Saeid Mahmoudian - ENT and Head & Neck Research Center and Department, Iran University of Medical Sciences Hazrate Rasoul Akram Hospital, Neyiayesh St., Sattarkhan Ave., Tehran, Iran
Zohreh Ziatabar Ahmadi - ENT and Head & Neck Research Center and Department, Iran University of Medical Sciences Hazrate Rasoul Akram Hospital, Neyiayesh St., Sattarkhan Ave., Tehran, Iran
Hasan Ashayeri - ENT and Head & Neck Research Center and Department, Iran University of Medical Sciences Hazrate Rasoul Akram Hospital, Neyiayesh St., Sattarkhan Ave., Tehran, Iran
Mohammad Farhadi - ENT and Head & Neck Research Center and Department, Iran University of Medical Sciences Hazrate Rasoul Akram Hospital, Neyiayesh St., Sattarkhan Ave., Tehran, Iran

1. BackgroundThis study aimed to investigate change detection of speech stimuli by means of topographical maps of MMNresponses in normal and cochlear implant (CI) Persian-speaking children.2. MethodTwenty subjects with CI and ten right-handed matched subjects, without visual acuity and neurologicaldisorders, participated in the study. A new auditory paradigm by 64 channels EEG machine was used withthree deviant stimuli (/gam/, /jam/, and /tam/) which differed in the first consonant from a repeated standardword (/dam/).3. ResultsThe results showed that MMN observed in 375-395 ms in fronto-central scalps (ROIs) in all stimuli. A positivemismatch response appeared before MMN only in /tam/ stimuli in 253 ms. In good cochlear implants (CI), Ap-MMR instead of MMN observed in /gam/ stimuli in 219 ms after the onset of stimuli. Also, the coexistenceof p-MMR and MMN acquired in 227 and 375 ms in /tam/ stimuli. In poor cochlear implants, no significantp-MMR and MMN was found in /gam/ stimuli. MMN observed only in /jam/ stimuli. P-MMR observed only in/tam/ in 242 ms. MMN was delayed in this group. The correlation between electrophysiological indexes andbehavioral tests was statistically significant.4. ConclusionsMMN and p-MMR can be used as a powerful electrophysiological index for objective assessment of phonologicalauditory discrimination. The existence of p-MMR in CI children shows immature brain pattern and/orexcessive neural activation to stimuli. In poor CI, MMN shows the involvement of somatosensory processingsites in the processing of complex lingual stimuli.