Objective: To elucidate the temporal profile of interactions between sensor
y information from both hands in the somatosensory cortex.
Methods: Somatosensory evoked fields (SEFs), generated by stimulation appli
ed to the right index finger after a preceding stimulation to the left inde
x finger, were recorded using a whole head-type magnetoencephalography (MEG
). The paired electrical stimuli were applied with a stimulation onset asyn
chrony (SOA) of 50, 100, 200, 300, or 400 ms.
Results: The mean SEF intensities in the primary somatosensory area (SI) of
five subjects, which were evoked approximately t0 ms after the latter of t
he paired stimuli, were not significantly smaller than that evoked in the c
ontrol condition when only the right linger was stimulated. In contrast, SE
Fs in the secondary somatosensory area (SII), generated approximately 100 m
s after the stimuli, were suppressed when the paired stimuli were applied a
t an SOA of 100 ms (P < 0.05, t test). In addition, SEFs at approximately 1
50 ms after the stimuli were significantly suppressed at SOAs of 50, 100 (P
< 0.05), 200, and 300 ms (P < 0.1).
Conclusion: Within a time window of approximately 300 ms, sensory informati
on from the left finger significantly affected the SEFs generated by sensor
y inputs from the right finger. This time window may be required for the in
tegration of sensory input. (C) 2001 Elsevier Science Ireland Ltd. All righ