What resolves this contention: Sign of the net L4→L5 effect in vivo (suppressio…

What resolves this contention: Sign of the net L4→L5 effect in vivo (suppression via translaminar inhibition vs. expectation of net excitation from monosynaptic E→E paired-recording data); methodology and behavioral state differ. / In awake mouse S1, optogenetic activation of L4 directly SUPPRESSES L5 firing via deep fast-spiking inhibition, sharpening L5 spatial representations — at odds with a purely excitatory L4→L5 feedforward path. / In mouse C2 barrel column paired recordings, L4 excitatory neurons provide the strongest excitatory influence on the column, including direct E→E input to L5 — supporting a primarily excitatory L4-driven feedforward microcircuit.