| 1. |
- Cowie, Dorothy, et al.
(author)
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The role of hand size in body representation : a developmental investigation
- 2022
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In: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
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Journal article (peer-reviewed)abstract
- Knowledge of one's own body size is a crucial facet of body representation, both for acting on the environment and perhaps also for constraining body ownership. However, representations of body size may be somewhat plastic, particularly to allow for physical growth in childhood. Here we report a developmental investigation into the role of hand size in body representation (the sense of body ownership, perception of hand position, and perception of own-hand size). Using the rubber hand illusion paradigm, this study used different fake hand sizes (60%, 80%, 100%, 120% or 140% of typical size) in three age groups (6- to 7-year-olds, 12- to 13-year-olds, and adults; N = 229). We found no evidence that hand size constrains ownership or position: participants embodied hands which were both larger and smaller than their own, and indeed judged their own hands to have changed size following the illusion. Children and adolescents embodied the fake hands more than adults, with a greater tendency to feel their own hand had changed size. Adolescents were particularly sensitive to multisensory information. In sum, we found substantial plasticity in the representation of own-body size, with partial support for the hypothesis that children have looser representations than adults.
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| 2. |
- Dayal, Viswas, et al.
(author)
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Pedunculopontine nucleus deep brain stimulation for parkinsonian disorders : a case series
- 2021
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In: Stereotactic and Functional Neurosurgery. - : S. Karger. - 1011-6125 .- 1423-0372. ; 99:4, s. 287-294
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Journal article (peer-reviewed)abstract
- Background: Deep brain stimulation (DBS) of the pedunculopontine nucleus (PPN) has been investigated for the treatment of levodopa-refractory gait dysfunction in parkinsonian disorders, with equivocal results so far.Objectives: To summarize the clinical outcomes of PPN-DBS-treated patients at our centre and elicit any patterns that may guide future research.Materials and Methods: Pre- and post-operative objective overall motor and gait subsection scores as well as patient-reported outcomes were recorded for 6 PPN-DBS-treated patients, 3 with Parkinson's disease (PD), and 3 with progressive supranuclear palsy (PSP). Electrodes were implanted unilaterally in the first 3 patients and bilaterally in the latter 3, using an MRI-guided MRI-verified technique. Stimulation was initiated at 20-30 Hz and optimized in an iterative manner.Results: Unilaterally treated patients did not demonstrate significant improvements in gait questionnaires, UPDRS-III or PSPRS scores or their respective gait subsections. This contrasted with at least an initial response in bilaterally treated patients. Diurnal cycling of stimulation in a PD patient with habituation to the initial benefit reproduced substantial improvements in freezing of gait (FOG) 3 years post-operatively. Among the PSP patients, 1 with a parkinsonian subtype had a sustained improvement in FOG while another with Richardson syndrome (PSP-RS) did not benefit.Conclusions: PPN-DBS remains an investigational treatment for levodopa-refractory FOG. This series corroborates some previously reported findings: bilateral stimulation may be more effective than unilateral stimulation; the response in PSP patients may depend on the disease subtype; and diurnal cycling of stimulation to overcome habituation merits further investigation.
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| 3. |
- Dewe, Hayley, et al.
(author)
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My Virtual Self : The Role of Movement in Children's Sense of Embodiment
- 2022
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In: IEEE Transactions on Visualization and Computer Graphics. - : Institute of Electrical and Electronics Engineers (IEEE). - 1077-2626 .- 1941-0506. ; 28:12, s. 4061-4072
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Journal article (peer-reviewed)abstract
- There are vast potential applications for children's entertainment and education with modern virtual reality (VR) experiences, yet we know very little about how the movement or form of such a virtual body can influence children's feelings of control (agency) or the sensation that they own the virtual body (ownership). In two experiments, we gave a total of 197 children aged 4-14 years a virtual hand which moved synchronously or asynchronously with their own movements and had them interact with a VR environment. We found that movement synchrony influenced feelings of control and ownership at all ages. In Experiment 1 only, participants additionally felt haptic feedback either congruently, delayed or not at all - this did not influence feelings of control or ownership. In Experiment 2 only, participants used either a virtual hand or non-human virtual block. Participants embodied both forms to some degree, provided visuomotor signals were synchronous (as indicated by ownership, agency, and location ratings). Yet, only the hand in the synchronous movement condition was described as feeling like part of the body, rather than like a tool (e.g., a mouse or controller). Collectively, these findings highlight the overall dominance of visuomotor synchrony for children's own-body representation; that children can embody non-human forms to some degree; and that embodiment is also somewhat constrained by prior expectations of body form.
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| 4. |
- Gottwald, Janna M., Dr, 1983-, et al.
(author)
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The Developing Bodily Self : How Posture Constrains Body Representation in Childhood
- 2021
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In: Child Development. - : Wiley. - 0009-3920 .- 1467-8624. ; 92:1, s. 351-366
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Journal article (peer-reviewed)abstract
- Adults’ body representation is constrained by multisensory information and knowledge of the body such as its possible postures. This study (N = 180) tested for similar constraints in children. Using the rubber hand illusion with adults and 6‐ to 7‐year olds, we measured proprioceptive drift (an index of hand localization) and ratings of felt hand ownership. The fake hand was either congruent or incongruent with the participant’s own. Across ages, congruency of posture and visual–tactile congruency yielded greater drift toward the fake hand. Ownership ratings were higher with congruent visual–tactile information, but unaffected by posture. Posture constrains body representation similarly in children and adults, suggesting that children have sensitive, robust mechanisms for maintaining a sense of bodily self.
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| 5. |
- Gottwald, Janna, Dr, 1983-, et al.
(author)
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The developing bodily self: Posture constrains embodiment in children and adults
- 2024
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Other publication (other academic/artistic)abstract
- For adults, the feeling of inhabiting a body (a sense of embodiment) is constrained by bottom-up multisensory information such as spatiotemporal correlations between visual and tactile sensations, and by top-down knowledge of the body such as its possible postures. However, to date it is unknown what kinds of body models children have. Here we asked whether common factors constrain embodiment in children and adults. In two experiments, we compared 6- to 7-year-olds’ and adults’ embodiment of a fake hand in the rubber hand illusion, measuring illusion-induced proprioceptive drift and questionnaire responses. In Experiment 1 (N = 120), the fake hand was either congruent with the participant’s own hand, or incongruent by 90° and, as a result, in an impossible posture with respect to the current position of their body. In Experiment 2 (N = 60), the fake hand was incongruent with the participant’s own hand by 20°, but still in a possible posture. Across both experiments, and in both children and adults, visual-proprioceptive congruency of posture, and visual-tactile spatiotemporal congruency in stroking independently yielded greater proprioceptive drift towards the rubber hand. Subjective ratings of embodiment were also higher when visual-tactile information was congruent, but were not affected by posture. Top-down knowledge of body posture therefore partially constrains embodiment in middle childhood, as in adulthood. This shows that, although childhood is a period of significant change in both bodily dimensions and sensory capabilities, 6- to 7-year-olds have sensitive, robust mechanisms for maintaining a sense of bodily self.
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| 6. |
- Mowbray, Rachel, et al.
(author)
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The development of visually guided stepping
- 2019
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In: Experimental Brain Research. - : Springer Science and Business Media LLC. - 0014-4819 .- 1432-1106. ; 237:11, s. 2875-2883
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Journal article (peer-reviewed)abstract
- Adults use vision during stepping and walking to fine-tune foot placement. However, the developmental profile of visually guided stepping is unclear. We asked (1) whether children use online vision to fine-tune precise steps and (2) whether preci- sion stepping develops as part of broader visuomotor development, alongside other fundamental motor skills like reaching. With 6-(N = 11), 7-(N = 11), 8-(N = 11)-year-olds and adults (N = 15), we manipulated visual input during steps and reaches. Using motion capture, we measured step and reach error, and postural stability. We expected (1) both steps and reaches would be visually guided (2) with similar developmental profiles (3) foot placement biases that promote stability, and (4) correlations between postural stability and step error. Children used vision to fine-tune both steps and reaches. At all ages, foot placement was biased (albeit not in the predicted directions). Contrary to our predictions, step error was not correlated with postural stability. By 8 years, children’s step and reach error were adult-like. Despite similar visual control mechanisms, stepping and reaching had different developmental profiles: step error reduced with age whilst reach error was lower and stable with age. We argue that the development of both visually guided and non-visually guided action is limb-specific.
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