TY - JOUR
T1 - Distinct fronto-central N60 and supra-sylvian N70 middle-latency components of the median nerve SEPs as assessed by scalp topographic analysis, dipolar source modelling and depth recordings
AU - Barba, Carmen
AU - Frot, M.
AU - Valeriani, M.
AU - Tonali, P.
AU - Mauguière, F.
PY - 2002
Y1 - 2002
N2 - Objectives: To investigate the possible contribution of the second somatosensory (SII) area in the generation of the N60 somatosensory evoked potential (SEP). Methods: In 7 epileptic patients and in 6 healthy subjects scalp SEPs were recorded by 19 electrodes placed according to the 10-20 system. All epileptic patients but one were also investigated using depth electrodes chronically implanted in the parieto-rolandic opercular cortex. Scalp SEPs underwent brain electrical source analysis. Results: In both epileptic patients and healthy subjects, scalp recordings showed two middle-latency components clearly distinguishable on the basis of latency and scalp distribution: a fronto-central N60 potential contralateral to stimulation and a later bilateral temporal N70 response. SEP dipolar source modelling showed that a contralateral perisylvian dipole was activated in the scalp N70 latency range whereas separate perirolandic and frontal sources were activated at the scalp N60 latency. Depth electrodes recorded a biphasic N60/P90 response in the parieto-rolandic opercular regions contra- and ipsilateral to stimulation. Conclusions: Two different middle-latency SEP components N60 and N70 can be distinguished by topographic analysis and source modelling of scalp recordings, the sources of which are located in the fronto-central cortex contralateral to stimulation and in the supra-sylvian cortex on both sides, respectively. The source location of the scalp N70 in the SII area is strongly supported by its spatio-temporal similarities with SEPs directly recorded in the supra-sylvian opercular cortex.
AB - Objectives: To investigate the possible contribution of the second somatosensory (SII) area in the generation of the N60 somatosensory evoked potential (SEP). Methods: In 7 epileptic patients and in 6 healthy subjects scalp SEPs were recorded by 19 electrodes placed according to the 10-20 system. All epileptic patients but one were also investigated using depth electrodes chronically implanted in the parieto-rolandic opercular cortex. Scalp SEPs underwent brain electrical source analysis. Results: In both epileptic patients and healthy subjects, scalp recordings showed two middle-latency components clearly distinguishable on the basis of latency and scalp distribution: a fronto-central N60 potential contralateral to stimulation and a later bilateral temporal N70 response. SEP dipolar source modelling showed that a contralateral perisylvian dipole was activated in the scalp N70 latency range whereas separate perirolandic and frontal sources were activated at the scalp N60 latency. Depth electrodes recorded a biphasic N60/P90 response in the parieto-rolandic opercular regions contra- and ipsilateral to stimulation. Conclusions: Two different middle-latency SEP components N60 and N70 can be distinguished by topographic analysis and source modelling of scalp recordings, the sources of which are located in the fronto-central cortex contralateral to stimulation and in the supra-sylvian cortex on both sides, respectively. The source location of the scalp N70 in the SII area is strongly supported by its spatio-temporal similarities with SEPs directly recorded in the supra-sylvian opercular cortex.
KW - Dipolar analysis
KW - Intracortical potentials
KW - N60 potential
KW - Second somatosensory area
KW - Somatosensory evoked potentials
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U2 - 10.1016/S1388-2457(02)00104-9
DO - 10.1016/S1388-2457(02)00104-9
M3 - Article
C2 - 12088690
AN - SCOPUS:84987684805
VL - 113
SP - 981
EP - 992
JO - Clinical Neurophysiology
JF - Clinical Neurophysiology
SN - 1388-2457
IS - 7
ER -