Distributed neural representations of phonological features during speech perception.

Area of Science:

• Neuroscience
• Auditory Perception
• Speech Processing

Background:

• The human auditory system maps acoustic signals to speech sound representations.
• Phonemes are fundamental speech units, but their neural basis and lateralization are debated.
• Frontal-motor cortex roles in speech and auditory cortex lateralization require further investigation.

Purpose of the Study:

• Investigate distributed brain activation patterns for speech sound perception.
• Examine the relationship between acoustic similarity and neural representations of phonemes.
• Determine the role of auditory cortex in representing phonological features.

Main Methods:

• Functional magnetic resonance imaging (fMRI) and multivoxel pattern analysis.
• Analysis of neural activity during incidental listening to 16 English consonant phonemes.
• Correlation of brain activity with perceptual similarity derived from multidimensional scaling.

Main Results:

• Neural activity in bilateral anterior superior temporal gyrus correlated with perceptual similarity.
• Representations of voicing, manner, and place of articulation were distributed in the superior temporal cortex.
• Left hemisphere showed stronger pattern information for place of articulation, but not voicing or manner.

Conclusions:

• Auditory cortex plays a key role in representing phonological features of speech.
• Phoneme representations are widely distributed across bilateral auditory cortex.
• Evidence suggests moderate left-lateralization for place of articulation processing in the auditory cortex.