SEEG stimulation position showed no detected within-patient difference by visual percept label in 9-patient tests

This analysis asked whether, within a patient, SEEG stimulation sites associated with colour or dynamic visual percepts differ in position from sites associated with non-colour or static percepts. The planned complex-versus-elementary anterior-axis comparison was not possible: among 112 stimulations, 95 were coded elementary only, 1 complex only, none both, and 16 neither. Three tests were then specified before calculating effects: anterior coordinate (colour minus non-colour; primary), superior coordinate (colour minus non-colour), and absolute lateral coordinate (dynamic minus static). The analysis used 112 stimulation pairs from 20 patients, with pair midpoints in native ScanRAS coordinates; seven missing contacts were estimated by fitting positions along their shaft. Each test included only unambiguously labelled events and patients with both labels, leaving 9 patients per test. Mean differences were +2.3 mm (anterior, 6/9 positive; exact sign-flip p=0.75; within-patient permutation p=0.69; Holm p=0.75), -5.0 mm (superior, 3/9 positive; p=0.19, 0.19, 0.56), and -3.9 mm (absolute lateral, 4/9 positive; p=0.27, 0.34, 0.56). No test detected a difference. This small sample does not establish that effects are absent; with nine patients, only large and consistent effects are detectable. Coordinates are native to scans and may have different axis tilts between patients; percept labels are curator codes from patient reports; the tests do not control for stimulation current or white-matter position. No iEEG samples were used.

SEEG · visual perception · cortical stimulation · electrode position · intracranial EEG · within-patient analysis · percept labels