TY - JOUR
T1 - Functional topography of the secondary somatosensory cortex for nonpainful and painful stimuli
T2 - An fMRI study
AU - Ferretti, Antonio
AU - Babiloni, Claudio
AU - Del Gratta, Cosimo
AU - Caulo, Massimo
AU - Tartaro, Armando
AU - Bonomo, Lorenzo
AU - Rossini, Paolo Maria
AU - Romani, Gian Luca
PY - 2003/11
Y1 - 2003/11
N2 - The regional activity of the contralateral primary (SI) and the bilateral secondary (SII) somatosensory areas during median nerve stimulations at five intensity levels (ranging from nonpainful motor threshold to moderate pain) was studied by means of functional magnetic resonance imaging (fMRI). The aim was to characterize the functional topography of SII compared to SI as a function of the stimulus intensity. Results showed that the galvanic stimulation of the median nerve activated the contralateral SI at all stimulus intensities. When considered as a single region, SII was more strongly activated in the contralateral than in the ipsilateral hemisphere. When a finer spatial analysis of the SII responses was performed, the activity for the painful stimulation was localized more posteriorly compared to that for the nonpainful stimulation. This is the first report on such a SII segregation for transient galvanic stimulations. The activity (relative signal intensity) of this posterior area increased with the increase of the stimulus intensity. These results suggest a spatial segregation of the neural populations that process signals conveyed by dorsal column-medial lemniscus (nonpainful signals) and neospinothalamic (painful signals) pathways. Further fMRI experiments should evaluate the functional properties of these two SII subregions during tasks involving sensorimotor integration, learning, and memory demands.
AB - The regional activity of the contralateral primary (SI) and the bilateral secondary (SII) somatosensory areas during median nerve stimulations at five intensity levels (ranging from nonpainful motor threshold to moderate pain) was studied by means of functional magnetic resonance imaging (fMRI). The aim was to characterize the functional topography of SII compared to SI as a function of the stimulus intensity. Results showed that the galvanic stimulation of the median nerve activated the contralateral SI at all stimulus intensities. When considered as a single region, SII was more strongly activated in the contralateral than in the ipsilateral hemisphere. When a finer spatial analysis of the SII responses was performed, the activity for the painful stimulation was localized more posteriorly compared to that for the nonpainful stimulation. This is the first report on such a SII segregation for transient galvanic stimulations. The activity (relative signal intensity) of this posterior area increased with the increase of the stimulus intensity. These results suggest a spatial segregation of the neural populations that process signals conveyed by dorsal column-medial lemniscus (nonpainful signals) and neospinothalamic (painful signals) pathways. Further fMRI experiments should evaluate the functional properties of these two SII subregions during tasks involving sensorimotor integration, learning, and memory demands.
KW - Functional magnetic resonance imaging (fMRI)
KW - Median-nerve electrical stimulation
KW - Pain
KW - Primary somatosensory area (SI)
KW - Secondary somatosensory area (SII)
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U2 - 10.1016/j.neuroimage.2003.07.004
DO - 10.1016/j.neuroimage.2003.07.004
M3 - Article
C2 - 14642473
AN - SCOPUS:0344121167
VL - 20
SP - 1625
EP - 1638
JO - NeuroImage
JF - NeuroImage
SN - 1053-8119
IS - 3
ER -