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Bansal A, 't Hart BM, Cauchan U, Eggert T, Straube A, Henriques DYP. Motor adaptation does not differ when a perturbation is introduced abruptly or gradually. Exp Brain Res 2023; 241:2577-2590. [PMID: 37690051 DOI: 10.1007/s00221-023-06699-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 08/30/2023] [Indexed: 09/12/2023]
Abstract
People continuously adapt their movements to ever-changing circumstances, and particularly in skills training and rehabilitation, it is crucial that we understand how to optimize implicit adaptation in order for these processes to require as little conscious effort as possible. Although it is generally assumed that the way to do this is by introducing perturbations gradually, the literature is ambivalent on the effectiveness of this approach. Here, we tested whether there are differences in motor performance when adapting to an abrupt compared to a ramped visuomotor rotation. Using a within-subjects design, we tested this question under 3 different rotation sizes: 30-degrees, 45-degrees, and 60-degrees, as well as in 3 different populations: younger adults, older adults, and patients with mild cerebellar ataxia. We find no significant differences in either the behavioural outcomes, or model fits, between abrupt and gradual learning across any of the different conditions. Neither age, nor cerebellar ataxia had any significant effect on error-sensitivity either. These findings together indicate that error-sensitivity is not modulated by introducing a perturbation abruptly compared to gradually, and is also unaffected by age or mild cerebellar ataxia.
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Affiliation(s)
- Ambika Bansal
- Centre for Vision Research, York University, Toronto, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
- School of Kinesiology and Health Science, Centre for Vision Research, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
| | - Bernard Marius 't Hart
- Centre for Vision Research, York University, Toronto, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Udai Cauchan
- Centre for Vision Research, York University, Toronto, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
| | - Thomas Eggert
- Department of Neurology, LMU University Hospital, LMU Munich, Fraunhoferstr. 20, 82152, Planegg, Martinsried, Germany
| | - Andreas Straube
- Department of Neurology, LMU University Hospital LMU, Munich, Marchioninistr. 15, 81377, Munich, Germany
| | - Denise Y P Henriques
- Centre for Vision Research, York University, Toronto, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
- School of Kinesiology and Health Science, Centre for Vision Research, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
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Eggert T, Kaltenbach K, Straube A. Error inconsistency does not generally inhibit saccadic adaptation: Support for linear models of multi-gainfield adaptation. Physiol Rep 2022; 10:e15180. [PMID: 35212174 PMCID: PMC8874290 DOI: 10.14814/phy2.15180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/04/2022] [Accepted: 01/13/2022] [Indexed: 11/24/2022] Open
Abstract
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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Affiliation(s)
- Thomas Eggert
- Department of Neurology, University Hospital, LMU Munich, Planegg/Martinsried, Germany
| | - Katharina Kaltenbach
- Department of Neurology, University Hospital, LMU Munich, Planegg/Martinsried, Germany
| | - Andreas Straube
- Department of Neurology and German Center for Vertigo and Balance Disorders-DSGZ, University Hospital, LMU Munich, Munich, Germany
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