Neuro Physiology Scanby Holistica World

Technology & Science

From light at the fingertip to a validated physiological signal.

Photoplethysmography (PPG) measures how much light is absorbed by blood in the microvessels of the fingertip. Each heartbeat pushes a pressure wave into those vessels, so the optical signal rises and falls with every beat. The interval between successive pulse peaks gives pulse rate variability, which under resting conditions closely tracks the heart rate variability measured by ECG.

The physiology

Two branches, two speeds.

The heart is under constant dual control. Vagal (parasympathetic) fibres slow the sinus node within a single beat through acetylcholine acting on fast muscarinic channels. Sympathetic fibres speed it up more slowly, over several seconds, through noradrenaline and cAMP signalling. Because the two branches act at different speeds, their influence appears at different frequencies in the beat-to-beat rhythm. Breathing adds a third rhythm: heart rate rises on inhalation and falls on exhalation (respiratory sinus arrhythmia), almost entirely through vagal modulation. Blood pressure regulation through the baroreflex adds a slower oscillation near 0.1 Hz. Reading these oscillations is the basis of frequency-domain HRV.

The heart-brain link

Why a pulse speaks for the nervous system.

The neurovisceral integration model (Thayer and Lane) describes a network linking the prefrontal cortex, anterior cingulate, amygdala, hypothalamus and brainstem nuclei to the vagal output that sets heart rhythm. Higher resting vagally mediated HRV is associated with better emotional regulation, executive function and stress recovery. This is why a pulse recording can say something about nervous system state, and why we label each report layer by its evidence level.

Evidence levels

Established physiology

Computed with published, standardised HRV methods (Task Force 1996 and later consensus).

Modelled index

Estimated by proprietary algorithms from pulse dynamics; useful for screening and trend tracking, confirmed with the reference test named in the report.

Interpretive framework

Maps measured signals onto Ayurvedic and yogic frameworks for practitioner dialogue, not clinical decisions.

The backend

Inside the processing pipeline.

The device captures and conditions the optical signal. All analysis runs on Holistica's secured cloud, so every clinic receives the same validated algorithms and every improvement reaches every device at once.

  1. Stage 1

    Acquisition

    10-minute seated resting recording at the fingertip after a short settling period.

  2. Stage 2

    Conditioning

    On-device filtering and signal quality scoring; recordings below threshold are flagged for repeat.

  3. Stage 3

    Secure upload

    Encrypted in transit and at rest; patient identity held separately from signal data.

  4. Stage 4

    Beat detection

    Pulse peaks located, artefacts and ectopic beats detected and corrected, clean NN interval series built.

  5. Stage 5

    Analysis

    Time, frequency and nonlinear HRV, pulse morphology and proprietary model layers.

  6. Stage 6

    Report

    18-page structured report with reference bands, evidence labels and practitioner notes.

Analysis methods

What the cloud computes.

Analysis familyMethods appliedReport layer
Time domainMean NN, SDNN, RMSSD, pNN50, HR rangeHRV Analytics, ANS
Frequency domainNN series resampled at 4 Hz, spectral power by Welch periodogram; VLF, LF, HF, total power, normalised units, LF/HFHRV Analytics, ANS, Bioenergy
NonlinearPoincaré SD1 and SD2, detrended fluctuation analysis (DFA α1), sample entropyHRV Analytics, Brain Rhythm
Stress physiologyBaevsky Stress Index from the NN histogram (mode, amplitude of mode, variation range)ANS
Pulse morphologyPulse amplitude and perfusion, second-derivative waveform ratios, reflection timingCellular Health
Model layerProprietary multivariate models trained on paired reference dataBrain Rhythm, Iodine indicator, Ayurvedic & Bioenergy

Data protection

Processing is designed around India's Digital Personal Data Protection Act 2023, with consent capture at the clinic, role-based practitioner access and deletion on request.

Always current

Algorithm and report updates are deployed in the cloud. Clinics never reinstall software to receive a new parameter or a corrected reference band.

Positioning

NPS is a wellness and physiological assessment tool. It does not diagnose, treat or prevent disease and does not replace ECG, EEG or laboratory testing.

References

  1. Task Force of the ESC and NASPE. Heart rate variability: standards of measurement, physiological interpretation and clinical use. Circulation, 1996.
  2. Shaffer F, Ginsberg JP. An overview of heart rate variability metrics and norms. Frontiers in Public Health, 2017.
  3. Nunan D, Sandercock GRH, Brodie DA. A quantitative systematic review of normal values for short-term HRV in healthy adults. PACE, 2010.
  4. Schäfer A, Vagedes J. How accurate is pulse rate variability as an estimate of heart rate variability? International Journal of Cardiology, 2013.
  5. Allen J. Photoplethysmography and its application in clinical physiological measurement. Physiological Measurement, 2007.
  6. Thayer JF, Lane RD. A model of neurovisceral integration in emotion regulation and dysregulation. Journal of Affective Disorders, 2000.
  7. Billman GE. The LF/HF ratio does not accurately measure cardiac sympatho-vagal balance. Frontiers in Physiology, 2013.
  8. Takazawa K et al. Assessment of vasoactive agents and vascular aging by the second derivative of the photoplethysmogram. Hypertension, 1998.
  9. Peng CK et al. Quantification of scaling exponents and crossover phenomena in heartbeat time series. Chaos, 1995.
  10. WHO, UNICEF, ICCIDD. Assessment of iodine deficiency disorders and monitoring their elimination. 3rd edition, 2007.

Experience it

See a live scan.

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