What resolves this contention: Whether IT-derived inputs in L1 / apical-tuft co…

What resolves this contention: Whether IT-derived inputs in L1 / apical-tuft compartments produce direct measurable excitatory drive onto L5 apical dendrites (yes in V1 looped circuit, no in S1 generically), and whether this difference is area-, target- or selectivity-dependent. / Intratelencephalic L5 pyramidal neurons in mouse S1 drive L1 interneurons but produce no direct local excitatory effect on neighboring L5 apical tuft dendrites — implying L5 IT axons in L1 act on inhibition, not on local L5 apical excitation. / In mouse V1, FF and FB cortico-cortical inputs (largely IT) deliver stronger excitatory synaptic input onto apical tufts of looped L5 neurons than onto non-looped L5 neurons, indicating that IT-derived L1/apical-tuft inputs do drive local L5 apical excitation in a projection-selective manner.