Phase-Amplitude Coupling Reflects Functional Cortical Engagement During Dynamic and Static Motor Tasks Publisher



Sajadi SS ; Keihani A ; Karbasi F ; Fathollahi MA ; Nafissi S ; Azizi E ; Jafari AH
Source: 32nd National and 10th International Iranian Conference on Biomedical Engineering, ICBME 2025 Published:2025

Abstract

Phase-amplitude coupling (PAC) links slow oscillatory phases with fast rhythmic amplitudes, offering insight into hierarchical brain coordination during movement. We investigated PAC across cortical regions during static and dynamic hand and foot contractions in fifteen healthy adults using EEG. PAC was quantified with the modulation index and validated through surrogate testing across 24 electrodes spanning frontal, premotor, motor, and occipital regions. Results revealed distinct task- and effector-specific coupling patterns. Static tasks were dominated by beta-gamma PAC (phase 18-20 Hz; amplitude 65-70 Hz) in contralateral motor and premotor regions, reflecting sustained force control. Dynamic tasks elicited stronger theta-gamma PAC (phase 68 Hz; amplitude 5 5 - 6 0 H z), particularly in motor (M I=0. 8 2 ± 0.12) and premotor (MI=0.84 ± 0.13) areas (p<0.01), consistent with sequencing and planning demands. Occipital theta-gamma PAC increased selectively during dynamic hand movements, indicating visuomotor integration, while foot tasks engaged mainly midline motor regions. Repeated-measures ANOVA showed significant main effects of Region (F=18.72, pvalue <0.001) and Task (F=6.85, p-value =0.001), confirming stronger coupling during dynamic versus static movements. These findings delineate the spectral and spatial organization of motor PAC, highlighting its role in flexible motor control can be interpreted as preliminary but suggestive of reproducible cortical engagement patterns relevant to motor neuroscience and neurological disorders. © 2025 IEEE.