At an assumed 0.5 ms relay delay, inhibition could not halve excitation in six of ten mouse V1 linear triplet models

We tested whether synaptic route timing and fitted voltage shapes permit a half-peak response limit. We rebuilt 25 three-cell route patterns from Allen Synaptic Physiology r2.1. Ten had accepted same-bin voltage fits for direct excitation and relay inhibition at the target. Targets included one known excitatory cell, six inhibitory cells and three untyped cells. Each model assumed one relay spike 0.5 ms after its input began and a fixed linear voltage sum. In six models, excitation crossed half height before inhibition started. No finite later inhibitory scale could meet the half-peak limit. Three of these six still had inhibitory onset before the excitatory peak. The other four models required inhibitory-to-excitatory peak ratios from 0.504 to 0.994. With shapes fixed and an added onset error bound of plus or minus 0.1 ms per edge, five models remained impossible and two remained feasible. We supply the pointwise bound, circuit thresholds, scalar source facts, code, checks, figures and repeat instructions. These are conditional model results from nine selected slice recordings. Relay recruitment was not measured. Linear voltage addition omits shunting and state changes. The counts do not estimate the prevalence of suppression in V1.

feedforward inhibition · synaptic timing · causal bound · multipatch recordings · mouse visual cortex · linear voltage model · response templates · reproducibility