Shape and roughness activate different somatosensory areas in the human brain

Per E. Roland, Brendan O'Sullivan, Ryuta Kawashima

Research output: Contribution to journalArticlepeer-review

150 Citations (Scopus)


Somatosensory stimuli are known to activate the postcentral gyrus, and neurons there fire when the skin is in contact with objects. Also neurons in the lateral fissure, the parietal operculum, fire when rough surfaces are felt. However the localization of somatosensory association areas in humans is largely unknown and differences in functional contributions between somatosensory association areas has not been previously demonstrated. For these reasons the regional cerebral blood flow was measured with 15O- butanol and positron-emission tomography in two groups of young volunteers discriminating the lengths, shapes, and roughness of objects with their right hand. Roughness discrimination activated the lateral parietal opercular cortex significantly more than did length or shape discrimination. A Boolean intersection of the cluster images showing the statistical significant increases of length and shape discrimination demonstrated that shape and length discrimination activated the same cortical field lining the anterior part of the intraparietal sulcus (IPA). Shape and length discrimination activated IPA significantly more than did roughness discrimination. These findings demonstrate a separation in functional contributions of lateral parietal opecular cortex and IPA. The results indicate different cortical processing streams for the somatosensory submodalities microgeometry and macrogeometry.

Original languageEnglish
Pages (from-to)3295-3300
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number6
Publication statusPublished - 1998 Mar 17


  • Human cerebral cortex
  • Intraparietal cortex
  • Parallel processing
  • Positron-emission tomography
  • Simple perception


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