Disintegration of Multisensory Signals from the Real Hand Reduces Default Limb Self-Attribution: An fMRI Study

TLDR

Limb perception relies on integrating visual, tactile, and proprioceptive signals, a process known to involve premotor, parietal, and cerebellar cortices. The study aimed to test whether neuronal populations in these regions integrate hand signals based on basic temporal and spatial congruence principles. Using a 3D video system, the authors manipulated the spatiotemporal relationships of visuotactile stimuli on a real hand during fMRI to examine neural and perceptual responses. They found that premotor, parietal, and cerebellar activity depended on spatial and temporal congruence of visuotactile cues, and that multisensory conflicts disrupted hand ownership, with the extent of disownership predicted by reduced activity in key multisensory areas.

Abstract

The perception of our limbs in space is built upon the integration of visual, tactile, and proprioceptive signals. Accumulating evidence suggests that these signals are combined in areas of premotor, parietal, and cerebellar cortices. However, it remains to be determined whether neuronal populations in these areas integrate hand signals according to basic temporal and spatial congruence principles of multisensory integration. Here, we developed a setup based on advanced 3D video technology that allowed us to manipulate the spatiotemporal relationships of visuotactile ( VT ) stimuli delivered on a healthy human participant's real hand during fMRI and investigate the ensuing neural and perceptual correlates. Our experiments revealed two novel findings. First, we found responses in premotor, parietal, and cerebellar regions that were dependent upon the spatial and temporal congruence of VT stimuli. This multisensory integration effect required a simultaneous match between the seen and felt postures of the hand, which suggests that congruent visuoproprioceptive signals from the upper limb are essential for successful VT integration. Second, we observed that multisensory conflicts significantly disrupted the default feeling of ownership of the seen real limb, as indexed by complementary subjective, psychophysiological, and BOLD measures. The degree to which self-attribution was impaired could be predicted from the attenuation of neural responses in key multisensory areas. These results elucidate the neural bases of the integration of multisensory hand signals according to basic spatiotemporal principles and demonstrate that the dis integration of these signals leads to “disownership” of the seen real hand.