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	Author	Liebermann, D.G.; Berman, S.; Weingarden H.; Levin, M.F.; Weiss, P.L.
	Title	Kinematic features of arm and trunk movements in stroke patients and age-matched healthy controls during reaching in virtual and physical environments			Type	Conference Article
	Year	2009	Publication	Virtual Rehabilitation International Conference	Abbreviated Journal
	Volume		Issue		Pages	179-184
	Keywords
	Abstract	Motor performance of stroke patients and healthy individuals was compared in terms of selected kinematic features of arm and trunk movements while subjects reached for visual targets in virtual (VR) and physical (PH) environments. In PH, the targets were placed at an extended arm distance, while in VR comparably placed virtual targets were presented via GestureTek's IREX system. Our goal was to obtain further insights into research methods related to VR-based rehabilitation. Eight right-hemiparetic stroke patients (age =46-87 years) and 8 healthy adults (age =51-73 years) completed 84 reaching movements in VR and PH environments while seated. The results showed that arm and trunk movements differed in the two environments in patients and to a lesser extent in healthy individuals. Arm motion of patients became jerkier in VR, with larger paths and longer movement durations, and presented greater arm torsion (i.e., larger elbow rotations around the hand-shoulder axis). Interestingly, patients also showed a significant reduction of compensatory trunk movements during VR reaching. The findings indicate that when targets were perceived to be beyond hand reach, stroke patients may be less able to estimate 3D virtual target locations obtained from the 2D TV planar displays. This was not the case for healthy participants.
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	Notes				Approved	no
	Call Number				Serial	52
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	Author	Liebermann, D.G.; Krasovsky, T.; Berman, S.
	Title	Planning maximally smooth hand movements constrained to nonplanar workspaces			Type	Journal Article
	Year	2008	Publication	Journal of Motor Behavior	Abbreviated Journal	J Mot Behav
	Volume	40	Issue	6	Pages	516-531
	Keywords	Adaptation, Physiological; Adult; Algorithms; Female; Hand/physiology; Humans; Intention; Kinesthesis/physiology; Male; Models, Statistical; Movement/physiology; Psychomotor Performance/*physiology; Reference Values; Writing
	Abstract	The article characterizes hand paths and speed profiles for movements performed in a nonplanar, 2-dimensional workspace (a hemisphere of constant curvature). The authors assessed endpoint kinematics (i.e., paths and speeds) under the minimum-jerk model assumptions and calculated minimal amplitude paths (geodesics) and the corresponding speed profiles. The authors also calculated hand speeds using the 2/3 power law. They then compared modeled results with the empirical observations. In all, 10 participants moved their hands forward and backward from a common starting position toward 3 targets located within a hemispheric workspace of small or large curvature. Comparisons of modeled observed differences using 2-way RM-ANOVAs showed that movement direction had no clear influence on hand kinetics (p < .05). Workspace curvature affected the hand paths, which seldom followed geodesic lines. Constraining the paths to different curvatures did not affect the hand speed profiles. Minimum-jerk speed profiles closely matched the observations and were superior to those predicted by 2/3 power law (p < .001). The authors conclude that speed and path cannot be unambiguously linked under the minimum-jerk assumption when individuals move the hand in a nonplanar 2-dimensional workspace. In such a case, the hands do not follow geodesic paths, but they preserve the speed profile, regardless of the geometric features of the workspace.
	Address	Department of Physical Therapy, The Stanley Steyer School of Health Professions, Sackler Faculty of Medicine, Tel Aviv University, Israel. dlieberm@post.tau.ac.il
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Summary Language		Original Title
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0022-2895	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:18980905			Approved	no
	Call Number				Serial	33
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	Author	Liebermann, D.G
	Title	Biomechanical aspects of motor control in human landing			Type	Book Chapter
	Year	2008	Publication	Routledge Handbook of Biomechanics and Human Movement Science	Abbreviated Journal
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	Publisher	Routledge Ltd	Place of Publication		Editor	R. Bartlett; Y. Hong
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	Series Volume		Series Issue		Edition
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	Area		Expedition		Conference
	Notes				Approved	no
	Call Number				Serial	47
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	Author	Liebermann, D.G.; Franks I.M.
	Title	Video-feedback and information technologies			Type	Book Chapter
	Year	2008	Publication	Essentials of notational analysis	Abbreviated Journal
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	Publisher	E & FN Spon Pub	Place of Publication		Editor	I.M. Franks; M. Hughes
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	Series Volume		Series Issue		Edition
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	Notes				Approved	no
	Call Number				Serial	48
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	Author	Friedman, Jason; Flash, Tamar
	Title	Task-dependent selection of grasp kinematics and stiffness in human object manipulation			Type	Journal Article
	Year	2007	Publication	Cortex	Abbreviated Journal
	Volume	43	Issue	3	Pages	444-460
	Keywords
	Abstract	Object manipulation with the hand is a complex task. The task has redundancies at many levels, allowing many possibilities for the selection of grasp points, the orientation and posture of the hand, the forces to be applied at each fingertip and the impedance properties of the hand. Despite this inherent complexity, humans perform object manipulation nearly effortlessly. This article presents experimental findings of how humans grasp and manipulate objects, and examines the compatibility of grasps selected for specific tasks. This is accomplished by looking at the velocity transmission and force transmission ellipsoids, which represent the transmission ratios of the corresponding quantity from the joints to the object, as well as the stiffness ellipsoid which represents the directional stiffness of the grasp. These ellipsoids allow visualization of the grasp Jacobian and grasp stiffness matrices. The results show that the orientation of the ellipsoids can be related to salient task requirements.
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	Notes				Approved	no
	Call Number	Penn State @ write.to.jason @			Serial	14
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