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Reschechtko S, Gnanaseelan C, Pruszynski JA. Reach Corrections Toward Moving Objects are Faster Than Reach Corrections Toward Instantaneously Switching Targets. Neuroscience 2023; 526:135-143. [PMID: 37391122 DOI: 10.1016/j.neuroscience.2023.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 06/20/2023] [Accepted: 06/22/2023] [Indexed: 07/02/2023]
Abstract
Visually guided reaching is a common motor behavior that engages subcortical circuits to mediate rapid corrections. Although these neural mechanisms have evolved for interacting with the physical world, they are often studied in the context of reaching toward virtual targets on a screen. These targets often change position by disappearing from one place reappearing in another instantaneously. In this study, we instructed participants to perform rapid reaches to physical objects that changed position in different ways. In one condition, the objects moved very rapidly from one place to another. In the other condition, illuminated targets instantaneously switched position by being extinguished in one position and illuminating in another. Participants were consistently faster in correcting their reach trajectories when the object moved continuously.
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Affiliation(s)
- Sasha Reschechtko
- School of Exercise & Nutritional Sciences, San Diego State University, 351 ENS Building, 5500 Campanile Dr., San Diego, CA 92182, USA; Western BrainsCAN, Western University, 1151 Richmond St., London, ON N6A 3K7, Canada; Brain and Mind Institute, Western University, 1151 Richmond St., London, ON N6A 3K7, Canada; Robarts Research Institute, Western University, 1151 Richmond St., London, ON N6A 3K7, Canada; Department of Physiology & Pharmacology, Western University, 1151 Richmond St., London, ON N6A 3K7, Canada.
| | - Cynthiya Gnanaseelan
- Department of Physiology & Pharmacology, Western University, 1151 Richmond St., London, ON N6A 3K7, Canada
| | - J Andrew Pruszynski
- Brain and Mind Institute, Western University, 1151 Richmond St., London, ON N6A 3K7, Canada; Robarts Research Institute, Western University, 1151 Richmond St., London, ON N6A 3K7, Canada; Department of Physiology & Pharmacology, Western University, 1151 Richmond St., London, ON N6A 3K7, Canada; Department of Psychology, Western University, 1151 Richmond St., London, ON N6A 3K7, Canada
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2
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de Paz C, Travieso D. A direct comparison of sound and vibration as sources of stimulation for a sensory substitution glove. Cogn Res Princ Implic 2023; 8:41. [PMID: 37402032 DOI: 10.1186/s41235-023-00495-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 06/18/2023] [Indexed: 07/05/2023] Open
Abstract
Sensory substitution devices (SSDs) facilitate the detection of environmental information through enhancement of touch and/or hearing capabilities. Research has demonstrated that several tasks can be successfully completed using acoustic, vibrotactile, and multimodal devices. The suitability of a substituting modality is also mediated by the type of information required to perform the specific task. The present study tested the adequacy of touch and hearing in a grasping task by utilizing a sensory substitution glove. The substituting modalities inform, through increases in stimulation intensity, about the distance between the fingers and the objects. A psychophysical experiment of magnitude estimation was conducted. Forty blindfolded sighted participants discriminated equivalently the intensity of both vibrotactile and acoustic stimulation, although they experienced some difficulty with the more intense stimuli. Additionally, a grasping task involving cylindrical objects of varying diameters, distances and orientations was performed. Thirty blindfolded sighted participants were divided into vibration, sound, or multimodal groups. High performance was achieved (84% correct grasps) with equivalent success rate between groups. Movement variables showed more precision and confidence in the multimodal condition. Through a questionnaire, the multimodal group indicated their preference for using a multimodal SSD in daily life and identified vibration as their primary source of stimulation. These results demonstrate that there is an improvement in performance with specific-purpose SSDs, when the necessary information for a task is identified and coupled with the delivered stimulation. Furthermore, the results suggest that it is possible to achieve functional equivalence between substituting modalities when these previous steps are met.
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Affiliation(s)
- Carlos de Paz
- Facultad de Psicología, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - David Travieso
- Facultad de Psicología, Universidad Autónoma de Madrid, 28049, Madrid, Spain.
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3
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Wissing MBG, Golenia L, Smith J, Bongers RM. Adjustments in end-effector trajectory and underlying joint angle synergies after a target switch: Order of adjustment is flexible. PLoS One 2020; 15:e0238561. [PMID: 32886715 PMCID: PMC7473537 DOI: 10.1371/journal.pone.0238561] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/19/2020] [Indexed: 11/19/2022] Open
Abstract
Goal-directed reaching adapts to meet changing task requirements after unexpected perturbations such as a sudden switch of target location. Literature on adaptive behavior using a target switch has primarily focused on adjustments of the end-effector trajectory, addressing proposed feedback and feedforward processes in planning adjusted actions. Starting from a dynamical systems approach to motor coordination, the current paper focusses on coordination of joint angles after a target switch, which has received little attention in the literature. We argue that joint angles are coordinated in synergies, temporary task-specific units emerging from interactions amongst task, organism, and environmental constraints. We asked whether after a target switch: i) joint angles were coordinated in synergies, ii) joint angles were coordinated in a different synergy than the synergy used when moving to the original target, and iii) synergies or end-effector trajectory was adjusted first. Participants (N = 12) performed manual reaching movements toward a target on a table (stationary target trials), where in some trials the target could unexpectedly switch to a new location (switch trials). Results showed that the end-effector curved to the switched target. Joint angles were synergistically organized as shown by the large extent of co-variation based on Uncontrolled Manifold analyses. At the end of the target switch movement, joint angle configurations differed from the joint angle configurations used to move to the original stationary target. Hence, we argue, a new synergy emerged after the target switch. The order of adjustment in the synergies and in the end-effector was flexible within participants, though most often synergies were adjusted first. These findings support the two-step framework of Kay (1988) to understand the coordination of abundant degrees of freedom and to explain adaptive actions. The flexibility in the order of adjustments of synergies suggests that the coordination of DOF emerges from self-organization.
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Affiliation(s)
- Maureen B. G. Wissing
- Department of Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Laura Golenia
- Department of Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
- MEDIAN Unternehmensgruppe, Medicine and Quality Management, Berlin, Germany
| | - Joanne Smith
- Department of Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Raoul M. Bongers
- Department of Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
- * E-mail:
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4
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Camponogara I, Volcic R. Grasping adjustments to haptic, visual, and visuo-haptic object perturbations are contingent on the sensory modality. J Neurophysiol 2019; 122:2614-2620. [DOI: 10.1152/jn.00452.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Haptics provides information about the size and position of a handheld object. However, it is still unknown how haptics contributes to action correction if a sudden perturbation causes a change in the configuration of the handheld object. In this study, we have occasionally perturbed the size of an object that was the target of a right-hand reach-to-grasp movement. In some cases, participants were holding the target object with their left hand, which provided haptic information about the object perturbation. We compared the corrective responses to perturbations in three different sensory conditions: visual (participants had full vision of the object, but haptic information from the left hand was prevented), haptic (object size was sensed by the left hand and vision was prevented), and visuo-haptic (both visual and haptic information were available throughout the movement). We found that haptic inputs evoked faster contralateral corrections than visual inputs, although actions in haptic and visual conditions were similar in movement duration. Strikingly, the corrective responses in the visuo-haptic condition were as fast as those found in the haptic condition, a result that is contrary to that predicted by simple summation of unisensory signals. These results suggest the existence of a haptomotor reflex that can trigger automatic and efficient grasping corrections of the contralateral hand that are faster than those initiated by the well-known visuomotor reflex and the tactile-motor reflex. NEW & NOTEWORTHY We show that online grip aperture corrections during grasping actions are contingent on the sensory modality used to detect the object perturbation. We found that sensing perturbations with the contralateral hand only (haptics) leads to faster action corrections than when object perturbations are only visually sensed. Moreover, corrections following visuo-haptic perturbations were as fast as those to haptic perturbations. Thus a haptomotor reflex triggers faster automatic responses than the visuomotor reflex.
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Affiliation(s)
- Ivan Camponogara
- Department of Psychology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Robert Volcic
- Department of Psychology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
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5
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Karl JM, Slack BM, Wilson AM, Wilson CA, Bertoli ME. Increasing task precision demands reveals that the reach and grasp remain subject to different perception-action constraints in 12-month-old human infants. Infant Behav Dev 2019; 57:101382. [PMID: 31580995 DOI: 10.1016/j.infbeh.2019.101382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 07/29/2019] [Accepted: 09/16/2019] [Indexed: 11/19/2022]
Abstract
The reach and grasp follow different developmental trajectories, but are often considered to have achieved nearly adult-like precision and integration by 12 months of age. This study used frame-by-frame video analysis to investigate whether increasing precision demands, by placing small reaching targets on a narrow pedestal rather than on a flat table, would influence the reach and grasp movements of 12-month-old infants in a complementary or differential fashion. The results reveal that placing the target atop a pedestal impaired the infants's ability to direct an appropriate digit towards the small target, but did not produce a corresponding decrease in the frequency with which they used an index-thumb pincer grip to grasp the target. This was due to the fact that, although infants were more likely to contact the target with a suboptimal part of the hand in the pedestal condition, a greater proportion of these suboptimal contacts ultimately transitioned to a successful index-thumb pincer grip. Thus, increasing task precision demands impaired reach accuracy, but facilitated index-thumb grip formation, in 12-month-old infants. The differential response of the reach and grasp to the increased precision demands of the pedestal condition suggests that the two movements are not fully integrated and, when precision demands are great, remain sensitive to different perception-action constraints in 12-month-old infants.
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Affiliation(s)
- Jenni M Karl
- Department of Psychology, Thompson Rivers University, Kamloops, BC, Canada.
| | - Braydon M Slack
- Department of Psychology, Thompson Rivers University, Kamloops, BC, Canada
| | - Alexis M Wilson
- Department of Psychology, Thompson Rivers University, Kamloops, BC, Canada
| | | | - Marisa E Bertoli
- Department of Psychology, Thompson Rivers University, Kamloops, BC, Canada
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6
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Smeets JBJ, van der Kooij K, Brenner E. A review of grasping as the movements of digits in space. J Neurophysiol 2019; 122:1578-1597. [DOI: 10.1152/jn.00123.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is tempting to describe human reach-to-grasp movements in terms of two, more or less independent visuomotor channels, one relating hand transport to the object’s location and the other relating grip aperture to the object’s size. Our review of experimental work questions this framework for reasons that go beyond noting the dependence between the two channels. Both the lack of effect of size illusions on grip aperture and the finding that the variability in grip aperture does not depend on the object’s size indicate that size information is not used to control grip aperture. An alternative is to describe grip formation as emerging from controlling the movements of the digits in space. Each digit’s trajectory when grasping an object is remarkably similar to its trajectory when moving to tap the same position on its own. The similarity is also evident in the fast responses when the object is displaced. This review develops a new description of the speed-accuracy trade-off for multiple effectors that is applied to grasping. The most direct support for the digit-in-space framework is that prism-induced adaptation of each digit’s tapping movements transfers to that digit’s movements when grasping, leading to changes in grip aperture for adaptation in opposite directions for the two digits. We conclude that although grip aperture and hand transport are convenient variables to describe grasping, treating grasping as movements of the digits in space is a more suitable basis for understanding the neural control of grasping.
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Affiliation(s)
- Jeroen B. J. Smeets
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Katinka van der Kooij
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Eli Brenner
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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7
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Camponogara I, Volcic R. Grasping movements toward seen and handheld objects. Sci Rep 2019; 9:3665. [PMID: 30842478 PMCID: PMC6403353 DOI: 10.1038/s41598-018-38277-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 12/21/2018] [Indexed: 11/29/2022] Open
Abstract
Grasping movements are typically performed toward visually sensed objects. However, planning and execution of grasping movements can be supported also by haptic information when we grasp objects held in the other hand. In the present study we investigated this sensorimotor integration process by comparing grasping movements towards objects sensed through visual, haptic or visuo-haptic signals. When movements were based on haptic information only, hand preshaping was initiated earlier, the digits closed on the object more slowly, and the final phase was more cautious compared to movements based on only visual information. Importantly, the simultaneous availability of vision and haptics led to faster movements and to an overall decrease of the grip aperture. Our findings also show that each modality contributes to a different extent in different phases of the movement, with haptics being more crucial in the initial phases and vision being more important for the final on-line control. Thus, vision and haptics can be flexibly combined to optimize the execution of grasping movement.
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Affiliation(s)
- Ivan Camponogara
- Department of Psychology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.
| | - Robert Volcic
- Department of Psychology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
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8
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Schot WD, Brenner E, Smeets JB. Unusual prism adaptation reveals how grasping is controlled. eLife 2017; 6:21440. [PMID: 28891465 PMCID: PMC5619946 DOI: 10.7554/elife.21440] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 09/09/2017] [Indexed: 11/30/2022] Open
Abstract
There are three main theories on how human grasping movements are controlled. Two of them state that grip aperture and the movement of the hand are controlled. They differ in whether the wrist or the thumb of the hand is controlled. We have proposed a third theory, which states that grasping is a combination of two goal-directed single-digit movements, each directed at a specific position on the object. In this study, we test predictions based on each of the theories by examining the transfer of prism adaptation during single-digit pointing movements to grasping movements. We show that adaptation acquired during single-digit movements transfers to the hand opening when subsequently grasping objects, leaving the movement of the hand unaffected. Our results provide strong evidence for our theory that grasping with the thumb and index finger is based on a combination of two goal-directed single-digit movements.
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Affiliation(s)
- Willemijn D Schot
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Eli Brenner
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Jeroen Bj Smeets
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
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9
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Schettino LF, Adamovich SV, Tunik E. Coordination of pincer grasp and transport after mechanical perturbation of the index finger. J Neurophysiol 2017; 117:2292-2297. [PMID: 28331008 DOI: 10.1152/jn.00642.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 03/15/2017] [Accepted: 03/15/2017] [Indexed: 11/22/2022] Open
Abstract
Our understanding of reach-to-grasp movements has evolved from the original formulation of the movement as two semi-independent visuomotor channels to one of interdependence. Despite a number of important contributions involving perturbations of the reach or the grasp, some of the features of the movement, such as the presence or absence of coordination between the digits during the pincer grasp and the extent of spatio-temporal interdependence between the transport and the grasp, are still unclear. In this study, we physically perturbed the index finger into extension during grasping closure on a minority of trials to test whether modifying the movement of one digit would affect the movement of the opposite digit, suggestive of an overarching coordinative process. Furthermore, we tested whether disruption of the grasp results in the modification of kinematic parameters of the transport. Our results showed that a continuous perturbation to the index finger affected wrist velocity but not lateral displacement. Moreover, we found that the typical flexion of the thumb observed in nonperturbed trials was delayed until the index finger counteracted the extension force. These results suggest that physically perturbing the grasp modifies the kinematics of the transport component, indicating a two-way interdependence of the reach and the grasp. Furthermore, a perturbation to one digit affects the kinematics of the other, supporting a model of grasping in which the digits are coordinated by a higher-level process rather than being independently controlled.NEW & NOTEWORTHY A current debate concerning the neural control of prehension centers on the question of whether the digits in a pincer grasp are controlled individually or together. Employing a novel approach that perturbs mechanically the grasp component during a natural reach-to-grasp movement, this work is the first to test a key hypothesis: whether perturbing one of the digits during the movement affects the other. Our results support the idea that the digits are not independently controlled.
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Affiliation(s)
- Luis F Schettino
- Department of Psychology, Lafayette College, Easton, Pennsylvania
| | - Sergei V Adamovich
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, New Jersey.,Department of Rehabilitation and Movement Sciences, Rutgers Biomedical Health Sciences, Newark, New Jersey
| | - Eugene Tunik
- Department of Physical Therapy, Movement, and Rehabilitation Sciences, Northeastern University, Boston, Massachusetts; and .,Department of Bioengineering, Northeastern University, Boston, Massachusetts
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10
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11
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Koester D, Schack T. Action Priority: Early Neurophysiological Interaction of Conceptual and Motor Representations. PLoS One 2016; 11:e0165882. [PMID: 27973539 PMCID: PMC5156427 DOI: 10.1371/journal.pone.0165882] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 10/19/2016] [Indexed: 11/18/2022] Open
Abstract
Handling our everyday life, we often react manually to verbal requests or instruction, but the functional interrelations of motor control and language are not fully understood yet, especially their neurophysiological basis. Here, we investigated whether specific motor representations for grip types interact neurophysiologically with conceptual information, that is, when reading nouns. Participants performed lexical decisions and, for words, executed a grasp-and-lift task on objects of different sizes involving precision or power grips while the electroencephalogram was recorded. Nouns could denote objects that require either a precision or a power grip and could, thus, be (in)congruent with the performed grasp. In a control block, participants pointed at the objects instead of grasping them. The main result revealed an event-related potential (ERP) interaction of grip type and conceptual information which was not present for pointing. Incongruent compared to congruent conditions elicited an increased positivity (100–200 ms after noun onset). Grip type effects were obtained in response-locked analyses of the grasping ERPs (100–300 ms at left anterior electrodes). These findings attest that grip type and conceptual information are functionally related when planning a grasping action but such an interaction could not be detected for pointing. Generally, the results suggest that control of behaviour can be modulated by task demands; conceptual noun information (i.e., associated action knowledge) may gain processing priority if the task requires a complex motor response.
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Affiliation(s)
- Dirk Koester
- Neurocognition and Action Research Group–Biomechanics, Faculty of Psychology and Sport Science, Bielefeld University, Bielefeld, Germany
- Cluster of Excellence–Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany
- * E-mail:
| | - Thomas Schack
- Neurocognition and Action Research Group–Biomechanics, Faculty of Psychology and Sport Science, Bielefeld University, Bielefeld, Germany
- Cluster of Excellence–Cognitive Interaction Technology (CITEC), Bielefeld University, Bielefeld, Germany
- Research Institute for Cognition and Robotics (CoR lab), Bielefeld University, Bielefeld, Germany
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12
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Titchener's ⊥ in context 1--delimited, discrete monomotif patterns, line arrangements, and branching patterns. Atten Percept Psychophys 2015; 78:278-92. [PMID: 26486639 DOI: 10.3758/s13414-015-0996-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Three experiments tested the effects of the presence of nontarget ⊥s on Titchener's (1901) ⊥-illusion. Experiment 1 used patterns of four separate ⊥s, Experiment 2 used branching patterns in which four ⊥s were stuck together, and Experiment 3 used patterns of four triangles or four beehive forms for which the ⊥ could be seen as a skeleton. Three independent samples of 12 observers each had to haptically indicate the lengths of target lines and verbally judge the relative lengths of the two lines of target ⊥s. The illusion to judge or indicate the ⊥’s undivided line as longer than its divided line survived throughout except for the branching patterns: here, haptic indications did not differ between the two types of lines. Specific features of these patterns and of the ⊥ itself may be responsible for these effects.
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13
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Worssam CJ, Meade LC, Connolly JD. Non-obstructing 3D depth cues influence reach-to-grasp kinematics. Exp Brain Res 2014; 233:385-96. [PMID: 25311388 DOI: 10.1007/s00221-014-4119-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Accepted: 09/30/2014] [Indexed: 12/01/2022]
Abstract
It has been demonstrated that both visual feedback and the presence of certain types of non-target objects in the workspace can affect kinematic measures and the trajectory path of the moving hand during reach-to-grasp movements. Yet no study to date has examined the possible effect of providing non-obstructing three-dimensional (3D) depth cues within the workspace and with consistent retinal inputs and whether or not these alter manual prehension movements. Participants performed a series of reach-to-grasp movements in both open- (without visual feedback) and closed-loop (with visual feedback) conditions in the presence of one of three possible 3D depth cues. Here, it is reported that preventing online visual feedback (or not) and the presence of a particular depth cue had a profound effect on kinematic measures for both the reaching and grasping components of manual prehension-despite the fact that the 3D depth cues did not act as a physical obstruction at any point. The depth cues modulated the trajectory of the reaching hand when the target block was located on the left side of the workspace but not on the right. These results are discussed in relation to previous reports and implications for brain-computer interface decoding algorithms are provided.
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Affiliation(s)
- Christopher J Worssam
- Science Laboratories, Department of Psychology, Durham University, South Road, Durham, DH1 3LE, UK
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14
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Zaal FTJM, Bongers RM. Movements of individual digits in bimanual prehension are coupled into a grasping component. PLoS One 2014; 9:e97790. [PMID: 24870948 PMCID: PMC4037218 DOI: 10.1371/journal.pone.0097790] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 04/24/2014] [Indexed: 11/18/2022] Open
Abstract
The classic understanding of prehension is that of coordinated reaching and grasping. An alternative view is that the grasping in prehension emerges from independently controlled individual digit movements (the double-pointing model). The current study tested this latter model in bimanual prehension: participants had to grasp an object between their two index fingers. Right after the start of the movement, the future end position of one of the digits was perturbed. The perturbations resulted in expected changes in the kinematics of the perturbed digit but also in adjusted kinematics in the unperturbed digit. The latter effects showed up when the end position of the right index finger was perturbed, but not when the end position of the left index finger was perturbed. Because the absence of a coupling between the digits is the core assumption of the double-pointing model, finding any perturbation effects challenges this account of prehension; the double-pointing model predicts that the unperturbed digit would be unaffected by the perturbation. The authors conclude that the movement of the digits in prehension is coupled into a grasping component.
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Affiliation(s)
- Frank T. J. M. Zaal
- Center for Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
- * E-mail:
| | - Raoul M. Bongers
- Center for Human Movement Sciences, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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15
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Di Rienzo F, Guillot A, Mateo S, Daligault S, Delpuech C, Rode G, Collet C. Neuroplasticity of prehensile neural networks after quadriplegia. Neuroscience 2014; 274:82-92. [PMID: 24857709 DOI: 10.1016/j.neuroscience.2014.05.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/06/2014] [Accepted: 05/08/2014] [Indexed: 01/19/2023]
Abstract
Targeting cortical neuroplasticity through rehabilitation-based practice is believed to enhance functional recovery after spinal cord injury (SCI). While prehensile performance is severely disturbed after C6-C7 SCI, subjects with tetraplegia can learn a compensatory passive prehension using the tenodesis effect. During tenodesis, an active wrist extension triggers a passive flexion of the fingers allowing grasping. We investigated whether motor imagery training could promote activity-dependent neuroplasticity and improve prehensile tenodesis performance. SCI participants (n=6) and healthy participants (HP, n=6) took part in a repeated measurement design. After an extended baseline period of 3 weeks including repeated magnetoencephalography (MEG) measurements, MI training was embedded within the classical course of physiotherapy for 5 additional weeks (three sessions per week). An immediate MEG post-test and a follow-up at 2 months were performed. Before MI training, compensatory activations and recruitment of deafferented cortical regions characterized the cortical activity during actual and imagined prehension in SCI participants. After MI training, MEG data yielded reduced compensatory activations. Cortical recruitment became similar to that in HP. Behavioral analysis evidenced decreased movement variability suggesting motor learning of tenodesis. Data suggest that MI training participated to reverse compensatory neuroplasticity in SCI participants, and promoted the integration of new upper limb prehensile coordination in the neural networks functionally dedicated to the control of healthy prehension before injury.
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Affiliation(s)
- F Di Rienzo
- Université de Lyon, Université Claude Bernard Lyon 1, Performance Motrice, Mentale et du Matériel (P3M), Centre de Recherche et d'Innovation sur le Sport (EA 647), F-69622 Villeurbanne, France
| | - A Guillot
- Université de Lyon, Université Claude Bernard Lyon 1, Performance Motrice, Mentale et du Matériel (P3M), Centre de Recherche et d'Innovation sur le Sport (EA 647), F-69622 Villeurbanne, France; Institut Universitaire de France, F-75000 Paris, France
| | - S Mateo
- Université de Lyon, Université Claude Bernard Lyon 1, Performance Motrice, Mentale et du Matériel (P3M), Centre de Recherche et d'Innovation sur le Sport (EA 647), F-69622 Villeurbanne, France; Hôpital Henri Gabrielle, Hospices Civils de Lyon, F-69230 Saint Genis-Laval, France
| | - S Daligault
- CERMEP imagerie du vivant, Département MEG, F-69677 Bron, France
| | - C Delpuech
- CERMEP imagerie du vivant, Département MEG, F-69677 Bron, France; INSERM U1028, CNRS UMR5292, Centre des neurosciences de Lyon, F-69000 Lyon, France
| | - G Rode
- Hôpital Henri Gabrielle, Hospices Civils de Lyon, F-69230 Saint Genis-Laval, France; INSERM U1028, CNRS UMR5292, Centre des neurosciences de Lyon, F-69000 Lyon, France
| | - C Collet
- Université de Lyon, Université Claude Bernard Lyon 1, Performance Motrice, Mentale et du Matériel (P3M), Centre de Recherche et d'Innovation sur le Sport (EA 647), F-69622 Villeurbanne, France.
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16
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Direction-dependent differences in temporal kinematics for vertical prehension movements. Exp Brain Res 2013; 232:703-11. [DOI: 10.1007/s00221-013-3783-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 11/15/2013] [Indexed: 11/29/2022]
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17
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Verheij R, Brenner E, Smeets JBJ. Gravity affects the vertical curvature in human grasping movements. J Mot Behav 2013; 45:325-32. [PMID: 23819650 DOI: 10.1080/00222895.2013.798251] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
When humans make grasping movements their digits' paths are curved vertically. In a previous study the authors found that this curvature is largely caused by the local constraints at the start and end of the movement. Here the authors examined the contribution of gravity to the part of the curvature that was not explained by the local constraints. Subjects had to grasp a tealight (small cylinder) while sitting on a chair. The authors could rotate the whole setup, including the subject, relative to gravity, whereby the positions of the starting point and of the tealight relative to the subject did not change. They found differences between the paths that are consistent with a direct effect of gravity pulling the arm downward.
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Affiliation(s)
- Rebekka Verheij
- MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, the Netherlands
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18
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Heath M, Holmes SA, Mulla A, Binsted G. Grasping time does not influence the early adherence of aperture shaping to Weber's law. Front Hum Neurosci 2012; 6:332. [PMID: 23267323 PMCID: PMC3527824 DOI: 10.3389/fnhum.2012.00332] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 12/03/2012] [Indexed: 11/19/2022] Open
Abstract
The “just noticeable difference” (JND) represents the minimum amount by which a stimulus must change to produce a noticeable variation in one's perceptual experience (i.e., Weber's law). Recent work has shown that within-participant standard deviations of grip aperture (i.e., JNDs) increase linearly with increasing object size during the early, but not the late, stages of goal-directed grasping. A visually based explanation for this finding is that the early and late stages of grasping are respectively mediated by relative and absolute visual information and therefore render a time-dependent adherence to Weber's law. Alternatively, a motor-based explanation contends that the larger aperture shaping impulses required for larger objects gives rise to a stochastic increase in the variability of motor output (i.e., impulse-variability hypothesis). To test the second explanation, we had participants grasp differently sized objects in grasping time criteria of 400 and 800 ms. Thus, the 400 ms condition required larger aperture shaping impulses than the 800 ms condition. In line with previous work, JNDs during early aperture shaping (i.e., at the time of peak aperture acceleration and peak aperture velocity) for both the 400 and 800 ms conditions scaled linearly with object size, whereas JNDs later in the response (i.e., at the time of peak grip aperture) did not. Moreover, the 400 and 800 ms conditions produced comparable slopes relating JNDs to object size. In other words, larger aperture shaping impulses did not give rise to a stochastic increase in aperture variability at each object size. As such, the theoretical tenets of the impulse-variability hypothesis do not provide a viable framework for the time-dependent scaling of JNDs to object size. Instead, we propose that a dynamic interplay between relative and absolute visual information gives rise to grasp trajectories that exhibit an early adherence and late violation to Weber's law.
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Affiliation(s)
- Matthew Heath
- NeuroBehavioural Lab, School of Kinesiology and Graduate Program in Neuroscience, University of Western Ontario London, ON, Canada
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19
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Rácz K, Brown D, Valero-Cuevas FJ. An involuntary stereotypical grasp tendency pervades voluntary dynamic multifinger manipulation. J Neurophysiol 2012; 108:2896-911. [PMID: 22956798 DOI: 10.1152/jn.00297.2012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We used a novel apparatus with three hinged finger pads to characterize collaborative multifinger interactions during dynamic manipulation requiring individuated control of fingertip motions and forces. Subjects placed the thumb, index, and middle fingertips on each hinged finger pad and held it-unsupported-with constant total grasp force while voluntarily oscillating the thumb's pad. This task combines the need to 1) hold the object against gravity while 2) dynamically reconfiguring the grasp. Fingertip force variability in this combined motion and force task exhibited strong synchrony among normal (i.e., grasp) forces. Mechanical analysis and simulation show that such synchronous variability is unnecessary and cannot be explained solely by signal-dependent noise. Surprisingly, such variability also pervaded control tasks requiring different individuated fingertip motions and forces, but not tasks without finger individuation such as static grasp. These results critically extend notions of finger force variability by exposing and quantifying a pervasive challenge to dynamic multifinger manipulation: the need for the neural controller to carefully and continuously overlay individuated finger actions over mechanically unnecessary synchronous interactions. This is compatible with-and may explain-the phenomenology of strong coupling of hand muscles when this delicate balance is not yet developed, as in early childhood, or when disrupted, as in brain injury. We conclude that the control of healthy multifinger dynamic manipulation has barely enough neuromechanical degrees of freedom to meet the multiple demands of ecological tasks and critically depends on the continuous inhibition of synchronous grasp tendencies, which we speculate may be of vestigial evolutionary origin.
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Affiliation(s)
- Kornelius Rácz
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA
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20
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Mateo S, Revol P, Fourtassi M, Rossetti Y, Collet C, Rode G. Kinematic characteristics of tenodesis grasp in C6 quadriplegia. Spinal Cord 2012; 51:144-9. [PMID: 22945744 DOI: 10.1038/sc.2012.101] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
STUDY DESIGN Descriptive control case study. OBJECTIVES To analyze the kinematics of tenodesis grasp in participants with C6 quadriplegia and healthy control participants in a pointing task and two daily life tasks involving a whole hand grip (apple) or a lateral grip (floppy disk). SETTING France. METHODS Four complete participants with C6 quadriplegia were age matched with four healthy control participants. All participants were right-handed. The measured kinematic parameters were the movement time (MT), the peak velocity (PV), the time of PV (TPV) and the wrist angle in the sagittal plane at movement onset, at the TPV and at the movement end point. RESULTS The participants with C6 quadriplegia had significantly longer MTs in both prehension tasks. No significant differences in TPV were found between the two groups. Unlike control participants, for both prehension tasks the wrist of participants with C6 quadriplegia was in a neutral position at movement onset, in flexion at the TPV, and in extension at the movement end point. CONCLUSION Two main kinematic parameters characterize tenodesis grasp movements in C6 quadriplegics: wrist flexion during reaching and wrist extension during the grasping phase, and increased MT reflecting the time required to adjust the wrist's position to achieve the tenodesis grasp. These characteristics were observed for two different grips (whole hand and lateral grip). These results suggest sequential planning of reaching and tenodesis grasp, and should be taken into account for prehension rehabilitation in patients with quadriplegia.
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Affiliation(s)
- S Mateo
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, ImpAct Team, Lyon, France.
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21
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Verheij R, Brenner E, Smeets JBJ. Grasping kinematics from the perspective of the individual digits: a modelling study. PLoS One 2012; 7:e33150. [PMID: 22412997 PMCID: PMC3296685 DOI: 10.1371/journal.pone.0033150] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 02/09/2012] [Indexed: 11/26/2022] Open
Abstract
Grasping is a prototype of human motor coordination. Nevertheless, it is not known what determines the typical movement patterns of grasping. One way to approach this issue is by building models. We developed a model based on the movements of the individual digits. In our model the following objectives were taken into account for each digit: move smoothly to the preselected goal position on the object without hitting other surfaces, arrive at about the same time as the other digit and never move too far from the other digit. These objectives were implemented by regarding the tips of the digits as point masses with a spring between them, each attracted to its goal position and repelled from objects' surfaces. Their movements were damped. Using a single set of parameters, our model can reproduce a wider variety of experimental findings than any previous model of grasping. Apart from reproducing known effects (even the angles under which digits approach trapezoidal objects' surfaces, which no other model can explain), our model predicted that the increase in maximum grip aperture with object size should be greater for blocks than for cylinders. A survey of the literature shows that this is indeed how humans behave. The model can also adequately predict how single digit pointing movements are made. This supports the idea that grasping kinematics follow from the movements of the individual digits.
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Affiliation(s)
- Rebekka Verheij
- Faculty of Human Movement Sciences, Research Institute MOVE, VU University, Amsterdam, The Netherlands.
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22
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Gilster R, Hesse C, Deubel H. Contact points during multidigit grasping of geometric objects. Exp Brain Res 2011; 217:137-51. [PMID: 22198529 DOI: 10.1007/s00221-011-2980-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 12/03/2011] [Indexed: 11/27/2022]
Abstract
We investigated the choice of contact points during multidigit grasping of different objects. In Experiment 1, cylinders were grasped and lifted. Participants were either instructed as to the number of fingers they should use, ranging from a two-finger grasp to a five-finger grasp, or could grasp with their preferred number of fingers. We found a strong relationship between the position of the fingertips on the object and the number of fingers used. In general, variability in the choice of contact points was low within- as well as between participants. The virtual finger, defined as the geometric mean position of fingers opposing the thumb, was in almost perfect opposition to the thumb, suggesting the formation of a functional unit using all contributing fingers in the grasp. In Experiment 2, four more complex shapes (rectangle, hexagon, pentagon, curved object) were grasped. Although we found some moderate between-participant variability in the choice of contact points, the within-participant variability was again remarkably low. In both experiments, participants showed a strong preference to use four or five fingers during grasping when left with free choice. Taken together, our findings suggest a preplanning of the grasping movement and that grasping results from a coordinated interplay between the fingers contributing to the grasp that cannot be understood as independent digit movements.
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Affiliation(s)
- René Gilster
- General and Experimental Psychology, Ludwig-Maximilians-University, Leopoldstr. 13, 80802, Munich, Germany.
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23
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Bongers RM, Zaal FTJM, Jeannerod M. Hand aperture patterns in prehension. Hum Mov Sci 2011; 31:487-501. [PMID: 22130470 DOI: 10.1016/j.humov.2011.07.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 07/22/2011] [Accepted: 07/23/2011] [Indexed: 11/17/2022]
Abstract
Although variations in the standard prehensile pattern can be found in the literature, these alternative patterns have never been studied systematically. This was the goal of the current paper. Ten participants picked up objects with a pincer grip. Objects (3, 5, or 7cm in diameter) were placed at 30, 60, 90, or 120cm from the hands' starting location. Usually the hand was opened gradually to a maximum immediately followed by hand closing, called the standard hand opening pattern. In the alternative opening patterns the hand opening was bumpy, or the hand aperture stayed at a plateau before closing started. Two participants in particular delayed the start of grasping with respect to start of reaching, with the delay time increasing with object distance. For larger object distances and smaller object sizes, the bumpy and plateau hand opening patterns were used more often. We tentatively concluded that the alternative hand opening patterns extended the hand opening phase, to arrive at the appropriate hand aperture at the appropriate time to close the hand for grasping the object. Variations in hand opening patterns deserve attention because this might lead to new insights into the coordination of reaching and grasping.
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24
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Goodale MA. Transforming vision into action. Vision Res 2011; 51:1567-87. [PMID: 20691202 DOI: 10.1016/j.visres.2010.07.027] [Citation(s) in RCA: 201] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 07/20/2010] [Accepted: 07/29/2010] [Indexed: 11/27/2022]
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25
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Schot WD, Brenner E, Smeets JBJ. Grasping and hitting moving objects. Exp Brain Res 2011; 212:487-96. [PMID: 21667040 PMCID: PMC3133698 DOI: 10.1007/s00221-011-2756-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 05/30/2011] [Indexed: 11/18/2022]
Abstract
Some experimental evidence suggests that grasping should be regarded as independent control of the thumb and the index finger (digit control hypothesis). To investigate this further, we compared how the tips of the thumb and the index finger moved in space when grasping spheres to how they moved when they were hitting the sphere using only one digit. In order to make the tasks comparable, we designed the experiment in such a way that subjects contacted the spheres in about the same way in the hitting task as when grasping it. According to the digit control hypothesis, the two tasks should yield similar digit trajectories in space. People hit and grasped stationary and moving spheres. We compared the similarity of the digits’ trajectories across the two tasks by evaluating the time courses of the paths of the average of the thumb and the index finger. These paths were more similar across tasks than across sphere motion, supporting the notion that grasping is not controlled fundamentally differently than hitting.
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Affiliation(s)
- Willemijn D Schot
- Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, Van der Boechorststraat 9, 1081 BT Amsterdam, The Netherlands.
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26
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Discovering affordances that determine the spatial structure of reach-to-grasp movements. Exp Brain Res 2011; 211:145-60. [PMID: 21484397 DOI: 10.1007/s00221-011-2659-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Accepted: 03/25/2011] [Indexed: 10/18/2022]
Abstract
Extensive research has identified the affordances used to guide actions, as originally conceived by Gibson (Perceiving, acting, and knowing: towards an ecological psychology. Erlbaum, Hillsdale, 1977; The ecological approach to visual perception. Erlbaum, Hillsdale, 1979/1986). We sought to discover the object affordance properties that determine the spatial structure of reach-to-grasp movements--movements that entail both collision avoidance and targeting. First, we constructed objects that presented a significant collision hazard and varied properties relevant to targeting, namely, object width and size of contact surface. Participants reached-to-grasp objects at three speeds (slow, normal, and fast). In Experiment 1, we explored a "stop" task where participants grasped the objects without moving them. In Experiment 2, we studied "fly-through" movements where the objects were lifted. We discovered the object affordance properties that produced covariance in the spatial structure of reaches-to-grasp. Maximum grasp aperture (MGA) reflected affordances determined by collision avoidance. Terminal grasp aperture (TGA)--when the hand stops moving but prior to finger contact--reflected affordances relevant to targeting accuracy. A model with a single free parameter predicted the prehensile spatial structure and provided a functional affordance-based account of that structure. In Experiment 3, we investigated a "slam" task where participants reached-to-grasp flat rectangular objects on a tabletop. The affordance structure of this task was found to eliminate the collision risk and thus reduced safety margins in MGA and TGA to zero for larger objects. The results emphasize the role of affordances in determining the structure and scaling of reach-to-grasp actions. Finally, we report evidence supporting the opposition vector as an appropriate unit of analysis in the study of grasping and a unit of action that maps directly to affordance properties.
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Chinellato E, Grzyb BJ, Marzocchi N, Bosco A, Fattori P, del Pobil AP. The Dorso-medial visual stream: From neural activation to sensorimotor interaction. Neurocomputing 2011. [DOI: 10.1016/j.neucom.2010.07.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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28
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Grafton ST. The cognitive neuroscience of prehension: recent developments. Exp Brain Res 2010; 204:475-91. [PMID: 20532487 PMCID: PMC2903689 DOI: 10.1007/s00221-010-2315-2] [Citation(s) in RCA: 184] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2009] [Accepted: 05/22/2010] [Indexed: 12/04/2022]
Abstract
Prehension, the capacity to reach and grasp, is the key behavior that allows humans to change their environment. It continues to serve as a remarkable experimental test case for probing the cognitive architecture of goal-oriented action. This review focuses on recent experimental evidence that enhances or modifies how we might conceptualize the neural substrates of prehension. Emphasis is placed on studies that consider how precision grasps are selected and transformed into motor commands. Then, the mechanisms that extract action relevant information from vision and touch are considered. These include consideration of how parallel perceptual networks within parietal cortex, along with the ventral stream, are connected and share information to achieve common motor goals. On-line control of grasping action is discussed within a state estimation framework. The review ends with a consideration about how prehension fits within larger action repertoires that solve more complex goals and the possible cortical architectures needed to organize these actions.
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Affiliation(s)
- Scott T Grafton
- Department of Psychology, Sage Center for the Study of Mind, University of California at Santa Barbara, Santa Barbara, CA 93106, USA.
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29
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Smeets JBJ, Martin J, Brenner E. Similarities between digits' movements in grasping, touching and pushing. Exp Brain Res 2010; 203:339-46. [PMID: 20379703 PMCID: PMC2871104 DOI: 10.1007/s00221-010-2236-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 03/17/2010] [Indexed: 11/29/2022]
Abstract
In order to find out whether the movements of single digits are controlled in a special way when grasping, we compared the movements of the digits when grasping an object with their movements in comparable single-digit tasks: pushing or lightly tapping the same object at the same place. The movements of the digits in grasping were very similar to the movements in the single-digit tasks. To determine to what extent the hand transport and grip formation in grasping emerges from a synchronised motion of individual digits, we combined movements of finger and thumb in the single-digit tasks to obtain hypothetical transport and grip components. We found a larger peak grip aperture earlier in the movement for the single-digit tasks. The timing of peak grip aperture depended in the same way on its size for all tasks. Furthermore, the deviations from a straight line of the transport component differed considerably between subjects, but were remarkably similar across tasks. These results support the idea that grasping should be regarded as consisting of moving the digits, rather than transporting the hand and shaping the grip.
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Affiliation(s)
- Jeroen B J Smeets
- Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, van der Boechorststraat 9, 1081 BT, Amsterdam, The Netherlands.
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30
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Schot WD, Brenner E, Smeets JB. Robust movement segmentation by combining multiple sources of information. J Neurosci Methods 2010; 187:147-55. [PMID: 20096305 DOI: 10.1016/j.jneumeth.2010.01.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 01/04/2010] [Accepted: 01/05/2010] [Indexed: 10/19/2022]
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31
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Kamp CVD, Bongers RM, Zaal FTJM. Effects of Changing Object Size During Prehension. J Mot Behav 2009; 41:427-35. [DOI: 10.3200/35-08-033] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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32
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