Assessing MMN and P3b reliably within-participant -- a comparison
between the local-global paradigm and two specialized oddball sequences.
Abstract
Mismatch negativity (MMN) and P3b are well known for their clinical
utility. There exists no gold standard, however, to acquire these
markers. This may explain why the within-individual sensitivity of
MMN/P3b is often quite poor and why seemingly identical markers can
behave differently across studies. Here we compare two traditional
paradigms for MMN or P3b assessment with the recently more popular
local-global paradigm which promises to assess MMN and P3b orthogonally
within one oddball sequence. All three paradigms were administered to
healthy participants (N=15) with concurrent EEG. A clear MMN and local
effect were found for 15/15 participants. The P3b and global effect were
found for 14/15 and 13/15 participants, respectively. There were no
systematic differences between the global effect and P3b. Indeed, P3b
amplitude was highly correlated across paradigms. The local effect
differed clearly from the MMN, however. It occurred earlier compared to
MMN and was followed by a much more prominent P3a effect. The two sets
of peak latencies and amplitudes were also not correlated across
paradigms. We conclude that the local-global paradigm is effective in
evoking the traditional P3b component, but it does not capture the MMN.
Caution should therefore be exercised when comparing the local effect
and MMN across studies. Nevertheless, the within-individual sensitivity
of both MMN and the local effect was satisfactory. The within-individual
sensitivity of P3b was lower than expected in a healthy control group,
which may explain the often-low sensitivity of P3b in patients with
disorders of consciousness.