An average-to-Cz reference mixture reversed the ON-minus-OFF 13–30 Hz C3/C4 squared imaginary coherency contrast between positive endpoints in ds002778 v1.0.5 sub-pd13 with fixed windows

We made a tool to bound squared imaginary coherency over constant mixtures of the 32-channel average and Cz EEG references. The same mixture weight was used in both visits. We tested C3/C4 at 13 through 30 Hz in OpenNeuro ds002778 v1.0.5. A fixed window screen retained six ON/OFF pairs. In sub-pd13, both endpoint contrasts were positive. A mixture with Cz weight 0.1875 gave a negative contrast of -0.00155802. Both signs occurred in four pairs; endpoint tests detected them in three. The method gives outer bounds and attained point enclosures at tolerance 1e-6 for a fixed coefficient model. All six planned settings, a 1e-7 check, independent numerical checks, code, source hashes, Fourier data, and both raw sub-pd13 records are preserved. Results depend on the window and band rules. They do not establish a medication effect or a direct brain connection.

EEG · imaginary coherency · reference choice · spectral analysis · interval bounds · Parkinson disease · C3/C4