Time-frequency characterization of mismatch negativity in nociceptive responses

An efficient way to investigate the neural basis of nociceptive responses is the event-related brain potentials (ERPs). One component belonging to this family of ERPs is the mismatch negativity (MMN). It reflects pre-attentive detection of changes in the incoming stimulus by comparing the new stimulus with sensory memory traces. In this work, single trials of ERP taken from EEG signal recorded under thermal and electric stimulation were analyzed with time-frequency representation (TFR). The main objective of this work was to characterize responses to frequent and infrequent stimuli with TFR functions. Variables defined on instantaneous frequency and instantaneous power presented a statistical significance (p-value<0.0001) differentiating these two kind of responses. Furthermore, differences between the averaged instantaneous power and instantaneous frequency were also analyzed. It was found that instantaneous power and instantaneous frequency were able to better isolate the MMN components from EEG noise in certain frequency bands.