Folding/Measurements

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Folding Measurements

Unless otherwise noted, all measurements are viewed with Auto Scale Percentage (2-98), the PSYCH-NO-NONE palette, and interpolate enabled.

The measurements are taken on the right hemisphere fiducial surface from the Colin Atlas in 711-2B stereotaxic space.

Principal Curvature k1

Principal Curvature k2

Mean Curvature (H)

H = (k1 + k2) / 2.0

Gaussian Curvature (K)

K = k1 * k2

Intrinsic Curvature Index (ICI)

ICI = MAX(K, 0)

Negative Intrinsic Curvature Index (NICI)

NICI = MIN(K, 0)

Gaussian L2 Norm (GLN)

GLN = K * K

Absolute Intrinsic Curvature Index (AICI)

AICI = ABS(K)

Mean Curvature Index (MCI)

MCI = MAX(H, 0)

Negative Mean Curvature Index (NMCI)

NMCI = MIN(H, 0)

Mean L2 Form (MLN)

MLN = H * H

Absolute Mean Curvature Index (AMCI)

AMCI = ABS(H)

Folding Index (FI)

FI = ABS(K1) * (ABS(K1) - ABS(K2))

Curvedness Index (CI)

CI = SQRT((k1*k1 + k2*k2) / 2.0)

Shape Index (SI)

SI = (2.0 / PI) * ATAN((k1 + k2) / (k2 - k1))

Area Fraction of Intrinsic Curvature Index (FICI)

FICI = if (K > 0) then 1, else 0

Viewed with Auto Scale

Area Fraction of Negative Intrinsic Curvature Index (FNICI)

FNICI = if (K < 0) then 1, else 0

Viewed with Auto Scale

Area Fraction of Mean Curvature Index (FMCI)

FMCI = if (H > 0) then 1, else 0

Viewed with Auto Scale

Area Fraction of Negative Mean Curvature Index (FNMCI)

FNMCI = if (H < 0) then 1, else 0

Viewed with Auto Scale

SH2SH

SH2SH = MLN / AMCI = (H * H) / ABS(H)

SK2SK

SK2SK = GLN / AICI = (K * K ) / ABS(K)

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