Left hemispheric dipole locations of the neuromagnetic mismatch negativity to frequency, intensity and duration deviants.
ABSTRACT The aim of the current study was to differentiate the sources of neuromagnetic mismatch negativity (MMNm) to deviants of different features. For this purpose, the MMNm of twenty-one healthy subjects (seven males) were recorded left-hemispherically. Subjects were stimulated monaurally in an oddball paradigm with standard tones of 1000 Hz and three different kinds of mismatch tones (frequency, duration and intensity deviants). Data analysis revealed mean MMNm dipole locations anterior, inferior and more medial than the N100m dipoles. The mean difference between the N100m and MMNm dipoles was in the range of up to 6 mm in one dimension. The dipole locations of all three kinds of deviants differed significantly from each other. The MMNm dipoles of both frequency and duration deviants were found to be significantly inferior to the corresponding source of intensity deviants, while the MMNm dipoles of duration and frequency deviants significantly differed in anterior-posterior direction. This differentiation between sources emphasizes the importance of feature analysis in MMN(m) generation.
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ABSTRACT: Multiple risk factors can affect the development of specific reading problems or dyslexia. In addition to the most prevalent and studied risk factor, phonological processing, also auditory discrimination problems have been found in children and adults with reading difficulties. The present study examined 37 children between the ages of 5 and 6, 11 of which had multiple risk factors for developing reading problems. The children participated in a passive oddball EEG experiment with sinusoidal sounds with changes in sound frequency, duration, or intensity. The responses to the standard stimuli showed a negative voltage shift in children at risk for reading problems compared to control children at 107-215ms in frontocentral areas corresponding to P1 offset and N250 onset. Source analyses showed that the difference originated from the left and right auditory cortices. Additionally, the children at risk for reading problems had a larger late discriminative negativity (LDN) response in amplitude for sound frequency change than the control children. The amplitudes at the P1-N250 time window showed correlations to letter knowledge and phonological identification whereas the amplitudes at the LDN time window correlated with verbal short-term memory and rapid naming. These results support the view that problems in basic auditory processing abilities precede the onset of reading instruction and can act as one of the risk factors for dyslexia.International journal of psychophysiology: official journal of the International Organization of Psychophysiology 04/2014; · 3.05 Impact Factor
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ABSTRACT: The Mismatch Negativity (MMN) is an event-related potential (ERP) sensitive to early auditory deviance detection and has been shown to be reduced in schizophrenia patients. Moreover, MMN amplitude reduction to duration deviant tones was found to be related to functional outcomes particularly, to neuropsychological (working memory and verbal domains) and psychosocial measures. While MMN amplitude is thought to be correlated with deficits of early sensory processing, the functional significance of MMN latency remains unclear so far. The present study focused on the investigation of MMN in relation to neuropsychological function in schizophrenia. Forty schizophrenia patients and 16 healthy controls underwent a passive oddball paradigm (2400 binaural tones; 88% standards [1 kHz, 80 db, 80 ms], 11% frequency deviants [1.2 kHz], 11% duration deviants [40 ms]) and a neuropsychological test-battery. Patients were assessed with regard to clinical symptoms. Compared to healthy controls schizophrenia patients showed diminished MMN amplitude and shorter MMN latency to both deviants as well as an impaired neuropsychological test performance. Severity of positive symptoms was related to decreased MMN amplitude to duration deviants. Furthermore, enhanced verbal memory performance was associated with prolonged MMN latency to frequency deviants in patients. The present study corroborates previous results of a diminished MMN amplitude and its association with positive symptoms in schizophrenia patients. Both, the findings of a shorter latency to duration and frequency deviants and the relationship of the latter with verbal memory in patients, emphasize the relevance of the temporal aspect of early auditory discrimination processing in schizophrenia.PLoS ONE 04/2014; 9(4):e84536. · 3.53 Impact Factor