Notes of the „frontal somatosensory generator“.
A preface to the article „Evidence for perirolandic generators of median nerve SEPs
from differential scalp recording“
Stejskal L.1, Štětkářová I.2, Ostrý S.1
1Neurochirurgická klinika, 1. LF UK, Ústřední vojenská nemocnice, Praha 2Neurologické oddělení nemocnice Na Homolce, Praha |
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Summary:
Scalp somatosensory (SEP) P22/N30/P45 are non-constant waveforms evoked by stimulation of the
median nerve, attributed to the frontal somatosensory generator. Transcortical, cortical, epidural and
scalp recordings of evoked responses are discussed, demonstrating their generation in the rolandic
fissure and the perirolandic region and their spreading as a remote response over the scalp, diminished
and deformed by the high resistance of bone. They counterbalance the constant somatosensory
postrolandic response of the opposite polarity. It is argued that they do not represent a direct „motor“
thalamocortical response. There are no valid reasons for the hypothesis that abnormalities of
„P22/N30/P45“ are manifestations of extrapyramidal disorders. Bipolar scalp recordings presented in
the accompanying paper confirm these facts.
Key words:
somatosensory response generator, rolandic region, phase reversal
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