Article

The Cutaneous Rabbit Illusion Affects Human Primary Sensory Cortex Somatotopically

UCL Institute of Cognitive Neuroscience, Department of Psychology, University College London, London, United Kingdom.
PLoS Biology (Impact Factor: 11.77). 04/2006; 4(3):e69. DOI: 10.1371/journal.pbio.0040069
Source: PubMed

ABSTRACT We used functional magnetic resonance imaging (fMRI) to study neural correlates of a robust somatosensory illusion that can dissociate tactile perception from physical stimulation. Repeated rapid stimulation at the wrist, then near the elbow, can create the illusion of touches at intervening locations along the arm, as if a rabbit hopped along it. We examined brain activity in humans using fMRI, with improved spatial resolution, during this version of the classic cutaneous rabbit illusion. As compared with control stimulation at the same skin sites (but in a different order that did not induce the illusion), illusory sequences activated contralateral primary somatosensory cortex, at a somatotopic location corresponding to the filled-in illusory perception on the forearm. Moreover, the amplitude of this somatosensory activation was comparable to that for veridical stimulation including the intervening position on the arm. The illusion additionally activated areas of premotor and prefrontal cortex. These results provide direct evidence that illusory somatosensory percepts can affect primary somatosensory cortex in a manner that corresponds somatotopically to the illusory percept.

Download full-text

Full-text

Available from: Felix Blankenburg, Jul 07, 2015
0 Followers
 · 
118 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper surveys the research literature on robust tactile and haptic illusions. The illusions are organized into two categories. The first category relates to objects and their properties, and is further differentiated in terms of haptic processing of material versus geometric object properties. The second category relates to haptic space, and is further differentiated in terms of the observer's own body versus external space. The illusions are initially described and where possible addressed in terms of their functional properties and/or underlying neural processes. The significance of these illusions for the design of tactile and haptic displays is also discussed. We conclude by briefly considering a number of important general themes that have emerged in the materials surveyed.
    IEEE Transactions on Haptics 09/2011; DOI:10.1109/TOH.2011.2 · 2.03 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An immediate need exists for a portable diagnostic device for the assessment of cortical function, and diagnosis of mTBI. This paper presents initial results using a vibrotactile acuity test for the objective and quantitative diagnosis of acute mTBI suspects. mTBI is hypothesized to involve derangement or damage to the underlying cortical network. In particular, fundamental building blocks of the cortex are changed in such a way as to limit the functional connectivity within and between cortical columns. Our approach is based on sensory illusions that are configured as a test of neural connectivity. Pilot clinical test data showed differences between a small healthy normal group and a concussion group using a sports concussion model.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2011; 2011:2041-4. DOI:10.1109/IEMBS.2011.6090376
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A critical assumption underlying the practice of functional localization is that the voxels identified by functional localization are essentially the same as those activated in the main experiment for a particular anatomical area. Violations of this assumption bias the resulting analyses and can dramatically increase the likelihood of both Type I and Type II errors. Here we investigated how the amount of data affects the reliability of a set of common functionally-defined regions-of-interest (fROIs). Four participants were scanned ten times each to functionally localize extrastriate regions sensitive to visually presented words, objects and faces. A within-subject random-effects analysis was used as the "gold standard" for identifying the fROIs and the results were compared to within-subject, fixed-effect analyses typically used for functional localization. By varying the quantity of data included in the analyses, we empirically assessed the amount needed to ensure reliable identification of the fROIs. The results demonstrated that the most consistent fROIs were based on either stringent statistical thresholding (Z>5.0) of large quantities of data or on lenient thresholding (Z>2.3) of a modest amount of data, with both methods yielding 70-80% overlap between the functional localization results and the "gold standard." Stringent statistical thresholds on typical quantities of localizer data led to the poorest reliability (<20% overlap). These findings suggest that the most reliable and cost-efficient method for functional localization involves collecting a relatively small amount of data (~10 min) and using a lenient statistical threshold to identify all voxels in a given region that are sensitive to the process-of-interest.
    NeuroImage 05/2011; 57(3):1022-30. DOI:10.1016/j.neuroimage.2011.05.009 · 6.13 Impact Factor