vlt.neuro.vision.contrast.indexes.fitindexes
FITINDEXES - compute contrast fit index values from a response structure
FI = vlt.neuro.vision.contrast.index.fitindexes(RESPSTRUCT, FITTERMS)
RESPSTRUCT is a structure of response properties with fields:
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| Field | Description |
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| curve | 4xnumber of contrasts tested, |
| | curve(1,:) is contrasts tested |
| | curve(2,:) is mean response at each contrast |
| | curve(3,:) is standard deviation at each contrast|
| | curve(4,:) is standard error at each contrast |
| ind | cell list of individual trial responses for each |
| | contrast |
| blankresp | 1x3 vector of mean control response, mean control |
| | response standard deviation, and mean control |
| | response standard error.
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FITTERMS is the number of terms to include in the Naka-Rushton Fit
(R = RM * C.^N/(C.^(N*S)+c50^.(N*S))
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| FITTERMS | Description |
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| 2 | Uses only RM and C50 (N and S are 1) |
| 3 | Uses only RM, C50, and N (S is 1) |
| 4 | Uses RM, C50, N, and S |
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Returns a structure FI with fields:
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| Field | Description |
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| fit_parameters | [RM C50 N S] Naka Rushton fit params |
| | N and S are left off if FITTERMS<3,4 |
| fit | 2x101 matrix; first row is contrasts |
| | 0:0.01:1; second row is fit of |
| | responses for those contrasts |
| r2 | Fit r^2 value |
| empirical_C50 | Empirical fit contrast that gives 50% of|
| | response to 100% contrast (differs |
| | from C50 of the fit b/c max response |
| | is not usually at 100% contrast) |
| relative_max_gain | Relative maximum gain (Heimel et al. |
| | 2005) |
| saturation_index | Saturation index (only meaningful for |
| | fits including S but provided always) |
| sensitivity | 1x10 vector of contrast sensitivity with|
| | criteria of [1 ... 10] standard |
| | deviations of the control response. |
| | If the standard deviation of the |
| | control response is 0, then it is |
| | recalculated assuming the response is |
| | 1 unit on one trial. |
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