Probing the neurophysiology of temporal sensitivity in the somatosensory system using the mismatch negativity (MMN) sensory memory paradigm

ABSTRACT Duration is an amodal feature common to all sensory experiences, but current understanding of sensory-perceptual processing of the temporal qualities of somatosensation remains incomplete. The goal here was to better understand how the brain processes the duration of vibrotactile information, which was assessed by parametrically varying the extent of duration deviance in a somatosensory mismatch negativity (sMMN) paradigm while high-density event-related potential (ERP) recordings were acquired. Healthy young adults (N = 20; aged 18-31 years) received stimulation of the right index fingertip with a 100 ms vibro-tactile input on 80% of trials while the other 20% of trials consisted of deviant stimuli with one of the following durations: 115, 130, 145, or 160 ms. Deviant conditions were presented in separate blocks with deviants pseudo-randomly distributed amongst the 100 ms standards. Participants ignored these inputs while watching a silent movie. Robust sMMN responses, with a dipolar field over the left antero-superior parietal cortex, were detected when deviant stimuli were 130, 145, and 160 ms, but not when they were 115 ms. The amplitudes of the sMMN correlated with individuals’ subsequent abilities to detect duration deviants when actively attempting to discriminate their presence. This simple-to-execute sMMN paradigm holds promise for the assessment of tactile processing differences in clinical populations where tactile sensitivities are a common aspect of the phenotype (e.g., Autism, Fragile-X syndrome).