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Updated: Feb 5, 2026

Quantitative Assessment of Cortical Auditory-tactile Processing in Children with Disabilities
Published on: January 29, 2014
Detecting differences with magnetoencephalography of somatosensory processing after tactile and electrical stimuli
Pekka Hautasaari1, Urho M Kujala2, Ina M Tarkka1
1Health Sciences, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland; Jyväskylä Centre for Interdisciplinary Brain Research, University of Jyväskylä, Jyväskylä, Finland.
Background:
Deviant stimuli within a standard, frequent stimulus train induce a cortical somatosensory mismatch response (SMMR). The SMMR reflects the brain's automatic mechanism for the detection of change in a somatosensory domain. It is usually elicited by electrical stimulation, which activates nerve fibers and receptors in superficial and deep skin layers, whereas tactile stimulation is closer to natural stimulation and activates uniform fiber types. We recorded SMMRs after electrical and tactile stimuli.
Method:
306-channel magnetoencephalography recordings were made with 16 healthy adults under two conditions: electrical (eSMMR) and tactile (tSMMR) stimulations. The SMMR protocol consisted of 1000 stimuli with 10% deviants to fingers.
Results:
Sensor-level analysis revealed stronger activation after deviant stimulation in bilateral channel locations approximately corresponding to parietal cortical areas within both stimulation conditions. Between conditions, deviant tSMMR showed stronger activation in the ipsilateral channels. Based on sensor-level results, two components, M50 and SMMR (40-58 and 110-185 ms), were compared at the source-level. Deviant stimulation elicited stronger contralateral SI activation during M50 component in both conditions. SMMR was observed with both conditions, activating contralateral SII after deviant stimulation. However, only tSMMR showed long latency activation in bilateral SI cortices. This suggests that there is an integration of both body sides during the automatic stages of tactile processing in SI cortices.
Conclusions:
This study indicates that tactile stimulation (tSMMR) is a feasible method for investigating the brain's mechanism for detecting somatosensory changes; this may extend the clinical utility of tSMMR for assessing disorders involving altered somatosensory processing.
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