Motor learning reveals the existence of multiple codes for movement planning

Hudson, Todd E.; Landy, Michael S.

doi:10.1152/jn.00355.2012

Cited by 24 publications

(39 citation statements)

References 40 publications

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“…We have previously shown that motor planning during unperturbed reaches is based on both a polar and a Cartesian coordinate encoding, even for the identical reaches (Hudson & Landy, 2012a), and it is clear that these plans can be updated when an imposed perturbation is apparent [when it is large and/or self-imposed, such as when using a tablet-based input device, e.g., Wu & Smith (2013), who used large perturbations of drawing/tracing movements]. Here, we examined whether motor plans in both coordinate systems are updated in response to perturbations that are too small to be noticed, consistent with the notion of an automatic sensory-motor adaptive response as opposed to a deliberate, cognitively mediated correction.…”

Section: Discussionmentioning

confidence: 99%

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Sinusoidal error perturbation reveals multiple coordinate systems for sensorymotor adaptation

Hudson

Landy

2016

Vision Research

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A coordinate system is composed of an encoding, defining the dimensions of the space, and an origin. We examine the coordinate encoding used to update motor plans during sensory-motor adaptation to center-out reaches. Adaptation is induced using a novel paradigm in which feedback of reach endpoints is perturbed following a sinewave pattern over trials; the perturbed dimensions of the feedback were the axes of a Cartesian coordinate system in one session and a polar coordinate system in another session. For center-out reaches to randomly chosen target locations, reach errors observed at one target will require different corrections at other targets within Cartesian- and polar-coded systems. The sinewave adaptation technique allowed us to simultaneously adapt both dimensions of each coordinate system (x-y, or reach gain and angle), and identify the contributions of each perturbed dimension by adapting each at a distinct temporal frequency. The efficiency of this technique further allowed us to employ perturbations that were a fraction the size normally used, which avoids confounding automatic adaptive processes with deliberate adjustments made in response to obvious experimental manipulations. Subjects independently corrected errors in each coordinate in both sessions, suggesting that the nervous system encodes both a Cartesian- and polar-coordinate-based internal representation for motor adaptation. The gains and phase lags of the adaptive responses are not readily explained by current theories of sensory-motor adaptation. Motor adaptation is fundamental to the neural control of movement, affording an automatic process to maintain a consistent relationship between motor plans and movement outcomes. That is, adaptation is described as updating an internal mapping between desired motor outcome and motor output (Sanger, 2004; Shadmehr, Smith, & Krakauer, 2010), not a deliberate corrective action. Here, using a method that relies on extremely small perturbations that are unlikely to recruit explicit corrective mechanisms, we revisit one of the central questions of sensory-motor adaptation: coordinate encoding.

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Section: Discussionmentioning

confidence: 99%

“…The experiment was run using the Psychophysics Toolbox software (Brainard, 1997; Pelli, 1997) and the Northern Digital API (for controlling the Optotrak). Details of the apparatus and method of calibration are the same as used previously (Hudson & Landy, 2012a,b). …”

Section: Methodsmentioning

confidence: 99%

Sinusoidal error perturbation reveals multiple coordinate systems for sensorymotor adaptation

Hudson

Landy

2016

Vision Research

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“…We demonstrated the use of the method for identifying regions of movement impairment, in individuals with upper limb hemiparesis due to a stroke, and how it can be applied as a basis for performance-based selection of training movements for rehabilitation. The advantages of the performance mapping principle are that (1) mapping spans a wide region of the reaching movement conditions, and is fine-grained, potentially allowing high sensitivity to patterns of motor impairment, which may be overlooked by coarser clinical diagnostic scores (2) it is reasonably quick and easy to produce and to interpret, and (3) the maps’ coordinates (movement and target directions) relate to established basic elements of movement coding [22–27]. The mapping principle can be easily applied to any quantifiable scalar measures of reaching performance – behavioural metrics (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…The range of target and start locations tests both postural and movement-related aspects of motor control, respectively. Importantly, muscle activation patterns and population neural activity in the motor-related cortices show tuning to one or both task dimensions [22–25], and behavioural studies support the essential underlying role of these parameters in planning of reaching movements [26, 27]. …”

Section: Introductionmentioning

confidence: 99%

Mapping upper-limb motor performance after stroke - a novel method with utility for individualized motor training

Rosenthal

Wing

Wyatt

et al. 2017

J NeuroEngineering Rehabil

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BackgroundChronic upper limb motor impairment is a common outcome of stroke. Therapeutic training can reduce motor impairment. Recently, a growing interest in evaluating motor training provided by robotic assistive devices has emerged. Robot-assisted therapy is attractive because it provides a means of increasing practice intensity without increasing the workload of physical therapists. However, movements practised through robotic assistive devices are commonly pre-defined and fixed across individuals. More optimal training may result from individualizing the selection of the trained movements based on the individual’s impairment profile. This requires quantitative assessment of the degree of the motor impairment prior to training, in relevant movement tasks. However, standard clinical measures for profiling motor impairment after stroke are often subjective and lack precision. We have developed a novel robot-mediated method for systematic and fine-grained mapping (or profiling) of individual performance across a wide range of planar arm reaching movements. Here we describe and demonstrate this mapping method and its utilization for individualized training. We also present a novel principle for the individualized selection of training movements based on the performance maps.Methods and ResultsTo demonstrate the utility of our method we present examples of 2D performance maps produced from the kinetic and kinematics data of two individuals with stroke-related upper limb hemiparesis. The maps outline distinct regions of high motor impairment. The procedure of map-based selection of training movements and the change in motor performance following training is demonstrated for one participant.ConclusionsThe performance mapping method is feasible to produce (online or offline). The 2D maps are easy to interpret and to be utilized for selecting individual performance-based training. Different performance maps can be easily compared within and between individuals, which potentially has diagnostic utility.Electronic supplementary materialThe online version of this article (10.1186/s12984-017-0335-x) contains supplementary material, which is available to authorized users.

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“…В тоже время, подобие распределений по выбранному критерию (хи-квадрат) свидетельствует в пользу того, что при запоминании используется позиционное кодирование положений фигуры на шахматной доске. Подобные распределения ошибок человека в моторных задачах также были интерпретированы как проявление искажений при воспроизведении позиционно закодированных стимулов в [17]. Отметим, что при использовании иного стимульного материала или иной инструкции для испытуемых в рабочей пространственной памяти может осуществляться и векторное кодирование, для которого характерны принципиально иные распределения ошибок [10,11,17].…”

Section: Discussionunclassified

Presentation of Information at the Working Spatial Memory in Processes of Recognition and Reproducing

Ляховецкий¹,

Lyakhovetskii²

2014

Math.Biol.Bioinf.

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ВВЕДЕНИЕУзнавание и воспроизведение -задачи, которые широко используются при изучении памяти человека. При узнавании испытуемый оценивает знакомость стимулов, часть которых была предъявлена ранее, или выбирает из набора стимулов те, которые были прежде запомнены. При воспроизведении испытуемый без дополнительных подсказок припоминает запомненные ранее стимулы. В психологии и философии процесс узнавания иногда рассматривается как нечто удивительное (человек знает запомненное до узнавания, хотя зачастую и не может припомнить то, что он знает) [1,2]. Однако с точки зрения моделирования достаточно очевидно, что наличие дополнительной информации (по сравнению с процессом воспроизведения) облегчает припоминание. Для нейронных сетей типа ассоциативная память найдены различные функции (энергия нейронной сети, скорость убывания энергии и т. д.), позволяющие оценить знакомость (familiarity) предъявленного стимула с большей скоростью или точностью по сравнению с воспроизведением запомненного стимула [3,4]. То есть для моделей так же, как и для человека, узнавание или оценка знакомости запомненного -более простая задача, чем воспроизведение запомненного. В известной нам литературе модели узнавания и воспроизведения запомненного существуют отдельно друг от друга, без привязки к результатам конкретных психофизических * v_la2002@mail.ru

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Motor learning reveals the existence of multiple codes for movement planning

Abstract: Hudson TE, Landy MS. Motor learning reveals the existence of multiple codes for movement planning.

Cited by 24 publications

References 40 publications

Sinusoidal error perturbation reveals multiple coordinate systems for sensorymotor adaptation

Sinusoidal error perturbation reveals multiple coordinate systems for sensorymotor adaptation

Mapping upper-limb motor performance after stroke - a novel method with utility for individualized motor training

Presentation of Information at the Working Spatial Memory in Processes of Recognition and Reproducing

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