Limits...
Visuomotor adaptation needs a validation of prediction error by feedback error.

Gaveau V, Prablanc C, Laurent D, Rossetti Y, Priot AE - Front Hum Neurosci (2014)

Bottom Line: As far as subjects remained unaware of the optical deviation and self-assigned pointing errors, prediction error alone was insufficient to induce adaptation.These results indicate a critical role of hand-to-target feedback error signals in visuomotor adaptation; consistent with recent neurophysiological findings, they suggest that a combination of feedback and prediction error signals is necessary for eliciting aftereffects.They also suggest that feedback error updates the prediction of reafferences when a visual perturbation is introduced gradually and cognitive factors are eliminated or strongly attenuated.

View Article: PubMed Central - PubMed

Affiliation: INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center Bron, France.

ABSTRACT
The processes underlying short-term plasticity induced by visuomotor adaptation to a shifted visual field are still debated. Two main sources of error can induce motor adaptation: reaching feedback errors, which correspond to visually perceived discrepancies between hand and target positions, and errors between predicted and actual visual reafferences of the moving hand. These two sources of error are closely intertwined and difficult to disentangle, as both the target and the reaching limb are simultaneously visible. Accordingly, the goal of the present study was to clarify the relative contributions of these two types of errors during a pointing task under prism-displaced vision. In "terminal feedback error" condition, viewing of their hand by subjects was allowed only at movement end, simultaneously with viewing of the target. In "movement prediction error" condition, viewing of the hand was limited to movement duration, in the absence of any visual target, and error signals arose solely from comparisons between predicted and actual reafferences of the hand. In order to prevent intentional corrections of errors, a subthreshold, progressive stepwise increase in prism deviation was used, so that subjects remained unaware of the visual deviation applied in both conditions. An adaptive aftereffect was observed in the "terminal feedback error" condition only. As far as subjects remained unaware of the optical deviation and self-assigned pointing errors, prediction error alone was insufficient to induce adaptation. These results indicate a critical role of hand-to-target feedback error signals in visuomotor adaptation; consistent with recent neurophysiological findings, they suggest that a combination of feedback and prediction error signals is necessary for eliciting aftereffects. They also suggest that feedback error updates the prediction of reafferences when a visual perturbation is introduced gradually and cognitive factors are eliminated or strongly attenuated.

No MeSH data available.


Related in: MedlinePlus

Functional schema of unaware visuomotor adaptation to lateral prism deviations (derived from Miall and Wolpert, 1996). The visual target location is laterally shifted using small prism increments, every 10 pointing trials. To produce a reaching movement toward the target, the inverse model uses initial hand estimate and the seen target positions to compute a motor command, which is sent to the motor system. The output of the latter controls the physical position of the hand. The actual prism-displaced hand position (right red arrow) is sent to a comparator. In parallel, the inverse model sends a copy (corollary discharge) to the forward model, the output of which gives a prediction of the hand visual reafferences (upper green arrow) sent to the comparator. The prediction error (lower green arrow) is supposed to iteratively update the forward model, which in turn (blue dotted arrow) updates the inverse model. A new feature, in this schema, relates to the need of combining feedback and prediction error signals to iteratively update the forward model. The visual feedback error signal (red arrow) that is sent to the validation gate (g) has a very low (retinal) detection threshold, whereas the prediction error signal (green) also sent to this validation gate has a high detection threshold, which makes it unreliable alone to induce adaptive updating in the forward model, except for large deviations perceived as resulting from external perturbations. However, for small or moderate prediction errors, the feedback signal allows a disambiguation of the prediction error and allows an adaptive updating of the forward model. The hand-position estimate prior to movement onset is a weighted average of proprioceptive (p) and visual (v) hand positions; the latter (gray yellow arrow) is absent here.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4219430&req=5

Figure 4: Functional schema of unaware visuomotor adaptation to lateral prism deviations (derived from Miall and Wolpert, 1996). The visual target location is laterally shifted using small prism increments, every 10 pointing trials. To produce a reaching movement toward the target, the inverse model uses initial hand estimate and the seen target positions to compute a motor command, which is sent to the motor system. The output of the latter controls the physical position of the hand. The actual prism-displaced hand position (right red arrow) is sent to a comparator. In parallel, the inverse model sends a copy (corollary discharge) to the forward model, the output of which gives a prediction of the hand visual reafferences (upper green arrow) sent to the comparator. The prediction error (lower green arrow) is supposed to iteratively update the forward model, which in turn (blue dotted arrow) updates the inverse model. A new feature, in this schema, relates to the need of combining feedback and prediction error signals to iteratively update the forward model. The visual feedback error signal (red arrow) that is sent to the validation gate (g) has a very low (retinal) detection threshold, whereas the prediction error signal (green) also sent to this validation gate has a high detection threshold, which makes it unreliable alone to induce adaptive updating in the forward model, except for large deviations perceived as resulting from external perturbations. However, for small or moderate prediction errors, the feedback signal allows a disambiguation of the prediction error and allows an adaptive updating of the forward model. The hand-position estimate prior to movement onset is a weighted average of proprioceptive (p) and visual (v) hand positions; the latter (gray yellow arrow) is absent here.

Mentions: Figure 4 shows a very schematic representation of the processes underlying goal-directed adaptation to visually displaced vision of the world and of one’s own body (please refer to the legend for more details). One additional feature to Miall and Wolpert’s (1996) model is suggested by the results of the present study. It highlights the need of combining feedback and prediction error signals to iteratively update the forward model. The visual feedback error signal (red arrow) that is sent to the validation gate (g) has a very low (retinal) detection threshold, whereas the prediction error signal (green) also sent to this validation gate has a high detection threshold, which makes it unreliable alone to induce adaptive updating in the forward model, except for large deviations perceived as resulting from external perturbations. However, for small or moderate prediction errors, the feedback signal allows a disambiguation of the prediction error and allows an adaptive updating of the forward model.


Visuomotor adaptation needs a validation of prediction error by feedback error.

Gaveau V, Prablanc C, Laurent D, Rossetti Y, Priot AE - Front Hum Neurosci (2014)

Functional schema of unaware visuomotor adaptation to lateral prism deviations (derived from Miall and Wolpert, 1996). The visual target location is laterally shifted using small prism increments, every 10 pointing trials. To produce a reaching movement toward the target, the inverse model uses initial hand estimate and the seen target positions to compute a motor command, which is sent to the motor system. The output of the latter controls the physical position of the hand. The actual prism-displaced hand position (right red arrow) is sent to a comparator. In parallel, the inverse model sends a copy (corollary discharge) to the forward model, the output of which gives a prediction of the hand visual reafferences (upper green arrow) sent to the comparator. The prediction error (lower green arrow) is supposed to iteratively update the forward model, which in turn (blue dotted arrow) updates the inverse model. A new feature, in this schema, relates to the need of combining feedback and prediction error signals to iteratively update the forward model. The visual feedback error signal (red arrow) that is sent to the validation gate (g) has a very low (retinal) detection threshold, whereas the prediction error signal (green) also sent to this validation gate has a high detection threshold, which makes it unreliable alone to induce adaptive updating in the forward model, except for large deviations perceived as resulting from external perturbations. However, for small or moderate prediction errors, the feedback signal allows a disambiguation of the prediction error and allows an adaptive updating of the forward model. The hand-position estimate prior to movement onset is a weighted average of proprioceptive (p) and visual (v) hand positions; the latter (gray yellow arrow) is absent here.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4219430&req=5

Figure 4: Functional schema of unaware visuomotor adaptation to lateral prism deviations (derived from Miall and Wolpert, 1996). The visual target location is laterally shifted using small prism increments, every 10 pointing trials. To produce a reaching movement toward the target, the inverse model uses initial hand estimate and the seen target positions to compute a motor command, which is sent to the motor system. The output of the latter controls the physical position of the hand. The actual prism-displaced hand position (right red arrow) is sent to a comparator. In parallel, the inverse model sends a copy (corollary discharge) to the forward model, the output of which gives a prediction of the hand visual reafferences (upper green arrow) sent to the comparator. The prediction error (lower green arrow) is supposed to iteratively update the forward model, which in turn (blue dotted arrow) updates the inverse model. A new feature, in this schema, relates to the need of combining feedback and prediction error signals to iteratively update the forward model. The visual feedback error signal (red arrow) that is sent to the validation gate (g) has a very low (retinal) detection threshold, whereas the prediction error signal (green) also sent to this validation gate has a high detection threshold, which makes it unreliable alone to induce adaptive updating in the forward model, except for large deviations perceived as resulting from external perturbations. However, for small or moderate prediction errors, the feedback signal allows a disambiguation of the prediction error and allows an adaptive updating of the forward model. The hand-position estimate prior to movement onset is a weighted average of proprioceptive (p) and visual (v) hand positions; the latter (gray yellow arrow) is absent here.
Mentions: Figure 4 shows a very schematic representation of the processes underlying goal-directed adaptation to visually displaced vision of the world and of one’s own body (please refer to the legend for more details). One additional feature to Miall and Wolpert’s (1996) model is suggested by the results of the present study. It highlights the need of combining feedback and prediction error signals to iteratively update the forward model. The visual feedback error signal (red arrow) that is sent to the validation gate (g) has a very low (retinal) detection threshold, whereas the prediction error signal (green) also sent to this validation gate has a high detection threshold, which makes it unreliable alone to induce adaptive updating in the forward model, except for large deviations perceived as resulting from external perturbations. However, for small or moderate prediction errors, the feedback signal allows a disambiguation of the prediction error and allows an adaptive updating of the forward model.

Bottom Line: As far as subjects remained unaware of the optical deviation and self-assigned pointing errors, prediction error alone was insufficient to induce adaptation.These results indicate a critical role of hand-to-target feedback error signals in visuomotor adaptation; consistent with recent neurophysiological findings, they suggest that a combination of feedback and prediction error signals is necessary for eliciting aftereffects.They also suggest that feedback error updates the prediction of reafferences when a visual perturbation is introduced gradually and cognitive factors are eliminated or strongly attenuated.

View Article: PubMed Central - PubMed

Affiliation: INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center Bron, France.

ABSTRACT
The processes underlying short-term plasticity induced by visuomotor adaptation to a shifted visual field are still debated. Two main sources of error can induce motor adaptation: reaching feedback errors, which correspond to visually perceived discrepancies between hand and target positions, and errors between predicted and actual visual reafferences of the moving hand. These two sources of error are closely intertwined and difficult to disentangle, as both the target and the reaching limb are simultaneously visible. Accordingly, the goal of the present study was to clarify the relative contributions of these two types of errors during a pointing task under prism-displaced vision. In "terminal feedback error" condition, viewing of their hand by subjects was allowed only at movement end, simultaneously with viewing of the target. In "movement prediction error" condition, viewing of the hand was limited to movement duration, in the absence of any visual target, and error signals arose solely from comparisons between predicted and actual reafferences of the hand. In order to prevent intentional corrections of errors, a subthreshold, progressive stepwise increase in prism deviation was used, so that subjects remained unaware of the visual deviation applied in both conditions. An adaptive aftereffect was observed in the "terminal feedback error" condition only. As far as subjects remained unaware of the optical deviation and self-assigned pointing errors, prediction error alone was insufficient to induce adaptation. These results indicate a critical role of hand-to-target feedback error signals in visuomotor adaptation; consistent with recent neurophysiological findings, they suggest that a combination of feedback and prediction error signals is necessary for eliciting aftereffects. They also suggest that feedback error updates the prediction of reafferences when a visual perturbation is introduced gradually and cognitive factors are eliminated or strongly attenuated.

No MeSH data available.


Related in: MedlinePlus