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Tuning and balancing in multisensory body representation| old_uid | 10398 |
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| title | Tuning and balancing in multisensory body representation |
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| start_date | 2011/11/18 |
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| schedule | 14h30-16h30 |
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| online | no |
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| summary | The body is a multisensory object par excellence. Most multisensory studies consider how information about a single stimulus object is combined across two different sensory channels. However, focussing on body representations allows us to identify other forms of multisensory interaction. These involve top-down multisensory modulation, rather than bottom-up multisensory convergence. In one example, viewing one’s own body improves the sense of touch, and also reduces intensity of pain. Recent results identify multisensory circuits in the parietal lobe as the key intermediate node in the visual-somatosensory link that underlies these interactions. Viewing the body seems to activate a representation that regulates the cortical circuits for somatosensation.
In a second example, I focus on a recently discovered interaction between vestibular signals and somatosensory signals. The vestibular system gives the orientation of the head with respect to the external environment. Interestingly, there is no unisensory vestibular cortex: vestibular projects are shared with other sensory channels, in particular somatosensation. We have shown that vestibular stimulation improves tactile detection, and decreases pain sensation. It also increases the perceived distance of visual objects far from the body, without affecting peripersonal distance perception. Thus, the sensory balancing triggered by reorienting the body relative to the environment seems to increase the influence of proximal, self-related signals, re-emphasising the self when the exteroceptive inputs change.
I conclude that multisensory modulation is an intrinsic element in setting the appropriate relation between the self and the world. Representations of a supramodal, continuous self may be a consequence of first implementing new balances of multisensory gains when we interact with the world, and then maintaining appropriately-tuned multisensory balance. |
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| responsibles | de Vignemont |
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