Frontal brain oscillatory coupling among men who vary in salivary testosterone levels

Recent studies suggest that cross-frequency coupling supports the integration of distinct neuronal oscillatory modes. In particular, spectral coupling between slow-wave delta and fast-wave beta oscillations may reflect subcortical–cortical interactions. Prior experiments have shown that delta–beta coupling appears to be sensitive to steroid hormone patterning. We attempted to extend this hypothesis by examining the relation between delta–beta EEG spectral coupling and endogenous testosterone measures in men. We collected resting regional brain electrical (EEG) activity and salivary testosterone from 34 healthy young adult males (M age = 24 years). Males with high testosterone showed non-significant delta–beta coupling (delta–beta decoupling), while males with low testosterone exhibited significant delta–beta coupling. These relations were only found for the frontal brain region. There was also a significant group difference in the magnitude of coupling, but no differences in absolute delta and beta power. Findings are discussed in terms of emerging evidence relating steroid hormones to cross-frequency spectral coupling and directions for future work.