Lack of correlation between phonetic magnetic mismatch field and plasma d-serine levels in humans

Abstract

ObjectiveUncovering molecular bases for auditory language processing in the human brain is a fundamental scientific challenge. The power and latency of the magnetic mismatch field (MMF) elicited by phoneme change, which are magnetoencephalographic indices of language function in its early stage of information processing, are theoretically thought to be modulated by N-methyl-d-aspartate-type glutamate receptor (NMDAR) function, but no study has yet assessed this possibility. We have thus sought to demonstrate an association between phonetic MMF power/latency and levels of plasma d-serine, an intrinsic co-agonist of glycine binding sites on NMDAR, in adults. MethodsThe MMF response to phoneme changes was recorded using 204-channel magnetoencephalography in 61 healthy, right-handed, Japanese adults. Plasma levels of d- and l-serine were measured for each participant. ResultsWe did not find a significant correlation between MMF power/latency and plasma serine levels. ConclusionsDespite a sufficient sample size, we failed to find an association between the physiological markers of the early stage of information processing of language in the auditory cortex and biomarkers indexing glutamatergic function. SignificanceOur study did not indicate that a molecular index of glutamatergic function could be a surrogate marker for the early stage of information processing of language in humans.