Abstract
Mismatch negativity (MMN) is an N-methyl-D-aspartic acid-mediated component and thus has been widely considered a major candidate biomarker of schizophrenia. However, at present, no direct evidence has linked the MMN response and aberrant salience processing reported in schizophrenia patients, i.e., whether MMN represents empirical salience of the deviant stimulus. To test the eligibility of the MMN response as a biomarker of schizophrenia, we hypothesized and verified that the MMN in the rat auditory cortex encodes empirical salience, which depends on both empirical rarity of sound and association of sound with salient events through classical conditioning. We exposed rats to sound or appetitive or aversive classical conditioning and extinction training of aversive conditioning, then recorded MMN from the auditory cortex. We focused on the frequency-dependent asymmetry of the MMN amplitude; increment frequency changes elicit asymmetrically larger MMN amplitudes than do decremental frequency changes. We found that sound exposure reversed this asymmetry in rats, indicating that MMN encodes the empirical rarity of deviant sounds. The MMN amplitude was larger in the appetitive or aversive classical conditioning groups, and smaller after extinction training following aversive conditioning. These results indicate that the MMN response reflects the empirical salience of sound. The present work first linked MMN with empirical salience processing and expands the possibilities of MMN as a strong clinical biomarker of schizophrenia.
Highlights
Since its first description in 1978, the mismatch negativity (MMN) response has been widely investigated in the context of the memory-based deviance detection system
We hypothesized that the MMN response in the rat auditory cortex encodes the empirical salience of sound, which depends on both the (i) empirical rarity of sound and (ii) association of sound with salient events through classical conditioning
We examined whether MMN encodes empirical salience, which depends on both the (i) empirical rarity of sound and (ii) association of the sound with salient events through classical conditioning
Summary
Since its first description in 1978, the mismatch negativity (MMN) response has been widely investigated in the context of the memory-based deviance detection system. MMN is a component of the auditory evoked potential (AEP) and occurs in response to a deviant stimulus embedded within repetitive standard stimuli (Näätänen et al, 1978). Empirical Salience of Sounds Represented by MMN signal, enhanced MMN, supporting the view that MMN is not fully mediated by adaptation but reflects an experiencedependent deviance detection system (Menning et al, 2002; Kujala et al, 2003; Näätänen et al, 2007). Despite numerous studies using discrimination learning, few have applied classical conditioning of a particular sound and investigated what kind of sound information is represented in MMN
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
