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	Author	Noy, L.; Alon, U.; Friedman, J.
	Title	Corrective jitter motion shows similar individual frequencies for the arm and the finger			Type	Journal Article
	Year	2015	Publication	Experimental Brain Research	Abbreviated Journal	Exp Brain Res
	Volume	233	Issue	4	Pages	1307-1320
	Keywords
	Abstract	A characteristic of visuomotor tracking of non-regular oscillating stimuli are high-frequency jittery corrective motions, oscillating around the tracked stimuli. However, the properties of these corrective jitter responses are not well understood. For example, does the jitter response show an idiosyncratic signature? What is the relationship between stimuli properties and jitter properties? Is the jitter response similar across effectors with different inertial properties? To answer these questions, we measured participants' jitter frequencies in two tracking tasks in the arm and the finger. Thirty participants tracked the same set of eleven non-regular oscillating stimuli, vertically moving on a screen, once with forward-backward arm movements (holding a tablet stylus) and once with upward-downward index finger movements (with a motion tracker attached). Participants' jitter frequencies and tracking errors varied systematically as a function of stimuli frequency and amplitude. Additionally, there were clear individual differences in average jitter frequencies between participants, ranging from 0.7 to 1.15 Hz, similar to values reported previously. A comparison of individual jitter frequencies in the two tasks showed a strong correlation between participants' jitter frequencies in the finger and the arm, despite the very different inertial properties of the two effectors. This result suggests that the corrective jitter response stems from common neural processes.
	Address
	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	0014-4819	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:25630905			Approved	no
	Call Number				Serial	76
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	Author	Berman, S.; Liebermann, D.G.; McIntyre, J.
	Title	Constrained Motion Control on a Hemispherical Surface – Path Planning			Type	Journal Article
	Year	2014	Publication	Journal of Neurophysiology	Abbreviated Journal	J Neurophysiol
	Volume	111	Issue	5	Pages	954-968
	Keywords	Constrained motion; geodesics; path planning
	Abstract	Surface-constrained motion, i.e., motion constraint by a rigid surface, is commonly found in daily activities. The current work investigates the choice of hand paths constrained to a concave hemispherical surface. To gain insight regarding the paths and their relationship with task dynamics, we simulated various control policies. The simulations demonstrated that following a geodesic path is advantageous not only in terms of path length, but also in terms of motor planning and sensitivity to motor command errors. These stem from the fact that the applied forces lie in a single plane (that of the geodesic path itself). To test whether human subjects indeed follow the geodesic, and to see how such motion compares to other paths, we recorded movements in a virtual haptic-visual environment from eleven healthy subjects. The task was comprised of point-to-point motion between targets at two elevations (30 degrees and 60 degrees ). Three typical choices of paths were observed from a frontal plane projection of the paths: circular arcs, straight lines, and arcs close to the geodesic path for each elevation. Based on the measured hand paths, we applied k-means blind separation to divide the subjects into three groups and compared performance indicators. The analysis confirmed that subjects who followed paths closest to the geodesic produced faster and smoother movements, compared to the others. The 'better' performance reflects the dynamical advantages of following the geodesic path, as shown by the simulations, and may also reflect invariant features of the control policies used to produce such a surface-constrained motion.
	Address	Ben-Gurion University of the Negev
	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	0022-3077	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:24259548			Approved	no
	Call Number				Serial	72
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	Author	Frenkel-Toledo, S.; Bentin, S.; Perry, A.; Liebermann, D.G.; Soroker, N.
	Title	Dynamics of the EEG Power in the Frequency and Spatial Domains During Observation and Execution of Manual Movements			Type	Journal Article
	Year	2013	Publication	Brain Research	Abbreviated Journal	Brain Res
	Volume	1509	Issue		Pages	43-57
	Keywords
	Abstract	Mu suppression is the attenuation of EEG power in the alpha frequency range (8-12Hz) while executing or observing a motor action. Whereas typically observed at central scalp sites, there are diverging reports about the extent of the attenuation over the cortical mantle, its exact frequency range and the specificity of this phenomenon. We investigated the modulation of EEG oscillations in frequency-bands from 4 to 12Hz at frontal, central, parietal and occipital sites during the execution of manual movements and during observation of similar actions from allocentric (i.e., facing the actor) and egocentric (i.e., seeing the actor from behind) viewpoints. Suppression was determined relative to observation of a non-biological movement. Action observation elicited greater suppression in the lower (8-10Hz) compared to the higher mu range (10-12Hz), and greater suppression in the entire 4-12Hz range at frontal and central sites compared to parietal and occipital sites. In addition, suppression tended to be greater during observation of a motor action from allocentric compared to egocentric viewpoints. During execution of movement, suppression of the EEG occurred primarily in the higher alpha range and was absent at occipital sites. In the theta range (4-8Hz), the EEG amplitude was suppressed during action observation and execution. The results suggest a functional distinction between modulation of mu and alpha rhythms, and between the higher and lower ranges of the mu rhythms. The activity of the presumed human mirror neuron system seems primarily evident in the lower mu range and in the theta range.
	Address	Sackler Faculty of Medicine, Tel Aviv University, Israel; Department of Neurological Rehabilitation, Loewenstein Hospital, Raanana, Israel. Electronic address: silvi197@bezeqint.net
	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	0006-8993	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:23500633			Approved	no
	Call Number				Serial	68
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	Author	Liebermann, D.G.; Berman, S.; Weiss, P.L.T.; Levin, M.F.
	Title	Kinematics of reaching movements in a 2-d virtual environment in adults with and without stroke			Type	Journal Article
	Year	2012	Publication	IEEE Transactions on Neural Systems and Rehabilitation Engineering : a Publication of the IEEE Engineering in Medicine and Biology Society	Abbreviated Journal	IEEE Trans Neural Syst Rehabil Eng
	Volume	20	Issue	6	Pages	778-787
	Keywords
	Abstract	Virtual reality environments are increasingly being used for upper limb rehabilitation in poststroke patients. Our goal was to determine if arm reaching movements made in a 2-D video-capture virtual reality environment are similar to those made in a comparable physical environment. We compared arm and trunk kinematics for reaches made with the right, dominant arm to three targets (14 trials per target) in both environments by 16 adults with right poststroke hemiparesis and by eight healthy age-matched controls. Movement kinematics were recorded with a three-camera optoelectronic system at 100 samples/s. Reaching movements made by both control and stroke subjects were affected by viewing the targets in the video-capture 2-D virtual environment. Movements were slower, shorter, less straight, less accurate and involved smaller ranges of shoulder and elbow joint excursions for target reaches in the virtual environment compared to the physical environment in all subjects. Thus, there was a decrease in the overall movement quality for movements made in the 2-D virtual environment. This suggests that 2-D video-capture virtual reality environments should be used with caution when the goal of the rehabilitation program is to improve the quality of movement patterns of the upper limb.
	Address
	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	1534-4320	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:22907972			Approved	no
	Call Number				Serial	28
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	Author	Biess, A.; Flash, T.; Liebermann, D.G.
	Title	Riemannian geometric approach to human arm dynamics, movement optimization, and invariance			Type	Journal Article
	Year	2011	Publication	Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics	Abbreviated Journal	Phys Rev E Stat Nonlin Soft Matter Phys
	Volume	83	Issue	3 Pt 1	Pages	031927
	Keywords	Arm/physiology; Biomechanics; Computer Simulation; Humans; Kinetics; Male; Models, Biological; Models, Statistical; Models, Theoretical; Movement; Psychomotor Performance/physiology; Range of Motion, Articular/physiology; Reaction Time/physiology; Space Perception/physiology; Torque
	Abstract	We present a generally covariant formulation of human arm dynamics and optimization principles in Riemannian configuration space. We extend the one-parameter family of mean-squared-derivative (MSD) cost functionals from Euclidean to Riemannian space, and we show that they are mathematically identical to the corresponding dynamic costs when formulated in a Riemannian space equipped with the kinetic energy metric. In particular, we derive the equivalence of the minimum-jerk and minimum-torque change models in this metric space. Solutions of the one-parameter family of MSD variational problems in Riemannian space are given by (reparameterized) geodesic paths, which correspond to movements with least muscular effort. Finally, movement invariants are derived from symmetries of the Riemannian manifold. We argue that the geometrical structure imposed on the arm's configuration space may provide insights into the emerging properties of the movements generated by the motor system.
	Address	Bernstein Center for Computational Neuroscience, DE-37073 Gottingen, Germany. armin@nld.ds.mpg.de
	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	1539-3755	ISBN		Medium
	Area		Expedition		Conference
	Notes	PMID:21517543			Approved	no
	Call Number				Serial	29
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