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Interdisciplinary Glossary and Academic References

Standardized Terminology Across Computational Neuroscience, Psychotherapy, and Clinical Engineering

Because the Digital Mirror synthesizes methods from computational neuroscience, philosophy of mind, affective computing, and third-wave psychotherapy, this glossary provides standardized definitions for the clinical, biological, and architectural terms used across the portal.

1. Cortical and Spectral Neurotelemetry

  • Alpha-Band Phase Synchrony (8–13 Hz): A measure of phase consistency across electrode pairs (ranging from 0 to 1), calibrated against the participant's resting baseline to track network coherence and synchronization shifts.
  • Aperiodic 1/f Spectral Exponent (χ): The power-law decay slope of the non-oscillatory EEG background spectrum fitted in log₁₀–log₁₀ frequency-power space (2–40 Hz, excluding the alpha peak). Flatter slopes (lower χ) index an elevated cortical excitation–inhibition (E:I) ratio and heightened neural excitability, whereas steeper slopes (higher χ) index increased GABAergic inhibition.
  • Default Mode Network (DMN): A large-scale cortical network active during internally directed cognition, autobiographical memory retrieval, self-referential thought, and maladaptive rumination.
  • Focus Index — log(β/θ): The symmetric log-ratio of frontal Beta power (13–30 Hz, indexing active external attentional engagement) to frontal Theta power (4–8 Hz, indexing internal processing or drowsiness).
  • Frontal Alpha Asymmetry (FAA): The natural logarithm difference between right and left anterior alpha power: ln(PRight) − ln(PLeft) in the 8–13 Hz band. Because cortical alpha power is inversely related to regional cortical activation, positive FAA values index left-frontal approach motivation, whereas negative values index right-frontal withdrawal and avoidance valence.
  • High-Beta Band (20–30 Hz): The upper sub-band of frontal beta activity, frequently elevated during cognitive tension, hypervigilance, and anxious rumination.
  • Individual Alpha Frequency (IAF): The subject-specific center-of-gravity peak frequency within the 8–13 Hz alpha band (measured in Hz), indexing individual differences in thalamocortical processing speed and cognitive readiness.
  • Sensorimotor Rhythm (SMR, 12–15 Hz): A low-beta oscillatory rhythm recorded over sensorimotor and anterior regions that indexes calm physical stillness paired with alert mental focus.
  • Shannon Spectral Entropy (Hs): A normalized information-theoretic measure (0–1) of how evenly spectral power is distributed across the 1–45 Hz power spectral density (PSD). High values reflect broadband desynchronized cortical complexity, whereas low values reflect narrowband oscillatory locking.
  • Task Positive Network (TPN): The large-scale cortical network engaged during externally focused, goal-directed, and cognitively demanding tasks, operating in dynamic reciprocity with the Default Mode Network.

2. Psychotherapy, Philosophy of Mind, and Psychometrics

  • Acceptance and Commitment Therapy (ACT): A third-wave cognitive behavioral therapy that uses acceptance, mindfulness, and cognitive defusion strategies to increase psychological flexibility rather than attempting to suppress or eliminate distressing internal experiences.
  • Cognitive Defusion: The therapeutic process of stepping back from internal verbal narratives so that thoughts are observed as transient neurophysiological and psychological events rather than literal truths dictating behavior.
  • Cognitive Fusion: The psychological state in which an individual becomes entangled with their internal narrative, treating thoughts and evaluations as objective reality.
  • Concealment Burden: The cumulative emotional, cognitive, and autonomic cost of actively suppressing or withholding distressing personal material due to evaluative shame or anticipated judgment.
  • Disclosure Readiness: A pre-session psychometric dimension indexing the participant's current willingness and perceived safety to engage with vulnerable autobiographical material without triggering acute defensive shutdown.
  • Phenomenal Self-Model (PSM): Thomas Metzinger's neuro-philosophical model of the conscious self as an ongoing, internally generated representational simulation produced by the central nervous system.
  • Phenomenological Transparency vs. Opacity: A representational state is transparent when the brain cannot recognize it as an internal model—causing the subject to look through the thought as if it were direct reality. It becomes opaque when the subject recognizes the representation as a representation, restoring metacognitive distance.
  • Predictive Processing (Predictive Coding): A computational neuroscience framework in which the brain functions as a hierarchical hypothesis-testing engine that continuously generates top-down predictions and updates its internal models to minimize bottom-up sensory and interoceptive prediction errors.

3. Somatic, Autonomic, and Acoustic Biomarkers

  • Biomechanical Visemes: Sub-graduated visual speech articulation states (mapping jaw kinematics, dental fricatives, and vowel formants from real-time audio envelopes) used to drive natural, low-latency lip synchronization on the reflective digital avatar.
  • Eye Aspect Ratio (EAR): A scale-invariant geometric ratio derived from 3D periocular facial landmarks that continuously tracks eyelid aperture and blink dynamics to distinguish sustained ocular closure from natural micro-blinks and verify eyes-open/eyes-closed protocol adherence.
  • Facial Action Coding System (FACS): An anatomically based taxonomy of facial muscle movements (Action Units, such as AU4 Brow Lowerer, AU6+12 Duchenne Zygomaticus, and AU15+17 Lip Corner Depressor / Chin Raiser) quantified against rolling subject-relative baselines to index implicit somatic affect.
  • Heart Rate Variability (RMSSD): The root mean square of successive differences between normal inter-beat intervals (measured in milliseconds), serving as a real-time biomarker of parasympathetic vagal tone and autonomic regulation.
  • Prosodic Onset Latency and Turn-Taking Dynamics: Parallel acoustic biomarkers measuring the temporal delay between a prompt and participant vocal onset, speech silence cadences, and spontaneous conversational turn-taking.

4. Clinical Engineering, Governance, and Statistical Rigor

  • Benjamini-Hochberg False Discovery Rate (FDR): A statistical multiple-hypothesis correction procedure applied across spectral and somatic metrics during craniofacial artifact benchmarking to control the expected proportion of false-positive discoveries.
  • Client-Side Authenticated Encryption (Zero-Access Vault): A local storage architecture utilizing authenticated AES-GCM symmetric encryption and asymmetric PGP keys held exclusively on the workstation—paired with automated idle-session lockouts—ensuring that raw participant records cannot be accessed without investigator authentication.
  • Clinical AI Red-Teaming: Structured adversarial stress-testing of the localized copilot against safety boundaries—verifying 100% refusal of medical diagnosis and pharmacology, crisis escalation compliance, non-reinforcement of delusional content, and immunity to prompt injection.
  • Cold Path / Hot Path ("Therapist-in-Control") Governance: The core safety architecture separating pre-session human clinician protocol authoring and approval (Cold Path) from live, sentinel-monitored biofeedback execution under human supervisory triage (Hot Path).
  • Lab Streaming Layer (LSL): A sub-millisecond network and hardware time-synchronization protocol used to align heterogeneous time series (256 Hz raw EEG, 30 Hz somatic computer vision, autonomic telemetry, and event markers) onto a unified master clock.
  • Local Named Entity Recognition (NER) De-Identification: An automated, air-gapped natural language processing pipeline that detects and scrubs personally identifiable information (names, dates, locations, and identifiers) from session transcripts prior to research archiving.

5. Foundational Academic References

  1. Allen, J. J. B., Keune, P. M., Schönenberg, M., & Nusslock, R. (2018). Frontal EEG alpha asymmetry and emotion: From neural underpinnings and methodological considerations to psychopathology and social cognition. Psychophysiology, 55(1), e13028.
  2. Davidson, R. J. (2004). What does the prefrontal cortex "do" in affect: Perspectives on frontal EEG asymmetry research. Biological Psychology, 67(1–2), 219–234.
  3. Donoghue, T., Haller, M., Peterson, E. J., Varma, P., Sebastian, P., Gao, R., ... & Voytek, B. (2020). Parameterizing neural power spectra into periodic and aperiodic components. Nature Neuroscience, 23(12), 1655–1665.
  4. Ekman, P., & Friesen, W. V. (1978). Facial Action Coding System: A Technique for the Measurement of Facial Movement. Consulting Psychologists Press.
  5. Friston, K. (2010). The free-energy principle: A unified brain theory? Nature Reviews Neuroscience, 11(2), 127–138.
  6. Gao, R., Peterson, E. J., & Voytek, B. (2017). Inferring synaptic excitation/inhibition balance from field potentials. NeuroImage, 158, 70–78.
  7. Hayes, S. C., Strosahl, K. D., & Wilson, K. G. (2012). Acceptance and Commitment Therapy: The Process and Practice of Mindful Change (2nd ed.). Guilford Press.
  8. Iftikhar, Z., Xiao, A., Ransom, S., & Huang, J. (2025). Therapy as an NLP task: Psychologists' comparison of LLMs and human peers in CBT and ACT boundaries. arXiv / Clinical AI Safety Benchmark.
  9. Inouye, T., Shinosaki, K., Sakamoto, H., Toi, S., Ukai, S., Iyama, A., ... & Hirano, M. (1991). Quantification of EEG irregularity by use of the entropy of the power spectrum. Electroencephalography and Clinical Neurophysiology, 79(3), 204–210.
  10. Metzinger, T. (2003). Being No One: The Self-Model Theory of Subjectivity. MIT Press.