With neuron input and output counts fixed, 45 three-cell loops were within the exact reference range in 168 human cortex recording graphs

We tested three-cell feedback loops in released human layer 2–3 recording graphs. The main panel had 168 complete epilepsy recording graphs, 1,132 neurons, and 1,123 directed links. We counted every binary graph with the recorded input and output counts at each neuron. The 45 recorded loops were within the exact central 95% reference range of 42–62. The reference mean was 51.92, and the lower-tail fraction was 0.1024. Fixing each graph’s reciprocal pair total gave a mean of 47.33 and a range of 39–56. A control that fixed only each graph’s link total gave a mean of 75.29. An added check found eight three-link loops with no reverse links. Their low reference tails depended on this stricter motif definition. This added result was exploratory. A linear model identity shows why extra reverse links do not remove the three-cell return term. The separate tumor cohort had six loops, within its exact range of 3–9. These are conditional tests of selected slice recordings. They do not show the absence of feedback or a lack of biological cell roles. The package contains source tables, graph masks, exact distributions, code, figures, and repeat instructions.

human cortex · local connectivity · feedback loops · neuron degrees · exact graph counts · conditional graph reference · induced motifs · linear response