How Do The Neural Oscillations In The Left Inferior Frontal Gyrus (Broca's Area) And The Posterior Middle Temporal Gyrus (Wernicke's Area) Differ In Their Phase-locking Values And Cross-frequency Coupling Patterns When Native English Speakers Process Words With Sound Symbolism, Such As 'buzz' And 'sizzle', Versus Words With Arbitrary Sound-meaning Mappings, Such As 'dog' And 'chair'?

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When processing words with sound symbolism (e.g., 'buzz', 'sizzle') versus arbitrary words (e.g., 'dog', 'chair'), neural oscillations in Broca's and Wernicke's areas exhibit distinct patterns in phase-locking values (PLV) and cross-frequency coupling:

Broca's Area (Left Inferior Frontal Gyrus)

  • Phase-Locking Values (PLV):

    • Higher PLV in gamma (30-100 Hz) and beta (13-30 Hz) bands for sound symbolic words. Gamma oscillations are linked to sensory and phonological processing, while beta is associated with motor and speech production, reflecting the sound-meaning connection.

  • Cross-Frequency Coupling:

    • Increased beta-gamma coupling, indicating integration of motor and sensory processing, as sound symbolic words may engage both phonological and motor-related circuits.

Wernicke's Area (Posterior Middle Temporal Gyrus)

  • Phase-Locking Values (PLV):

    • Higher PLV in theta (4-8 Hz) and alpha (8-12 Hz) bands for arbitrary words, associated with semantic processing and memory retrieval.
    • For sound symbolic words, higher PLV in gamma band, reflecting sensory processing tied to sound-meaning integration.

  • Cross-Frequency Coupling:

    • Theta-alpha coupling for arbitrary words, supporting standard semantic processing.
    • Theta-gamma coupling for sound symbolic words, integrating semantic processing with sensory information from sound symbolism.

Summary

Sound symbolic words evoke higher gamma and beta PLV in Broca's area and theta-gamma coupling in Wernicke's area, indicating enhanced phonological and semantic integration. Arbitrary words show higher theta and alpha PLV in Wernicke's area, reflecting standard semantic processing. These patterns suggest that sound symbolic words engage both phonological and semantic processing more intensely, leveraging sound-meaning connections.