Open AccessFunctional deactivations: Multiple ipsilateral brain areas engaged in the processing of somatosensory information
Author(s) -
Klingner Carsten M.,
Huonker Ralph,
Flemming Sandra,
Hasler Caroline,
Brodoehl Stefan,
Preul Christoph,
Burmeister Hartmut,
Kastrup Andreas,
Witte Otto W.
Publication year - 2011
Publication title -
human brain mapping
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.005
H-Index - 191
eISSN - 1097-0193
pISSN - 1065-9471
DOI - 10.1002/hbm.21006
Subject(s) - somatosensory system , functional magnetic resonance imaging , neuroscience , psychology , insula , brain mapping , supplementary motor area , stimulation , somatosensory evoked potential , brain activity and meditation , secondary somatosensory cortex , electroencephalography
Somatosensory signals modulate activity throughout a widespread network in both of the brain hemispheres: the contralateral as well as the ipsilateral side of the brain relative to the stimulated limb. To analyze the ipsilateral somatosensory brain areas that are engaged during limb stimulation, we performed functional magnetic resonance imaging (fMRI) in 12 healthy subjects during electrical median nerve stimulation using both a block‐ and an event‐related fMRI design. Data were analyzed through the use of model‐dependent (SPM) and model‐independent (ICA) approaches. Beyond the well‐known positive blood oxygenation level‐dependent (BOLD) responses, negative deflections of the BOLD response were found consistently in several ipsilateral brain areas, including the primary somatosensory cortex, the supplementary motor area, the insula, the dorsal part of the posterior cingulate cortex, and the contralateral cerebellum. Compared to their positive counterparts, the negative hemodynamic responses showed a different time course, with an onset time delay of 2.4 s and a peak delay of 0.7 s. This characteristic delay was observed in all investigated areas and verified by a second (purely tactile) event‐related paradigm, suggesting a systematic difference for brain areas involved in the processing of somatosensory information. These findings may indicate that the physiological basis of these deactivations differs from that of the positive BOLD responses. Therefore, an altered model for the negative BOLD response may be beneficial to further model‐dependent fMRI analyses. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.