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Shape and roughness activate different somatosensory areas in the human brain
P E Roland1, B O'Sullivan, R Kawashima
1Division of Human Brain Research, Department of Neuroscience, The Karolinska Institute, S-171 77 Stockholm, Sweden. Per.Roland@neuro.ki.se
Summary
This study reveals distinct brain regions for processing object shape, length, and roughness. The intraparietal sulcus handles shape and length, while the lateral parietal operculum processes roughness, showing specialized somatosensory pathways.
Area of Science:
- Neuroscience
- Somatosensory System Research
- Functional Brain Imaging
Background:
- The postcentral gyrus and lateral fissure are known somatosensory areas.
- Localization of human somatosensory association areas and their functional differences remain unclear.
Purpose of the Study:
- To investigate the functional contributions of somatosensory association areas.
- To differentiate brain activity related to discriminating object length, shape, and roughness.
Main Methods:
- Regional cerebral blood flow measured using 15O-butanol and positron-emission tomography.
- Two groups of young volunteers discriminated object properties (length, shape, roughness) with their right hand.
Main Results:
- Roughness discrimination showed higher activation in the lateral parietal opercular cortex compared to length or shape.
- Length and shape discrimination activated a common cortical field in the anterior part of the intraparietal sulcus (IPA).
- IPA activation was significantly greater for shape and length discrimination than for roughness.
Conclusions:
- Demonstrates a functional separation between the lateral parietal opercular cortex and the intraparietal sulcus.
- Suggests distinct cortical processing streams for somatosensory microgeometry (shape, length) and macrogeometry (roughness).