Inter-individual variability and consistency of saccade adaptation in oblique saccades: Amplitude increase and decrease in the horizontal or vertical saccade component

Rahmouni, Sohir; Madelain, Laurent

doi:10.1016/j.visres.2019.05.001

Cited by 7 publications

(6 citation statements)

References 82 publications

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“…The inhibitory effect is likely to occur only for error variabilities that are markedly larger than those that normally occur due to variability in saccade gain in healthy subjects. Therefore, such a mechanism is quite compatible with the observation that the inter‐trial dispersion of baseline saccades in healthy subjects does not correlate with the magnitude of adaptive changes (Rahmouni & Madelain, 2019). The question of whether increased error variability generally inhibits saccade adaptation in healthy individuals is also important for interpreting adaptation deficits in patients with motor disorders.…”

Section: Introductionsupporting

confidence: 82%

Error inconsistency does not generally inhibit saccadic adaptation: Support for linear models of multi‐gainfield adaptation

Eggert

Kaltenbach

Straube

2022

Physiological Reports

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This study examined saccade adaptation induced by intrasaccadic target steps (ITS). By manipulating the ITS, we investigated potential effects of the consistency of the feedback error on saccade adaptation, which would provide evidence against the linearity of standard models of visuomotor adaptation. Previous studies addressing saccade adaptation arrived at different interpretations, but in these experiments only a single saccade amplitude was trained rather than a variety of saccade amplitudes in random order (mixed training). We extend previous studies by testing for effects of error consistency under additional control conditions described by the factors training protocol (single‐amplitude/mixed), ITS direction (onward/backward), and adaptation phase (training/washout). Adaptation dynamics were assessed using a model of “multi‐gainfield adaptation” developed by tailoring an existing linear model for visuomotor adaptation of movements with multiple target positions to gain adaptation of saccades with multiple amplitudes. The total adaptive change did not depend on the consistency of the ITS in either mixed or single‐amplitude training. The initial adaptation speed was lower with inconsistent ITS. However, the effect on adaptation speed occurred only during amplitude reduction and not during enlargement or washout. These results corroborate the linearity of saccade adaptation in that the mean error is the main factor determining the total adaptive change, independent of error consistency. The multi‐gainfield adaptation model was confirmed in that the retention rate and error sensitivity did not depend on the training protocol. The absence of effects of error consistency on saccade adaptation is relevant in the context of adaptive deficits in movement disorders.

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Section: Introductionsupporting

confidence: 82%

Error inconsistency does not generally inhibit saccadic adaptation: Support for linear models of multi‐gainfield adaptation

Eggert

Kaltenbach

Straube

2022

Physiological Reports

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“…Other authors investigated the saccadic adaptation process to targets shifting not only on axis with respect to the main saccade direction but also cross axis (Chen-Harris, Joiner, Deubel, 1987;Ethier et al, 2008;Rahmouni & Madelain, 2019). In all cases, they found consistent changes in saccadic amplitude according to the direction of target shift, confirming that "the saccadic system's flexibility in response to change in environmental contingencies is certainly a general learning phenomenon" (Rahmouni & Madelain, 2019). However, in all of these studies, the targets were represented by small and localized points that shifted in position with respect to the initial step.…”

Section: Discussionmentioning

confidence: 99%

“…Consistent with this expectation, we did not find any significant modification of saccade amplitude and saccade angles that could be concomitant with the direction of the size change of the target. Other authors investigated the saccadic adaptation process to targets shifting not only on axis with respect to the main saccade direction but also cross axis ( Chen-Harris, Joiner, Ethier, Zee, & Shadmehr, 2008 ; Deubel, 1987 ; Ethier et al, 2008 ; Rahmouni & Madelain, 2019 ). In all cases, they found consistent changes in saccadic amplitude according to the direction of target shift, confirming that “the saccadic system's flexibility in response to change in environmental contingencies is certainly a general learning phenomenon” ( Rahmouni & Madelain, 2019 ).…”

Section: Discussionmentioning

confidence: 99%

“…For this latter situation, it is well established that the saccades to small targets adapt their amplitude when the target is horizontally shifted during the saccade to another position with respect to the original one. A large number of studies used many variations of the double-step paradigm to demonstrate the conditions under which saccade amplitude would adapt to changes in the post-saccadic target shift, either along or orthogonal to the main direction of the saccade ( Deubel, 1987 ; Ethier, Zee, & Shadmehr, 2008 ; Hopp & Fuchs, 2006 ; Kojima, Iwamoto, & Yoshida, 2005 ; McLaughlin, 1967 ; Miller, Anstis, & Templeton, 1981 ; Rahmouni & Madelain, 2019 ; Watanabe, Ogino, Nakamura, & Koizuka, 2003 ). In all of these studies, the target of saccade was represented by a small point that shifted on-axis or cross-axis with respect to the main direction of the saccade.…”

Section: Introductionmentioning

confidence: 99%

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Trans-saccadic adaptation of perceived size independent of saccadic adaptation

et al. 2020

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Systematic shortening or lengthening of target objects during saccades modifies saccade amplitudes and perceived size of the objects. These two events are concomitant when size change during the saccade occurs asymmetrically, thereby shifting the center of mass of the object. In the present study, we asked whether or not the two are necessarily linked. We tested human participants in symmetrical systematic shortening and lengthening of a vertical bar during a horizontal saccade, aiming to not modify the saccade amplitude. Before and after a phase of trans-saccadic changes of the target bar, participants manually indicated the sizes of various vertically oriented bars by open-loop grip aperture. We evaluated the effect of trans-saccadic changes of bar length on manual perceptual reports and whether this change depended on saccade amplitude. As expected, we did not induce any change in horizontal or vertical components of saccade amplitude, but we found a significant difference in perceived size after the lengthening experiment compared to after the shortening experiment. Moreover, after the lengthening experiment, perceived size differed significantly from pre-lengthening baseline. These findings suggest that a change of size perception can be induced trans-saccadically, and its mechanism does not depend on saccadic amplitude change.

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“…As observed in size perceptual responses, the reported impact was not strictly bidirectional, suggesting different mechanisms in the oculomotor system for different size perturbation conditions [ 46 , 51 , 52 ]. Several studies have investigated the plasticity of the saccadic system; observing how changes in object size during saccadic execution generate changes in amplitude, consistent with the direction in size change [ 33 , 38 , 46 , 53 , 54 ]. Although shortening and lengthening conditions were generated symmetrically, keeping the centre of gravity constant [ 55 , 56 ], in the reported linear relationships we observed downward slopings, meaning that smaller objects resulted in larger saccade amplitudes, and vice versa.…”

Section: Discussionmentioning

confidence: 99%

Horizontal target size perturbations during grasping movements are described by subsequent size perception and saccade amplitude

et al. 2022

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Perception and action are essential in our day-to-day interactions with the environment. Despite the dual-stream theory of action and perception, it is now accepted that action and perception processes interact with each other. However, little is known about the impact of unpredicted changes of target size during grasping actions on perception. We assessed whether size perception and saccade amplitude were affected before and after grasping a target that changed its horizontal size during the action execution under the presence or absence of tactile feedback. We have tested twenty-one participants in 4 blocks of 30 trials. Blocks were divided into two experimental tactile feedback paradigms: tactile and non-tactile. Trials consisted of 3 sequential phases: pre-grasping size perception, grasping, and post-grasping size perception. During pre- and post-phases, participants executed a saccade towards a horizontal bar and performed a manual size estimation of the bar size. During grasping phase, participants were asked to execute a saccade towards the bar and to make a grasping action towards the screen. While grasping, 3 horizontal size perturbation conditions were applied: non-perturbation, shortening, and lengthening. 30% of the trials presented perturbation, meaning a symmetrically shortened or lengthened by 33% of the original size. Participants’ hand and eye positions were assessed by a motion capture system and a mobile eye-tracker, respectively. After grasping, in both tactile and non-tactile feedback paradigms, size estimation was significantly reduced in lengthening (p = 0.002) and non-perturbation (p<0.001), whereas shortening did not induce significant adjustments (p = 0.86). After grasping, saccade amplitude became significantly longer in shortening (p<0.001) and significantly shorter in lengthening (p<0.001). Non-perturbation condition did not display adjustments (p = 0.95). Tactile feedback did not generate changes in the collected perceptual responses, but horizontal size perturbations did so, suggesting that all relevant target information used in the movement can be extracted from the post-action target perception.

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Inter-individual variability and consistency of saccade adaptation in oblique saccades: Amplitude increase and decrease in the horizontal or vertical saccade component

Cited by 7 publications

References 82 publications

Error inconsistency does not generally inhibit saccadic adaptation: Support for linear models of multi‐gainfield adaptation

Error inconsistency does not generally inhibit saccadic adaptation: Support for linear models of multi‐gainfield adaptation

Trans-saccadic adaptation of perceived size independent of saccadic adaptation

Horizontal target size perturbations during grasping movements are described by subsequent size perception and saccade amplitude

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