A sst GABAergic cortical interneuron with a soma found in L5 and possesses 'T-shaped' Martinotti morphologies with local axonal plexus in L5a and translaminar axons restricted to the uppermost part of L1. They show low-threshold spiking patterns with strong rebound firing, and inhibit the L1 apical tuft of nearby pyramidal cells. [ http://www.ncbi.nlm.nih.gov/pubmed/29326172 http://www.ncbi.nlm.nih.gov/pubmed/28254942 ]