| Records |
| Author |
Zopf, R.; Friedman, J.; Williams, M.A. |
| Title |
The plausibility of visual information for hand ownership modulates multisensory synchrony perception |
Type |
Journal Article |
| Year |
2015 |
Publication |
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Abbreviated Journal |
Experimental Brain Research |
Volume  |
233 |
Issue |
8 |
Pages |
2311-2321 |
| Keywords |
Multisensory perception; Temporal synchrony perception; Virtual hand; Body representations; Body ownership; Sensory predictions |
| Abstract |
We are frequently changing the position of our bodies and body parts within complex environments. How does the brain keep track of one’s own body? Current models of body ownership state that visual body ownership cues such as viewed object form and orientation are combined with multisensory information to correctly identify one’s own body, estimate its current location and evoke an experience of body ownership. Within this framework, it may be possible that the brain relies on a separate perceptual analysis of body ownership cues (e.g. form, orientation, multisensory synchrony). Alternatively, these cues may interact in earlier stages of perceptual processing—visually derived body form and orientation cues may, for example, directly modulate temporal synchrony perception. The aim of the present study was to distinguish between these two alternatives. We employed a virtual hand set-up and psychophysical methods. In a two-interval force-choice task, participants were asked to detect temporal delays between executed index finger movements and observed movements. We found that body-specifying cues interact in perceptual processing. Specifically, we show that plausible visual information (both form and orientation) for one’s own body led to significantly better detection performance for small multisensory asynchronies compared to implausible visual information. We suggest that this perceptual modulation when visual information plausible for one’s own body is present is a consequence of body-specific sensory predictions. |
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Thesis |
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| Publisher |
Springer Berlin Heidelberg |
Place of Publication |
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| Language |
English |
Summary Language |
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Edition |
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| ISSN |
0014-4819 |
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Conference |
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| Notes |
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Approved |
no |
| Call Number |
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Serial |
78 |
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| Author |
Shaklai, S.; Mimouni-Bloch, A.; Levin, M.; Friedman, J. |
| Title |
Development of finger force coordination in children |
Type |
Journal Article |
| Year |
2017 |
Publication |
Experimental Brain Research |
Abbreviated Journal |
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| Volume |
235 |
Issue |
12 |
Pages |
3709–3720 |
| Keywords |
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| Abstract |
Coordination is often observed as body parts moving together. However, when producing force with multiple fingers, the optimal coordination is not to produce similar forces with each finger, but rather for each finger to correct mistakes of other fingers. In this study, we aim to determine whether and how this skill develops in children aged 4-12 years. We measured this sort of coordination using the uncontrolled manifold hypothesis (UCM). We recorded finger forces produced by 60 typically developing children aged between 4 and 12 years in a finger-pressing task. The children controlled the height of an object on a screen by the total amount of force they produced on force sensors. We found that the synergy index, a measure of the relationship between “good” and “bad” variance, increased linearly as a function of age. This improvement was achieved by a selective reduction in “bad” variance rather than an increase in “good” variance. We did not observe differences between males and females, and the synergy index was not able to predict outcomes of upper limb behavioral tests after controlling for age. As children develop between the ages of 4 and 12 years, their ability to produce negative covariation between their finger forces improves, likely related to their improved ability to perform dexterous tasks. |
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Edition |
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| ISSN |
1432-1106 |
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Approved |
no |
| Call Number |
Shaklai2017 |
Serial |
86 |
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| Author |
Frenkel-Toledo, S.; Yamanaka, J.; Friedman, J.; Feldman, A.G.; Levin, M.F. |
| Title |
Referent control of anticipatory grip force during reaching in stroke: an experimental and modeling study |
Type |
Journal Article |
| Year |
2019 |
Publication |
Experimental Brain Research |
Abbreviated Journal |
Exp Brain Res |
| Volume |
237 |
Issue |
7 |
Pages |
1655-1672 |
| Keywords |
Anticipatory grip force; Referent control; Stroke |
| Abstract |
To evaluate normal and impaired control of anticipatory grip force (GF) modulation, we compared GF production during horizontal arm movements in healthy and post-stroke subjects, and, based on a physiologically feasible dynamic model, determined referent control variables underlying the GF-arm motion coordination in each group. 63% of 13 healthy and 48% of 13 stroke subjects produced low sustained initial force (< 10 N) and increased GF prior to arm movement. Movement-related GF increases were higher during fast compared to self-paced arm extension movements only in the healthy group. Differences in the patterns of anticipatory GF increases before the arm movement onset between groups occurred during fast extension arm movement only. In the stroke group, longer delays between the onset of GF change and elbow motion were related to clinical upper limb deficits. Simulations showed that GFs could emerge from the difference between the actual and the referent hand aperture (Ra) specified by the CNS. Similarly, arm movement could result from changes in the referent elbow position (Re) and could be affected by the co-activation (C) command. A subgroup of stroke subjects, who increased GF before arm movement, could specify different patterns of the referent variables while reproducing the healthy typical pattern of GF-arm coordination. Stroke subjects, who increased GF after arm movement onset, also used different referent strategies than controls. Thus, altered anticipatory GF behavior in stroke subjects may be explained by deficits in referent control. |
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English |
Summary Language |
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0014-4819 |
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| Notes |
PMID:30976821 |
Approved |
no |
| Call Number |
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Serial |
98 |
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