approach to the existence of multiple elements at every level of analysis of movements has been developed based on the principle of abundance ( Gelfand & Latash, 1998 ; Latash, 2012 ). Within this principle, the excess of elements is viewed not as a computational problem but as a very important feature of
Mark L. Latash
eliminated. This is particularly puzzling given another very well known expression by Bernstein: “repetition without repetition”, implying variable means of performing actions over repetitive trials. The Principle of Abundance and the Uncontrolled Manifold Concept An alternative view at the problem of
Geetanjali Gera, Sandra Freitas, Mark Latash, Katherine Monahan, Gregor Schöner, and John Scholz
This study investigated the use of motor abundance during the transport and placing of objects that required either precise or minimal orientation to the target. Analyses across repetitions of the structure of joint configuration variance relative to the position and orientation constraints were performed using the Uncontrolled Manifold (UCM) approach. Results indicated that the orientation constraint did not affect stability of the hand’s spatial path. Orientation was weakly stabilized during the late transport phase independent of the orientation constraint, indicating no default synergy stabilizing orientation. Stabilization of orientation for conditions most requiring it for successful insertion of the object was present primarily during the adjustment phase. The results support the hypothesis that a major advantage of a control scheme that utilizes motor abundance is the ability to resolve multiple task constraints simultaneously without undue interference among them.
Ya-weng Tseng and John P. Scholz
The uncontrolled manifold approach was used to examine the effect of workspace location on the use of motor abundance to control the hand’s path during reaching. Participants pointed to targets located in the contralateral and ipsilateral workspaces at two different distances. When reaching to all parts of the workspace, the component of joint configuration variance consistent with an identical hand path across trials was significantly higher than the component of joint configuration variance leading to a variable hand path. The relative magnitude of this difference was affected primarily by target orientation and minimally by target distance. The control of hand-path direction when reaching ipsilaterally was associated with more selective use of motor abundance compared to reaching contralaterally. The control of hand-path extent was not affected by target orientation. Biomechanical factors are discussed as possible reasons that lead to the observed selective workspace effects.
Edited by Mark Latash
It is suggested that the famous problem of motor redundancy is inapplicable to human voluntary movements. Such notions as “the elimination of biomechanical degrees of freedom” should not be used in human movement studies. During natural movements, elements within apparently redundant sets are all involved in solving motor tasks. The abundance of elements is a keystone forming the foundation of motor synergies. It allows natural movements to display both flexibility and stability.
Jiajun Shi, Danxia Yu, Yaohua Yang, Hui Cai, Jie Wu, Qiuyin Cai, Jirong Long, Wei Zheng, Wanghong Xu, and Xiao-Ou Shu
.S. individuals (aged 49 ± 12 years) involved in a nonmedical lifestyle intervention program, showing a positive association with microbiome α -diversity and genus Veillonella abundance independently of major dietary factors and body mass index (BMI) ( Manor et al., 2020 ). In the present study, we evaluated
Ian A.J. Darragh, Lorraine O’Driscoll, and Brendan Egan
model variance, respectively. expl.var = explained variance; PCA = principal component analysis. The results of univariate within-subject analyses demonstrated that no metabolites displayed significantly different abundances between visits within any group (Figure 3 ). Univariate tests comparing the
Mark L. Latash
( Feldman, 1966 , 1986 ). The second is the principle of abundance ( Gelfand & Latash, 1998 ; Latash, 2012 ), which views the availability of numerous elements as essential for ensuring the controlled, task-specific stability of movements, not as a computational burden. Within this framework, stability of
Momoko Yamagata, Ali Falaki, and Mark L. Latash
, including standing, involve large (abundant, Latash, 2012 ) sets of effectors such as joints and muscles. The principle of abundance ( Gelfand & Latash, 1998 ) views this apparently redundant design of the body as an important mechanism that allows stabilizing different performance variables in a task
Neda Nasrollahi, Jordan Quensell, and Liana Machado
, acute exercise does not necessarily improve mood states in older adults. Despite an abundance of evidence that exercise benefits cognitive functioning, physical activity levels among older adults remain low ( Guiney & Machado, 2018 ; Guthold et al., 2018 ). Lack of time has been reported as the most