Abnormal development of zinc-containing cortical circuits in the absence of the transcription factor Tailless.

Absence of the transcription factor tailless (tlx) leads to premature laminar development and thinning of neocortex. We used zinc autometallography to determine if tailless deletion alters the organization of cortical circuits. In tlx-/- mice, layer 4 barrels, which normally lack synaptic zinc, are densely innervated by zinc-containing terminals. Furthermore, barrels with zinc inputs are constructed, in part, from zinc-sequestering neurons, a phenotype not normally found in layer 4.