Cortical Generators and Connections Underlying Phoneme Perception: A Mismatch Negativity and P300 Investigation

Area of Science:

• Neuroscience
• Cognitive Science
• Auditory Perception

Background:

• The neural basis of phoneme perception, specifically the cortical generators of MMN and P300, remains incompletely understood.
• Investigating the interaction between these auditory event-related potentials and speech sound processing is crucial for understanding auditory cognition.

Purpose of the Study:

• To identify the cortical sources and functional connections underlying the mismatch negativity (MMN) and P300.
• To differentiate the neural networks involved in passive versus active speech sound perception.

Main Methods:

• Employed an inattentive (MMN) and attentive (P300) phonemic oddball paradigm in 60 healthy adults.
• Utilized high-density EEG recording with eLORETA source reconstruction and cross-correlation analysis for functional connectivity.

Main Results:

• MMN activation clusters were found in temporal, frontal, and parietal cortices, supporting passive phoneme discrimination via a right temporoparietal to left frontal network.
• P300 activation was prominent in frontal, parietal, and cingulate cortices, with networks connecting parietal, cingulate, and occipital regions for active target detection.
• Both MMN and P300 processing involved predominantly bilateral neural networks.

Conclusions:

• Passive phoneme discrimination relies on a fronto-temporo-parietal network, while active categorization engages fronto-parieto-cingulate cortices.
• Neural processing of phonemic contrasts, as reflected by MMN and P300, shows no significant lateralization to the language-dominant hemisphere.