Signature Patterns for Top-Down and Bottom-Up Information Processing via Cross-Frequency Coupling in Macaque Auditory...

Area of Science:

• Neuroscience
• Computational Neuroscience
• Auditory Neuroscience

Background:

• Predictive coding theory explains sensory processing via top-down and bottom-up interactions.
• Differences in message passing (linear feedforward errors vs. nonlinear feedback predictions) are theorized.
• It is unknown if these theoretical differences manifest in brain cross-frequency interactions.

Purpose of the Study:

• To investigate bidirectional cross-frequency coupling in the macaque auditory hierarchy.
• To determine if distinct patterns exist for top-down versus bottom-up information processing.
• To test the consistency of these patterns across coupling types and stimuli.

Main Methods:

• Examined bidirectional cross-frequency coupling in four sectors of the macaque auditory cortex.
• Utilized phase-amplitude coupling (PAC) and amplitude-amplitude coupling (AAC) measures.
• Analyzed responses to both natural and synthetic auditory stimuli.

Main Results:

• Distinct patterns of cross-frequency interactions were observed for bottom-up and top-down processing.
• Top-down processing predominantly involved low-to-low-frequency (theta, alpha, beta) and low-frequency-to-high-gamma couplings.
• Bottom-up processing predominantly involved low-frequency-to-low-gamma couplings.
• These patterns were consistent across PAC, AAC, and stimulus types.

Conclusions:

• Cross-frequency interactions exhibit distinct characteristics for top-down and bottom-up auditory information flow.
• Low-frequency modulation of gamma rhythms is crucial for bidirectional information transfer.
• Findings support the predictive coding framework and suggest nonlinearities in feedforward processing.