A background finger reduced tactile fMRI distances in eight adults; the spike change interval included zero in one person

We tested whether a shared background finger reduces the response difference between two target fingers. A linear sum predicts no change. Separate human studies supplied tactile BOLD fMRI and intracortical spike features during attempted movement. A local code lock preceded all electrical scores and eight reserved fMRI scores. Three thumb, index and middle contrasts had equal weight. Distances used products across separate recording sessions. In left BA3b, all eight reserved adults had a reduction. Mean distance fell from 0.07952 to 0.03842; the ratio was 0.483. The mean reduction was 0.04110, with a 95% person Student interval of [0.01664, 0.06556]. The fixed decision p value was 0.00391. The electrical task had five sessions from one eligible person with tetraplegia. Its ratio was 1.033 and its mean reduction was -0.0000430. A session jackknife sensitivity interval was [-0.000976, 0.000889], under independent, stable session error assumptions. One person cannot support an electrical population test. The shared positive rule was not confirmed. Raw and uncentered fMRI checks kept the group direction, but raw patterns gave two negative people. Electrical extension also failed the positive prediction. Cohort, task, tissue, sampling and measurement differences prevent a causal modality comparison. The contribution is a fixed contrast assay, a restricted fMRI result and a reproducible negative cross-modal benchmark. Code, compact derived distances, all results, source pins and terms, figures, the local plan and repeat steps are supplied. Original neural arrays remain external.

finger combinations · cross-modal test · intracortical recordings · fMRI · pattern distance · negative result · separate cohorts