Anatomical and functional properties of the foot and leg representation in areas 3b, 1 and 2 of primary somatosensory cortex in humans: A 7T fMRI study.

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Version: Final published version
Serval ID
serval:BIB_2847BE30CB54
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Anatomical and functional properties of the foot and leg representation in areas 3b, 1 and 2 of primary somatosensory cortex in humans: A 7T fMRI study.
Journal
NeuroImage
Author(s)
Akselrod M., Martuzzi R., Serino A., van der Zwaag W., Gassert R., Blanke O.
ISSN
1095-9572 (Electronic)
ISSN-L
1053-8119
Publication state
Published
Issued date
01/10/2017
Peer-reviewed
Oui
Volume
159
Pages
473-487
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Abstract
Primary somatosensory cortex (S1) processes somatosensory information and is composed of multiple subregions. In particular, tactile information from the skin is encoded in three subregions, namely Brodmann areas (BAs) 3b, 1 and 2, with each area representing a complete map of the contralateral body. Although, much is known about the somatotopic organization of the hand in human S1, less research has been carried out regarding the somatotopic maps of the foot and leg in S1. Moreover, a latero-medial S1 organization along the superior part of the postcentral gyrus has been reported when moving from hip to toes, yet to date there is no study investigating leg/foot maps within the different subregions of S1. Using ultra-high field MRI (7T), we mapped six cortical representations of the lower limb (hip to toes) at the single subject level and performed this analysis separately for BAs 3b, 1 and 2. Analyzing the BOLD responses associated with tactile stimulations of the mapped foot and leg regions on each side, we quantified the extent and the strength of activation to determine somatotopic organization. In addition, we investigated whether each mapped representation also responded to the stimulation of other body parts (i.e. response selectivity) and conducted dissimilarity analysis relating these anatomical and functional properties of S1 to the physical structure of the lower limbs. Our data reveal somatotopy for the leg, but not for the foot in all investigated BAs, with large inter-subject variability. We found only minor differences between the properties of the three investigated BAs, suggesting that S1 maps for the lower limbs differ from those described for the hand. We also describe greater extent/strength of S1 activation for the big toe representation (compared to the other mapped representations) within all BAs, suggesting a possible homology between the first digit of upper and lower extremity in humans, and report different patterns of selectivity in the foot representations (i.e. lower selectivity) compared to the other leg representations (i.e. greater selectivity). These data provide a detailed description of human S1 subregions for the foot and leg, highlight the importance of high-resolution mapping studies and of single subject analysis, and indicate potential differences between the lower and the upper limb.
Keywords
Adolescent, Adult, Brain Mapping/methods, Female, Foot/innervation, Humans, Leg/innervation, Magnetic Resonance Imaging/methods, Male, Somatosensory Cortex/anatomy & histology, Somatosensory Cortex/physiology, Young Adult, 7T fMRI, Brodmann areas 3b-1-2, Lower limb representation, Primary somatosensory cortex, Somatotopy
Pubmed
Web of science
Open Access
Yes
Create date
13/11/2017 17:57
Last modification date
20/08/2019 13:07
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