Clustered Intrinsic Connections: Not a Single System.

Organization of horizontal axons in the inferior temporal cortex and primary visual cortex of the macaque monkey. Keywords: axon collaterals; cortical column; diversity; horizontal connections; like-to-like; pyramidal cells; recurrent EN axon collaterals cortical column diversity horizontal connections like-to-like pyramidal cells recurrent 1 6 6 06/07/22 20220603 NES 220603 Introduction In both sensory and non-sensory cortical areas, pyramidal neurons typically have horizontal collaterals spatially extending in a 1.0-3.0 mm radius from the cell body; and in primates and cats, these often have a patchy or discontinuous conformation (aka "daisy", Douglas and Martin, [17]). Axon topography of layer 6 spiny cells to orientation map in the primary visual cortex of the cat (area 18). The architectural significance of this mixed linear-and-clustered geometry is unclear; but, intriguingly in the context of cortical organization, something similar has been observed for some feedback axons (e.g., V4 to V1, figure 12 in Rockland et al., [53]) and for some pulvinocortical axons in V2 (figures 8, 17 in Rockland et al., [50]). [Extracted from the article]