Table 1.

Properties and connectivity of layer 5 pyramidal neurons.

Type (Other common nomenclatures)	Pyramidal Tract (PT) (Thick tufted, intrinsic bursting)	Intratelencephalic (IT) (Slender tufted/short, regular spiking)
Morphology
Larsen and Callaway (2006); Schubert et al. (2006); Oberlaender et al. (2011); Narayanan et al. (2015); and Ramaswamy and Markram (2015)	Broad, thick-tufted apical dendritic arbor, often with a prominent bifurcation in L4 or L2/3. Local axonal ramification is sparse and mostly restricted to infragranular layers, but spans multiple columns. Preferentially occupy L5B	Smaller dendritic arbor, with a slender apical tuft or no apical tuft. Local axonal ramification is dense, spans multiple columns and often ascends to supragranular layers. Preferentially occupy L5A
Projection targets
Wise and Jones (1977); Lévesque et al. (1996); Veinante et al. (2000); Hattox and Nelson (2007); and Groh et al. (2010)	Spinal cord, brainstem, superior colliculus, pontine nucleus, ipsilateral striatum, higher-order thalamus	Ipsilateral and contralateral striatum, contralateral S1, M1 and other cortical areas
Intrinsic properties
Larkum et al. (1999a,b, 2009); Schubert et al. (2006); Grewe et al. (2010); and Groh et al. (2010)	Can fire bursts or doublets, Prominent dendritic spiking, Non-adapting after burst	Regular or doublet spiking, Little dendritic excitability Adapting somatic spikes
Local excitatory connectivity
Markram (1997); Schubert et al. (2001); Schubert et al. (2006); Feldmeyer et al. (2005); Song et al. (2005); Krieger et al. (2007); Frick et al. (2008); Lefort et al. (2009); Hooks et al. (2011); Perin et al. (2011); Kiritani et al. (2012); and Kim et al. (2014)	Receive excitatory input from PCs in all cortical layers; strong inputs from L3, L5PT Engage in reciprocally connected subnetworks with other PT cells but rarely connect to L5 IT	Receive excitatory input from PCs in all cortical layers; strong inputs from L2, L4, L5IT, L6 corticothalamic cells Reciprocally connected to other L5 IT; provide excitation to L5 PT
Long-range inputs
Agmon and Connors (1992); Petreanu et al. (2007); Petreanu et al. (2009); Wimmer et al. (2010); Oberlaender et al. (2012); Xu et al. (2012); Constantinople and Bruno (2013); and Rah et al. (2013)	Strong input from ventral posteriomedial nucleus of thalamus (VPM) Weak input from posteromedial nucleus of thalamus (POm) Primary motor cortex and other cortical areas	Weak or no input from VPM Strong input from POM Primary motor cortex and other cortical areas