Adaptation is the reduction of neural responses with the stimulus repetition. In the magnetoencephalogram (MEG), this adaptation manifests itself most clearly in the N1m response, the most prominent deflection of the auditory event-related field. Short-term synaptic depression (STSD), which reflects vesicle depletion due to pre-synaptic activity, is a potential explanation for neural adaptation.
A classical paradigm to study response adaptation in auditory cortex (AC) is the so-called regular-SOI paradigm in which a sequence of identical tones is presented at a regular stimulus onset interval (SOI).