SEEG shaft direction did not predict visual-percept current within patients, but steep shafts were rare

In 16 patients with stereo-electroencephalography (SEEG), we tested whether the direction of a stimulated shaft predicted the reported current that caused a visual percept. The analysis used 57 shafts and 112 visual-percept stimulations from OpenNeuro ds005169. Within each patient, shaft-level mean log2 current and absolute scanner-axis components of shaft direction were centred on the patient mean; significance was assessed with 10,000 within-patient permutations. We found no association for left-right alignment (Spearman rho = -0.02, p = 0.91), up-down alignment (rho = -0.06, p = 0.73), or front-back alignment (rho = -0.03, p = 0.84); Holm-adjusted p = 1.00 for all three. Stimulation-level and lateral-position sensitivity analyses were also not significant. The reported current was not a measured threshold, and effects with |rho| below about 0.3 cannot be excluded. Most shafts pointed left-right (median |u_x| = 0.90), so steep and front-back shafts were rare. Coordinates were native scanner axes, not aligned to cortex; an effect for rare shaft directions is not excluded.

stereo-electroencephalography · SEEG · cortical stimulation · visual percepts · shaft direction · current · within-patient analysis · permutation test