The 'F-complex' and MMN tap different aspects of deviance.
OBJECTIVE
To compare the 'F(fusion)-complex' with the Mismatch negativity (MMN), both components associated with automatic detection of changes in the acoustic stimulus flow.


METHODS
Ten right-handed adult native Hebrew speakers discriminated vowel-consonant-vowel (V-C-V) sequences /ada/ (deviant) and /aga/ (standard) in an active auditory 'Oddball' task, and the brain potentials associated with performance of the task were recorded from 21 electrodes. Stimuli were generated by fusing the acoustic elements of the V-C-V sequences as follows: base was always presented in front of the subject, and formant transitions were presented to the front, left or right in a virtual reality room. An illusion of a lateralized echo (duplex sensation) accompanied base fusion with the lateralized formant locations. Source current density estimates were derived for the net response to the fusion of the speech elements (F-complex) and for the MMN, using low-resolution electromagnetic tomography (LORETA). Statistical non-parametric mapping was used to estimate the current density differences between the brain sources of the F-complex and the MMN.


RESULTS
Occipito-parietal regions and prefrontal regions were associated with the F-complex in all formant locations, whereas the vicinity of the supratemporal plane was bilaterally associated with the MMN, but only in case of front-fusion (no duplex effect).


CONCLUSIONS
MMN is sensitive to the novelty of the auditory object in relation to other stimuli in a sequence, whereas the F-complex is sensitive to the acoustic features of the auditory object and reflects a process of matching them with target categories.


CONCLUSIONS
The F-complex and MMN reflect different aspects of auditory processing in a stimulus-rich and changing environment: content analysis of the stimulus and novelty detection, respectively.
Laufer
Ilan
I
Evoked Potentials Laboratory, Technion-Israel Institute of Technology, Gutwirth Building, 3200 Haifa, Israel.
Pratt
Hillel
H
D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D004569:Electroencephalography; D055590:Electromagnetic Phenomena; D004594:Electrophysiology; D005072:Evoked Potentials, Auditory; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007088:Illusions; D008297:Male; D013067:Speech Perception / Q000502:physiology*; D014054:Tomography; D014584:User-Computer Interface