Revol P, Farnè A, Pisella L, Holmes N P, Imai A, Susami K, Koga K, Rossetti Y
Inserm UMR-S 864, Bron, et Hospices Civils de Lyon, Service de Médecine Physique et Réadaptation, Hôpital Henry Gabrielle, Université de Lyon, Université Lyon 1, Saint-Genis-Laval, France.
Exp Brain Res. 2009 Mar;193(4):633-8. doi: 10.1007/s00221-008-1696-y. Epub 2009 Feb 8.
The coding of body part location may depend upon both visual and proprioceptive information, and allows targets to be localized with respect to the body. The present study investigates the interaction between visual and proprioceptive localization systems under conditions of multisensory conflict induced by optokinetic stimulation (OKS). Healthy subjects were asked to estimate the apparent motion speed of a visual target (LED) that could be located either in the extrapersonal space (visual encoding only, V), or at the same distance, but stuck on the subject's right index finger-tip (visual and proprioceptive encoding, V-P). Additionally, the multisensory condition was performed with the index finger kept in position both passively (V-P passive) and actively (V-P active). Results showed that the visual stimulus was always perceived to move, irrespective of its out- or on-the-body location. Moreover, this apparent motion speed varied consistently with the speed of the moving OKS background in all conditions. Surprisingly, no differences were found between V-P active and V-P passive conditions in the speed of apparent motion. The persistence of the visual illusion during the active posture maintenance reveals a novel condition in which vision totally dominates over proprioceptive information, suggesting that the hand-held visual stimulus was perceived as a purely visual, external object despite its contact with the hand.
身体部位位置的编码可能取决于视觉和本体感觉信息，并允许相对于身体对目标进行定位。本研究调查了在视动刺激（OKS）引起的多感官冲突条件下视觉和本体感觉定位系统之间的相互作用。健康受试者被要求估计一个视觉目标（发光二极管）的视在运动速度，该目标可以位于个人空间之外（仅视觉编码，V），或者在相同距离处，但贴在受试者右手食指指尖上（视觉和本体感觉编码，V-P）。此外，多感官条件是在食指被动（V-P被动）和主动（V-P主动）保持在原位的情况下进行的。结果表明，无论视觉刺激是在身体外部还是在身体上，总是被感知为在移动。此外，在所有条件下，这种视在运动速度都与移动的OKS背景速度一致变化。令人惊讶的是，在视在运动速度方面，V-P主动和V-P被动条件之间没有发现差异。在主动姿势维持期间视觉错觉的持续存在揭示了一种新的情况，即视觉完全主导本体感觉信息，这表明手持视觉刺激尽管与手接触，但仍被视为一个纯粹的视觉外部物体。
