The second feature of interest in the network change is that it is observed in the early stages of auditory processing. The MMNm component is an early (between 100 and 200 ms), automatic or largely pre-attentive response (Naatanen et al., 2007). Particularly relevant is that a prefrontal contribution to change detection also occurs within this early time window, demonstrated in Garrido and colleagues' dynamic causal modelling of a roving oddball paradigm (Garrido et al., 2008) and the effects of frontal lesions (Alho et al., 1994). This suggests that if the prefrontal cortical dysfunction in the two patient groups is the cause of the altered network response, then this affects the very early stages of stimuli processing. Although this early component is distinct from the later M300 response, which reflects attentional processing (Wronka et al., 2008), it is still relevant to high order cognitive processes, (Naatanen et al., 2007, 2012).
MMNm component
between 100 and 200 ms
ms