PMID- 10802461
OWN - NLM
STAT- MEDLINE
DCOM- 20000714
LR  - 20190921
IS  - 1388-2457 (Print)
IS  - 1388-2457 (Linking)
VI  - 111
IP  - 5
DP  - 2000 May
TI  - Characteristics of the human contra- versus ipsilateral SII cortex.
PG  - 894-900
AB  - OBJECTIVES: In order to study the interaction between left- and right-sided 
      stimuli on the activation of cortical somatosensory areas, we recorded 
      somatosensory evoked magnetic fields (SEFs) from 8 healthy subjects with a 122 
      channel whole-scalp SQUID gradiometer. METHODS: Right and left median nerves were 
      stimulated either alternately within the same run, with interstimulus intervals 
      (ISIs) of 1.5 and 3 s, or separately in different runs with a 3 s ISI. In all 
      conditions 4 cortical source areas were activated: the contralateral primary 
      somatosensory cortex (SI), the contra- and ipsilateral secondary somatosensory 
      cortices (SII) and the contralateral posterior parietal cortex (PPC). RESULTS: 
      The earliest activity starting at 20 ms was generated solely in the SI cortex, 
      whereas longer-latency activity was detected from all 4 source areas. The mean 
      peak latencies for SII responses were 86-96 ms for contralateral and 94-97 ms for 
      ipsilateral stimuli. However, the activation of right and left SII areas started 
      at 61+/-3 and 62+/-3 ms to contralateral stimuli and at 66+/-2 and 63+/-2 ms to 
      ipsilateral stimuli, suggesting a simultaneous commencing of activation of the 
      SII areas. PPC sources were activated between 70 and 110 ms in different 
      subjects. The 1.5 s ISI alternating stimuli elicited smaller SII responses than 
      the 3 s ISI non-alternating stimuli, suggesting that a considerable part of the 
      neural population in SII responds both to contra- and ipsilateral stimuli. The 
      earliest SI responses did not differ between the two conditions. There were no 
      significant differences in source locations of SII responses to ipsi- and 
      contralateral stimuli in either hemisphere. Subaverages of the responses in sets 
      of 30 responses revealed that amplitudes of the SII responses gradually 
      attenuated during repetitive stimulation, whereas the amplitudes of the SI 
      responses were not changed. CONCLUSIONS: The present results implicate that ipsi- 
      and contralateral SII receive simultaneous input, and that a large part of SII 
      neurons responds both to contra- and ipsilateral stimulation. The present data 
      also highlight the different behavior of SI and SII cortices to repetitive 
      stimuli.
FAU - Wegner, K
AU  - Wegner K
AD  - Brain Research Unit, Low Temperature Laboratory, Helsinki University of 
      Technology, P.O. Box 2200, FIN-02015 HUT, Espoo, Finland. 
      wegner@landgraf.med.uni-jena.de
FAU - Forss, N
AU  - Forss N
FAU - Salenius, S
AU  - Salenius S
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Netherlands
TA  - Clin Neurophysiol
JT  - Clinical neurophysiology : official journal of the International Federation of 
      Clinical Neurophysiology
JID - 100883319
SB  - IM
MH  - Adult
MH  - *Brain Mapping
MH  - Electric Stimulation
MH  - Electromagnetic Fields
MH  - Evoked Potentials, Somatosensory/*physiology
MH  - Female
MH  - Functional Laterality/*physiology
MH  - Humans
MH  - Male
MH  - Median Nerve/*physiology
MH  - Reaction Time/physiology
MH  - Reference Values
MH  - Scalp/innervation
MH  - Somatosensory Cortex/*physiology
EDAT- 2000/05/10 09:00
MHDA- 2000/07/25 11:00
CRDT- 2000/05/10 09:00
PHST- 2000/05/10 09:00 [pubmed]
PHST- 2000/07/25 11:00 [medline]
PHST- 2000/05/10 09:00 [entrez]
AID - S1388-2457(99)00319-3 [pii]
AID - 10.1016/s1388-2457(99)00319-3 [doi]
PST - ppublish
SO  - Clin Neurophysiol. 2000 May;111(5):894-900. doi: 10.1016/s1388-2457(99)00319-3.