Distinguished Lecture Series: Risto Näätänen (Helsinki/Tartu/Århus)
There is an urgent need for biomarkers that could help clinicians reliably to identify individuals in clinically at-risk-populations who are most likely to convert to psychosis in the near future. Very recently, several different electrophysiological studies unanimously showed that the auditory mismatch negativity (MMN), an automatic change-detection response to any detectable auditory change, is this biomarker long sought for. These studies unanimously demonstrated that the MMN peak amplitude is considerably attenuated in particular in response to duration changes in a stream of repetitive homogeneous tone pips while the patient´s attention is directed elsewhere, for example, to an interesting movie presented on a video screen. This MMN deficit which is further enhanced by using double deviants (deviant stimuli differing from the repetitive, standard stimuli both in duration and frequency) is mainly accounted for by the deficient functioning of the N-methyl-d- Aspartate (NMDA) receptor system essential for the formation of memory traces at different levels of environmental representations and can therefore account for cognitive decline, a core element of the pathology involved in schizophrenia.
Risto Näätänen
Inst. for Psychology, University of Tartu, Tartu, Estonia
Center of Functionally Integrative Neurosciences (CFIN),
University of Århus, Århus, Denmark
