Stroking or Buzzing? A Comparison of Somatosensory Touch Stimuli Using 7 Tesla fMRI.
Studying body representations in the brain helps us to understand how we humans relate to our own bodies. The in vivo mapping of the somatosensory cortex, where these representations are found, is greatly facilitated by the high spatial resolution and high sensitivity to brain activation available at ultra-high field. In this study, the use of different stimulus types for somatotopic mapping of the digits at ultra-high field, specifically manual stroking and mechanical stimulation, was compared in terms of sensitivity and specificity of the brain responses. Larger positive responses in digit regions of interest were found for manual stroking than for mechanical stimulation, both in terms of average and maximum t-value and in terms of number of voxels with significant responses to the tactile stimulation. Responses to manual stroking were higher throughout the entire post-central sulcus, but the difference was especially large on its posterior wall, i.e. in Brodmann area 2. During mechanical stimulation, cross-digit responses were more negative than during manual stroking, possibly caused by a faster habituation to the stimulus. These differences indicate that manual stroking is a highly suitable stimulus for fast somatotopic mapping procedures, especially if Brodmann area 2 is of interest.
Centre d'Imagerie Biomédicale (CIBM), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Spinoza Centre for Neuroimaging, Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands.
Wietske
W
van der Zwaag
Centre d'Imagerie Biomédicale (CIBM), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Department of Radiology, University Hospital, Lausanne, Switzerland; Department of Radiology, University Hospital, Geneva, Switzerland.
Rolf
R
Gruetter
Center for Neuroprosthetics, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Laboratory of Cognitive Neuroscience, Brain Mind Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Fondation Campus Biotech Geneva, Geneva, Switzerland.
Roberto
R
Martuzzi
D000328:Adult; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D055595:Mechanical Phenomena; D010812:Physical Stimulation; D013003:Somatosensory Cortex / Q000502:physiology*; D013997:Time Factors; D055698:Touch Perception; D055815:Young Adult