Glossary

Glossary

Domain terms used across golgi and this wiki.

Imaging & segmentation

• µCT (micro-CT) — high-resolution X-ray computed tomography used to image the nerve cross-section that golgi segments and extrudes. See Geometry Import & Segmentation.
• SAM2 — a general-purpose "segment-anything" model used to segment the µCT image and propagate masks through a z-stack (treated as video frames).
• CLAHE — Contrast-Limited Adaptive Histogram Equalization, a local contrast enhancement that helps segment faint structures before the model runs.

Anatomy

• Endoneurium — the connective tissue inside a fascicle, surrounding the axons. Anisotropic (conducts better along the fiber axis). Mesh tag 1.
• Perineurium — the thin, highly resistive sheath around each fascicle. Modeled as a contact-impedance sheet, not a meshed volume. See Conductivity & Tissue Properties.
• Epineurium — the outer connective sheath binding fascicles into the nerve trunk. Mesh tag 5.
• Fascicle — a bundle of axons enclosed by perineurium. A nerve has one or many.
• Branch — a distal division of the nerve trunk (e.g. cardiac, recurrent laryngeal). golgi traces fibers through bifurcations and labels them by branch.

Electrodes

• Cuff electrode — a sleeve placed around the nerve carrying contacts (e.g. LivaNova helical, ring arrays). See Electrodes & Cuff Designer.
• LIFE / TIME — Longitudinal / Transverse Intrafascicular Electrodes: thin contacts inserted into the nerve.
• Polarity — a contact's role: anode, cathode, ground, or off.
• Current fraction — how the stimulus current is split among contacts in a polarity group.
• Current steering — shaping the field by re-weighting multi-contact polarities/fractions.
• Montage — a specific assignment of polarities (e.g. bipolar, tripolar guard).

Field & solver

• Quasi-static / electro-quasistatic — the resistive regime where ∇·(σ∇Vₑ)=0 governs the field.
• Vₑ (extracellular potential) — the potential the cuff produces in tissue; drives the fibers.
• σ (conductivity) — tissue electrical conductivity (S/m); anisotropic for endoneurium and muscle.
• Cole–Cole model — a frequency-dependent dispersion model for tissue permittivity/conductivity.
• IT'IS database — the IT'IS Foundation tissue-property database golgi bundles for σ(f).
• Lead field — the per-contact unit-current field; montages and amplitudes are linear combinations of lead fields. Also used (by reciprocity) for recording.
• Activating function — the second spatial derivative of Vₑ along a fiber; predicts where it's excited.
• Access impedance (Z_access) — the resistance seen at a contact, from a DC dual-solve.
• PLC — Piecewise-Linear Complex: the surface description TetGen tetrahedralizes. See Meshing.
• TetGen / Gmsh — the tetrahedral mesh generators that discretize the model for the FEM solve (Gmsh conformal, with a TetGen fallback). See Meshing.
• Characteristic length (lc) — target element size for a mesh region.

Fibers

• MRG model — the McIntyre–Richardson–Grill double-cable model of a myelinated axon.
• SUNDT — a cable model for unmyelinated C fibers, used for the C-fiber subpopulation.
• PyFibers — the NEURON-based fiber-simulation library golgi uses by default.
• AxonML — an optional GPU surrogate of the MRG model (separately licensed).
• Threshold — the minimum stimulus amplitude that elicits a propagating action potential.
• Recruitment — the fraction of a fiber population activated at a given amplitude.
• Selectivity index (Veraart SI) — (R_target − R_offtarget)/(R_target + R_offtarget), in [−1, 1].
• Conduction velocity (CV) — how fast an action potential propagates (scales with diameter).
• CNAP / ECAP — compound nerve / evoked compound action potential: the population response a cuff records. See Recording & CNAP.

Platform

• Study — the unit of work: a project directory plus the golgi.Study API over it.
• Design — one electrode geometry on the nerve. Config — one polarity/current montage for a design.
• Study bundle — a hashed, replayable archive of an entire study. See Reproducible Study Bundles.
• Replay — re-hashing (or re-running) a bundle to verify it reproduces.
• Lead-field basis — the cached set of per-contact lead fields enabling fast steering/sweeps.

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See also

Pipeline Overview · Finite-Element Solver · Fiber Models & Activation · Electrodes & Cuff Designer