Meditation EEG Reveals a Distinctive Theta-Beta Anticorrelation: A Single-Subject Case Study

We report a single-subject anomaly in a 24-subject meditation EEG dataset (OpenNeuro ds001787). One subject (sub-017, labeled novice) showed a combination of three features not observed in any other subject: 1. The highest mean anchor score (0.184), a model-free metric of bimodal theta structure2. The strongest negative correlation between theta and beta band power over time (r = -0.64)3. The second-highest temporal variability of the anchor score (std = 0.110) Two subjects showed partial matches: sub-010 (expert) showed a weak negative theta-beta correlation (r = -0.17) with high anchor score; sub-022 (novice) showed a moderate negative correlation (r = -0.30) but very low anchor score (0.027). No other subject showed all three features simultaneously. Band composition analysis showed that the anchor score fluctuations in sub-017 were not accompanied by changes in total delta, theta, alpha, or beta power. Only the internal structure of the theta band changed, not the overall spectral energy. This excludes mind wandering, emotional arousal, and sleep onset as explanations. The available data cannot determine whether this signature reflects a transient state, a stable trait, or a specific contemplative stage. No behavioral or phenomenological data was collected from this subject. The signature is reported as an observation, not as a diagnosis or categorical label. The anchor score method and its implementation are retained as a commercial asset. Commercial applications require a separate license agreement.