Motor Memory Is Encoded as a Gain-Field Combination of Intrinsic and Extrinsic Action Representations

Brayanov, Jordan; Press, Daniel Z.; Smith, Maurice A.

doi:10.1523/jneurosci.1928-12.2012

Cited by 94 publications

(145 citation statements)

References 68 publications

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“…Instead, generalization of a motor control strategy depends on whether the central nervous system attributes performance error to the human motor system or to the external environment. Recent work by Brayanov et al (2012) also suggests that adaptation to a visuomotor rotation does not transfer in a single coordinate frame, instead arm movements are representation in both intrinsic and extrinsic coordinate frames.…”

Section: Discussionmentioning

confidence: 99%

The coordinate system for force control

Saha

Perreault

et al. 2014

Exp Brain Res

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The primary objective of this study was to establish the coordinate frame for force control by observing how parameters of force that are not explicitly specified by a motor task vary across the workspace. We asked subjects to apply a force of a specific magnitude with their hand. Subjects could complete the task by applying forces in any direction of their choice in the transverse plane. They were tested with the arm in seven different configurations. To estimate whether contact forces are represented in extrinsic or intrinsic coordinates, we applied the parallel transport method of differential geometry to the net joint torques applied during the task. This approach allowed us to compare the force variability observed at different arm configurations with the force variability that would be expected if the control system were applying an invariant pattern of joint torques at the tested configurations. The results indicate that for the majority of the subjects, the predominant pattern was consistent with an invariant representation in joint coordinates. However, two out of eleven subjects also demonstrated a preference for extrinsic representation. These findings suggest that the central nervous system can represent contact forces in both coordinate frames, with a prevalence toward intrinsic representations.

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Section: Discussionmentioning

confidence: 99%

The coordinate system for force control

Saha

Perreault

et al. 2014

Exp Brain Res

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“…One possibility is that this residual learning could have been caused by non-specific generalization of learning over directions. Although Krakauer et al in their original study claim that the learning of a visuomotor rotation is local with regards to the direction of movements, their results suggest at least some degree of generalization (Krakauer et al, 2000, Figures 7A and B), especially where there is more than one training direction (see also Brayanov, Press & Smith, 2012). The distance between forward and backward movement directions in our third experiment at 120° was quite large, rendering generalization from the directions of forward movements to the directions of backward movements unlikely.…”

Section: Backward Movementsmentioning

confidence: 98%

There and back again: Putting the vectorial movement planning hypothesis to a critical test

Kobak

Oliveira

2013

Preprint

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There and back again: Putting the vectorial movement planning hypothesis to a critical testBased on psychophysical evidence about how learning of visuomotor transformation generalizes, it has been suggested that movements are planned on the basis of movement direction and magnitude, i.e. the vector connecting movement origin and targets. This notion is also known under the term "vectorial planning hypothesis". Previous psychophysical studies, however, have included separate areas of the workspace for training movements and testing the learning. This study eliminates this confounding factor by investigating the transfer of learning from forward to backward movements in a center-out-and-back task, in which the workspace for both movements is completely identical. Visual feedback allowed for learning only during movements towards the target (forward movements) and not while moving back to the origin (backward movements). When subjects learned the visuomotor rotation in forward movements, initial directional errors in backward movements also decreased to some degree. This learning effect in backward movements occurred predominantly when backward movements featured the same movement directions as the ones trained in forward movements (i.e., when opposite targets were presented). This suggests that learning was transferred in a direction specific way, supporting the notion that movement direction is the most prominent parameter used for motor planning.PeerJ PrePrints | https://peerj.com/preprints/114v1/ | v1 received:

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“…This contrasts with extrinsic coordinate control, in which movement paths are specified with respect to locations in the world (e.g., a hand trajectory’s amplitude and direction; Gordon, Ghilardi, Cooper, & Ghez, 1994). Evidence from a range of tasks indicates that the nervous system may use both forms of control in a flexible task-dependent manner (Brayanov, Press, & Smith, 2012; Meghani, Burgess, & Patton, 2009; Parmar, Huang, & Patton, 2011). On our previous account (Jax et al, 2006), apraxics may be impaired at imitating meaningless body postures because such postures are defined by body positions and would logically be performed most efficiently using body-based intrinsic coordinate control.…”

Section: Introductionmentioning

confidence: 99%

Conceptual- and production-related predictors of pantomimed tool use deficits in apraxia

2014

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Apraxia following left hemisphere stroke disrupts pantomimed tool use (PTU), a task that requires the integrity of a number of cognitive and motor processes. Although previous studies have identified that apraxics have deficits in (1) the integrity of/access to stored tool-use gesture representations, (2) deficits in intrinsic (body-based) coordinate control, and (3) abnormal reliance on visual feedback, no study to date has simultaneously tested the relative contribution of these three deficits to poor PTU performance. In this study we assessed 38 chronic left hemisphere stroke survivors on tests of PTU and the 3 component processes. We then attempted to predict PTU with the component scores using hierarchical regression to control for overall stroke severity and the possibility of correlated component scores. Results showed that over half of the variability in PTU was predictable, with the strongest independent predictor being a test of intrinsic coordinate control without visual feedback. A test of the integrity of/access to stored representations also predicted PTU. These results confirm and extend previous claims that conceptual- and production-related factors affect PTU, even after considering that deficits in both factors are commonly observed to varying degrees in apraxic patients.

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Motor Memory Is Encoded as a Gain-Field Combination of Intrinsic and Extrinsic Action Representations

Cited by 94 publications

References 68 publications

The coordinate system for force control

The coordinate system for force control

There and back again: Putting the vectorial movement planning hypothesis to a critical test

Conceptual- and production-related predictors of pantomimed tool use deficits in apraxia

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