed an altered pattern of temporal eye-Hand Coordination during the reach acceleration phase, which might affect their ability to modify reach trajectory using early online control. Secondary reach-related saccades may provide a compensatory mechanism with which to facilitate the late online control process in order to ensure relatively good reaching performance during binocular and fellow eye viewing.
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effects of induced monocular blur versus anisometropic amblyopia on saccades reaching and eye Hand Coordination
Investigative Ophthalmology & Visual Science, 2012Co-Authors: Ewa Niechwiejszwedo, Sean A Kennedy, Linda Colpa, Manokaraananthan Chandrakumar, Herbert C Goltz, Agnes M F WongAbstract:PURPOSE. We previously showed that anisometropic amblyopia affects the programming and execution of saccades and reaching movements. In our current study, we investigated whether these amblyopia-related changes simply are due to a reduction in visual acuity alone by inducing artificial blur in one eye in visually-normal participants. METHODS. Twelve visually-normal participants performed saccades and reach-to-touch movements to targets presented on a computer screen during binocular and monocular viewing. A contact lens was used to blur the vision of one eye to a mean acuity level of 20/50. Saccades and reaching kinematics were compared before blur, immediately after blur, and 5 hours after blur was induced. The 5 hours after blur kinematic data from visually-normal participants also were compared to those from 12 patients with anisometropic amblyopia who had comparable acuity in the amblyopic eye. RESULTS. Primary saccades (latency, amplitude, peak velocity), reaching movements (reaction time, movement time, peak acceleration, duration of the acceleration phase), and eye-Hand Coordination (saccade-to-reach planning interval, saccade-toreach peak velocity interval) were not affected by induced monocular blur in visually-normal participants, either immediately or 5 hours after blur. Compared to visually-normal participants after 5 hours of blur, patients with anisometropic amblyopia had significantly longer and more variable saccade latency during amblyopic eye viewing, lower peak acceleration, and a longer acceleration phase during reaching, and a different temporal pattern of eye-Hand Coordination. CONCLUSIONS. Artificially-induced monocular blur in visuallynormal participants did not affect saccades, reaching movements, and eye-Hand Coordination during a simple reach-totouch task even after a period of blur exposure. In contrast, patients with anisometropic amblyopia demonstrated significantly different kinematics while performing the same task. These results indicate that loss of visual acuity alone cannot explain the kinematic changes seen in patients with mild anisometropic amblyopia. (Invest Ophthalmol Vis Sci. 2012; 53:4354‐4362) DOI:10.1167/iovs.12-9855
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effects of anisometropic amblyopia on visuomotor behavior iii temporal eye Hand Coordination during reaching
Investigative Ophthalmology & Visual Science, 2011Co-Authors: Ewa Niechwiejszwedo, Manokaraananthan Chandrakumar, Herbert C Goltz, Agnes M F Wong, Zahra HirjiAbstract:PURPOSE. To examine the effects of anisometropic amblyopia on the temporal pattern of eye-Hand Coordination during visually-guided reaching. METHODS. Eighteen patients with anisometropic amblyopia and 18 control subjects were recruited. Participants executed reach-to-touch movements toward visual targets under three viewing conditions: binocular, monocular amblyopic eye, and monocular fellow eye viewing. Temporal Coordination between eye and Hand movements was examined during reach planning (interval between the initiation of saccade and reaching) and reach execution (interval between the initiation of saccade and reach peak velocity). The frequency and dynamics of secondary saccades were also examined. RESULTS. Patients with severe amblyopia spent a longer time planning the reaching response after fixating the target in comparison with control subjects and patients with mild amblyopia (P 0.029). In comparison with control subjects, all patients extended the acceleration phase of the reach after target fixation (P 0.018). Secondary (reach-related) saccades were initiated during the acceleration phase of the reach and patients executed these saccades with greater frequency than control subjects (P 0.0001). The amplitude and peak velocity of reach-related saccades were higher when patients viewed with the amblyopic eye in comparison with the other viewing conditions (P 0.001). CONCLUSIONS. This is the first study to show that patients with anisometropic amblyopia modified the temporal dynamics of eye-Hand Coordination during visually-guided reaching. They extended the planning and execution intervals after target fixation and increased the frequency of secondary, reach-related saccades. These may represent visuomotor strategies to compensate for the spatiotemporal visual deficits to achieve good reaching accuracy and precision. (Invest Ophthalmol Vis Sci. 2011;52:5853‐5861) DOI:10.1167/iovs.11-7314
Herbert C Goltz - One of the best experts on this subject based on the ideXlab platform.
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effects of strabismic amblyopia and strabismus without amblyopia on visuomotor behavior iii temporal eye Hand Coordination during reaching
Investigative Ophthalmology & Visual Science, 2014Co-Authors: Ewa Niechwiejszwedo, Manokaraananthan Chandrakumar, Herbert C Goltz, Agnes M F WongAbstract:PURPOSE To examine the effects of strabismic amblyopia and strabismus only, without amblyopia, on the temporal patterns of eye-Hand Coordination during both the planning and execution stages of visually-guided reaching. METHODS Forty-six adults (16 with strabismic amblyopia, 14 with strabismus only, and 16 visually normal) executed reach-to-touch movements toward targets presented randomly 5° or 10° to the left or right of central fixation. Viewing conditions were binocular, monocular viewing with the amblyopic eye, and monocular viewing with the fellow eye (dominant and nondominant viewing for participants without amblyopia). Temporal Coordination between eye and Hand movements was examined during reach planning (interval between the initiation of saccade and reaching, i.e., saccade-to-reach planning interval) and reach execution (interval between the initiation of saccade and reach peak velocity [PV], i.e., saccade-to-reach PV interval). The frequency and dynamics of secondary reach-related saccades were also examined. RESULTS The temporal patterns of eye-Hand Coordination prior to reach initiation were comparable among participants with strabismic amblyopia, strabismus only, and visually normal adults. However, the reach acceleration phase of participants with strabismic amblyopia and those with strabismus only were longer following target fixation (saccade-to-reach PV interval) than that of visually normal participants (P < 0.05). This effect was evident under all viewing conditions. The saccade-to-reach planning interval and the saccade-to-reach PV interval were not significantly different among participants with amblyopia with different levels of acuity and stereo acuity loss. Participants with strabismic amblyopia and strabismus only initiated secondary reach-related saccades significantly more frequently than visually normal participants. The amplitude and peak velocity of these saccades were significantly greater during amblyopic eye viewing in participants with amblyopia who also had negative stereopsis. CONCLUSIONS Adults with strabismic amblyopia and strabismus only showed an altered pattern of temporal eye-Hand Coordination during the reach acceleration phase, which might affect their ability to modify reach trajectory using early online control. Secondary reach-related saccades may provide a compensatory mechanism with which to facilitate the late online control process in order to ensure relatively good reaching performance during binocular and fellow eye viewing.
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effects of induced monocular blur versus anisometropic amblyopia on saccades reaching and eye Hand Coordination
Investigative Ophthalmology & Visual Science, 2012Co-Authors: Ewa Niechwiejszwedo, Sean A Kennedy, Linda Colpa, Manokaraananthan Chandrakumar, Herbert C Goltz, Agnes M F WongAbstract:PURPOSE. We previously showed that anisometropic amblyopia affects the programming and execution of saccades and reaching movements. In our current study, we investigated whether these amblyopia-related changes simply are due to a reduction in visual acuity alone by inducing artificial blur in one eye in visually-normal participants. METHODS. Twelve visually-normal participants performed saccades and reach-to-touch movements to targets presented on a computer screen during binocular and monocular viewing. A contact lens was used to blur the vision of one eye to a mean acuity level of 20/50. Saccades and reaching kinematics were compared before blur, immediately after blur, and 5 hours after blur was induced. The 5 hours after blur kinematic data from visually-normal participants also were compared to those from 12 patients with anisometropic amblyopia who had comparable acuity in the amblyopic eye. RESULTS. Primary saccades (latency, amplitude, peak velocity), reaching movements (reaction time, movement time, peak acceleration, duration of the acceleration phase), and eye-Hand Coordination (saccade-to-reach planning interval, saccade-toreach peak velocity interval) were not affected by induced monocular blur in visually-normal participants, either immediately or 5 hours after blur. Compared to visually-normal participants after 5 hours of blur, patients with anisometropic amblyopia had significantly longer and more variable saccade latency during amblyopic eye viewing, lower peak acceleration, and a longer acceleration phase during reaching, and a different temporal pattern of eye-Hand Coordination. CONCLUSIONS. Artificially-induced monocular blur in visuallynormal participants did not affect saccades, reaching movements, and eye-Hand Coordination during a simple reach-totouch task even after a period of blur exposure. In contrast, patients with anisometropic amblyopia demonstrated significantly different kinematics while performing the same task. These results indicate that loss of visual acuity alone cannot explain the kinematic changes seen in patients with mild anisometropic amblyopia. (Invest Ophthalmol Vis Sci. 2012; 53:4354‐4362) DOI:10.1167/iovs.12-9855
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effects of anisometropic amblyopia on visuomotor behavior iii temporal eye Hand Coordination during reaching
Investigative Ophthalmology & Visual Science, 2011Co-Authors: Ewa Niechwiejszwedo, Manokaraananthan Chandrakumar, Herbert C Goltz, Agnes M F Wong, Zahra HirjiAbstract:PURPOSE. To examine the effects of anisometropic amblyopia on the temporal pattern of eye-Hand Coordination during visually-guided reaching. METHODS. Eighteen patients with anisometropic amblyopia and 18 control subjects were recruited. Participants executed reach-to-touch movements toward visual targets under three viewing conditions: binocular, monocular amblyopic eye, and monocular fellow eye viewing. Temporal Coordination between eye and Hand movements was examined during reach planning (interval between the initiation of saccade and reaching) and reach execution (interval between the initiation of saccade and reach peak velocity). The frequency and dynamics of secondary saccades were also examined. RESULTS. Patients with severe amblyopia spent a longer time planning the reaching response after fixating the target in comparison with control subjects and patients with mild amblyopia (P 0.029). In comparison with control subjects, all patients extended the acceleration phase of the reach after target fixation (P 0.018). Secondary (reach-related) saccades were initiated during the acceleration phase of the reach and patients executed these saccades with greater frequency than control subjects (P 0.0001). The amplitude and peak velocity of reach-related saccades were higher when patients viewed with the amblyopic eye in comparison with the other viewing conditions (P 0.001). CONCLUSIONS. This is the first study to show that patients with anisometropic amblyopia modified the temporal dynamics of eye-Hand Coordination during visually-guided reaching. They extended the planning and execution intervals after target fixation and increased the frequency of secondary, reach-related saccades. These may represent visuomotor strategies to compensate for the spatiotemporal visual deficits to achieve good reaching accuracy and precision. (Invest Ophthalmol Vis Sci. 2011;52:5853‐5861) DOI:10.1167/iovs.11-7314
Lawrence H Snyder - One of the best experts on this subject based on the ideXlab platform.
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spatial eye Hand Coordination during bimanual reaching is not systematically coded in either lip or prr
Proceedings of the National Academy of Sciences of the United States of America, 2018Co-Authors: Eric Mooshagian, Lawrence H SnyderAbstract:We often orient to where we are about to reach. Spatial and temporal correlations in eye and arm movements may depend on the posterior parietal cortex (PPC). Spatial representations of saccade and reach goals preferentially activate cells in the lateral intraparietal area (LIP) and the parietal reach region (PRR), respectively. With unimanual reaches, eye and arm movement patterns are highly stereotyped. This makes it difficult to study the neural circuits involved in Coordination. Here, we employ bimanual reaching to two different targets. Animals naturally make a saccade first to one target and then the other, resulting in different patterns of limb–gaze Coordination on different trials. Remarkably, neither LIP nor PRR cells code which target the eyes will move to first. These results suggest that the parietal cortex plays at best only a permissive role in some aspects of eye–Hand Coordination and makes the role of LIP in saccade generation unclear.
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the parietal reach region is limb specific and not involved in eye Hand Coordination
Journal of Neurophysiology, 2014Co-Authors: Eric A Yttri, Cunguo Wang, Yuqing Liu, Lawrence H SnyderAbstract:Primates frequently reach toward visual targets. Neurons in early visual areas respond to stimuli in the contralateral visual hemifield and without regard to which limb will be used to reach toward that target. In contrast, neurons in motor areas typically respond when reaches are performed using the contralateral limb and with minimal regard to the visuospatial location of the target. The parietal reach region (PRR) is located early in the visuomotor processing hierarchy. PRR neurons are significantly modulated when targets for either limb or eye movement appear, similar to early sensory areas; however, they respond to targets in either visual field, similar to motor areas. The activity could reflect the subject's attentional locus, movement of a specific effector, or a related function, such as coordinating eye-arm movements. To examine the role of PRR in the visuomotor pathway, we reversibly inactivated PRR. Inactivation effects were specific to contralateral limb movements, leaving ipsilateral limb and saccadic movements intact. Neither visual hemifield bias nor visual attention deficits were observed. Thus our results are consistent with a motoric rather than visual organization in PRR, despite its early location in the visuomotor pathway. We found no effects on the temporal coupling of coordinated saccades and reaches, suggesting that this mechanism lies downstream of PRR. In sum, this study clarifies the role of PRR in the visuomotor hierarchy: despite its early position, it is a limb-specific area influencing reach planning and is positioned upstream from an active eye-Hand Coordination-coupling mechanism.
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lesions of cortical area lip affect reach onset only when the reach is accompanied by a saccade revealing an active eye Hand Coordination circuit
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: Eric A Yttri, Lawrence H SnyderAbstract:The circuits that drive visually guided eye and arm movements transform generic visual inputs into effector-specific motor commands. As part of the effort to elucidate these circuits, the primate lateral intraparietal area (LIP) has been interpreted as a priority map for saccades (oculomotor-specific) or a salience map of space (not effector-specific). It has also been proposed as a locus for eye–Hand Coordination. We reversibly inactivated LIP while monkeys performed memory-guided saccades and reaches. Coordinated saccade and reach reaction times were similarly impaired, consistent with a nonspecific role. However, reaches made without an accompanying saccade remained intact, and the relative temporal coupling of saccades and reaches was unchanged. These results suggest that LIP contributes to saccade planning but not to reach planning. Coordinated reaches are delayed as a result of an eye–Hand Coordination mechanism, located outside of LIP, that actively delays reaches until shortly after the onset of an associated saccade. We conclude with a discussion of how to reconcile specificity for saccades with a possible role in directing attention.
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eye Hand Coordination saccades are faster when accompanied by a coordinated arm movement
Journal of Neurophysiology, 2002Co-Authors: Lawrence H Snyder, Jeffrey L Calton, Anthony R Dickinson, Bonnie M LawrenceAbstract:When primates reach for an object, they very often direct an eye movement toward the object as well. This pattern of directing both eye and limb movements to the same object appears to be fundament...
Ewa Niechwiejszwedo - One of the best experts on this subject based on the ideXlab platform.
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effects of strabismic amblyopia and strabismus without amblyopia on visuomotor behavior iii temporal eye Hand Coordination during reaching
Investigative Ophthalmology & Visual Science, 2014Co-Authors: Ewa Niechwiejszwedo, Manokaraananthan Chandrakumar, Herbert C Goltz, Agnes M F WongAbstract:PURPOSE To examine the effects of strabismic amblyopia and strabismus only, without amblyopia, on the temporal patterns of eye-Hand Coordination during both the planning and execution stages of visually-guided reaching. METHODS Forty-six adults (16 with strabismic amblyopia, 14 with strabismus only, and 16 visually normal) executed reach-to-touch movements toward targets presented randomly 5° or 10° to the left or right of central fixation. Viewing conditions were binocular, monocular viewing with the amblyopic eye, and monocular viewing with the fellow eye (dominant and nondominant viewing for participants without amblyopia). Temporal Coordination between eye and Hand movements was examined during reach planning (interval between the initiation of saccade and reaching, i.e., saccade-to-reach planning interval) and reach execution (interval between the initiation of saccade and reach peak velocity [PV], i.e., saccade-to-reach PV interval). The frequency and dynamics of secondary reach-related saccades were also examined. RESULTS The temporal patterns of eye-Hand Coordination prior to reach initiation were comparable among participants with strabismic amblyopia, strabismus only, and visually normal adults. However, the reach acceleration phase of participants with strabismic amblyopia and those with strabismus only were longer following target fixation (saccade-to-reach PV interval) than that of visually normal participants (P < 0.05). This effect was evident under all viewing conditions. The saccade-to-reach planning interval and the saccade-to-reach PV interval were not significantly different among participants with amblyopia with different levels of acuity and stereo acuity loss. Participants with strabismic amblyopia and strabismus only initiated secondary reach-related saccades significantly more frequently than visually normal participants. The amplitude and peak velocity of these saccades were significantly greater during amblyopic eye viewing in participants with amblyopia who also had negative stereopsis. CONCLUSIONS Adults with strabismic amblyopia and strabismus only showed an altered pattern of temporal eye-Hand Coordination during the reach acceleration phase, which might affect their ability to modify reach trajectory using early online control. Secondary reach-related saccades may provide a compensatory mechanism with which to facilitate the late online control process in order to ensure relatively good reaching performance during binocular and fellow eye viewing.
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effects of induced monocular blur versus anisometropic amblyopia on saccades reaching and eye Hand Coordination
Investigative Ophthalmology & Visual Science, 2012Co-Authors: Ewa Niechwiejszwedo, Sean A Kennedy, Linda Colpa, Manokaraananthan Chandrakumar, Herbert C Goltz, Agnes M F WongAbstract:PURPOSE. We previously showed that anisometropic amblyopia affects the programming and execution of saccades and reaching movements. In our current study, we investigated whether these amblyopia-related changes simply are due to a reduction in visual acuity alone by inducing artificial blur in one eye in visually-normal participants. METHODS. Twelve visually-normal participants performed saccades and reach-to-touch movements to targets presented on a computer screen during binocular and monocular viewing. A contact lens was used to blur the vision of one eye to a mean acuity level of 20/50. Saccades and reaching kinematics were compared before blur, immediately after blur, and 5 hours after blur was induced. The 5 hours after blur kinematic data from visually-normal participants also were compared to those from 12 patients with anisometropic amblyopia who had comparable acuity in the amblyopic eye. RESULTS. Primary saccades (latency, amplitude, peak velocity), reaching movements (reaction time, movement time, peak acceleration, duration of the acceleration phase), and eye-Hand Coordination (saccade-to-reach planning interval, saccade-toreach peak velocity interval) were not affected by induced monocular blur in visually-normal participants, either immediately or 5 hours after blur. Compared to visually-normal participants after 5 hours of blur, patients with anisometropic amblyopia had significantly longer and more variable saccade latency during amblyopic eye viewing, lower peak acceleration, and a longer acceleration phase during reaching, and a different temporal pattern of eye-Hand Coordination. CONCLUSIONS. Artificially-induced monocular blur in visuallynormal participants did not affect saccades, reaching movements, and eye-Hand Coordination during a simple reach-totouch task even after a period of blur exposure. In contrast, patients with anisometropic amblyopia demonstrated significantly different kinematics while performing the same task. These results indicate that loss of visual acuity alone cannot explain the kinematic changes seen in patients with mild anisometropic amblyopia. (Invest Ophthalmol Vis Sci. 2012; 53:4354‐4362) DOI:10.1167/iovs.12-9855
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effects of anisometropic amblyopia on visuomotor behavior iii temporal eye Hand Coordination during reaching
Investigative Ophthalmology & Visual Science, 2011Co-Authors: Ewa Niechwiejszwedo, Manokaraananthan Chandrakumar, Herbert C Goltz, Agnes M F Wong, Zahra HirjiAbstract:PURPOSE. To examine the effects of anisometropic amblyopia on the temporal pattern of eye-Hand Coordination during visually-guided reaching. METHODS. Eighteen patients with anisometropic amblyopia and 18 control subjects were recruited. Participants executed reach-to-touch movements toward visual targets under three viewing conditions: binocular, monocular amblyopic eye, and monocular fellow eye viewing. Temporal Coordination between eye and Hand movements was examined during reach planning (interval between the initiation of saccade and reaching) and reach execution (interval between the initiation of saccade and reach peak velocity). The frequency and dynamics of secondary saccades were also examined. RESULTS. Patients with severe amblyopia spent a longer time planning the reaching response after fixating the target in comparison with control subjects and patients with mild amblyopia (P 0.029). In comparison with control subjects, all patients extended the acceleration phase of the reach after target fixation (P 0.018). Secondary (reach-related) saccades were initiated during the acceleration phase of the reach and patients executed these saccades with greater frequency than control subjects (P 0.0001). The amplitude and peak velocity of reach-related saccades were higher when patients viewed with the amblyopic eye in comparison with the other viewing conditions (P 0.001). CONCLUSIONS. This is the first study to show that patients with anisometropic amblyopia modified the temporal dynamics of eye-Hand Coordination during visually-guided reaching. They extended the planning and execution intervals after target fixation and increased the frequency of secondary, reach-related saccades. These may represent visuomotor strategies to compensate for the spatiotemporal visual deficits to achieve good reaching accuracy and precision. (Invest Ophthalmol Vis Sci. 2011;52:5853‐5861) DOI:10.1167/iovs.11-7314
Miya K. Rand - One of the best experts on this subject based on the ideXlab platform.
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eye Hand Coordination during visuomotor adaptation effects of hemispace and joint Coordination
Experimental Brain Research, 2017Co-Authors: Miya K. Rand, Sebastian RentschAbstract:We previously examined adaptive changes of eye–Hand Coordination during learning of a visuomotor rotation. Gazes during reaching movements were initially directed to a feedback cursor in early practice, but were gradually shifted toward the target with more practice, indicating an emerging gaze anchoring behavior. This adaptive pattern reflected a functional change of gaze control from exploring the cursor–Hand relation to guiding the Hand to the task goal. The present study further examined the effects of hemispace and joint Coordination associated with target directions on this behavior. Young adults performed center-out reaching movements to four targets with their right Hand on a horizontal digitizer, while looking at a rotated visual feedback cursor on a computer monitor. To examine the effect of hemispace related to visual stimuli, two out of the four targets were located in the ipsilateral workspace relative to the Hand used, the other two in the contralateral workspace. To examine the effect of hemispace related to manual actions, two among the four targets were related to reaches made in the ipsilateral workspace, the other two to reaches made in the contralateral workspace. Furthermore, to examine the effect of the complexity of joint Coordination, two among the four targets were reaches involving a direct path from the start to the target involving elbow movements (simple), whereas the other two targets were reaches involving both shoulder and elbow movements (complex). The results showed that the gaze anchoring behavior gradually emerged during practice for reaches made in all target directions. The speed of this change was affected mainly by the hemispace related to manual actions, whereas the other two effects were minimal. The gaze anchoring occurred faster for the ipsilateral reaches than for the contralateral reaches; gazes prior to the gaze anchoring were also directed less at the cursor vicinity but more at the mid-area between the starting point and the target. These results suggest that ipsilateral reaches result in a better predictability of the cursor–Hand relation under the visuomotor rotation, thereby prompting an earlier functional change of gaze control through practice from a reactive to a predictive control.
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eye Hand Coordination during visuomotor adaptation with different rotation angles effects of terminal visual feedback
PLOS ONE, 2016Co-Authors: Miya K. Rand, Sebastian RentschAbstract:This study examined adaptive changes of eye-Hand Coordination during a visuomotor rotation task under the use of terminal visual feedback. Young adults made reaching movements to targets on a digitizer while looking at targets on a monitor where the rotated feedback (a cursor) of Hand movements appeared after each movement. Three rotation angles (30°, 75° and 150°) were examined in three groups in order to vary the task difficulty. The results showed that the 30° group gradually reduced direction errors of reaching with practice and adapted well to the visuomotor rotation. The 75° group made large direction errors of reaching, and the 150° group applied a 180° reversal shift from early practice. The 75°and 150° groups, however, overcompensated the respective rotations at the end of practice. Despite these group differences in adaptive changes of reaching, all groups gradually adapted gaze directions prior to reaching from the target area to the areas related to the final positions of reaching during the course of practice. The adaptive changes of both Hand and eye movements in all groups mainly reflected adjustments of movement directions based on explicit knowledge of the applied rotation acquired through practice. Only the 30° group showed small implicit adaptation in both effectors. The results suggest that by adapting gaze directions from the target to the final position of reaching based on explicit knowledge of the visuomotor rotation, the oculomotor system supports the limb-motor system to make precise preplanned adjustments of reaching directions during learning of visuomotor rotation under terminal visual feedback.
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Eye-Hand Coordination during Visuomotor Adaptation with Different Rotation Angles
PloS one, 2014Co-Authors: Sebastian Rentsch, Miya K. RandAbstract:This study examined adaptive changes of eye-Hand Coordination during a visuomotor rotation task. Young adults made aiming movements to targets on a horizontal plane, while looking at the rotated feedback (cursor) of Hand movements on a monitor. To vary the task difficulty, three rotation angles (30°, 75°, and 150°) were tested in three groups. All groups shortened Hand movement time and trajectory length with practice. However, control strategies used were different among groups. The 30° group used proportionately more implicit adjustments of Hand movements than other groups. The 75° group used more on-line feedback control, whereas the 150° group used explicit strategic adjustments. Regarding eye-Hand Coordination, timing of gaze shift to the target was gradually changed with practice from the late to early phase of Hand movements in all groups, indicating an emerging gaze-anchoring behavior. Gaze locations prior to the gaze anchoring were also modified with practice from the cursor vicinity to an area between the starting position and the target. Reflecting various task difficulties, these changes occurred fastest in the 30° group, followed by the 75° group. The 150° group persisted in gazing at the cursor vicinity. These results suggest that the function of gaze control during visuomotor adaptation changes from a reactive control for exploring the relation between cursor and Hand movements to a predictive control for guiding the Hand to the task goal. That gaze-anchoring behavior emerged in all groups despite various control strategies indicates a generality of this adaptive pattern for eye-Hand Coordination in goal-directed actions.
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effects of Hand termination and accuracy requirements on eye Hand Coordination in older adults
Behavioural Brain Research, 2011Co-Authors: Miya K. Rand, George E StelmachAbstract:This study investigated how aging compromises the control of saccades and eye-Hand Coordination when accuracy constraints and termination requirements of Hand movement are altered. Seventeen older adults and seventeen young controls performed two-segment aiming movements. The first segment had two target sizes to alter accuracy constraints. Two-segment eye movements were always made to first and second targets, whereas Hand movements were varied across three Hand-movement types with different termination requirements: 1) stop both at the first and second targets, 2) stop at the first target and discontinue, and 3) move through the first target and discontinue. Compared to the young adults, the older adults produced hypometric primary saccades and delayed gaze fixation to the first target. The older adults also modified eye movements less depending on the Hand termination and accuracy requirements. After pointing completion to the first target, the older adults maintained their gaze fixation to that target for a longer duration than young adults. However, this prolonged gaze fixation was minimized when a Hand termination was not required. Conversely, the prolongation of gaze fixation was magnified when the Hand termination was required at the first target while the eye movement was continuing to the next target. Thus, older adults have difficulties in concurrent control of inhibiting Hand movement and initiating eye movement at a target within a sequence. Taken together, it is suggested that aging reduces the ability to modify eye movements to meet various behavioral constraints imposed on manual aiming tasks.
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effects of Hand termination and accuracy constraint on eye Hand Coordination during sequential two segment movements
Experimental Brain Research, 2010Co-Authors: Miya K. Rand, George E StelmachAbstract:The purpose of this study was to examine the effects of accuracy constraints and termination requirements of Hand movement on eye-Hand Coordination. Healthy adults performed two-segment eye and Hand aiming movements to predetermined stationary targets. While two-segment eye movements were made to the first and second targets for all conditions, Hand movements were varied across conditions. The first segment had two target sizes to alter accuracy constraints. There were three Hand movement types with different termination requirements: (1) stop both at the first and at the second targets, (2) stop at the first target and discontinue, and (3) move through the first target and discontinue. The results showed that the initiation of saccades was moderately correlated with the initiation of Hand movements, and both initiations changed in a similar fashion depending on various Hand termination requirements. Amplitude of primary saccades and frequency of corrective saccades during the first segment were affected by the combined effects of accuracy constraints and Hand termination requirements. These results suggest that the planning and execution of saccades are based in part on global task constraints related to the accuracy and termination demands of Hand movements over the two segments. During the transition from the first to the second segment, the gaze was held on the first target until shortly after the pointing to that target was terminated, showing gaze anchoring. The gaze anchoring was prolonged due to the increased accuracy constraint of that target or by including pointing to the second target. However, the gaze anchoring was broken prior to the completion of pointing when the accuracy constraint was reduced and pointing to the second target was excluded. The observed modifications of gaze anchoring imply that the oculomotor system is functionally obligated to fixate a gaze to a pointing target only to the extent that successful completion of a pointing task is ensured by the actual completion or by a predictive assessment of pointing termination.
