Abstract
The major output cell type of the neocortex, pyramidal tract neurons in layer 5 (L5 PTs), fire action potentials (APs) in response to a broad range of stimuli. The latency to the first AP is largely independent of the peripheral receptor that is stimulated and rivals those in the major thalamorecipient layer (L4). Mechanisms underlying this fast and unspecific activation of PTs are unknown. We combined reconstructions of synaptic input patterns with simulations and in vivo pharmacology to assess the origin of short-latency APs in PTs.
