An exploratory pilot study tested whether speech prosody can serve as a biosignal to measure stress reduction. Thirty participants were split into three groups: guided mindfulness meditation, a vibroacoustic intervention, or a control. Each read a text aloud before and after a single 20-minute session. Acoustic-prosodic analysis of the sixty readings showed that both intervention groups spoke with a breathier vocal quality in the second reading, indicating relaxation, while the control group's speech became tenser and less variable in loudness. The findings suggest that speech prosody is a sensitive biomarker for classifying treatment effects and evaluating relaxation outcomes.
The natural visibility graph method (NVGM) builds complex networks from time series, but earlier work overlooked conditions where the system deviates from ordinary ergodicity due to turbulent events with an inverse power law index μ ranging from 1 to ∞. For 2 < μ < 3, the non-ergodic signal becomes nearly indistinguishable from fractional Gaussian noise (FGN). Using diffusion entropy analysis (DEA) with stripes reveals that meditation significantly reduces the scaling δ. NVGM generates a homogeneous network. The analysis distinguishes sick from healthy patients: in healthy patients, stripes leave δ virtually unchanged, while in sick patients, stripes yield a significantly lower δ, suggesting their heartbeats contain an FGN contribution.
Normal waking consciousness requires a balance between global integration (long-distance brain interactions) and segregation (local processing). Altered states, such as anesthesia, tip this balance. Using electrocorticography (ECoG) in a monkey under ketamine or propofol anesthesia, the study examined band-specific synchronization across the whole brain and within localized clusters. Both anesthetics caused a loss of long-range integration in multiple frequency bands, most pronounced in beta (13-30 Hz) and low-gamma (30-80 Hz) bands, while local synchrony was strongly preserved in all bands. This demonstrates a shift away from the integration/segregation equilibrium at sub-second time scales.