1-A-D-23. A magnetoencephalographic study on neural substrates for the vibrotactile temporal discrimination

Abstract

Temporal discrimination is important for tactile object recognition. For instance, texture segregation in real-life consists of vibrotactile inputs with successive changes in frequency. In this study, we recorded vibrotactile somatosensory evoked magnetic fields in ten healthy participants. We used vibrotactile train stimuli (1.5 s in duration) with two different temporal sequences: regular train stimuli with a constant frequency of 10 Hz and irregular train stimuli harboring variable inter-stimulus intervals within the train (corresponding to 6.25–25 Hz). The stimuli were delivered to the right index finger, and the two types of train were presented in a random sequence with intervals of 1200–1600 ms. Participants discriminated regularity of the train stimuli in an attended condition. We focused on very low frequency components (less than 1 Hz, duration of 1000–2000 ms; designated as sustained magnetic fields (SFs)). Minimum norm estimates revealed that SFs were localized in the secondary somatosensory area (SII). We found the increased source-level amplitudes with dissociation between the train types in the right SII in the attended condition but not in the unattended condition. Therefore, it is likely that the right SII is involved in the active vibrotactile frequency discrimination.